ELECTRORHEOLOGICAL CLAY LIQUID CRYSTAL-BASED SUPERCAPACITORS FOR ENERGY STORAGE APPLICATIONS

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is based upon and claims priority to India provisional patent application number 202241036476 filed on June 24, 2022, titled “Electrorheological clay liquid crystal-based supercapacitors for energy storage applications”, the entire contents of which is herein incorporated by reference.

FIELD

The present disclosure relates to supercapacitors, more particularly relates to liquid crystal-based supercapacitors.

BACKGROUND

Supercapacitors are the next-generation energy storage device. Their main aim is to reconcile the seemingly incompatible conventional capacitor, which has high power density, and rechargeable batteries, which have high energy density, thus bridging the gap as disclosed in .S'. Westerlind, and L. Ekstam, Capacitor theory. IEEE Trans. Dielectr. Electr. Instil. 1, 826 (1994).

In the present world situation, renewable energy storage devices are of great demand, in terms of energy security of the nations, transportation, telecommunication and the inevitable climate change. In this context, supercapacitors have a significant role as they can store a large amount of charge between two electrode plates with minimum distance, thus paving a path to miniature and portable energy storage devices. Based on the storage principle, they are of two main types: electric double layer capacitors (EDLC) and pseudocapacitors. In EDLC, charges are stored due to the electrostatic forces (physical forces) observed between the electrodes and the electrolyte due to the generation of a Helmholtz electrical double layer. Here, no new chemical bonds are formed. These supercapacitors usually incorporate carbon-based electrode materials as the active electrode material as disclosed in:

R. Kotz, and M. Carlen, Principles and applications of electrochemical capacitors. Electrochim. Acta 45, 2483 (2000), and

A. Burke, Ultracapacitors: why, how, and where is the technology. J. Power Sources 91, 37 (2000).

In pseudo-capacitors, the charges are stored as a result of the actual transfer of electrons or charges between electrode and electrolyte (redox reactions). They are usually made from transition metallic oxides or conducting polymer. Thus, the combination of EDLC and pseudo-capacitor forms a hybrid capacitor as disclosed in B.E. Conway, V. Birss, and J. Wojtowicz, The role and utilization of pseudocapacitance for energy storage by supercapacitors. J. Power Sources 66, 1 (1997), which as disclosed in various literature, can be of three different types: (1) composites, where electrodes have carbon derivatives along with conducting polymer or metal oxides; (2) asymmetric, where one electrode is an EDLC electrode, and the other electrode is a faradic electrode; (3) battery-like, where a supercapacitor electrode is coupled with a battery-type electrode. All these classifications are compiled together as the Taxonomy of Supercapacitors. Metal oxides along with other inorganic compounds can exhibit pseudo-capacitance along with electrically operated hydrogen production. Carbon-based symmetric micro-supercapacitors have been reported with greater specific capacitance, cyclic stability, specific energy using conventional organic binders and separators. Highly efficient self-healing poly-electrodes with high flexibility, mechanical endurance and electrochemical character using SWCNTs are also available as disclosed in B. Zhang, J. Li, F. Liu, T. Wang, Y. Wang, R. Xuan, G. Zhang, R. Sun, and C.P. Wong, Self-healable polyelectrolytes with mechanical enhancement for flexible and durable supercapacitors. Chem. Eur. J. 25, 11715 (2019). Some studies employing the biological chitosan and CNT nanocomposite as electrode material were also investigated, which led to the enhancement of supercapacitors as disclosed inf?. Teimuri-Mofrad, R. Hadi, H. Abbasi, andR. Fadakar Bajeh Baj, Synthesis, characterization and electrochemical study of carbon nanotube/chitosan-ferrocene nanocomposite electrode as supercapacitor material. J. Electron. Mater. 48, 4573 (2019).

Liquid crystals are a state of matter that have properties linking traditional isotropic liquids and crystalline solids. They have liquid-like fluidity and solidlike orientation. Thus, based on physicochemical parameters, there are two main types: thermotropic, where the thermal process is responsible for transformation into the mesophase, and lyotropic, where the main constituent is the amphiphilic molecules which have a polar head and non-polar tail. These lyotropic liquid crystals (LLC) are capable of forming self-assembled systems, micelles, at a particular concentration in a suitable solvent. This is considered as their critical micelle concentration (CMC). Thus, if the concentration of the amphiphilic molecules is equal to CMC, micelle formation enhances.

Also, there is direct and indirect polymorphism in LLC. In a polar solvent, the non-polar chains are squeezed into the inner region, and the polar head forms the outer region, forming direct polymorphism. In a non-polar solvent, the polar head is confined in a closed region and the nonpolar tail is exposed to the external solvent medium, leading to inverted polymorphism as disclosed in A.M.F. Neto, and S.R.A. Salinas, The Physics of Lyotropic Liquid Crystals Phase Transitions and Structural Properties (Oxford University Press, New York, 2005).

Bentonite clay is an aluminum phyllosilicate absorbent swelling clay. These bentonite clays are framed of two structural sheets in a T-O-T fashion, i.e., they have two tetrahedral silica sheets, which sandwiches a central octahedral aluminium sheet. They form the negative crystal charge, which is stabilized by the exchangeable cations such as Na ⁺ , Ca ²⁺ , K ⁺ . It is these cations that interact with the water molecules through ion-dipole secondary interaction bonds as disclosed in S.L. Abdullahi, and A.A. Audu, Comparative analysis on chemical composition of bentonite clays obtained from Ashaka and Tango Deposits in Gombe State, Nigeria. ChemSearch J. 8, 35 (2017). The following literature discloses that clay showed liquid crystalline properties.

J.C.P. Gabriel, C. Sanchez, and P. Davidson, Observation of Nematic Liquid- Crystal Textures in Aqueous Gels of Smectite Clays. J. Phys. Chem. 100, 11139 (1996).

E. Paineau, K. Antonova, C. Baravian, I. Bihannic, P. Davidson, I. Dozov, M. Imperor-Clerc, P. Levitz, A. Madsen, F. Meneau, and L.J. Michot, Liquidcrystalline nematic phase in aqueous suspensions of a disk-shaped natural beidellite clay. J. Phys. Chem. B 113, 15858 (2009).

S. Maiti, A. Pramanik, S. Chattopadhyay, G. De, and S. Mahanty, Electrochemical energy storage in montmorillonite K10 clay based composite as supercapacitor using ionic liquid electrolyte. J. Colloid Interface Sci. 464, 73 (2015).

Gabriel said that bentonite liquid crystals showed nematic lyotropic liquid crystalline properties when observed under POM.

The article, M.M. del Ramos-Tejada, J.M. Rodriguez, and A.V. Delgado, Electrorheology of clay particle suspensions. Effects of shape and surface treatment. Rheol. Acta 57, 405 (2018) investigated the electrorheological response of different clay particle suspensions and claimed that they have sufficient electrorheological response. Electrorheological fluid is a suspension with an apparent viscosity that changes to a great extent in response to the electric field. Research as disclosed in J.E. Stangroom, Electrorheological fluids. Phys. Technol. 14, 290 (1983), shows that by regulating the applied electric field, the viscosity of the fluid can be controlled.

In most of cases in the existing literature where additive electrolyte has been added to enhance the supercapacitor performance, i.e., either by increasing the specific capacitance or decreasing the self-discharge, there was not much change in the electrochemical behaviour of the supercapacitors. Additive electrolytes have only a positive impact on reducing self-discharge. Supercapacitors in the charged state are in a high-energy state. Any matter that does not stay in its particular charged state for a long time will tend toward the lower stable energy state. There is a quasi-driving force for material to return to the lower energy state. As it follows, the charged supercapacitors gravitate towards the steady low- energy discharged state. This phenomenon is called ‘self- discharge’, which is one of the main limitations of supercapacitors as disclosed in B.E. Conway, W.G. Pell, and T.C. Liu, Diagnostic analyses for mechanisms of self-discharge of electrochemical capacitors and batteries. J. Power Sources 65, 53 (1997).

Hence, different aspects were explored by researchers to enhance the supercapacitor performance. Fic, in 2010 carried out a comparative work on the effect of three different types of surfactants on the self-discharging phenomena in supercapacitors. The non-ionic surfactant TRITON in acidic medium showed only 25% of self-discharge when compared with the pure acidic medium which showed 63% after 20 h at open circuit voltage as disclosed in K. Fic, G. Lota, and E. Frackowiak, Electrochemical properties of supercapacitors operating in aqueous electrolyte with surfactants. Electrochim. Acta 55, 7484 (2010).

As disclosed in the literature, B. Wang, J. A. Macia-Agullo, D.G. Prendiville, X. Zheng, D. Liu, Y. Zhang, S. W. Boettcher, X. Ji, and G.D. Stucky, A hybrid redoxsupercapacitor system with anionic catholyte and cationic anolyte. J. Electrochem. Soc. 161, A1090 (2014), a solvated species of electrolyte is utilised to increase voltage retention in supercapacitors by 62%.

As disclosed in the literature, M. Xia, J. Nie, Z. Zhang, X. Lu, and Z.L. Wang, Suppressing self-discharge of supercapacitors via electrorheological effect of liquid crystals. Nano Energy 47, 43 (2018).Xia in 2018, the researchers employed nematic liquid crystal (LC) — [4-r|-pentyl-4'-cyanobiphenyl] (5CB) as an additive electrolyte to arrest the self-discharge of EDLCs to a great extent. Also, for EDLCs, lyotropic liquid crystal (LLC) formed by the assembly of copolymer and an ion liquid is used as an additive electrolyte, which was studied in the literature M. Liu, M. Xia, R. Qi, Q. Ma, M. Zhao, Z. Zhang, and X. Lu, Lyotropic liquid crystal as an electrolyte additive for suppressing self-discharge of supercapacitors. ChemElectroChem 6, 2531 (2019).

As disclosed in the literature, M. Haque, Q. Li, A.D. Smith, V. Kuzmenko, P. Rudquist, P. Lundgren, and P. Enoksson, Self-discharge and leakage current mitigation of neutral aqueous-based supercapacitor by means of liquid crystal additive. J. Power Sources 453, 227897 (2020), the researchers employed 5CB LLC in Li2SC>4 electrolyte which showed 96% voltage retention.

The inventors of the present disclosure aim at achieving an improved supercapacitor, by exploring the addition of the naturally abundant and cost- effective bentonite clay that possesses lyotropic liquid crystal properties with electrorheological response, as an additive electrolyte in supercapacitors containing poly aniline (PANI) composite electrodes.

SUMMARY

The present disclosure provides a supercapacitor, wherein the positive electrode (cathode) comprises Emeraldine Acid of polyaniline (PANI), and the negative electrode (anode) comprises Emeraldine Acid of poly aniline (PANI), and bentonite clay liquid crystal (BCLC) soaked in a monovalent or divalent cationbased sulphate salt such as Na2SC>4 or MgSCL as electrolyte.

Cathode: PANI is coated on a cathode current collector, preferably Stainless steel (SS) current collector.

Anode: PANI is coated on an anode current collector, preferably Aluminium (Al) current collector.

Electrolyte: Bentonite clay liquid crystals (BCLC) soaked in monovalent or divalent cation-based sulphate salt such as Na2SC>4 or MgSCL as electrolyte. When the bentonite clay liquid crystal electrolyte is soaked in 0.05M Na2SC>4, at a discharge current density of ImA/cm ² , difference in voltage of 0.45 V, and active mass of Img, the specific capacity of the supercapacitor obtained is 111.11 F/g for a discharge time of 25s.

When the bentonite clay liquid crystal electrolyte is soaked in 0.5M Na2SC>4, at a discharge current density of ImA/cm ² , difference in voltage of 0.45 V, and active mass of Img, the specific capacity of the supercapacitor obtained is 444. 44 F/g for a discharge time of 100s.

When the bentonite clay liquid crystal electrolyte is soaked in 0.05M MgSC>4, at a discharge current density of ImA/cm ² , difference in voltage of 0.375 V, and active mass of Img, the specific capacity of the supercapacitor obtained is 142.86 F/g for a discharge time of 250s.

When the bentonite clay liquid crystal electrolyte is soaked in 0.5M MgSC>4, at a discharge current density of ImA/cm ² , difference in voltage of 0.375 V, and active mass of Img, the specific capacity of the supercapacitor obtained is 666. 67 F/g for a discharge time of 50s.

The specific capacity of the supercapacitor, when the bentonite clay liquid crystal electrolyte is soaked in IM MgSC>4, at a discharge current density of ImA/cm ² , difference in voltage of 0.375 V, and active mass of Img obtained is 640 F/g for a discharge time of 240s.

The cycle stability of the supercapacitor, when the bentonite clay liquid crystal electrolyte is soaked in 0.05M MgSC>4, is up to 951 cycles, and when soaked in 0.5M MgSC>4, is up to 15000 cycles, and when soaked in IM MgSC>4, is up to 2000 cycles. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Fig. 1 is an Illustrative representation of Bentonite clay Liquid crystal (BCLC) based symmetric supercapacitors

Fig. 2 illustrates the CV diagrams of Polyaniline (PANI) in IM H2SO4 used for electrodeposition of Polyaniline (PANI) on Stainless steel (SS) current collector by CV (cycles 11 to 20)

Fig. 3A represents First 10 cycles of CV during electrodeposition of PANI on SS current collector in IM H2SO4.

Fig. 3B represents 11 ^th cycle of CV during electrodeposition of PANI on SS current collector in IM H2SO4.

Fig. 4 is a flow chart for the process of preparation of Lyotropic liquid crystals of Bentonite clay.

Fig. 5 illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//0.05M Na2SC>4 soaked BCLC//PANI/A1 at current density of ImA/cm ² , discharge time of 25s.

Fig. 6 illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//0.5M Na2SC>4 soaked BCLC//PANI/A1 at current density of ImA/cm ² , discharge time of 100s.

Fig. 7 illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANL/0.05M MgSO4 soaked BCLC//PANI/A1 at current density of ImA/cm ² , discharge time of 250s.

Fig. 8 illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//0.5M MgSO4 soaked BCLC7/PANI/AI at current density of ImA/cm ² , discharge time of 50s.

Fig. 9 illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//1M MgSO4 soaked BCLC//PANI/A1 at current density of ImA/cm ² , discharge time of 240s.

Fig. 10A illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//0.05M MgSO4 soaked BCLC//PANI/A1 at current density of ImA/cm ² for 1000 cycles. Fig. 10B illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//0.05M MgSC>4 soaked BCLC//PANI/A1 at current density of ImA/cm ² for the first 50 cycles.

Fig. 11 illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//0.5M MgSC soaked BCLC//PANI/A1 at current density of ImA/cm ² for 15000 cycles.

Fig. 12A illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//1M MgSO4 soaked BCLC//PANI/A1 at current density of ImA/cm ² for 20000 cycles.

Fig. 12B illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//1M MgSO4 soaked BCLC//PANI/AI at current density of ImA/cm ² up to 327 cycles.

Fig. 12C illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//1M MgSO4 soaked BCLC7/PANI/AI at current density of ImA/cm ² from 327 to 20000 cycles.

DETAILED DESCRIPTION

The preferred embodiments of the present disclosure will be described in detail with the following disclosure and examples. The foregoing general description and the following detailed description are provided to illustrate only some embodiments of the present disclosure and not to limit the scope of the present disclosure. The disclosure is capable of other embodiments and can be carried out or practiced in various other ways.

Unless otherwise specified, all the technical and scientific terms used herein have the same meaning as is generally understood by a person skilled in the art pertaining to the present disclosure.

Headings are used solely for organizational purposes, and are not intended to limit the disclosure in any way.

The use of the singular includes the plural unless specifically stated otherwise. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well. The use of “or” means “and/or” unless stated otherwise.

As used herein, the terms “comprises” and/or “comprising” specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Furthermore, to the extent that the terms “includes,” “having,” “has,” “with,” “composed,” “comprised” or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.”

As used herein, ranges and amounts can be expressed as “about” a particular value or range. “About” is intended to also include the exact amount. Hence “about 5 percent” means “about 5 percent” and also “5 percent.” “About” means within typical experimental error for the application or purpose intended.

It is to be understood that wherein a numerical range is recited, it includes all values within that range, and all narrower ranges within that range, whether specifically recited or not.

Reference throughout this specification to “one embodiment,” “an embodiment,” “one example,” or “an example” means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” “one example,” or “an example” in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combinations and/or sub -combinations in one or more embodiments or examples. In addition, it should be appreciated that if any figures are provided herewith, they are for explanation purposes to persons ordinarily skilled in the art and that the drawings of them are not necessarily drawn to scale.

In this specification, certain aspects of one embodiment include process steps and/or operations and/or instructions described herein for illustrative purposes in a particular order and/or grouping. However, the particular order and/or grouping shown and discussed herein are illustrative only and not limiting. Those of skill in the art will recognise that other orders and/or grouping of the process steps and/or operations and/or instructions are possible and, in some embodiments, one or more of the process steps and/or operations and/or instructions discussed above can be combined and/or deleted. In addition, portions of one or more of the process steps and/or operations and/or instructions can be re-grouped as portions of one or more other of the process steps and/or operations and/or instructions discussed herein. Consequently, the particular order and/or grouping of the process steps and/or operations and/or instructions discussed herein do not limit the scope of the disclosure.

The present disclosure provides a supercapacitor, wherein the positive electrode (cathode) comprises Emeraldine Acid of polyaniline (PANI), and the negative electrode (anode) comprises Emeraldine Acid of poly aniline (PANI), and bentonite clay liquid crystal (BCLC) soaked in a monovalent or divalent cationbased sulphate salt such as Na2SC>4 or MgSCL as electrolyte.

Cathode: PANI is coated on a cathode current collector, preferably Stainless steel (SS) current collector.

Anode: PANI is coated on an anode current collector, preferably Aluminium (Al) current collector.

Electrolyte: Bentonite clay liquid crystals (BCLC) soaked in monovalent or divalent cation-based sulphate salt such as Na2SC>4 or MgSCL as electrolyte.

Materials and Methods:

Commercially available bentonite clay was used for liquid crystalline analysis. Aniline, sulphuric acid, and sodium dodecyl sulphate, conducting carbon black, were procured from Sigma Aldrich. Commercial 304-grade stainless steel (ss) was used as an electrode substrate. Electropolymerization of aniline and electrochemical characterization were executed on a Zahner Zennium E4 Potentiostat.

Electrodeposition of conducting polymer - Emeraldine Acid of Polyaniline (PANI)

PANI was deposited on the stainless-steel electrode by using CV. The electrodes employed in three electrode assembly were Pt wire (counter electrode), Ag/AgCl (reference electrode), and the working electrode (stainless steel). IM H2SO4 was prepared and SS strips of dimensions of 0.5 * 10 cm ² were cut and sonicated using ethanol for a period of 20 minutes. The prepared IM H2SO4 was added along with few drops of aniline. The voltage range was fixed between -0.2V to 1 ,2V at a scan rate of 25mV/s for 20 cycles. The deposited strips were dried and then used as electrode in Supercapacitors.

As shown in Fig. 2, the CV of PANI exhibits two oxidative peaks (Al & A2) coupled with two reductive peaks (C1&C2). The first oxidative peak was related to the Leucoemeraldine/Emeraldine (A1/A2) redox couple and the second peak was related to the formation of diradical cation(Cl/C2). An increase in peak current with cycle number indicates the growth of PANI and directly influences the thickness of PANI film. From Fig 2, we can infer that the oxidation of aniline takes place in two steps:

11C6H5NH2— > (CeHsNH) „ + 2nH ⁺ + 2ne-

It was found that in the case of IM H2SO4 solution the CV of PANI exhibited oxidative peaks, coupled with reductive peaks.

As shown in Fig. 3, the first 10 cycles of the CV of PANI in H2SO4 solution indicated active dissolution current in the anodic scan, followed by a broad anodic peak which coupled with the broad cathodic peak in the reverse scan. Further, the formation of aniline radicals on the passivated steel commences at -0.33 V, initiating the polymerization of aniline. On the negative sweep of this curve are relatively broad reduction peak was obtained from 0.55 to 0 V.

As shown in Fig. 3, from the 11 ^th cycle, the first oxidative peak appeared due to the LE/EM redox couple. The second one, related to the formation of diradical cation (bipolaronic pernigraniline). As mentioned before the intermediate small redox peaks are due to the degradation product of BQ/HQ couple in IM H2SO4 acidic solution. The interpretation of these peaks was not been unanimous. It has been attributed to the presence of ortho coupled polymers formed under certain experimental conditions. Another assignment associate’s peaks with the products of PANI degradation, soluble species such as benzoquinone (BQ) and hydroquinone (HQ), and/or insoluble fragments containing quinonic functional groups at their ends. The increase in voltammetry peak current was an indication of the growth of PANI. Since the voltammetry charge increases on the repeated potential scan and deposition of the PANI layer was visually observed, it is inferred that the oxidation potential of aniline overlaps with the potential of oxidation of the SS surface. The initial layer of the deposit consists of the surface oxide on SS and PANI. On the further continuation of the potential sweeps, the magnitude of current of the voltammograms increases suggesting an increase in the thickness of the PANI over SS substrate.

PANI was deposited on the Aluminium current collector to act as anode using the same method as the PANI was deposited on the SS current collector to act as cathode.

Preparation of Lyotropic liquid crystals of Bentonite Clay (BCLC)

Fig. 4 as a flow chart for the process of preparation of Lyotropic liquid crystals of Bentonite clay. This includes three steps:

Step 1

- 10 w/v of bentonite clay is dissolved in distilled water, bentonite clay solution is maintained at pH=6

Step 2

- Centrifuged for 6-8 hrs, yellow coloured, homogeneous exfoliated clay.

Step 3

- Dissolve exfoliated clay in solutions of different pH, lyotropic liquid crystals are obtained.

Examples:

The present disclosure will now be explained in further detail by the following examples. These examples are illustrative of certain embodiments of the disclosure without limiting the scope of the present disclosure.

Fabrication of coin cell of symmetric supercapacitor with BCLC electrolyte

- The anode and cathode sheets prepared according to the teachings of the present invention were cut into circles with dimensions of 15mm diameter and 1mm thickness.

- The cathode case is taken, spacer is attached to it.

- On the spacer, PANI coated SS current collector cut into circular dimension is placed.

- Above the cathode sheet, the BCLC soaked in appropriate salt solution is placed.

- Above the BCLC, anode sheet is placed with the PANI facing the BCLC.

- Above the anode sheet (on the Al side), spacer is placed.

- The anode side casing is placed on the spacer.

- The whole coin cell set up is crimped at 5 bar pressure in a crimper and sealed.

- The crimped coin cell is further subjected to GCD studies. Five different coin cells of symmetric supercapacitors were formed with the following configurations by using the cathode, the anode and the electrolytes prepared by soaking the Bentonite clay liquid crystals (BCLC) in varying concentrations of Na ₂ SO4 or MgSC>4.

Cell 1: SS/PANI// 0.05M Na ₂ SO ₄ soaked BCLC// PANI/A1

Cell 2: SS/PANI// 0.5M Na ₂ SO ₄ soaked BCLC// PANI/A1

Cell 3: SS/PANI// 0.05M MgSO ₄ soaked BCLC// PANI/A1

Cell 4: SS/PANI// 0.5M MgSO ₄ soaked BCLC// PANI/A1

Cell 5: SS/PANI// IM MgSO ₄ soaked BCLC// PANI/A1

GCD studies:

Cell 1:

The configuration of the supercapacitor coin cell is:

SS/PANI// 0.05M Na ₂ SO ₄ soaked MCLC//PANI/A1

Fig. 5 indicates the GCD profile of coin cell with configuration of SS/PANI//0.05M Na ₂ SO4 soaked MCLC//PANI/A1 as supercapacitor.

The specific capacitance of the coin cell is calculated according to the equation (1): equation (1) where I dis is the discharge current in Amps, ‘t’ is the discharge time in seconds, AV is the difference between charging and discharging voltage in Volts, m is the active mass of electrode material (PANI).

For the discharge current density of ImA/cm ² , discharge time of 25s, difference in voltage of 0.45 V and active mass of Img, the specific capacity of the supercapacitor coin cell with 0.05M Na ₂ SO4 soaked BCLC electrolyte is obtained to be 111.11 F/g. The electrochemical series resistance (ESR) for the coin cell is obtained as 0.225 Q, for an IR drop of 0.45 V. The specific energy of the coin cell supercapacitor is calculated from equation (2): equation (2)

The specific energy for the above-mentioned parameters is obtained as 3.125 Wh/kg.

The specific power of the coin cell is calculated from equation (3): equation (3)

The specific power is 450 W/kg for the parameters of the coin cell.

The Columbic efficiency of the supercapacitor coin cell with 0.05M Na ₂ SO ₄ soaked BCLC electrolyte is evaluated via equation (4) equation (4)

The Columbic efficiency of the supercapacitor is found to be 25%.

Thus, coin cell supercapacitor with configuration of

SS/PANP/0.05M Na ₂ SO ₄ soaked BCLC//PANI/A1 functions with low ESR, high SE, SP and CE.

Cell 2

The configuration of the supercapacitor coin cell is:

SS/PANU/ 0.5M Na ₂ SO ₄ soaked BCLC//PANI/A1 Fig. 6 depicts the GCD profile of coin cell supercapacitor of configuration

SS/PANI//0.5MNa2SO4 soaked BCLC//PANI/A1.

For the discharge current density of ImA/cm ² , discharge time of 100s, difference in voltage of 0.45 V and active mass of Img, the specific parameters employing equations (1) to (4) obtained as:

- Specific Capacity = 444. 44 F/g

- ESR = 0.225 Q

- IRdrop = 0.45 V

- Specific Energy = 12.5 Wh/g

- Specific Power = 450 W/kg

- Columbic Efficiency = 66.66%

The above evaluated parameters for supercapacitor coin cell of configuration SS/PANP/0.5Na2SO4 soaked BCLC//PANI/AI agreed satisfactorily with the literature M. K. Neelamma, Sowmya R. Holla, M. Selvakumar, P. Akhil Chandran, Shounak De, Bentonite Clay Liquid Crystals for High-Performance Supercapacitors Journal of Electronic Materials (2022) 51:2192-2202 involving the same configuration. The specific parameters obtained in the literature are:

- Specific Capacity = 234. 9 F/g

- ESR = 0.2 Q

- IR drop = 0.3 V

- Specific Energy = 12.33 Wh/g

- Specific Power = 614.80 W/kg

- Columbic Efficiency = 61.5%

These parameters benchmark the device fabricated in the present invention and motivates to experiment other divalent salts like MgSC>4 as cation exchange in the Metal-SCE soaked BCLC electrolyte to improve the performance parameters of the supercapacitor. Cell 3

The configuration of the supercapacitor coin cell is:

SS/PANV/ 0.05M MgSO ₄ soaked BCLC// PANI/A1

Fig. 7 represents the GCD profile of the 0.05 M MgSO ₄ soaked BCLC based supercapacitor. For the discharge current density of ImA/cm ² , discharge time of 250s, difference in voltage of 0.375 V and active mass of Img, the specific parameters employing equations (1) to (4) obtained as:

- Specific Capacity = 142.86 F/g

- ESR = 0.375 Q

- IR drop = 0.75 V

- Specific Energy = 10.42 Wh/g

- Specific Power = 750 W/kg

- Columbic Efficiency = 16.67%

Cell 4

The configuration of the supercapacitor coin cell is:

SS/PANI// 0.5M MgSO ₄ soaked BCLC// PANI/A1

Fig. 8 represents the GCD profile of the 0.5 M MgSO ₄ soaked BCLC based supercapacitor. For the discharge current density of ImA/cm ² , discharge time of 50s, difference in voltage of 0.375 V and active mass of Img, the specific parameters employing equations (1) to (4) obtained as:

- Specific Capacity = 666. 67 F/g

- ESR = 0.375 Q

- IR drop = 0.75 V

- Specific Energy = 52.08 Wh/g

- Specific Power = 750 W/kg

- Columbic Efficiency = 16.67% Cell s

The configuration of the coin cell is:

SS/PANU/ IM MgSO ₄ soaked BCLC// PANI/AI

Fig 9 represents the GCD profile of the 1 M MgSO ₄ soaked BCLC based supercapacitor. For the discharge current density of ImA/cm ² , discharge time of 240s, difference in voltage of 0.375 V and active mass of Img, the specific parameters employing equations (1) to (4) obtained as:

- Specific Capacity = 640 F/g

- ESR = 0.375 Q

- IR drop = 0.75 V

- Specific Energy = 50 Wh/g

- Specific Power = 750 W/kg

- Columbic Efficiency = 16.67%

Table 1 summarizes the specific parameters of the GCD profiles of the five supercapacitor coin cells fabricated with Na2SO ₄ /MgSO ₄ soaked BCLC as electrolyte.

Table 1

Cycle life and longevity of SS/PANI/Z MgS04 soaked BCLC// PANE Al

Based on the GCD experiments with different concentrations of MgSC>4 soaked BCLC electrolyte-based supercapacitor, it is clear that at all concentrations for MgSCL, the cell produces higher values for all specific parameters. Thus, supercapacitor coin cell with configuration of SS/PANI// 0.05M soaked BCLC// PANI/A1 is subjected to higher cycle numbers of GCD to understand its cycle life, longevity and performance ability. Thus, at ImA/cm ² , the GCD profile for the supercapacitor is studied at 1000, 7500 and 10000 cycles. The specific parameters are deduced and the performance of the device is evaluated.

Fig. 10A illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//0.05M MgSO4 soaked BCLC//PANI/A1 at current density of ImA/cm ² for 1000 cycles. Fig. 10B illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//0.05M MgSC>4 soaked BCLC//PANI/A1 at current density of ImA/cm ² for the first 50 cycles.

Fig. 11 illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANP/0.5M MgSO4 soaked BCLC//PANI/A1 at current density of ImA/cm ² for 15000 cycles.

Fig. 12A illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANV/1M MgSO4 soaked BCLC//PANI/A1 at current density of ImA/cm ² for 20000 cycles.

Fig. 12B illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANV/1M MgSO4 soaked BCLC//PANI/A1 at current density of ImA/cm ² for the first 2000 cycles.

Fig. 10A and Fig. 10B imply that the supercapacitor of configuration SS/PANI// 0.05 MMgSO4 soaked BCLC// PANI/A1 is stable up to 951 cycles and stopped functioning. This indicates the cycle stability is at least up to 951 cycles is expected for the supercapacitor with specific parameters for discharge time of 250s, of (i) specific capacity = 714.29 F/g, (ii) ESR = 0.35 Q, (iii) IR drop =0.7 V, (iv) specific power = 700 W/kg, (v) specific energy = 48.61 Wh/kg and (vi) columbic efficiency = 17.65% .

Fig. 11 implies that the supercapacitor of configuration SS/PANI// 0.5M MgSO4 soaked BCLC// PANP Al is subjected to 15000 cycles at the discharge current density of ImA/cm ² . It is found that the cell is stable for all 15000 cycles and stopped functioning. This indicates the cycle stability is of up to 15000 cycles is expected for the supercapacitor with specific parameters for discharge time of 200s, of (i) specific capacity = 571.43 F/g, (ii) ESR = 0.37 Q, (iii) IR drop =0.74 V, (iv)specific power = 740 W/kg, (v) specific energy = 41.11 Wh/kg and (vi) columbic efficiency = 16.85%.

Fig. 12A illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI//1M MgSC>4 soaked BCLC//PANI/A1 at current density of ImA/cm ² for 20000 cycles. Fig. 12A implies that the supercapacitor of configuration SS/PANI// IM MgSC>4 soaked BCLC// PANP Al is subjected to 20000 cycles at the discharge current density of ImA/cm ² .

Fig. 12B illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANI// IM MgSO4 soaked BCLC// ANI/AI at current density of ImA/cm ² up to 327 cycles. As shown in Fig. 12B, it is found that the cell is stable for all 2000 cycles and falls in performance and maintains the functioning up to 20000. This indicates the cycle stability is of up to 2000 cycles is expected for the supercapacitor with specific parameters for discharge time of 67.5s, of (i) specific capacity = 158.82 F/g, (ii) ESR = 0.425 Q, (iii) IR drop =0.85 V, (iv)specific power = 850 W/kg, (v) specific energy = 47.22 Wh/kg and (vi) columbic efficiency = 15%.

Fig. 12C illustrates the GCD profile of coin cell supercapacitor of configuration SS/PANV/IM MgSO4 soaked BCLC//PANI/A1 at current density of ImA/cm ² from 327 to 20000 cycles. From Fig. 12C, it is inferred that the performance falls from 2001 to 3320 cycles and remains stable up to 20000 cycles, indicating the fact that at lower capacity also the cell functions properly. Hence, the cell possesses cycle life of 20000, with fall in performance at 2000 and 3320 ^th cycles. In spite of this anomalous behaviour, the cell functions up to 20000 cycles without hindrance. The specific parameters for the cell for operation between 3320 to 20000 cycles for discharge time of 81 s are as follows: (i) Specific capacity = 294.55 F/g, (ii) ESR = 0.275 Q, (iii) IR drop = 0.55 V, (iv) Specific Power = 550 W/kg, (v) Specific Energy = 12.45 Wh/kg and (vi) Columbic efficiency = 21.43%. Advantages:

- The BCLC electrolyte-based supercapacitors of the present disclosure has the following non-limiting advantages.

- Naturally abundant and cost-effective bentonite clay as electrolyte

- The common-ion rich bentonite clay (eg. Na-rich for Na2SC>4, and Mg-rich for MgSC ) facilitates faster ion transport in electrolyte via hydrophilic end of the micelles formed by LCBC and water or hydrophobic end of the reverse micelle formed by LCBC with non-aqueous solvent

- Very low IR drop ~ 750 mfl

- Non-carbon or very minimal carbon-based device

- Completely recyclable

- Bentonite clay is added as lyotropic liquid crystal (LCBC)

- Specific capacitance as high as ~ 666.67 F/g @ 1 mA/cm ²

- Long life (longevity); Limited or no self-discharge

- Electrorheological LCBC which at a particular viscosity responds in a particular fashion to the applied electric field

- Specific energy as high as 52.8 Wh/kg and Specific power as high as 750 W/kg

Applications:

The BCLC electrolyte based supercapacitors of the present disclosure has the following non-limiting industrial applications.

Stationary Energy Storage, automobiles, air transportation, Railways, buses, trucks, e-scooters, e-cycles and e-rickshaws, mobiles, laptops, tablets, walkie- talkies, drones, bio-medical devices so on and so forth. Although the present disclosure is described in terms of certain preferred embodiments, it is to be understood that they have been presented by way of example, and not limitation. Thus, the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.