Technical Field

[0001] This invention relates to an electric energy storage device. More particularly, this invention relates to a cylindrical or prismatic electric energy storage device which is self- inductive or self-wireless chargeable.

Background Art

[0002] Nowadays, most electronic devices can be charged through wire connection and/or wirelessly, and store received electric energy in their internal battery pack. For wireless charging such as inductive, microwave or radio wave charging, an energy receiver coil or inductive coil, or a circuit having the coil(s), which connects to a battery pack of an electronic device, is required in order to receive electric energy from a wireless charging platform. One example of such configurations is disclosed in US2017207495, which energy receiver coils are connected to a flat wound battery pack. Another example is disclosed in patent EP2942856, which an inductor harvests electric energy from electromagnetic field, and the electric energy is stored in separate electronic devices. A further example is disclosed in US7898214, which a cable-type lithium ion battery having an electrolyte core, and an outer wound current collector capable of receiving electric energy wirelessly.

[0003] Potential applications of wireless chargeable batteries or supercapacitors will be envisaged in autonomous car industry to replace plug-in charge in future.

Summary of the Invention

[0004] A principal object of the present invention is to propose an energy storage device which is self-inductive or self-wireless chargeable.

[0005] A further object of the present invention is to propose a circuit connection method of making an inductive chargeable energy storage device.

Brief Description of the Drawings

[0006] A number of preferred embodiments of the invention will now be described, with reference to the accompanying drawings, in which [0007] Fig. la is a partially-exploded perspective view of the fundamental structure of an inductive chargeable energy storage device, showing two electrodes electrically connected to a diode in series schematically;

[0008] Fig. lb illustrates a helical spiral structure which may represent a helical spiral electrode, a helical spiral separator or a flat wire helical spiral conductor;

[0009] Fig. lc is a magnified cross-sectional view of the portion P of the inductive chargeable energy storage device;

[0010] Fig. 2a is a perspective view showing the completed state of the inductive chargeable energy storage device having two electrode terminals;

[0011] Fig. 2b is a cross-sectional view of the completed device, showing the fundamental structure in Fig. la disposed in a hollow tubular casing;

[0012] Fig. 3 shows two diodes electrically connected in parallel between the electrodes schematically;

[0013] Fig. 4a is a perspective view of an inductive chargeable energy storage device, showing two helical spiral electrodes electrically connected to a diode in series schematically;

[0014] Fig. 4b shows two diodes electrically connected in parallel between the helical spiral electrodes schematically;

[0015] Fig. 5a is a perspective view of an inductive chargeable energy storage device, showing two helical spiral electrodes being spiralled in opposite directions and electrically connected to a diode in series schematically;

[0016] Fig. 5b shows two diodes electrically connected in parallel between the helical spiral electrodes schematically;

[0017] Fig. 6a is an exploded perspective view of an inductive chargeable energy storage device, showing two spiral electrodes electrically connected to a diode in series schematically;

[0018] Fig. 6b shows two diodes electrically connected in parallel between the spiral electrodes schematically;

[0019] Fig. 7 shows the curves of inductive charging, and discharging through a 1.2 V white LED for a silver-zinc battery as configured in Fig. la;

[0020] Fig. 8 shows inductive charging, and self-discharging cycles recorded for a supercapacitor configured in Fig. 3;

[0021] Fig. 9 shows inductive charging, and self-discharging cycles recorded for another supercapacitor as configured in Fig. 4a;

[0022] Fig. 10 shows curves of inductive charging, and self-discharging through a 1.2 V white LED for a nickel zinc battery as configured in Fig. 5b; [0023] Fig. 11 shows inductive charging, and self-discharging cycles for a strip wound supercapacitor as configured in Fig. 6a; and

[0024] Fig. 12 shows curves of inductive charging, and discharging through a 1.2 V white LED for a strip wound nickel zinc battery as configured in Fig. 6a.

Detailed Description of the Invention

[0025] In Figs la and lb, an inductive chargeable energy storage device 100 comprises an energy storage unit 150 and a diode 112. The unit 150 comprises a positive helical spiral electrode 101; a negative helical spiral electrode 102; and two helical spiral separators 103 a and l03b interposed between the helical spiral electrodes 101 and 102.

[0026] As shown in Fig. lb, the helical spiral structure has a void core 114 and a number of turns with a turn width 115.

[0027] As shown in Figs la, lb and lc, the helical spiral electrode 101 includes a flat wire helical spiral conductor 104 and an electrode material layer 106 which may be disposed on the whole surface of the turns of the conductor 104 having a top end l04a and a bottom end l04b; the helical spiral electrode 102 includes a flat wire helical spiral conductor 105 and an electrode material layer 107 which may be disposed on the whole surface of the turns of the conductor 105 having a top end l05a and a bottom end l05b. The separators l03a and l03b may be slightly wider than each helical spiral electrode. The separators l03a and l03b may be disposed on the helical spiral electrodes 101 and 102 respectively to cover one side of the turns thereof, and the unit 150 may be formed by disposing one separator pre-covered helical spiral electrode onto a supporting core 111 (Fig. la), and then screw the other separator pre-covered helical spiral electrode in from one end of the core 111 until two helical spiral electrodes reach desired match, next press two separator-pre-covered helical spiral electrodes together from both sides of the helical spiral electrodes 101 and 102 to make adjacent turns of the electrodes and separators in touch, and finally the device is wrapped using electrically insulating film.

[0028] Each of the helical spiral electrodes 101 and 102 may have an electrode material layer disposed on one side of the turns of its conductor, and the other side of the turns coated with electrically insulating material; in this case, the separator l03b may be omitted.

[0029] The word“spiral” herein may refer to a circular spiral, a rectangular spiral, a square spiral, an elliptic spiral, an oval spiral, a regular polygonal spiral or any other irregular polygonal spirals, which may be spiralled in clockwise or counterclockwise direction upwardly and downwardly. [0030] As shown in Fig. la, the diode 112 electrically connects the positive and negative helical spiral electrodes 101 and 102 therebetween to form an inductive chargeable circuit. The cathode of the diode 112 may be connected to the top conductor end l04a of the positive helical spiral electrode 101 via an electrode lead l08a which is electrically attached to the end l04a and the anode of the diode may be connected to the bottom conductor end l05b of the negative helical spiral electrode 102 via an electrode lead l09b which is electrically attached to the end l05b. Alternatively, the cathode of the diode 112 may be connected to the bottom conductor end l04b of the helical spiral electrode 101 via an electrode lead l08b and the anode of the diode may be connected to the top conductor end 105 a of the negative helical spiral electrode 102 via an electrode lead l09a (the connections not shown in Fig. la). The connections may be made directly without via respective electrode leads.

[0031] The electrode leads l08a or l08b, and l09a or l09b may be used for external connections. The conductor ends l04a or l04b, and l05a or l05b may extend as respective positive and negative electrode leads for external connections, in this case, the electrode leads l08a, l08b, l09a and l09b may be omitted.

[0032] Each of the helical spiral electrodes 101 and 102 may have a middle electrode lead which is electrically attached to the middle of the helical spiral conductor of the electrode for an external connection; the lead is not allowed to touch the diode electrically (not shown here).

[0033] The supporting core 111 may be an air core such as a tubular core or a solid core formed from electrically insulating material for conducting magnetic or electromagnetic field. Alternatively, the core 111 may be a magnetic core formed from magnetic material, or paramagnetic material such as ferrite for directing electromagnetic field, which may be encapsulated in electrically insulating material.

[0034] The supporting core 111 may be slightly longer than the helical spiral structure of each of said helical spiral electrodes and may be removable, when the core is removed from the unit 150; the unit 150 is left with a void core.

[0035] Each of the helical spiral separators 103 a and 103b is an electrically insulator and an ion conductor which may be formed from material selected from the group consisting of gel electrolyte, semi-solid-state electrolyte, solid-state electrolyte such as polymer solid electrolyte or ceramic electrolyte used in a solid-state lithium ion battery or Li-S rechargeable battery, ion conducting membrane such as polyethylene (PE) membrane, polypropylene (PP) membrane or filtration paper soaked with electrolyte, dielectric material and any combination thereof.

[0036] Each of the positive and negative helical spiral electrodes 101 and 102 may be formed by disposing electrode material on its flat wire helical spiral conductor by means of dipping coating, spray coating, vacuum coating, plasma coating, electro/electroless plating, brush coating or any combination thereof.

[0037] Each helical spiral conductor is a current collector which may be in the form of foil, mesh or net, which may be fabricated using conventional methods for flat wire inductor production.

[0038] Each helical spiral conductor may be formed from material selected from the group consisting of copper, aluminium, titanium, stainless steel, nickel, silver, tin, lead, cadmium, carbon formats such as graphite, graphene, amorphous carbon or mesophase carbon, conductive metal oxides such as dopanted SnO? or ZnO, and any combination thereof; and may still be additionally protected by a layer which is electrically conductive yet to resistant to corrosion in an electrolyte environment. The protection layer maybe formed from material selected from the group consisting of amorphous carbon, mesophase carbon, nanotube, graphene, graphite, copper, nickel, silver, titanium, tin, aluminium, lead, cadmium, conductive metal oxides such as dopanted SnO? or ZnO, or any combination thereof. The selection of the conductor and its protection layer may be dependent on the electrode polarity and electrolyte system used in the device.

[0039] The electrode materials may be selected from those used in conventional secondary batteries such as a nickel zinc battery, a silver zinc battery, a nickel metal hydride battery, a metal air battery, an aluminium ion battery, a lithium ion battery with liquid electrolyte, gel electrolyte, polymer gel electrolyte, polymer solid electrolyte or solid-state (ceramic) electrolyte, a lithium sulphur battery etc; supercapacitors (electrochemical double-layer capacitor) such as an aqueous, an organic or ionic liquid based supercapacitor; pseudo supercapacitor; a supercapacitor-battery and a capacitor. The batteries store electric energy as chemical energy; the supercapacitors store electric energy as charges, and the pseudo supercapacitors and supercapacitor-batteries may store electric energy as combinations of chemical energy and charges such that one electrode stores chemical energy and the other stores charges.

[0040] The electrode material may comprise active electrode material(s), and binding agent which may be one selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), hydroxyethyl carboxymethyl cellulose (HCMC), polyvinylidene fluoride (PVDF) and any combination thereof.

[0041] In the supercapacitors, the positive electrode material and negative electrode material may include carbon formats such as amorphous carbon, mesophase carbon, activated carbon, graphite, graphene, carbon nanotube or any combination thereof. [0042] In the aqueous based supercapacitor, the aqueous electrolyte material may include CH ₃ COONa, Na ₂ S0 ₄ , KN0 ₃ , LiCl, NaCl, KC1, KOH, LiOH, NaOH, H ₂ S0 ₄ , H ₃ P0 ₄ K ₃ [Fe(CN) ₆ ], K4[Fe(C )e] or any combination thereof.

[0043] In the organic based supercapacitor, the electrolyte material may include [N(Ci ₆ H ₃₆ )]PF ₆ , [N(C _I6 H ₃₆ )]BF ₄ , [N(Ci ₆ H ₃₆ )]Cl0 ₄ , [N(Ci ₆ H ₃₆ )]Cl, LiCl0 ₄ , LiBF ₄ , LiPF ₆ or any combination thereof; and the organic solvent may include acetonitrile, butylenecarbonate, dimethylcarbonate, ethylene carbonate, propylene carbonate or any combination thereof

[0044] In the nickel-zinc battery or the silver-zinc battery, the material for the nickel electrode may include NiOOH, Ni(OH) ₂ , NiO, Ni ₂ 0 ₃ , Ni or any combination thereof; the material for the silver electrode may include Ag, Ag ₂ 0, AgO or any combination thereof; the material for the zinc electrode may include Zn, ZnO or any combination thereof; the aqueous electrolyte for the nickel-zinc battery or the silver-zinc battery may include KOH, LiOH, NaOH, [Zn(OH) ₄ ] ² or any combination thereof; the separator may be formed from gel electrolyte of a mixture of PVA - the electrolyte, semi-solid state electrolyte, solid-state electrolyte, or ion conducting membrane PE or PP soaked with the electrolyte.

[0045] In the lithium ion battery, the material for the negative electrode may include carbonaceous materials such as graphite, graphene, amorphous carbon and mesophase carbon, transition metal oxides and sulphides, or amorphous metal oxide containing silicon and or tin such as lithium titanate; the material for the positive electrode may include LiCo0 ₂ , LiNiMnCo0 ₂ , LiFeP0 ₄ , or LiNiMno _.5 C0 _1.5 Cf; the electrolyte may include the organic salt of L1PF6, LiAsF ₆ , LiBF ₄ , LiQ0 ₄ , CF ₃ S0 ₃ Li, (CF ₃ S0 ₂ ) ₂ NLi or Lil in an organic solvent of acetonitrile, butylene carbonate (BC), dimethylenecarbonate (DC), ethylene carbonate (EC), propylene carbonate (PC), dimethylformamide (DMF) or any combination thereof; the solid- state (ceramic) electrolyte may include lithium ion contained sulfides, oxides and phosphates such as Li ₂ S-P ₂ S5, Li ₂ S-P ₂ S ₅ -LL _t Si0 ₄ , Li _3.2 sGeo _.25 Po _.75 S ₄ , Lio _.375 Lai _.i25 Ti0 ₃ LiTio _.5 Zri _.5 (P0 ₄ ) ₃ , Lii _+x Al _x Ge _2-x (P0 ₄ ) ₃ or any combination thereof; the polymer solid electrolyte may include a mixture of poly(ethylene oxide) or its derivatives with polyvinylidene fluoride (PVDF) and the lithium salt; or the polymer gel electrolyte may include a mixture of the lithium salt with EC-DC or EC-PC; and the separator maybe formed from the gel electrolyte, the polymer gel electrolyte, the polymer solid electrolyte, the solid-state electrolyte, ion conducting membrane PP or PE soaked with the liquid electrolyte or any combination thereof.

[0046] Each helical spiral conductor may have a thickness of 10 pm to 500 pm and a width of not less than 1.0 mm. [0047] The helical spiral electrodes 101 and 102 or the helical conductors thereof may have equal numbers of turns, equal turn widths, equal turn thickness and equal core areas.

[0048] The unit 150 may be a supercapacitor or a secondary battery.

[0049] When the device 100 is coupled to an inductive charging platform, one or both of the helical spiral conductors of the electrodes 101 and 102 function as two energy receiver coils, receive electric energy from electromagnetic field generated in a primary coil (s) or a transmitter coil (s) of the inductive charging platform and convert the electric energy back to a DC current flowing through the device, so that the received electric energy is stored in the electrode material layers thereof. The device will harvest electric energy through the helical spiral conductors thereof from half cycles of the electromagnetic field with the facilitation of the diode.

[0050] As there is no wire connection between the device and the inductive charging platform, the device is self-inductive or self-wireless chargeable, and rechargeable.

[0051] The inductive charging platform may have at least one wound or printed primary or transmitter coil.

[0052] At least one of the positive and negative helical spiral electrodes 101 and 102 may have two functionalities of receiving electric energy inductively or wirelessly by the helical spiral conductor thereof and storing the electric energy therein.

[0053] The device may be charged by other wireless charging means such as radio wave, microwave, capacitive coupling or variable magnetic field charging.

[0054] The diode may be a Zener or Schottky diode.

[0055] As shown in Figs. 2a and 2b, the device 100 may be disposed in a casing 200 which is capable of conducting magnetic or electromagnetic field to form a completed device. The casing 200 includes a hollow tubular body 201 and a lid 202; the body 201 has a side wall 203, a bottom ring wall 204, a central tube 205 with a closed top end 206, and a open end 207 at the bottom ring wall 204 of the tubular body 201. For the convenience, the supporting core 111 is not shown in Fig. 2b. The positive electrode lead 108 may extend upwardly and pass through the lid 202 and the negative electrode lead 109 may extend downwardly and pass through the bottom wall 204 of the tubular body 201 for external connections. The tubular body 201 and the lid 202 may be sealed together using electrically insulating resin, superglue or plastic O-ring. The casing may be cylindrical or prismatic. The casing may be formed from electrically insulating material such as polytetrafluoroethylene, polypopylene, polyethylene, polycarbonate, polycyclohexylene terephthalate, polyetheretherketone, polyoxymethylene, polybutylene terephthalate, nylon or any combination thereof. Alternatively, the casing may be formed from any combination of electrically insulating material and a non-fiilly closed metallic ring (s) to enforce the casing.

[0056] The inductive chargeable circuit may be disposed in a traditional cylindrical or prismatic battery cell casing which may be made from electrically insulating material or partially electrically insulating material for conducting magnetic field or electromagnetic field.

[0057] As shown in Fig. 2a, the device may comprise a positive terminal 238, and a negative terminal 239 which may be a non fully-closed ring; the terminals may be formed from electrically conductive materials such as copper or stainless steel. The positive and negative electrode leads 108 and 109 may be soldered or electrically glued to respective electrode terminals 238 and 239. The device may be sealed in an insulating shrinking plastic tube.

[0058] Fig. 3 shows a further embodiment in which the diode 112 and a diode 113 are electrically connected in parallel between the positive helical spiral electrode 101 and the negative helical spiral electrode 102 to form an inductive chargeable circuit, for instance, the cathode of the diode 112 may be connected to the top conductor end l04a via the lead l08a and the anode of the diode 112 may be connected to the bottom conductor end l05b via the lead l09b, and the cathode of the diode 113 may be connected to the bottom conductor end l04b via the lead l08b and the anode of the diode 113 may be connected to the top conductor end l05a via the lead l09a. The inductive chargeable circuit may be disposed in a casing with a pair of positive and negative electrode leads passing through the casing for external connections.

[0059] When coupled to an inductive charging platform, the device will harvest electric energy through the helical spiral conductors thereof from the full cycles of the electromagnetic field with the facilitation of the diodes 112 and 113.

[0060] Fig. 4a shows an embodiment in accordance with the present invention, an inductive chargeable energy storage device 400 comprises an energy storage unit 450 and a diode 415. The unit 450 comprises an inner separator 403a wrapping around a supporting core 404; a positive helical spiral electrode 401 and a negative helical spiral electrode 402 formed by winding a positive wire-like electrode and a negative wire-like electrode around the inner separator in turns spirally, adjacent turns thereof being in parallel and separated; and an outer separator 403b wrapping around the helical spiral electrodes 401 and 402. For the convenience, the both end parts of the outer separator are removed in the Fig. 4a. Each wire-like electrode includes a conductor coated with electrode material on the surface around the entire circumference of the conductor. A top end 406a and/or a bottom end 406b of the conductor of the helical spiral electrode 401 may be brought out of the electrode material coating for electrical connections; a top end 407a and/or a bottom end 407b of the conductor of the helical spiral electrode 402 maybe brought out of the electrode material coating for electrical connections.

[0061] As shown in Fig. 4a, the diode 415 electrically connects the positive helical spiral electrode 401 and the negative helical spiral electrode 402 therebetween to form an inductive chargeable circuit. The cathode of the diode 415 may be connected to the top end 406a of the conductor of the positive helical spiral electrode 401 and the anode of the diode may be connected to the bottom end 407b of the conductor of the negative helical spiral electrode 402. Alternatively, the cathode of the diode 415 may be connected to the bottom end 406b of the conductor of the positive helical spiral electrode 401 and the anode of the diode may be connected to the top end 407a of the conductor of the negative helical spiral electrode 402 (the connections not shown in Fig. 4a).

[0062] Each wire-like electrode may have a separator layer disposed on the surface around the entire circumference thereof before winding; the separator-covered positive and negative electrodes may be assembled together in parallel forming an energy storage string before winding. Alternatively, the separator-covered positive and negative wire-like electrodes may be twisted together forming an energy storage string before winding. In these cases, one or both of the inner and outer separators 403a and 403b may be omitted.

[0063] Each said layer may be formed by means of dip coating, extrusion, vacuum coating, spray coating, wrapping, electro/electroless plating, brush coating or any combination thereof.

[0064] Each said separator or separator layer may be formed from gel electrolyte, semi-solid state electrolyte, solid-state electrolyte, ion-conducting membrane polypropylene (PP) or polyethylene (PE) soaked with electrolyte, or any combination thereof.

[0065] Each said wire-like conductor may be in the form of wire, foil strip, mesh strip or net strip, and may have a radius or a thickness of 10 pm to 500 pm.

[0066] The core 404 may have a cross-sectional shape perpendicular to the Z-direction (shown in Fig. 4a) of square, rectangle, circle, oval, ellipse, regular polygons or any irregular polygonal shapes.

[0067] Fig. 4b shows a further embodiment in which the diode 415 and a diode 416 are electrically connected in parallel between the helical spiral electrodes 401 and 402 to form an inductive chargeable circuit, for instance, the cathode of the diode 415 may be connected to the top end 406a of the conductor of the positive helical spiral electrode 401 and the anode of the diode may be connected to the bottom end 407b of the conductor of the negative helical spiral electrode 402, and the cathode of the diode 416 may be connected to the bottom end 406b of the conductor of the positive helical spiral electrode 401 and the anode of the diode may be connected to the top end 407a of the conductor of the negative helical spiral electrode 402.

[0068] The device may be disposed in a casing to form a completed device; the respective conductor ends may extend as electrode leads which pass through the casing for an external connection.

[0069] Fig. 5 a shows an embodiment in accordance with the present invention, an inductive chargeable energy storage device 500 comprises an energy storage unit 550 and a diode 515. The unit 550 comprises an inner helical spiral electrode 501 formed by winding a wire-like electrode around a core 504 in turns spirally, a separator 503 wrapping around the inner helical spiral electrode 501, and an outer helical spiral electrode 502 formed by winding a wire-like electrode around the separator 503 in turns spirally. Adjacent turns of each helical spiral electrode maybe separated by a gap, an interposing wire-like separator or a pre-coated separator layer on the wire-like electrode.

[0070] For the convenience, the top and bottom parts of the separator 503 and/or the outer helical electrode may have been removed. The electrode 501 has a top conductor end 506a and a bottom conductor end 506b, and the electrode 502 has a top conductor end 507a and a bottom conductor end 507b.

[0071] As shown in Fig. 5 a, the diode 515 electrically connects the inner helical spiral electrode 501 and the outer helical spiral electrode 502 therebetween to form an inductive chargeable circuit. The helical spiral electrodes 501 and 502 may be spiralled in opposite directions, the electrode 501 may be a positive electrode and the electrode 502 may be a negative electrode. The cathode of the diode 515 may be connected to the top conductor end 506a of the inner helical spiral electrode 501 and the anode of the diode may be connected to the top conductor end 507a of the outer helical spiral electrode 502. Alternatively, the cathode of the diode 515 may be connected to the bottom conductor end 506b of the inner helical spiral electrode 501 and the anode of the diode may be connected to the bottom conductor end 507b of the outer helical spiral electrode 502 (the connections not shown in here).

[0072] The inner helical spiral electrode may be fabricated as a negative electrode and the outer helical spiral electrode may be fabricated as a positive electrode, and the inner and outer electrodes may be spiralled in opposite directions; the cathode of the diode may be connected to the top conductor end of the outer helical spiral electrode and the anode of the diode may be connected to the top conductor end of the inner helical spiral electrode, or the cathode of the diode may be connected to the bottom conductor end of the outer helical spiral electrode and the anode of the diode may be connected to the bottom conductor end of the inner helical spiral electrode (the details not shown here).

[0073] The inner and outer helical spiral electrodes may be fabricated and spiralled in the same direction, the cathode of the diode may be connected to the top conductor end of the positive electrode of the inner or outer helical spiral electrodes and the anode of the diode may be connected to the bottom conductor end of the negative electrode of the outer or inner helical spiral electrodes, or the cathode of the diode may be connected to the bottom conductor end of the positive electrode of the inner or outer helical spiral electrodes and the anode of the diode may be connected to the top conductor end of the negative electrode of the outer or inner helical spiral electrodes (not shown in here).

[0074] Fig. 5b shows a further embodiment in which the diode 515 and a diode 516 are electrically connected in parallel between the electrode 501 and the electrode 502 to form an inductive chargeable circuit, for instance, the inner helical spiral electrode 501 and the outer helical spiral electrode 502 may be spiralled in the opposite directions, and the electrode 501 may be a positive electrode and the electrode 502 may be a negative electrode. The cathode of the diode 515 may be connected to the top conductor end 506a of the inner helical spiral electrode 501 and the anode of the diode may be connected to the top conductor end 507a of the outer helical spiral electrode 502, and the cathode of the diode 516 may be connected to the bottom conductor end 506b of the inner helical spiral electrode 501 and the anode of the diode may be connected to the bottom conductor end 507b of the outer helical spiral electrode 502.

[0075] The inner helical spiral electrode 501 and the outer helical spiral electrode 502 may be spiralled in the opposite directions, and the inner helical spiral electrode may be fabricated as a negative electrode and the outer helical spiral electrode may be fabricated as a positive electrode, the cathode of the diode 515 may be connected to the top conductor end of the outer helical spiral electrode and the anode of the diode may be connected to the top conductor end of the inner helical spiral electrode, and the cathode of the diode 516 may be connected to the bottom conductor end of the outer helical spiral electrode and the anode of the diode may be connected to the bottom conductor end of the inner helical spiral electrode (the details not shown here).

[0076] The inner and outer helical spiral electrodes may be fabricated and spiralled in the same direction, the cathode of the diode 515 may be connected to the top conductor end of the positive electrode of the inner or outer helical spiral electrodes and the anode of the diode may be connected to the bottom conductor end of the negative electrode of the outer or inner helical spiral electrodes, and the cathode of the diode 516 may be connected to the bottom conductor end of the positive electrode of the inner or outer helical spiral electrodes and the anode of the diode may be connected to the top conductor end of the negative electrode of the outer or inner helical spiral electrodes (the details not shown here).

[0077] The device may be disposed in a casing which is capable of conducting magnetic or electromagnetic field.

[0078] Fig. 6a shows an embodiment in accordance with the present invention, an inductive chargeable energy storage device 600 comprises an energy storage unit 650 and a diode 609. The unit 650 comprises an inner spiral electrode 601; an outer spiral electrode 602; and two separators 603a and 603b interposed between the spiral electrodes 601 and 602. The device 600 may be formed by winding a positive strip electrode, a negative strip electrode with two separators therebetween around a core 604 in turns concentrically and spirally.

[0079] Each of the strip electrodes comprises a strip conductor coated with electrode material on both sides of the strip conductor, or on one side of the strip conductor and the other side of the conductor coated with insulating material. For the second case, the separator 603b may be omitted. The strip conductor may be a foil strip, a mesh strip or a net strip.

[0080] The electrode 601 may have an inner conductor end 605a and/or an outer conductor end 605b which are exposed without the electrode material coating; the electrode 602 may have an inner conductor end 606a and/or an outer conductor end 606b which are exposed without the electrode material coating. The inner spiral electrode 601 may have an inner electrode lead 607 which is electrically attached to the inner conductor end 605 a, and may extend upwardly; the outer spiral electrode 602 may have an electrode lead 608 which is electrically attached to the outer conductor end 606b, and may extend upwardly and downwardly.

[0081] As shown in Fig. 6a, the diode 609 electrically connects the electrodes 601 and 602 therebetween to form an inductive chargeable circuit. The inner spiral electrode 601 may be a positive electrode and the outer spiral electrode 602 may be a negative electrode. The cathode of the diode 609 may be connected to the inner end 605a of the conductor of the inner spiral electrode 601 via the electrode lead 607 and the anode of the diode may be connected to the outer end 606b of the conductor of the outer spiral electrode 602 via the electrode lead 608. Alternatively, the cathode of the diode 609 may be connected to an outer end 605b of the conductor of the inner spiral electrode 601 and the anode of the diode may be connected to an inner end 606a of the conductor of the outer spiral electrode 602 (the connections not shown in Fig. 6a).

[0082] The inner spiral electrode may be fabricated as a negative electrode and the outer spiral electrode maybe fabricated as a positive electrode, the cathode of the diode may be connected to the inner conductor end of the outer spiral electrode and the anode of the diode may be connected to the outer conductor end of the inner spiral electrode, or the cathode of the diode may be connected to the outer conductor end of the outer spiral electrode and the anode of the diode may be connected to the inner end of the inner spiral electrode (the connections not shown in here).

[0083] Each of the spiral electrodes 601 and 602 may have a middle electrode lead which is electrically attached the middle of the strip conductor for an external connection; the lead is not allowed to electrically touch the diode (not shown in here).

[0084] When the device is coupled to an inductive charging platform, one or both of the wound spiral conductors of the inner and outer spiral electrodes receive electric energy from a primary coil (s) or a transmitter coil(s) of the inductive charging platform and convert the electric energy back to a DC flowing through the device, so that the device is charged.

[0085] Fig. 6b shows a further embodiment in which the diode 609 and a diode 610 are electrically connected in parallel between the inner and outer spiral electrodes 601 and 602 to form an inductive chargeable circuit, for instance, the inner spiral electrode may be a positive electrode and the outer spiral electrode may be a negative electrode, the cathode of the diode 609 may be connected to the inner end 605a of the conductor of the inner spiral electrode 601 and the anode of the diode may be connected to the outer end 606b of the conductor of the outer spiral electrode 602, and the cathode of the diode 610 may be connected to an outer end 605b of the conductor of the inner spiral electrode 601 and the anode of the diode may be connected to an inner end 606a of the conductor of the outer spiral electrode 602. For the convenience, the electrode lead 607 and the top part of the lead 608 are omitted.

[0086] The inner spiral electrode may be a negative electrode and the outer spiral electrode may be a positive electrode, the cathode of the diode 609 may be connected to the outer end 606b of the conductor of the outer spiral electrode and the anode of the diode may be connected to the inner end 605a of the conductor of the inner spiral electrode, and the cathode of the diode 610 may be connected to an inner end 606a of the conductor of the outer spiral electrode and the anode of the diode may be connected to an outer end 605b of the conductor of the inner spiral electrode (the connections not shown here).

[0087] The device may be disposed in a casing which is capable of conducting magnetic or electromagnetic field, and each electrode lead may extend and pass through the casing for an external connection.

Experimental Section [0088] Example 1 : A silver zinc battery (as configured in Fig. la)

[0089] Two flat wire spiral helical copper conductors, each having a void core of 0.8 cm diameter, a flat wire width of 3 mm, a wire thickness of 0.2 mm and 10 turns, were prepared from two commercial inductors by removing the insulating layers in NaOH melt. One of the conductors was plated with a ~ 2 pm thick tin layer by immersing it in a commercial electroless tin solution for an hour; the other conductor was electroplated with a ~ 5 pm nickel layer in an electroplating aqueous solution of 1M NiCb for 20 minutes by applying a 5 V DC between the conductor and a 10 W resistor which is connected to a nickel barrel counter electrode. The plated tin and nickel layers are respective protection layers to prevent the conductors from electrochemical corrosion. The tined conductor was then electroplated with a porous zinc layer in 6M KOH-0.3M ZnO aqueous solution for half an hour by applying a 5 V DC between the conductor and a 10 W resistor which is connected to a stainless steel barrel as a counter electrode forming a zinc electrode; the nickel electroplated conductor was coated with electrically conductive silver paint and dried at l50°C for 30 minutes forming a sliver electrode. The silver and zinc electrodes were then coated with the 8wt% polyvinyl alcohol (PVA) - 8wt% KOH aqueous electrolyte slurry using a dip coating method and dried in air forming semi-solid gelled electrolyte covered silver and zinc electrodes respectively. Next, one electrode is arranged on a pencil by passing the pencil through the void core of the electrode; and then screw the other electrode in from one side of the pencil until two helical electrodes reach fully match; subsequently, press two electrodes from both sides thereof to make all adjacent turns in touch forming a silver zinc battery. Finally the battery was wrapped using thin plastic film, and the pencil was removed leaving the silver zinc battery with a void core. The electrodes were connected to a Zener diode (2.4 V, 0.5W) to form an inductive chargeable energy storage circuit and sealed in a plastic casing. The KOH - PVA semi-solid gelled electrolyte layer serves as a separator to prevent short circuit between two electrodes, and an ion conductor.

[0090] Example 2: A supercapacitor (as configured in Fig. 3)

[0091] The supercapacitor was fabricated using the same procedures as used for example I. Two helical electrodes were prepared by coating pen brush carbon ink - 5 wt% PVA aqueous slurry on two bare helical copper conductors and dried in air; and then the electrodes were coated with 8wt% PVA - 8wt% CH ₃ COONa aqueous electrolyte slurry and dried in air forming two semi-solid gelled electrolyte covered electrodes. Two Zener diodes were used for the circuit connections.

[0092] Example 3: A supercapacitor (as configured in Fig. 4a) [0093] Two 65 cm long, 300 mih diameter copper wires were coated with the pen brush carbon ink - 5wt% PVA aqueous slurry using a dip coating method and dried in air forming two wire like electrodes; the electrodes was then coated with the 8wt% PVA - 8wt% CH AOONa aqueous electrolyte slurry and dried in air forming two semi-solid gelled electrolyte coated electrodes. The supercapacitor was fabricated by winding two semi-solid gelled electrolyte coated electrodes side by side around a PVC core (inner diameter 1.0 cm and outer diameter 1.2 cm) in turns spirally. A further electrolyte coating was applied onto the wound helical electrodes to enforce the helical structure. Finally, the electrodes were connected to a 2.4 V Zener diode and sealed in a plastic casing.

[0094] Example 4: A nickel zinc battery (as configured in Fig. 5b)

[0095] A nickel electrode was fabricated by coating nickel electrode slurry (84 wt% Ni(OH) ₂ , 10 wt% carboxylmethylcellulose (CMC) as a binding agent, 5 wt% graphite and 1 wt % ZnO in deionised water) onto a 75 cm long, 300 pm in diameter silver plated copper wire using a dip coating method and dried in air; the electrode was then coated with the 8wt% PVA - 8wt% KOH gel electrolyte slurry and dried in air forming a semi-solid gelled nickel electrode. A zinc electrode was fabricated by coating zinc electrode ink (84.5 wt% ZnO nanoparticle powder, 10 wt% Zn powder, 5 wt% CMC and 0.5 wt % CafOH ) ₂ in deionised water) onto a 75 cm long, 300 pm in diameter copper wire and dried in air; the electrode was then coated with the PVA-KOH gel electrolyte slurry and dried in air forming a semi-solid gelled zinc electrode. The nickel zinc battery was fabricated by winding the zinc electrode on a PVC tube (inner diameter 1 cm and outer diameter 1.2 cm) in turns spirally forming a zinc helical spiral electrode first; next, the zinc electrode was wrapped around using a PVA-KOH electrolyte slurry coated filtration paper; finally, the nickel electrode was wound around the wrapped zinc electrode in turns spirally forming a nickel helical electrode. The electrolyte coated filtration paper serves as a separator to separate two electrodes and prevent short circuit between two electrodes. Two electrodes, being spiralled in opposite directions, were connected to two 2.4 V Zener diodes forming an inductive chargeable nickel zinc battery and sealed in a polyethylene casing having a 1.0 mm thick wall.

[0096] Example 5: A strip-wound spiral supercapacitor (as configured in Fig. 6a)

[0097] Gelled electrode preparation: a piece of copper tape was coated with the carbon ink slurry on its conductive side using a doctor-blade method and dried in air forming a strip electrode; the strip electrode was then coated with the gel electrolyte slurry, when the solvent vaporises, a gelled electrolyte layer is formed on the strip electrode. The gelled electrodes of 30 mhi thick electrode material layer and 50 mih gel electrolyte layer were prepared. The dense carbon ink layer also provides protection for the copper strip from electrochemical corrosion.

[0098] The supercapacitor was prepared by winding a pair of 70 cm long gelled electrodes around a 1 cm long PVC tube in turns concentrically and spirally, in which the unified gelled electrolyte layer functions as a separator to separate two strip electrodes and as an ion conductor to conduct current in the electrolyte layer between two strip electrode windings. Before winding, a piece of copper tape is glued to the inner end of one strip electrode using silver conductive paint as one electrode lead; after winding, another piece of copper tape is glued to the outer end of the other electrode as the other electrode lead. The electrode leads are connected to the cathode and anode of a diode (ST4148), respectively, forming an inductive chargeable circuit.

[0099] Example 6: A strip-wound nickel zinc battery (as configured in Fig. 6a)

[0100] A nickel electrode was fabricated by coating the nickel electrode ink on both sides of a stainless steel strip of 60 cm long, 1 cm wide and 10 pm thick and dried in air, and then the electrode was coated with the PVA - KOH aqueous electrolyte slurry forming a semi-solid gelled electrode. A zinc electrode was fabricated by coating the zinc electrode slurry on both sides of 25 pm thick conductive copper strip and dried in air, and then the electrode was coated with the PVA - KOH slurry forming a semi-solid gelled zinc electrode. The NiZn battery was fabricated by winding the two strip electrodes around a plastic bobbin (having a tubular core of an inner diameter 1.2 cm and outer diameter 1.4 cm, and a length of 1.2 cm) in turns concentrically and spirally; the battery was then connected to a 2.4V Zener diode and sealed using 1.0 mm thick polyethylene (PE) sheet.

Inductive Charging Test

[0101] An electric toothbrush charger (Oral-B) or a flat double-coil charging module (6 V ~ 12V) was used as an inductive charging platform. The RMS USB Multimeters (A UNI-T USB + RS232 Clas Ohison Edition UT61D) was used to monitor the voltage between two electrodes when the inductive charger is turned on and off manually, and the voltage variation was recorded by a laptop automatically through a USB connection.

[0102] Fig. 7 shows curves of inductive charging, and discharging through a 1.2 V white LED for the silver-zinc battery (example 1) conducted using the double-coil charging module. It can be seen that when the charger is turned on, the voltage of the device increases quickly, and then gradually reaches a steady-state value of 1.6V at around 100 seconds; when the charger is turned off, the battery is connected to the LED, the LED is illuminated and the voltage drops; when the voltage drops to ~ 0.75 V, the illumination gradually diminishes and the voltage is stabilized. Four charging-discharging cycles are repeatable, which demonstrates the device is stable during the consecutive charging-discharging.

[0103] Fig. 8 shows inductive charging, and self-discharging curves for the supercapacitor (example 2), it can be seen that during repeated inductive charging and self-discharging cycles, the device is stable. The self-discharging is a typical phenomenon in aqueous electrolyte based supercapacitor, which may originate from the stored charges’ re-organisation in the electrode material layers and thermal discharging. The steady-state voltage may include induced voltages in the conductors of the electrodes. The Oral-B charger was used.

[0104] Fig. 9 shows inductive charging, and self-discharging curves for the supercapacitor (example 3); stable and repeatable charging-self-discharging cycles are observed. The double coil charging module was used.

[0105] Fig. 10 shows curves of inductive charging, and discharging through a 1.2 V white LED, which was recorded for the NiZn battery (example 4) using the double-coil charging module. It can be seen that, when the charger is turned on, the voltage of the battery increases quickly and reaches a steady-state value of ~ 2.3 V; when the charger is turned off and the device is connected to the LED, the LED is illuminated and the voltage drops. The device is stable during repeated inductive charging, and discharging.

[0106] Fig. 11 shows inductive charging, self-discharging results recorded for a strip wound supercapacitor (examples 5). The device can be charged inductively and are stable during consecutive inductive charging, and self-charging cycles. The Oral -B charger was used.

[0107] Fig. 12 shows curves of inductive charging, and discharging through a 1.2 V white LED, which was recorded for the NiZn battery (example 6) using the double-coil charging module. It can be seen that when the inductive charger is turned on, the battery is quickly charged, and the voltage gradually reaches a steady-state value of ~ 1.53V; when the charger is turned off, the device is connected to the LED, the LED is illuminated and the voltage drops. The device is stable during repeated inductive charging, and discharging cycles.