Solvents and Methods of Recovering Current Collector

Technical Field

The present invention generally relates to solvents and methods of recovering current collectors from batteries, capacitors, or waste coatings, more particularly, the present invention relates to solvents for dissolving binders/ polymer binders and their use in methods of recovering current collectors.

Background Art

Various strategies have been adopted as part of a global effort towards carbon neutrality to alleviate climate change. Main strategies include transitioning from carbon-emitting to electric vehicles and replacing fossil fuels with renewable energy resources (e.g., solar, wind, hydrothermal, etc.). However, adopting such strategics present other challenges, such as the increase in electric waste generated.

The expanding market for hybrid electric vehicles (HE Vs) and electric vehicles (EVs) presents an ever-increasing demand for lithium-ion batteries (LIBs). With the growing demand for LIBs, the recycling of spent Li-ion batteries has also garnered increasing attention in the last decade. Most of the recycling processes involve the shredding and micro-grinding of spent batteries, with further harsh processing steps, such as the use of high temperatures and strong acids. However, these methods (such as hydrometallurgical methods and pyrometallurgical methods) encounter significant disadvantages. For example, current collectors arc dissolved and mixed with other precious transition metal ions present in the batteries when high temperatures and strong acids are used. This complicates the recovery of precious transition metal ions with high purity as the removal of the dissolved current collectors (e.g. aluminum and copper) is complex and costly. Additionally, hydrometallurgical methods such as using strong acids for leaching are not environmentally friendly, are difficult to handle and may be hazardous to health. Pyrometallurgical methods which involve using high temperatures disadvantageously require high energy input and may produce toxic gases which in turn require further treatment before releasing into the atmosphere.

There is therefore a need to provide solvents and methods of recovering current collectors from batteries, capacitors, or waste coatings that overcomes, or at least ameliorates, one or more of the disadvantages described above. Summary

In one aspect of the present disclosure, there is provided a solvent for dissolving binder, comprising:

(i) cyclopentanone as a first component; and

(ii) carboxylic acid, ascorbic acid, alkyl-substituted urea, or lactone as a second component.

Advantageously, the solvent may be non-corrosive which advantageously allows for the delamination/ dislodgement of electrode material from current collectors without any corrosion to the current collectors.

Further advantageously, the solvent may be cost-effective, non-toxic and environmentally friendly, allowing for a safe, sustainable, and scalable solution for large-scale direct recycling of batteries or capacitors.

The solvent may also advantageously be reused multiple times which leads to greater cost savings.

In another aspect of the present disclosure, there is provided a method of recovering current collector from a battery, a capacitor, or a waste coating comprising electrode material, current collector, and binder/ polymer binder, the method comprising adding a disassembled battery or capacitor, or a waste coating to a solvent disclosed herein.

Advantageously, the method may not require grinding current collectors together with the electrode materials into fine powders, which reduces the risks of releasing harmful pollutants, dust or fumes into the environment. Without the need for grinding, the disclosed method may also make it easier to separate and extract current collectors from spent batteries or capacitors.

Unlike hydrometallurgical or pyrometallurgical methods, the method of the present disclosure may advantageously be performed under ambient conditions which avoids harsh conditions such as highly acidic environments which can result in leaching of metal components. Additionally, the method of the present disclosure avoids the use of high temperatures, such as the high temperatures required to melt batteries or capacitors (smelting) which require high levels of energy input.

Unlike pyrometallurgical methods, the method of the present disclosure may also advantageously not release or emit toxic gases or fumes which can pose both health and environmental risks, thereby removing the need for additional pre-treatment processes before the releasing into the environment.

Also advantageously, the method of the present disclosure may comprise a facile and one-step separation of current collectors from spent batteries or capacitors, or waste coatings, removing the need for further extraction or extensive post-processing (e.g., leaching or re-calcination with metal precursors).

In a further aspect of the present disclosure, there is provided a current collector obtained by the method disclosed herein.

Advantageously, the current collector obtained by the method of the present disclosure may be directly used as electrode materials or reused as current collectors for battery applications.

Further advantageously, being able to directly use recovered current collectors reduces energy consumption and the overall cost of producing new batteries. Recovering and reusing current collectors may also lower the expenses associated with sourcing and processing new raw materials, rendering lower costs and higher affordability for consumers.

Also advantageously, direct recycling and reuse of batteries may prevent environmental contamination from hazardous materials such as heavy metals and toxic chemicals by reducing the risk of these substances entering ecosystems, groundwater, or air when improperly disposed of. In addition, direct recycling and reuse of the recovered current collectors may help create a closed- loop system by reintroducing materials from used batteries back into the production cycle. This promotes a circular economy approach, reducing waste and ensuring a sustainable supply of materials for future battery production.

Definitions

Unless otherwise defined herein, scientific and technical terms used in this application shall have the meanings that are commonly understood by those of ordinary skill in the art. Generally, nomenclature used in connection with, and techniques of, chemistry described herein, are those well-known and commonly used in the art.

As used herein, the term “current collector” refers to a substrate for an electrode material able to conduct electrons. By way of example, current collector may comprise metal, metallic or conductive current collectors. As used herein, the term “electrode material” refers to a material comprising either anode material, cathode material, or a mixture thereof.

As used herein, the term “binder” refers to a component of a battery electrode assembly and functions as a binding agent to immobilize and secure active material particles, conductive additives, and other electrode constituents into a cohesive, mechanically stable, and electrically conductive matrix structure.

As used herein, “slurry” or “slurry coating” refers to a mixture or coating that partially or fully covers the current collector in a battery and acts as electrodes (cathode/ anode) within the battery. The slurry or slurry coating typically comprises a thick suspension of active material, conductive additives, binder and a solvent.

As used herein, “waste coating” or “waste slurry coating”, refers to slurry coated onto a current collector during a coating process and subsequently rejected due to quality control measures, e.g., due to non-uniform coating, under-coating, or over-coating, etc. “Waste coating” may also refer to a current collector comprising the slurry that has been rejected due to reasons above.

Unless the context requires otherwise or specifically stated to the contrary, integers, steps, or elements of the invention recited herein as singular integers, steps or elements clearly encompass both singular and plural forms of the recited integers, steps or elements.

Unless specified otherwise, the terms “comprising” and “comprise”, and grammatical variants thereof, are intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, unrecited elements.

As used herein, the term “about”, in the context of concentrations of components of the formulations, typically means +/- 5% of the stated value, more typically +/- 4% of the stated value, more typically +/- 3% of the stated value, more typically, +/- 2% of the stated value, even more typically +/- 1% of the stated value, and even more typically +/- 0.5% of the stated value.

Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub - ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Certain embodiments may also be described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the disclosure. This includes the generic description of the embodiments with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein.

Brief Description of Drawings

Fig. l

Fig. 1 is a schematic diagram of a method of recycling of batteries, capacitors, and waste coatings in an embodiment of the present invention to obtain current collectors. The recovered current collector can be reused in new batteries and for further applications.

Fig. 2

Fig. 2 is a Raman spectrum of cyclopentanone (CP).

Fig. 3

Fig. 3 is a series of Raman spectra of: (a) 3g of CP in 0.9 g H2O; (b) 3 g CP with 0.3 g L-ascorbic acid in 0.6 g H2O; (c) pure CP; and (d) de-ionized H2O, with a magnified spectra between 400 cm ¹ to 1900 cm ¹ on the right. Peaks in the shaded region indicate peak shifting due to the mixture of cyclopentanone and water.

Fig. 4

Fig. 4 is a scries of Raman spectra of (a) 3 g of CP with 0.3 g 1,2,4,5-bcnzcnctctracarboxylic acid in 0.15 g H2O; and (b) pure CP, with the peaks in the shaded region indicating the presence of 1,2, 4, 5- benzenetetracarboxylic acid.

Fig. 5

Fig. 5 is a photograph showing the pH values of various solvents of the present invention: (I) 3 g of CP in 0.9 g H2O; (II) 0.3 g L-ascorbic acid in 3.6 g H2O; (III) 3 g CP with 0.3g L-ascorbic acid in 0.6 g H2O; and (IV) 3 g of CP with 0.3 g 1,2,4,5-benzenetetracarboxylic acid in 0.15 g H2O. Fig. 6 is a scanning electron microscope (SEM) image of recovered aluminum (Al) current collector in an embodiment of the present invention.

Fig. 7

Fig. 7 is a series of SEM images of the recovered Al current collector of Fig. 6.

Fig. 8

Fig. 8 is an energy dispersive X-ray spectrometer (EDS) spectrum of the elemental composition of the recovered Al current collector of Fig. 6.

Fig. 9

Fig. 9 is an X-ray diffraction (XRD) pattern of the recovered Al current collector of Fig. 6.

Fig. 10

Fig. 10 is a diagram of an electrochemical cell configuration using recovered current collector of the present invention as an anode and Prussian blue analogues (PB As) as cathode.

Fig. 11

Fig. 11 is a graph showing the galvanostatic charge and discharge curves of the electrochemical cell from Fig. 10, cycled between 1 .6V to 0.6V at a current density of 25 m A g ¹ across 100 cycles.

Fig. 12

Fig. 12 is a graph showing the galvanostatic charge and discharge curves of the electrochemical cell from Fig. 10, cycled between 1.6V to 0.6V at a current density of 25 mA g ¹ after (i) 1; (ii) 2; and (iii) 5 cycles.

Fig. 13

Fig. 13 is a scries of graphs comparing the galvanostatic charge and discharge curves of two Lithium Nickel Cobalt Manganese Oxide 622 (NMC622)/lithium half-cells, wherein NMC622 is separately coated with (a) fresh and (b) recovered Al current collectors of the present invention, at a current density of 160 mA g ¹ across 100 cycles.

Fig. 14

Fig. 14 is a Raman spectrum of a sample Al foil (pristine Al) and an Al foil recovered using the method of the present invention (recycled Al). Fig. 15

Fig. 15 is a series of photographs showing Al foil recovered using various conditions in Table 2.

Fig. 16

Fig. 16 is a series of photographs of recovered cunent collector after 2 minutes of using the solvents of

Table 3 (Top: Solvent 1; bottom left: LA-4; bottom right: LA-3).

Fig. 17

Fig. 17 is a photograph of recovered current collector after 5 minutes of using the solvents of Table 3 (left: LA-4; right: LA-3).

Fig. 18

Fig. 18 is a series of photographs of recovered current collector after 20 minutes of using the solvents of Table 3 (Top: Solvent 1; bottom left: LA-4; bottom right: LA-3).

Fig. 19

Fig. 19 is a series of photographs of recovered current collector after 1.5 hours of using the solvents of Table 3 (Top Left/Right: Solvent 1; bottom left: LA-4; bottom right: LA-3).

Fig. 20

Fig. 20 is a series of photographs of recovered cunent collector after 1 hour of using the following solvents (Top: Solvent 7; bottom left: pure CP; bottom nght: pure y-butyrolactonc).

Fig. 21a

Fig. 21a is a photograph of the spent batteries in Example 6 after mechanical treatment.

Fig. 21b

Fig. 21 b is a photograph of coated cun ent collectors separated from the spent batteries of Fig. 21 a.

Fig. 22

Fig. 22 is a series of photographs showing recovered current collectors from spent batteries using Solvent 1 (Top Left: t = 0 minute; Top Right: t = 2 minutes; bottom: 3 hours).

Fig. 23

Fig. 23 is a series of photographs showing the successful removal of slurry coating from current collector. Fig. 24

Fig. 24 is a series of photographs showing the recovery of electrode materials.

Detailed Disclosure of Drawings

Referring to Fig. 1(a) and Fig. 1(b), an overview of the recovery of current collectors from spent batteries using the solvent and method disclosed herein is illustrated. Spent batteries are first shredded and washed to expose internal components such as electrode materials and coated current collectors. The shredded batteries are then further cut into smaller pieces and immersed in the solvent of the present invention to dissolve the binder/ polymer binder, thereby facilitating the delamination/dislodgement of the electrode materials/ slurry coating from the current collectors. The dislodged cunent collectors are then filtered, washed and can be used directly for further applications.

Referring to Fig. 1(c), waste coatings are directly immersed in the solvent of the present invention to dissolve binder/ polymer binder, thereby facilitating the delamination/dislodgement of the electrode materials from the coated current collectors. The recovered current collectors can then be used directly for further applications, such as for battery fabrication and testing.

Detailed Disclosure of Embodiments

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description. It is the intent of the present invention to present a solvent for dissolving binder and a method of recovering current collectors from batteries, capacitors, or waste coatings that overcomes, or at least ameliorates, one or more of the disadvantages described earlier in the background of the disclosure.

Current approaches to recover cunent collectors from batteries, capacitors, or waste coatings involve laborious shredding, crushing and grinding of the spent batteries, with further energy-intensive and harsh processing steps such as the use of high temperatures and strong acids. These approaches have several disadvantages. Firstly, strong acids are not environmentally friendly, may be hazardous to health and are difficult to handle. Secondly, even with the use of strong acids, energy -intensive steps using high temperature is required. Thirdly, toxic gases and other products may be released which in turn require further treatment before releasing into the environment. Furthermore, these methods involve the dissolving and mixing of the current collectors with other precious transition metal ions. This further complicates the recovery of current collectors and precious transition metal ions with high purity and the removal of the dissolved current collectors is complex and costly.

To address the challenges discussed, the present invention relates to an environmentally friendly, easy-to-prepare, simple to use and cost-effective solvent to recover cunent collectors from batteries, capacitors, or waste coatings.

A battery generally comprises electrode material, current collector, and binder/ polymer binder.

The present invention comprises a solvent for dissolving a binder/ polymer binder, comprising:

(i) cyclopentanone as a first component; and

(ii) carboxylic acid, ascorbic acid, alkyl-substituted urea, or lactone as a second component.

The first component and the second component may have a weight ratio in the range of about 1:1 to about 60:1, about 1:1 to about 59:1, about 1:1 to about 58:1, about 1:1 to about 57:1, about 1:1 to about 56:1, about 1:1 to about 55:1, about 1:1 to about 54:1, about 1:1 to about 53:1, about 1:1 to about 52:1, about 1:1 to about 51:1, about 1:1 to about 50:1, about 1:1 to about 49:1, about 1:1 to about 48:1, about 1:1 to about 47:1, about 1:1 to about 46:1, about 1:1 to about 45:1, about 1:1 to about 44:1, about 1:1 to about 43:1, about 1:1 to about 42:1, about 1:1 to about 41:1, about 1:1 to about 40:1, about 1:1 to about 39:1, about 1:1 to about 38:1, about 1:1 to about 37:1, about 1:1 to about 36:1, about 1:1 to about 35:1 , about 1 :1 to about 34:1 , about 1 :1 to about 33:1 , about 1 :1 to about 32:1 , about 1 :1 to about 31:1, about 1:1 to about 30:1, about 1:1 to about 29:1, about 1:1 to about 28:1, about 1:1 to about 27:1, about 1:1 to about 26:1, about 1:1 to about 25:1, about 1:1 to about 24:1, about 1:1 to about 23:1, about 1:1 to about 22:1, about 1:1 to about 21:1, about 1:1 to about 20:1, about 1:1 to about 19:1, about 1:1 to about 18:1, about 1:1 to about 17:1, about 1:1 to about 16:1, about 1:1 to about 15:1, about 1:1 to about 14:1, about 1:1 to about 13:1, about 1:1 to about 12:1, about 1:1 to about 11:1, about 1:1 to about 10:1, about 1:1 to about 9:1, about 1:1 to about 8:1, about 1:1 to about 7:1, about 1:1 to about 6:1, about 1 :1 to about 5 : 1 , about 1 : 1 to about 4.5:1 , about 1 :1 to about 4: 1 , about 1 : 1 to about 3.5:1 , about 1:1 to about 3:1, about 1:1 to about 2.5:1, about 1:1 to about 2:1, about 1:1 to about 1.5:1, about 1:1 to about 1.25:1, about 1.25:1 to about 60:1, about 1.5:1 to about 60:1, about 2:1 to about 60:1, about 2.5:1 to about 60:1, about 3:1 to about 60:1, about 3.5:1 to about 60:1, about 4:1 to about 60:1, about 4.5:1 to about 60:1, about 5:1 to about 60:1, about 6:1 to about 60:1, about 7:1 to about 60:1, about 8:1 to about 60:1, about 9:1 to about 60:1, about 10:1 to about 60:1, about 11:1 to about 60:1, about 12:1 to about 60:1, about 13:1 to about 60:1, about 14:1 to about 60:1, about 15:1 to about 60:1, about 16:1 to about 60:1, about 17:1 to about 60:1, about 18:1 to about 60:1, about 19:1 to about 60:1, about 20:1 to about 60:1, about 21:1 to about 60:1, about 22:1 to about 60:1, about 23:1 to about 60:1, about 24:1 to about 60:1, about 25:1 to about 60:1, about 26:1 to about 60:1, about 27:1 to about 60:1, about 28:1 to about 60:1, about 29:1 to about 60:1, about 30:1 to about 60:1, about 31:1 to about 60:1, about 32:1 to about 60:1, about 33:1 to about 60:1, about 34:1 to about 60:1, about 35:1 to about 60:1, about 36:1 to about 60:1, about 37:1 to about 60:1, about 38:1 to about 60:1, about 39:1 to about 60:1, about 40:1 to about 60:1, about 41:1 to about 60:1, about 42:1 to about 60:1, about 43:1 to about 60:1, about 44:1 to about 60:1 , about 45:1 to about 60:1 , about 46:1 to about 60:1 , about 47:1 to about 60:1 , about 48:1 to about 60:1, about 49:1 to about 60:1, about 50:1 to about 60:1, about 51:1 to about 60:1, about 52:1 to about 60:1, about 53:1 to about 60:1, about 54:1 to about 60:1, about 55:1 to about 60:1, about 56:1 to about 60:1, about 57:1 to about 60:1, about 58:1 to about 60:1, about 59:1 to about 60:1, about 1:1, about 1.1:1, about 1.2:1, about 1.3:1, about 1.4:1, about 1.5:1, about 1.6:1, about 1.7:1, about 1.8:1, about 1.9:1, about 2:1, about 2.25:1, about 2.5:1, about 2.75:1, about 3:1, about 3.5:1, about 4:1, about 4.5:1, about 5:1, about 6:1, about 7:1, about 8:1, about 9:1, about 10:1, about 11:1, about 12:1, about 13:1 , about 14:1 , about 15:1 , about 16:1 , about 17:1 , about 18:1 , about 19:1 , about 20:1 , about 21 :1 , about 22:1, about 23:1, about 24:1, about 25:1, about 26:1, about 27:1, about 28:1, about 29:1, about

30:1, about 31:1, about 32:1, about 33:1, about 34:1, about 35:1, about 36:1, about 37:1, about 38:1, about 39:1, about 40:1, about 41:1, about 42:1, about 43:1, about 44:1, about 45:1, about 46:1, about

47:1, about 48:1, about 49:1, about 50:1, about 51:1, about 52:1, about 5x:l, about 54:1, about 55:1, about 56:1, about 57:1, about 58:1, about 59:1, about 60:1, or any ranges or values therebetween.

In some embodiments, the first component and the second component may have a weight ratio in the range of about 10:1 to about 30:1, about 10:1 to about 29:1, about 10:1 to about 28:1, about 10:1 to about 27:1 , about 10:1 to about 26:1 , about 10:1 to about 25:1 , about 10:1 to about 24:1 , about 10:1 to about 23:1, about 10:1 to about 22:1, about 10:1 to about 21:1, about 10:1 to about 20:1, about 10:1 to about 19:1, about 10:1 to about 18:1, about 10:1 to about 17:1, about 10:1 to about 16:1, about 10:1 to about 15:1, about 10:1 to about 14:1, about 10:1 to about 13:1, about 10:1 to about 12:1, about 10:1 to about 11.75:1, about 10:1 to about 11.5:1, about 10:1 to about 11.25:1, about 10:1 to about 11:1, about 10:1 to about 10.75:1, about 10:1 to about 10.5:1, about 10:1 to about 10.25:1, about 10:1 to about 30:1, about 10.25:1 to about 30:1, about 10.5:1 to about 30:1, about 10.75:1 to about 30:1, about 11:1 to about 30:1 , about 1 1.25:1 to about 30:1 , about 1 1 .75:1 to about 30:1 , about 12:1 to about 30: 1 , about 13:1 to about 30:1, about 14:1 to about 30:1, about 15:1 to about 30:1, about 16:1 to about 30:1, about

17:1 to about 30:1, about 18:1 to about 30:1, about 19:1 to about 30:1, about 20:1 to about 30:1, about

21:1 to about 30:1, about 22:1 to about 30:1, about 23:1 to about 30:1, about 24:1 to about 30:1, about

25:1 to about 30:1, about 26:1 to about 30:1, about 27:1 to about 30:1, about 28:1 to about 30:1, about

29:1 to about 30:1, about 10:1, about 10.25:1, about 10.5:1, about 10.75:1, about 11:1, about 11.25:1, about 11.5:1, about 11.75:1, about 12:1, about 13:1, about 14:1, about 15:1, about 16:1, about 17:1, about 18:1, about 19:1, about 20:1, about 21:1, about 22:1, about 23:1, about 24:1, about 25:1, about 26:1, about 27:1, about 28:1, about 29:1, about 30:1, or any ranges or values therebetween. The second component of the solvent may comprise a carboxylic acid. The carboxylic acid as a second component in the solvent may act as a reductant to enable better cathode reduction and may facilitate the dissolution of the binder/ polymer binder. The carboxylic acid may also act like a leaching agent and enable the dissolution of the transition metal ions. The carboxylic acid may also act as a chelating agent to form stable chelates with heavy metals, and thus improve the removal efficiency of electrode materials from the current collector. Also, the carboxylic acid may form hydrogen bonding to improve the removal efficiency of electrode materials from the current collector.

The carboxylic acid may be a C2-C12 dicarboxylic acid, C3-C12 tricarboxylic acid, or C4-C12 tetracarboxylic acid. The carboxylic acid may be selected from the group consisting of C2 dicarboxylic acid, C? dicarboxylic acid, C4 dicarboxylic acid, C, dicarboxylic acid, Ct, dicarboxylic acid, C7 dicarboxylic acid, Cg dicarboxylic acid, C9 dicarboxylic acid, C10 dicarboxylic acid, Cn dicarboxylic acid, C12 dicarboxylic acid, C3 tricarboxylic acid, C4 tricarboxylic acid, C- tricarboxylic acid, Ce tricarboxylic acid, C7 tricarboxylic acid, Cg tricarboxylic acid, C9 tricarboxylic acid, C10 tricarboxylic acid, Cn tricarboxylic acid, C12 tricarboxylic acid, C4 tetracarboxylic acid, C4 tetracarboxylic acid, Cs tetracarboxylic acid, Ce tetracarboxylic acid, C7 tetracarboxylic acid, Cg tetracarboxylic acid, C9 tetracarboxylic acid, C10 tetracarboxylic acid, Cn tetracarboxylic acid or C12 tetracarboxylic acid.

The dicarboxylic acid may be oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid,l,4-cyclohexanedicarboxylic acid, or sebacic acid. The dicarboxylic acid may also be azelaic acid, undecanedioic acid and/or dodecanedioic acid.

The tricarboxylic acid may be ethane- 1,1,1 -tricarboxylic acid, 1,1,2-hydrazinetricarboxylic acid, prop-l-ene-l,2,3-tricarboxylic acid, 2-oxoethane-l,l,2-tricarboxylic acid, oxirane-2,2,3- tricarboxylic acid, 2-hydroxypropane-l,2,3-tricarboxylic acid (citric acid), prop-l-ene-1,2,3- tricarboxylic acid (aconitic acid), or propane-1, 2, 3 -tricarboxylic acid. The tricarboxylic acid may also comprise ethene- 1,1, 2-tricarboxy lie acid, ethane- 1,1,2-tricarboxylic acid, prop-2-yne-l,l,3- tricarboxylic acid, cycloprop-2-ene-1 ,1 ,2-tricarboxylic acid, cyclopropane- 1 ,1 ,2-tricarboxylic acid, aziridinc-2,2,3-tricarboxylic acid, 1-mcthylcthanc- 1,1,2-tricarboxylic acid, l-hydroxypropanc-1,2,3- tricarboxylic acid (isocitric acid), benzene-l,3,5-tricarboxylic acid (trimesic acid) and/or propane-1, 2,3- tricarboxylic acid.

The tetracarboxylic acid may be selected from the group consisting of 1, 2,4,5- benzenetetracarboxylic acid, and ethylenetetracarboxylic acid. The tetracarboxylic acid may also comprise ethane- 1,1, 2, 2-tetracarboxy lie acid, ethane- 1,1,1,2-tetracarboxylic acid, cyclopropane - 1,1,2,2-tetracarboxylic acid, prop-l-ene-l,l,2,3-tetracarboxylic acid, prop-l-ene-1,1,3,3- tetracarboxylic acid, prop-2-ene-l,l,2,3-tetracarboxylic acid, prop-2-ene-l,l,l,2-tetracarboxylic acid, cyclopropane- 1,1, 2, 3-tetracarboxylic acid, oxirane-2,2,3,3-tetracarboxylic acid, propane-1, 1,3,3- tetracarboxylic acid, propane-1, 1,2, 3-tetracarboxylic acid, propane- 1,1,1, 3-tetracarboxylic acid, propane- 1 , 1 , 1 ,2-tetracarboxylic acid, propane-1, 2, 2, 3-tetracarboxylic acid, propane- 1,1, 2,2- tetracarboxylic acid, l-aminoethane-l,l,2,2-tetracarboxylic acid, 1 -hydroxyethane- 1,1, 2, 2- tetracarboxylic acid, and 2-hydroxyethane-1 ,1 ,1 ,2-tetracarboxylic acid.

The second component of the solvent may comprise an alkyl-substituted urea. The alkylsubstituted urea may be selected from the group consisting of methylurea, dimethylurea, trimethylurea, tetramethylurea, diethylurea, tetraethylurea, and propylurea. The alkyl-substituted urea may also comprise ethylurea, triethylurea, dipropylurea, tripropylurea, and/or tetrapropylurea.

The second component of the solvent may comprise a lactone. The lactone, by itself, may be a green, low-cost and effective solvent for dissolving a binder/ polymer binder. However, typically, a high processing temperature of about 100°C is required for the lactone to dissolve binder/ polymer binder. However, the inventors have advantageously discovered that a combination of cyclopentanone and a lactone avoids the need to use a high processing temperature.

The lactone may be selected from the group consisting of y-butyrolactone, E-caprolactone and D-glucono-5-lactone. The lactone may also be P-propiolactone.

The solvent may further comprise water. With the use of water in the solvent, the solvent may better dissolve the components of the solvent better, where in some cases, water increases the solubility of the first or second components in the solvent. For example, ascorbic acid may not dissolve well in cyclopentanone. However, the use of water may enable ascorbic acid to better dissolve in the solvent.

With the use of water in a limited and controlled quantity and tuned pH, a “water in organic’’ environment may be created. In doing so, the metal ions from the battery and waste coating may not leach out. pH may also be one of the factors influencing the leachability of heavy metals or transition metals.

The second component and the water may have a weight ratio in the range of about 10:1 to about 1:5, about 9:1 to about 1:5, about 8:1 to about 1:5, about 7:1 to about 1:5, about 6:1 to about 1:5, about 5:1 to about 1:5, about 4:1 to about 1:5, about 3:1 to about 1:5, about 2:1 to about 1:5, about

1.75:1 to about 1:5, about 1.5:1 to about 1:5, about 1.25:1 to about 1:5, about 1:1 to about 1:5, about

1:1.25 to about 1:5, about 1:1.5 to about 1:5, about 1:1.75 to about 1:5, about 1:2 to about 1:5, about

1:2.25 to about 1:5, about 1:2.5 to about 1:5, about 1:2.75 to about 1:5, about 1:3 to about 1:5, about 1:3.25 to about 1:5, about 1:3.5 to about 1:5, about 1:3.75 to about 1:5, about 1:4 to about 1:5, about 1:4.25 to about 1:5, about 1:4.5 to about 1:5, about 1 :4.75 to about 1:5, about 10:1 to about 1:4.75, about 10:1 to about 1:4.5, about 10:1 to about 1:4.25, about 10:1 to about 1:4, about 10:1 to about 1:3.75, about 10:1 to about 1:3.5, about 10:1 to about 1:3.25, about 10:1 to about 1:3, about 10:1 to about 1:2.75, about 10:1 to about 1:2.5, about 10:1 to about 1:2.25, about 10:1 to about 1:2, about 10:1 to about 1 : 1 .75, about 10:1 to about 1 :1.5, about 10:1 to about 1 : 1 .25, about 10:1 to about 1 :1 , about 10: 1 to about 1.25:1, about 10:1 to about 1.5:1, about 10:1 to about 1.75:1, about 10:1 to about 2:1, about 10:1 to about 2.25:1, about 10:1 to about 2.5:1, about 10:1 to about 2.75:1, about 10:1 to about 3:1, about 10:1 to about 3.25:1, about 10:1 to about 3.5:1, about 10:1 to about 3.75:1, about 10:1 to about 4:1, about 10:1 to about 5:1, about 10:1 to about 6:1, about 10:1 to about 7:1, about 10:1 to about 8:1, about 10:1 to about 9:1, or any ranges or values therebetween.

The pH of the solution may be in the range of about 3 to about 7, from about 3 to about 6.5, from about 3 to about 6, from about 3 to about 5.5, from about 3 to about 5, from about 3 to about 4.5, from about 3 to about 4, from about 3 to about 3.5, from about 3.5 to about 7, from about 3.5 to about 6.5, from about 3.5 to about 6, from about 3.5 to about 5.5, from about 3.5 to about 5, from about 3.5 to about 4.5, from about 3.5 to about 4, about 4 to about 7, from about 4 to about 6.5, from about 4 to about 6, from about 4 to about 5.5, from about 4 to about 5, from about 4 to about 4.5, from about 4.5 to about 7, from about 4.5 to about 6.5, from about 4.5 to about 6, from about 4.5 to about 5.5, from about 4.5 to about 5, from about 5 to about 7, from about 5 to about 6.5, from about 5 to about 6, from about 5 to about 5.5, from about 5.5 to about 7, from about 5.5 to about 6.5, from about 5.5 to about 6, from about 6 to about 7, from about 6 to about 6.5, from about 6.5 to about 7, or at most about 3, at most about 3.5, at most about 4, or at most about 4.5, or at most about 5, or at most about 5.5, at most about 6, at most about 6.5, at most about 7; or about 4, about 4.5, about 5, about 5.5, about 6, about 6.5, about 7, or any ranges or values therebetween.

The solvent may comprise:

(i) cyclopentanone as a first component; and

(ii) L-succinic acid, 1 ,2,4,5-benzenetetracarboxylic acid, malonic acid, sebacic acid, L-ascorbic acid, tctramcthyl-urca, or y-butyrolactonc as a second component.

The solvent may comprise:

(i) cyclopentanone as a first component; and

(ii) L-succinic acid, 1,2,4,5-benzenetetracarboxylic acid, malonic acid, sebacic acid, L-ascorbic acid, or tetramethyl-urea, as a second component, wherein the first component and L-succinic acid, 1,2,4,5-benzenetetracarboxylic acid, malonic acid, sebacic acid, L-ascorbic acid, or tetramethyl-urea have a weight ratio of about 30:1 to about 10:1, or wherein the first component and have a weight ratio of about 1:1.

With the use of the solvent described above, there is no need for strong acids and harsh conditions such as high temperature. The solvent may be used to dissolve a binder/ polymer binder and result in the recovery of the current collector.

The present invention also comprises a method of recovering current collector from a battery, a capacitor, or a waste coating comprising electrode material, current collector, and binder/ polymer binder, the method comprising adding a disassembled battery or capacitor, or a waste coating to a solvent disclosed in the present invention. The solvent enables the dissolution of the hinder/ polymer binder and allow the physical separation of the current collectors from the battery, capacitor, or the waste coating.

During the dissolution of the binder/ polymer binder, the solvent may also enable the release or detachment of a slurry, a slurry coating or a waste coating. The slurry or slurry coating may be a mixture or coating that partially or fully covers the current collector in a battery. The slurry or slurry coating may generally comprise a thick suspension of active material, conductive additives, binder and a solvent. The slurry or slurry coating may act as the electrodes (cathode/ anode) within the battery. The solvent may dissolve the binder/ polymer hinder, release or detach the slurry, slurry coating or waste coating, and result in the slurry , slurry coating or waste coating detaching or peeling off from the current collector. This results in the removal of the slurry, slurry coating or waste coating to obtain the current collector.

Accordingly, the present invention also comprises a method of recovering electrode material from a battery, capacitor or waste coating. The present invention further comprises a method of recovering binder/ polymer binder from a batteiy, capacitor or waste coating.

A disassembled battery or capacitor may comprise a battery or capacitor which is crushed, shredded, taken apart, smashed, or punctured, manually (by hand) or by a machine.

The method may be simple, easy to perform, a green environmentally friendly process, a low- cost and cost-effective method to recover current collector, electrode material, or binder/ polymer binder from a battery, capacitor, or a waste coating. The solvent used in the method may be reused to recover current collector, electrode material, or binder/ polymer binder from a battery, capacitor or a waste coating. The method is safe and scalable for large-scale applications.

The method may be performed at a temperature in a range of at least about 30 °C, at least about 35 °C, at least about 40 °C, at least about 45 °C, at least about 50 °C, at least about 55 °C, at least about 60 °C, at least about 65 °C, at least about 70 °C, at least about 75 °C, at least about 80 °C, at least about 85 °C, at least about 90 °C, at least about 95 °C, about 40 °C to about 100 °C, about 41 °C to about 100 °C, about 42 °C to about 100 °C, about 43 °C to about 100 °C, about 44 °C to about 100 °C, about 45 °C to about 100 °C, about 46 °C to about 100 °C, about 47 °C to about 100 °C, about 48 °C to about 100 °C, about 49 °C to about 100 °C. about 50 °C to about 100 °C, about 51 °C to about 100 °C, about 52 °C to about 100 °C, about 53 °C to about 100 °C, about 54 °C to about 100 °C, about 55 °C to about 100 °C, about 56 °C to about 100 °C, about 57 °C to about 100 °C, about 58 °C to about 100 °C, about 59 °C to about 100 °C, about 60 °C to about 100 °C, about 61 °C to about 100 °C, about 62 °C to about 100 °C, about 63 °C to about 100 °C, about 64 °C to about 100 °C, about 65 °C to about 100 °C, about 66 °C to about 100 °C, about 67 °C to about 100 °C, about 68 °C to about 100 °C, about 69 °C to about 100 °C, about 70 °C to about 100 °C, about 71 °C to about 100 °C, about 72 °C to about 100 °C, about 73 °C to about 100 °C, about 74 °C to about 100 °C, about 75 °C to about 100 °C, about 76 °C to about 100 °C, about 77 °C to about 100 °C, about 78 °C to about 100 °C, about 79 °C to about 100 °C, about 80 °C to about 100 °C, about 81 °C to about 100 °C, about 82 °C to about 100 °C, about 83 °C to about 100 °C, about 84 °C to about 100 °C, about 85 °C to about 100 °C, about 86 °C to about 100 °C, about 87 °C to about 100 °C, about 88 °C to about 100 °C, about 89 °C to about 100 °C, about 90 °C to about 100 °C, about 91 °C to about 100 °C, about 92 °C to about 100 °C, about 93 °C to about 100 °C, about 94 °C to about 100 °C, about 95 °C to about 100 °C, about 96 °C to about 100 °C, about 97 °C to about 100 °C, about 98 °C to about 100 °C, about 99 °C to about 100 °C, about 40 °C to about 99 °C, about 40 °C to about 98 °C, about 40 °C to about 97 °C, about 40 °C to about 96 °C, about 40 °C to about 95 °C, about 40 °C to about 94 °C, about 40 °C to about 93 °C, about 40 °C to about 92 °C, about 40 °C to about 91 °C, about 40 °C to about 90 °C, about 40 °C to about 89 °C, about 40 °C to about 88 °C, about 40 °C to about 87 °C, about 40 °C to about 86 °C, about 40 °C to about 85 °C, about 40 °C to about 84 °C, about 40 °C to about 83 °C, about 40 °C to about 82 °C, about 40 °C to about 81 °C, about 40 °C to about 80 °C, about 40 °C to about 79 °C, about 40 °C to about 78 °C, about 40 °C to about 77 °C, about 40 °C to about 76 °C, about 40 °C to about 75 °C, about 40 °C to about 74 °C, about 40 °C to about 73 °C, about 40 °C to about 72 °C, about 40 °C to about 71 °C, about 40 °C to about 70 °C, about 40 °C to about 69 °C, about 40 °C to about 68 °C, about 40 °C to about 67 °C, about 40 °C to about 66 °C, about 40 °C to about 65 °C, about 40 °C to about 64 °C, about 40 °C to about 63 °C, about 40 °C to about 62 °C, about 40 °C to about 61 °C, about 40 °C to about 60 °C, about 40 °C to about 59 °C, about 40 °C to about 58 °C, about 40 °C to about 57 °C, about 40 °C to about 56 °C, about 40 °C to about 55 °C, about 40 °C to about 54 °C, about 40 °C to about 53 °C, about 40 °C to about 52 °C, about 40 °C to about 51 °C, about 40 °C to about 50 °C, about 40 °C to about 49 °C, about 40 °C to about 48 °C, about 40 °C to about 47 °C, about 40 °C to about 46 °C, about 40 °C to about 45 °C, about 40 °C to about 44 °C, about 40 °C to about 43 °C, about 40 °C to about 42 °C, about 40 °C to about 41 °C, about 60 °C to about 99 °C, about 60 °C to about 98 °C, about 60 °C to about 97 °C, about 60 °C to about 96 °C, about 60 °C to about 95 °C, about 60 °C to about 94 °C, about 60 °C to about 93 °C, about 60 °C to about 92 °C, about 60 °C to about 91 °C, about 60 °C to about 90 °C, about 60 °C to about 89 °C, about 60 °C to about 88 °C, about 60 °C to about 87 °C, about 60 °C to about 86 °C, about 60 °C to about 85 °C, about 60 °C to about 84 °C, about 60 °C to about 83 °C, about 60 °C to about 82 °C, about 60 °C to about 81 °C, about 60 °C to about 80 °C, about 60 °C to about 79 °C, about 60 °C to about 78 °C, about 60 °C to about 77 °C, about 60 °C to about 76 °C, about 60 °C to about 75 °C, about 60 °C to about 74 °C, about 60 °C to about 73 °C, about 60 °C to about 72 °C, about 60 °C to about 71 °C, about 60 °C to about 70 °C, about 60 °C to about 69 °C, about 60 °C to about 68 °C, about 60 °C to about 67 °C, about 60 °C to about 66 °C, about 60 °C to about 65 °C, about 60 °C to about 64 °C, about 60 °C to about 63 °C, about 60 °C to about 62 °C, about 60 °C to about 61 °C, about 40 °C, about 41 °C, about 42 °C, about 43 °C, about 44 °C, about 45 °C, about 46 °C, about 47 °C, about 48 °C, about 49 °C, about 50 °C, about 51 °C, about 52 °C, about 53 °C, about 54 °C, about 55 °C, about 56 °C, about 57 °C, about 58 °C, about 59 °C, about 60 °C, about 61 °C, about 62 °C, about 63 °C, about 64 °C, about 65 °C, about 66 °C, about 67 °C, about 68 °C, about 69 °C, about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, about 80 °C, about 81 °C, about 82 °C, about 83 °C, about 84 °C, about 85 °C, about 86 °C, about 87 °C, about 88 °C, about 89 °C, about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, about 95 °C, about 96 °C, about 97 °C, about 98 °C, about 99 °C, about 100 °C, or any ranges or values therebetween.

The method may be performed at a temperature in the range of about 60°C to about 80 °C, about 61 °C to about 80 °C, about 62 °C to about 80 °C, about 63 °C to about 80 °C, about 64 °C to about 80 °C, about 65 °C to about 80 °C, about 66 °C to about 80 °C, about 67 °C to about 80 °C, about 68 °C to about 80 °C, about 69 °C to about 80 °C, about 70 °C to about 80 °C, about 71 °C to about 80 °C, about 72 °C to about 80 °C, about 73 °C to about 80 °C, about 74 °C to about 80 °C, about 75 °C to about 80 °C, about 76 °C to about 80 °C, about 77 °C to about 80 °C, about 78 °C to about 80 °C, about 79 °C to about 80 °C, about 60 °C to about 79 °C, about 60 °C to about 78 °C, about 60 °C to about 77 °C, about 60 °C to about 76 °C, about 60 °C to about 75 °C, about 60 °C to about 74 °C, about 60 °C to about 73 °C, about 60 °C to about 72 °C, about 60 °C to about 71 °C, about 60 °C to about 70 °C, about 60 °C to about 69 °C, about 60 °C to about 68 °C, about 60 °C to about 67 °C, about 60 °C to about 66 °C, about 60 °C to about 65 °C, about 60 °C to about 64 °C, about 60 °C to about 63 °C, about 60 °C to about 62 °C, about 60 °C to about 61 °C, about 60 °C, about 61 °C, about 62 °C, about 63 °C, about 64 °C, about 65 °C, about 66 °C, about 67 °C, about 68 °C, about 69 °C, about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, about 80 °C, or any ranges or values therebetween.

The method may be performed at a pH in the range of about 4 to about 7, from about 4 to about

6.5, from about 4 to about 6, from about 4 to about 5.5, from about 4 to about 5, from about 4 to about

4.5, from about 4.5 to about 7, from about 4.5 to about 6.5, from about 4.5 to about 6, from about 4.5 to about 5.5, from about 4.5 to about 5, from about 5 to about 7, from about 5 to about 6.5, from about 5 to about 6, from about 5 to about 5.5, from about 5.5 to about 7, from about 5.5 to about 6.5, from about 5.5 to about 6, from about 6 to about 7, from about 6 to about 6.5, from about 6.5 to about 7, or at most about 4, or at most about 4.5, or at most about 5, or at most about 5.5, at most about 6, at most about 6.5, at most about 7; or about 4, about 4.5, about 5, about 5.5, about 6, about 6.5, about 7, or any ranges or values therebetween.

The method may be performed for a duration in the range of about 5 minutes to about 4 hours (about 240 minutes), about 5 minutes to about 240 minutes, about 5 minutes to about 235 minutes, about 5 minutes to about 230 minutes, about 5 minutes to about 225 minutes, about 5 minutes to about 220 minutes, about 5 minutes to about 215 minutes, about 5 minutes to about 210 minutes, about 5 minutes to about 205 minutes, about 5 minutes to about 200 minutes, about 5 minutes to about 195 minutes, about 5 minutes to about 190 minutes, about 5 minutes to about 185 minutes, about 5 minutes to about 180 minutes, about 5 minutes to about 175 minutes, about 5 minutes to about 170 minutes, about 5 minutes to about 165 minutes, about 5 minutes to about 160 minutes, about 5 minutes to about 155 minutes, about 5 minutes to about 150 minutes, about 5 minutes to about 145 minutes, about 5 minutes to about 140 minutes, about 5 minutes to about 135 minutes, about 5 minutes to about 130 minutes, about 5 minutes to about 125 minutes, about 5 minutes to about 120 minutes, about 5 minutes to about 115 minutes, about 5 minutes to about 110 minutes, about 5 minutes to about 105 minutes, about 5 minutes to about 100 minutes, about 5 minutes to about 95 minutes, about 5 minutes to about 90 minutes, about 5 minutes to about 85 minutes, about 5 minutes to about 80 minutes, about 5 minutes to about 75 minutes, about 5 minutes to about 70 minutes, about 5 minutes to about 65 minutes, about 5 minutes to about 60 minutes, about 5 minutes to about 55 minutes, about 5 minutes to about 50 minutes, about 5 minutes to about 45 minutes, about 5 minutes to about 40 minutes, about 5 minutes to about 35 minutes, about 5 minutes to about 30 minutes, about 5 minutes to about 25 minutes, about 5 minutes to about 20 minutes, about 5 minutes to about 15 minutes, about 5 minutes to about 10 minutes, about 5 minutes to about 240 minutes, about 10 minutes to about 240 minutes, about 15 minutes to about 240 minutes, about 20 minutes to about 240 minutes, about 25 minutes to about 240 minutes, about 30 minutes to about 240 minutes, about 35 minutes to about 240 minutes, about 40 minutes to about 240 minutes, about 45 minutes to about 240 minutes, about 50 minutes to about 240 minutes, about 55 minutes to about 240 minutes, about 60 minutes to about 240 minutes, about 65 minutes to about 240 minutes, about 70 minutes to about 240 minutes, about 75 minutes to about 240 minutes, about 80 minutes to about 240 minutes, about 85 minutes to about 240 minutes, about 90 minutes to about 240 minutes, about 95 minutes to about 240 minutes, about 100 minutes to about 240 minutes, about 105 minutes to about 240 minutes, about 110 minutes to about 240 minutes, about 115 minutes to about 240 minutes, about 120 minutes to about 240 minutes, about 125 minutes to about 240 minutes, about 130 minutes to about 240 minutes, about 135 minutes to about 240 minutes, about 140 minutes to about 240 minutes, about 145 minutes to about 240 minutes, about 150 minutes to about 240 minutes, about 155 minutes to about 240 minutes, about 160 minutes to about 240 minutes, about 165 minutes to about 240 minutes, about 170 minutes to about 240 minutes, about 175 minutes to about 240 minutes, about 180 minutes to about 240 minutes, about 185 minutes to about 240 minutes, about 190 minutes to about 240 minutes, about 195 minutes to about 240 minutes, about 200 minutes to about 240 minutes, about 205 minutes to about 240 minutes, about 210 minutes to about 240 minutes, about 215 minutes to about 240 minutes, about 220 minutes to about 240 minutes, about 225 minutes to about 240 minutes, about 230 minutes to about 240 minutes, about 235 minutes to about 240 minutes, about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes (about 0.5 hours), about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, about 60 minutes (about 1 hour), about 65 minutes, about 70 minutes, about 75 minutes, about 80 minutes, about 85 minutes, about 90 minutes (about 1.5 hours), about 95 minutes, about 100 minutes, about 105 minutes, about 110 minutes, about 115 minutes, about 120 minutes (about 2 hours), about 125 minutes, about 130 minutes, about 135 minutes, about 140 minutes, about 145 minutes, about 150 minutes (about 2.5 hours), about 155 minutes, about 160 minutes, about 165 minutes, about 170 minutes, about 175 minutes, about 180 minutes (about 3 hours), about 185 minutes, about 190 minutes, about 195 minutes, about 200 minutes, about 205 minutes, about 210 minutes (about 3.5 hours), about 215 minutes, about 220 minutes, about 225 minutes, about 230 minutes, about 235 minutes, about 240 minutes (about 4 hours), or any ranges or values therebetween.

The present invention also relates to a current collector obtained by the method disclosed herein. The current collector may comprise aluminum titanium, stainless steel foil and/or copper.

The present invention also relates to electrode material obtained by the method disclosed herein. The present invention further relates to binder/ polymer binder obtained by the method disclosed herein.

Examples

Non-limiting examples of the invention and comparative examples will be further described in greater detail by reference to specific examples, which should not be construed as in any way limiting the scope of the invention. Example 1: Procedure for Preparing Solvents

The solvents used in this invention comprise cyclopentanone as a first component and a carboxylic acid, ascorbic acid, alkyl-substituted urea, or lactone as a second component.

Each solvent was formed by mixing the components together to form a homogenous solution. Their compositions are shown in Table 1 below.

Table 1: Solvents used in the present invention

¹ 1 ,2,4,5-Benzenetetracarboxylic acid

Example 2: Characterization of Solvents

Example 2a: Raman Spectroscopy of Cyclopentanone with L-Ascorbic Acid/HiO (Solvent 1)

The Raman spectrum of Solvent 1 in Example 1 was obtained (Fig. 3(b)) and compared to the representative Raman spectra of pure cyclopentanone (CP, Figs. 2 and 3(c)), pure H2O (Fig. 3(d)) and LA/H2O (w/w ratio 0.3g/3.6g, Fig. 3(a)). The peaks of Solvent 1 correspond to the individual components, with the circled region at ~3450 cm ¹ illustrating the water vibration band (-OH) corresponding to the presence of water. The circled region, in the magnified image, at -1060 cm ¹ corresponds to the vibration band of L-ascorbic acid. Example 2b: Raman Spectroscopy of Cyclopentanone with 1,2,4,5-Benzenetetracarboxylic Acid /H2O (Solvent 3)

The Raman spectrum of Solvent 3 in Example 1 was obtained (Fig. 4(a)) and compared to the Raman spectrum of pure cyclopentanone (CP) (Figs. 2 and 4(b)). The peaks of Solvent 3 correspond to the peaks of pure CP, with the presence of the additional peaks in the greyed band region at around 1500 to 1650 cm ⁴ , which correspond to the peaks of the 1,2,4,5-bcnzcnctctracarboxylic acid.

Example 2c: pH of the Solvents

Using CP/H2O (w/w ratio = 3g/0.9g, I) and L-ascorbic acid/HjO (w/w ratio = 0.3g/3.6g, II) as control solvents, the solvents in Examples 1 (111) and 1c (IV) were measured using pH-indicator strips and were found to be about pH 4 (Fig. 5). CP/H2O (w/w ratio of 3g to 0.9g) was found to have a pH value of ~4. L-ascorbic acid/H O (w/w ratio of 0.3g to 3.6g) was found to have a pH value of ~2.

Example 3: Method of Recovering Current Collectors

Example 3a: Pre-treatment of Spent Batteries

Spent batteries were firstly fully discharged and held at 0.5 V for at least 24 hours. The spent batteries were then disassembled and shredded using insulated cutters to expose the cathodes and anodes. The exposed cathodes were subsequently washed using diethyl carbonate or dimethyl carbonate and further cut into pieces with sizes ranging from about 1 cm by 1 cm to 8 cm by 12 cm (Fig. 1(a) and 1(b)).

Meanwhile, the waste coating from battery fabrication process was used directly in the subsequent Examples (Fig. 1(c)).

Example 3b: Recovering Current Collectors

The solvents in Example 1 were next employed to remove the electrode materials from the current collectors in the cathodes. The solvents in Example 1 were added into a container containing the cut cathode pieces in a weight/volume ratio of 1:20 g/mL, and then stirred continuously at 500-1000 rotations per minute (rpm) at temperatures of about 60°C-100°C for a time duration of about 0.5 hour to 1 hour. Polymer binder polyvinylidene fluoride (PVDF) was dissolved by the solvent, and the aluminum (Al) foil current collector was dislodged from the electrode materials without any corrosion. The dislodged current collector was then filtered and washed with ethanol before drying in an oven to obtain the fully recovered (100%) Al foil. The solvent used can be collected and reused for subsequent treatment of new batches of cut cathodes.

Example 4: Dissolution Performance of Different Solvents

Various solvents were tested according to the general method as described in Example 3b. Results and the discussion for each solvent tested follow in Table 2 and the subsequent sub-examples.

Table 2. Performance of different solvents Example 4a: Cyclopentanone with L-Ascorbic Acid/EhO (Solvent 1 )

Solvent 1 was able to dissolve the polymer binder and recover the Al foil current collector in about 2 minutes to 3 hours at a processing temperature of 60°C, depending on the condition of the spent battery or the amount of slurry coating present on top of the Al foil (Table 2, Entry 1). L- Ascorbic acid acts as a reductant to enable better cathode reduction. The unique combination of components allows for the good solubility of the L-Ascorbic acid in cyclopcntanonc.

To further show the effectiveness of the combination of CP and L-ascorbic acid over their separate components, further studies were performed with CP/HzO (w/w: 3g/0.9g) and L-ascorbic acid/PLO (0.3g/3.6g) solvents.

Table 3: Studies on effect of L-ascorbic acid

Photos showing the recovery process arc shown in Fig. 16 (after 2 minutes), Fig. 17 (after 5 minutes). Fig. 18 (after 20 minutes) and Fig. 19 (after 1.5 hours).

As shown in Fig. 16, after 2 minutes, the coatings in sample LA were successfully peeled off from the current collectors, However, for samples LA-3 and LA-4, there are no obvious changes.

As shown in Fig, 17, after 5 minutes, for sample LA-4 (left), the surface of the coating starts to swell and there is still no obvious change for sample LA-3 (right).

As shown in Fig. 18, the active materials in the coating of sample LA have been separated with conductive carbon, and the Al foil was still maintained after 20 minutes. At the same time, the coating on the current collector of sample LA-3 only shows pitted points. Only a partial of the coating in sample LA-4 has delaminated from the surface of the current collector.

As shown in Fig. 19, it can be clearly observed the separation of carbon and active material in sample LA. Even after 1 .5 hours, the surface of Al foil is clean and cannot observe any etch area. At the same time, the majority of the coating on the current collector of sample LA-3 still exists. And partial of the coating in sample LA-4 has peeled off from the surface of the current collector. Example 4b: Cyclopentanone with Succinic Acid/JIiO (Solvent!)

Solvent 2 was able to dissolve the polymer binder and recover the Al foil current collector in about 2 hours at a processing temperature of 60°C (Table 2, Entry 2). Succinic acid acts as a leaching agent and enables the dissolution of transition metal ions.

Example 4c: Cyclopentanone with 1,2,4,5-Benzenetetracarboxylic Acid (Solvent 3)

Solvent 3 was able to dissolve the polymer binder and recover the Al foil current collector in about 10 minutes to 2 hours, depending on the condition of the spent battery or the amount of coating present on top of the Al foil, at a processing temperature of 60°C (Table 2, Entry 3). Pyromellitic acid (1, 2,4,5- benzenetetracarboxylic acid) has the ability to form hydrogen bonds, thus improving the efficiency of electrode removal from the current collector.

Example 4d: Cyclopentanone with Malonic Acid (Solvent 4)

Solvent 4 was able to dissolve the polymer binder and recover the Al foil current collector in about 3 hours at a processing temperature of 80 °C (Table 2, Entry 4). As a dicarboxylic acid, malonic acid acts as a chelating agent which can form stable chelates with heavy metals, improving the efficiency of electrode removal from the current collector.

Example 4e: Cyclopentanone with Sebacic Acid (Solvent 5)

Solvent 5 was able to dissolve the polymer binder and recover the Al foil current collector in about 4 hours at a processing temperature of 80 °C (Table 2, Entry 5). Similar to malonic acid, sebacic acid is a dicarboxylic acid which acts as a chelating agent which can form stable chelates with heavy metals, improving the efficiency of electrode removal from the current collector.

Example 4f: Cyclopentanone with Tetramethyl Urea (TMU) (Solvent 6)

Solvent 6 was able to dissolve the polymer binder and recover the Al foil current collector in about 1.5 hours at a processing temperature of 60 °C (Table 2, Entry 6). TMU has a good surfactant property which enables significant improvement in the efficiency of electrode removal from the current collector. Example 4g: Cyclopentanone with y-Butyrolactone (Solvent 7)

Solvent 7 was able to dissolve the polymer binder and recover the Al foil current collector in about 1 hour at a processing temperature of 60°C (Table 2, Entry 7).

To further demonstrate the effectiveness of y-butyrolactone as an additive, Solvent 7 was tested against pure CP and pure GBL (Fig. 20).

As shown in Fig. 20, the presence of y-butyrolactone in CP provided an improvement in efficiency of electrode removal from the current collector than either pure CP or pure y-butyrolactone.

Example 5: Recovered Current Collector

Example 5a: Characterization

The elemental composition and crystal structure of the recovered aluminum current collector was characterized using a scanning electron microscope (SEM) coupled with an electron dispersive X-ray spectrometer (EDS) (JEOL FESEM 7600F) and X-ray diffractometer (Bruker D8 Advance, XRD), respectively. Match! Software was applied to analyze the X-ray diffraction pattern based on the inorganic crystal structure database (ICSD). As a result, the recovered aluminum current collector is composed of aluminum element without any trace of other transition metal ions from battery materials on its surface (e.g., nickel, manganese or cobalt content from cathode) (Figs. 6-8), which is in good agreement with the XRD result (Fig. 9).

The Raman spectrum of the recycled aluminum was also compared with fresh (pristine) aluminum (Fig. 14). It shows that the recycled aluminum has no residual active materials on the surface, demonstrating the successful recovery of Al.

Example 5b: Application of Recovered Current Collector

A coin cell configuration was assembled using Prussian blue analogues (PBAs) as the cathode and the recovered aluminum current collector as the anode to test the feasibility of the recycled aluminum as the energy source for rechargeable energy storage applications (Fig. 10). Whatman glass fiber was used as the separator, and 2 m (mol kg ’) aluminum trifluoromethanesulfonate (A1TFS) in deionized water was employed as the electrolyte. At a current density of 25 mA g ¹ , the assembled cell, cycled between 1.6 V to 0.6 V, exhibited excellent electrochemical cycle stability performance (Fig. 11) with an energy density of 52.4 Wh kg ', higher than the state-of-art lead-acid battery (-40 Wh kg '). The reversible redox processes of the prototype cell are illustrated in Fig. 12.

The scalability of the direct recycling process was also demonstrated in the application to waste coating. As a proof of concept, the recycled aluminum was used as the current collector for lithium-ion batteries (LTBs). Using the typical battery slurry coating process, the cathode slurry was prepared with 80 wt% NMC622, 10 wt% Super C65 conductive carbon and 10 wt% HSV1810 binder, before stirring in 1- methyl-2-pyrrolidone (NMP) for at least 5 hours. The slurry was then coated onto the recovered aluminum current collector and dried in a convection oven at 80 °C for at least 1 hour. Electrode coatings were then dried and degassed overnight in a vacuum oven. Circular electrodes with a diameter of 12 mm were punched out and assembled into coin cells. Celgard 2400 was used as a separator with lithium foil as the counter electrode, and 1 M Li PE, in ethylene carbonate (EC): ethyl methyl carbonate (EMC) (3:7 v/v) was used as the electrolyte. The cells were electrochemically tested at a 1 C charging rate (1C = 160 mA g ') on a NEW ARE battery tester. In comparison to the cell with the fresh aluminum foil as the current collector (Fig. 13), the cell with the recycled aluminum foil exhibited comparable electrochemical performance with high coulombic efficiency due to the good contact between new electrode materials and recycled Al foil.

The above results show that the aluminum foil was unchanged during the recycling process of the present invention, and further shows that the recovered Al foils may be further used in new battery applications with no impact to their performance. This illustrates the practicality of the method of the present invention for recovering cunent collectors for energy storage applications.

Example 6: Recovering Current Collector from Batteries

To further illustrate the commercial viability of the present invention, the method was tested on spent batteries.

To do so, spent batteries were sourced from the electronic waste collected in Nanyang Technological University in Singapore.

The spent batteries were then shredded by a battery shredder Photos of the spent batteries after treatment are shown in Fig. 21. Example 6a: Recovering Current Collectors

The spent batteries were immersed in Solvent 3 of Table 1 (cyclopentanone :L-ascorbic acid:water = 3g:0.3g:0.6g) and subjected to the recovery conditions in Example 3b.

Photos showing the recovery process is shown in Fig 22. From the photos, it was noted that as the reaction progressed, the coatings were gradually peeled off from the current collectors.

After stirring, the spent batteries were filtered out from the solvent. Fig. 23 (a) shows the existence of Al foil. After washing, the surface of recovered Al is clean, demonstrating successful removal of the coating, as shown in Fig. 23 (b).

Example 6b: Recovering Electrode Materials, Binders, Active Materials, and Carbon

Fig. 24 shows the remaining solution after separating the current collectors. It can be observed that there is a black residue on the top surface of the solution and grey sediments at the bottom. These indicate the successful recovery of carbon black and active materials, respectively.

Industrial Applicability

The present invention relates to solvents for dissolving binders and a method of recovering current collectors from batteries, capacitors, or waste coatings. The present disclosure also relates to current collectors obtained by the method, and batteries comprising the recovered cunent collectors. The solvent disclosed herein is environmentally friendly and non-hazardous, which obviates the need for conventional strong acids used in leaching or high energy input for pyrometallurgical means, and may not require extensive post-treatment steps to recover current collectors. Furthermore, the disclosed method of recovering current collectors from a battery or a capacitor may be cost-effective, simple, environmentally friendly, and scalable in the manufacturing process for mass production.

It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.