AU2012206930A1

AU2012206930A1 - Ion-exchange battery

Info

Publication number: AU2012206930A1
Application number: AU2012206930A
Authority: AU
Inventors: Pu Chen
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-01-15
Filing date: 2012-01-12
Publication date: 2013-05-16
Also published as: WO2012094761A1

Abstract

A rechargeable battery consists of a cathode electrode, an anode electrode and an electrolyte. The cathode active material is one or more of lithium or sodium ion intercalation compounds; the anode electrode is conductive and electrochemically inert that does not participate in the electrochemical reaction; the electrolyte is a water or alcohol solution, which at least contains a kind of dissolved metal ion that can be reduced to metallic state and deposit on the surface of the anode electrode when the battery is charging. The discharging process reverses the reactions of the charging process.

Description

WO 2012/094761 PCT/CA2012/050019 ION-EXCHANGE BATTERY CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority under the Paris Convention to US Application Number 61/433,216, filed January 15, 2011, the entire contents of which are incorporated herein by reference. FIELD OF THE INVENTION [0002] The present invention relates to a secondary battery. In particular, the invention relates to an aqueous, ion exchange secondary battery. BACKGROUND OF THE INVENTION [0003] Since the invention of lead-acid batteries, the energy storage and conversion industry has entered the "secondary battery times". As known in the art, a "secondary battery", also referred to as a rechargeable battery, is a battery wherein the internal electrochemical reactions are reversible. Various kinds of secondary batteries are applied in different fields depending on their specific requirements. For example, portable electronic devices require a battery with a high energy density as in lithium ion (Li-ion) batteries, electric tools require a high power output as in Li-ion, Ni-MH, and Ni-Cd batteries, and large energy storage applications (such as a UPS), motor start-up batteries, wind power/solar energy storage devices all require batteries with low cost and long service life. [0004] Lead-acid batteries have been occupying the majority of the battery market share, especially among energy storage fields for several decades. But this fact should not conceal many disadvantages of the lead-acid batteries, in particular, the lead pollution problem associated with its manufacture, battery recall and recycle after use, short service life (typically 2 years), and low energy density. It is necessary to find a new battery, which comes with low cost, long service life, environment friendly and good safety characteristics, to replace the present lead-acid batteries. Although the current Li-ion and Ni-MH batteries have better performance than lead-acid batteries in energy density, power density, service life and environment aspects, they still cannot replace the lead-acid batteries mainly because of the cost. [0005] To solve this problem, many researchers turned to aqueous Li-ion battery, hoping to use water based electrolytes in place of organic electrolytes and drastically reduce the 1 WO 2012/094761 PCT/CA2012/050019 cost of Li-ion batteries, and also to solve the safety problem with Li-ion batteries. In 1994, Jeff Dahn et al. presented an aqueous battery with LiMn 2 0 4 as the cathode material, vanadium oxide such as V0 2 as the anode material, and a water solution of lithium salts as the electrolyte [LI W., DAHN J.R., WAINWRIGHT D.S., Science, 264 (1994), 1115]. Up to now, all reported aqueous Li-ion batteries used the same principle as the Li-ion battery, based on an embedded type structure on both positive and negative electrodes, such as LiMn 2 04/VO 2 , LiNio 81 CoO 19 0 2 /LiV 3 0 8 , LiMn 2 0 4 /TiP 2 0 7 , LiMn 2 0 4 /LiTi 2

(PO

4

)

3 , and LiCoO 2 /LiV 3 0 8 . A further example of such batteries is provided in US Patent Number 7,189,475. However, all these batteries have a low energy density and poor cycle life, because of the decomposition of the intercalation anode materials during charging and discharging in the aqueous solution (i.e. water). [0006] A need exists for an improved aqueous secondary battery that can replace current lead-acid batteries. SUMMARY OF THE INVENTION [0007] Accordingly to one aspect, the invention provides a rechargeable battery consisting of a cathode electrode, an anode electrode and an electrolyte. [0008] The cathode active material comprises one or more intercalation compounds, such as lithium or sodium intercalation compounds; the anode electrode generally comprises a conductive and electrochemically inert material that does not participate in the electrochemical reaction; and the electrolyte is a water or alcohol solution, which contains ions of at least one dissolved metal that can be reduced to a metallic state and deposited on the surface of the anode electrode when the battery is charging. The discharging process reverses the reaction of the charging process. [0009] Thus, in one aspect, the invention provides a rechargeable battery, capable of charge and discharge cycles, comprising a cathode, an anode and an electrolyte, wherein: [0010] - the cathode includes a cathode active material; [0011] - the anode comprises a conductive and electrochemically inert material that does not participate in the electrochemical reaction; 2 WO 2012/094761 PCT/CA2012/050019 [0012] - the electrolyte comprises a water or alcohol solution, which includes ions of at least one dissolved metal that can be reduced to a metallic state during the charge cycle and oxidized from the metallic state to the dissolved ion state during the discharge cycle. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The features of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein: [0014] Figure 1 shows a schematic of the battery, which is composed of a cathode electrode, an anode electrode and an electrolyte. The cathode material is a lithium or sodium intercalation compound and the anode electrode is an inert, conductive material. [0015] Figure 2 shows a schematic of the battery charging process. When the battery is charging, lithium/sodium ions deintercalate from the cathode material and one kind of active metal ions in the electrolyte is reduced to metallic state and plates on the surface of anode. [0016] Figure 3 shows a schematic of the battery discharge process. When the battery is discharging, lithium/sodium ions intercalate into the cathode material and the active metal on the surface of the anode electrode oxidizes to ionic state and dissolves into the electrolyte. [0017] Figure 4 shows the charge and discharge curve at a 1.5C rate for the spinel LiMn 2 0 4 , as the cathode material, and tin plated copper as the anode electrode, and 4M zinc chloride and 1 M lithium chloride in the electrolyte. [0018] Figure 5 shows the cyclability curve at a 5C rate for spinel LiMn 2 0 4 as the cathode material and tin plated copper as the anode electrode, and 4M zinc chloride and 1 M lithium chloride in the electrolyte. The discharge capacity almost does not fade after 250 cycles. [0019] Figure 6 shows the charge and discharge curve at a 1.5C rate for the olivine LiFePO 4 as the cathode material and tin plated copper as the anode electrode, and 4M zinc chloride and 6M lithium chloride in the electrolyte. [0020] Figure 7 shows the cyclability curve at a 5C rate for olivine LiFePO 4 as the cathode material and tin plated copper as the anode electrode, and 4M zinc chloride and 1 M lithium chloride in the electrolyte. The discharge capacity almost does not fade after 100 cycles. 3 WO 2012/094761 PCT/CA2012/050019 DETAILED DESCRIPTION OF THE INVENTION [0021] As used herein, the terms "comprise", "comprises", "comprised" or "comprising" are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not as precluding the presence of one or more other features, integers, steps, components or a group thereof as would be apparent to persons having ordinary skill in the relevant art. [0022] In one aspect, the present invention provides a secondary battery based on the principle of ion-exchange in the electrolyte. The present battery is referred to as an Ion Exchange Battery (IEB). The battery comprises a positive electrode, a negative electrode and an electrolyte. The cathode preferably contains one or more active intercalation materials. The anode is preferably conductive and electrochemically inert. The electrolyte is preferably a solution containing one or more metal ions. [0023] The cathode material of the present ion-exchange battery may comprise one of the lithium intercalation compounds with a layer structure, spinel structure or olivine structure, or sodium intercalation compounds, such as NaVPO 4 F. During charging, Li/Na ions inside the cathode material deintercalate into the electrolyte, and during discharging, Li/Na ions in the electrolyte intercalate into the cathode. [0024] The anode electrode of the present ion-exchange battery is conductive and preferably electrochemically inert. The anode material may be selected from carbon based materials, or metals electroplated or coated by one or more of Sn, In, Ag, Pb, Co, and Zn. [0025] The electrolyte according to one aspect of the present ion-exchange battery comprises a solution containing at least one metal ion, such as Zn, Ni, Fe, Cr, Cu and Mn. This sort of metal ion is reduced and deposited onto the surface of the anode during the charging step. The discharging process reverses this reaction. The solvent of the electrolyte is preferably an aqueous solution. By way of example, the electrolyte may comprise water, ethanol, methanol, or mixtures thereof. To accelerate the rate of ion exchange, suitable amounts of additional Li or Na salts may be preferably added into the electrolyte. [0026] Without being restricted to any theory, the working principle of the present ion exchange battery may be summarized as follows: during the charging process, Li/Na ions inside the cathode deintercalate into the electrolyte, while, simultaneously, the metal ions in the electrolyte are reduced and deposited onto the surface of the anode. The discharging 4 WO 2012/094761 PCT/CA2012/050019 process reverses the reaction. Thus, the present battery operates, according to one aspect, with an ion exchange process in the electrolyte. [0027] The novel battery according to one aspect of the present invention has one or more of the following characteristics: long life; environmentally friendly; and safe. As will be understood by persons skilled in the art, a battery according to the present invention may comprise a number of suitable combinations of the cathodes, anodes and electrolytes. [0028] The battery according to the present invention was developed after extensive and in-depth research. The battery, according to one aspect of the invention, includes cathode, anode and electrolyte materials. The cathode includes a current collector and cathode active material, and the cathode active material participates in the electrochemical reaction. The cathode active material is preferably a lithium or sodium ion intercalation compound; the anode is an inert electrode that is not involved in the electrochemical reaction; the electrolyte is a solution, which contains certain metal ions. During the charging process, the ions deintercalate from the cathode into the electrolyte, and the metal ions, which exist in the electrolyte, are reduced into metal atoms and deposit onto the anode at the same time. The discharging process reverses the reactions of the charging process. [0029] Without being limited to any theory, when the battery of the invention is charging, the lithium or sodium ions deintercalate from the cathode active material, accompanied by oxidation of the valency varying metal in the active material and releasing electrons. The electrons flow through the external circuit to reach the anode of the battery; meanwhile metal ions in the electrolyte (at least one sort of metal ion among the elements of Zn, Ni, Fe, Cr, Cu and Mn) are reduced to metallic state and are deposited onto the anode surface. The discharging process is the reverse of the charging process. [0030] Again, without limiting the invention in any way, the principle of the battery of the invention is: when charging (reference to Figure 2), the cathode active material reacts, where Li (HOST)- e--> Li + + (HOST), and the anode presents Mx+ + xe--> M. Li (HOST) is a lithium ion intercalation compound; M is a metal; Mx+ is the ionic state of M. If the cathode active material is a sodium ion intercalation compound, the cathode active material reacts with Na (HOST)-e--> Na + + (HOST), and the anode presents Mx+ + xe--> M when charging. [0031] According to one embodiment, the invention comprises a LiMn 2 0 4 /Zn battery (as illustrated in Figures 3 and 4), with LiMn 2 0 4 as the cathode active material, tin plated copper film/foil as the anode, and 5 mol/L ZnCl 2 as the electrolyte. In such example, during 5 WO 2012/094761 PCT/CA2012/050019 charging, Li+ ions deintercalate from the spinel crystal lattice of LiMn 2 0 4 , while trivalent manganese is oxidized to tetravalent manganese with an accompanying electron output. In this example of the invention, LiMn 2 0 4 turns to Lij-x Mn 2 0 4 and Zn 2 + ions in the electrolyte are reduced to a metallic state and are deposited on the anode surface. When the battery is charging (as shown in Figure 2), the reaction at the cathode is LiMn 2 0 4 -xe--> Li+ + Lij_ xMn 2 0 4 , and the reaction at the anode is Zn 2 + + xe--> (x / 2) Zn. The discharging process reverses these reactions. [0032] In the current lithium battery industry, almost all cathode materials are doped, coated, or modified by various methods. For example, LiMn 2 0 4 is no longer able to represent the general formula of a "lithium manganese oxide" that is widely used. Strictly, the general formula of the material should be according to the general formula of the spinel structure compound that the present invention involves. However, doping, coating and other modifications cause the chemical formula of the material to be more complex, so the formula LiMn 2 0 4 should include the cathode materials of a variety of modifications, and be consistent with the general formula of the spinel structure compounds, as described in the present invention. The chemical formula of LiFePO 4 , and other materials described herein, will be understood to include the materials of a variety of modifications and to be consistent with the general formulae of layered structure, spinel structure or olivine structure compounds. [0033] In a preferred embodiment, according to the present invention, the material that can reversibly intercalate-deintercalate includes the compounds that are able to intercalate deintercalate lithium, sodium and other ions. The present inventor has found that: when the cathode active material is a lithium ion intercalation-deintercalation compound, it can be selected from, for example, LiMn 2 0 4 , LiFePO 4 , LiCoO 2 , LiMxPO 4 , LiMxSiOy (where M is a metal with a variable valence, x) and other compounds; when the cathode active material is a sodium ion intercalation-deintercalation compounds, it can be, for example, NaVPO 4 F. [0034] According to one aspect of the invention, the intercalation-deintercalation compounds may comprise: layered structure compounds, spinel structure compounds, olivine structure compounds, or other lithium ion or sodium ion intercalation-deintercalation compounds. [0035] According to one aspect of the present invention, the intercalation-deintercalation compound comprises a layered structure compounds having the general formula Li+xMyM'zM"c 0 2 +n, wherein 0 <x:5 0.5, 0 5 y 5 1, 0 5 z < 1, 0 5 c < 1, and -0.2 s n 5 0.2. M, M 6 WO 2012/094761 PCT/CA2012/050019 and M" are selected from one of the following: Ni, Mn, Co, Mg, Ti, Cr, V, Zn, Zr, Si, and Al. According to one embodiment, the layered structure compound comprises LiCoO 2 . [0036] According to one aspect of the present invention, the intercalation-deintercalation compound comprises a spinel structure compound having the general formula Lil+XMnyMzOk, wherein O<x0.5, 1:5ys2.5, Osz:0.5, and 3:5k6. M is selected from one of the following: Na, Mg, Ti, Cr, V, Zn, Zr, Si, and Al. In one embodiment, the compound is LiMn 2 0 4 , which also includes the LiMn 2 0 4 that has been doped, coated, or modified by other methods. [0037] According to one aspect of the present invention, the intercalation-deintercalation compound comprises an olivine structure compound having the general formula LixM1-y M'y(X'0 4 )n, in which O<x<2, Oy:0.6, and 1:5ns1.5. M is selected from the transition metals: Fe, Mn, V, and Co. M' is selected from one of Mg, Ti, Cr, V and Al. X' is selected from S, P and Si. For example it is LiFePO4, which includes the LiFePO4 that has been doped, coated by carbon, or modified by other methods as known in the art. [0038] According to one aspect of the present invention, the cathode structure further includes a cathode current collector. In one aspect, the current collector may comprise: stainless steel, carbon fibre, graphite, or other electrochemically stable electron conductors known in the art, or combinations thereof. [0039] According to one aspect of the invention, the material of the anode electrode may comprise various elements or alloys known in the art. In one aspect, the anode material may comprise one or more of: Cu, Ag, Fe, Sn, Al and Ni. In another aspect, such anode material may be covered by a layer of metal or metal oxide via coating or plating. The coating/plating material may comprise one or more of: C, Sn, In, Ag, Pb, Co, and Zn. [0040] According to one aspect of the invention, the electrolyte of the subject battery comprises a salt solution. In one aspect, the salts in the electrolyte may be selected from chloride, sulphate, nitrate, acetate and formate salts. In another aspect, the concentration of the electrolyte salt solution may range from 0.1 mol/L to 15 mol/L. If the cathode active material is a lithium intercalation compound, the electrolyte may also contain a lithium salt to accelerate the rate of ion exchange. In one aspect, the lithium salt concentration may range from 0.1 mol/L to 10 mol/L. [0041] According to one aspect of the invention, a process is provided for manufacturing the cathode, the process comprising combining the cathode material, a conductive agent 7 WO 2012/094761 PCT/CA2012/050019 and a binder, which are mixed together and coated on a graphite plate, a conductive carbon matrix, or a stainless steel plate. In one aspect, the cathode material comprises LiMn 2 0 4 . [0042] In one aspect of the invention, the anode comprises a tin plated copper foil. In another aspect, the thickness of the copper foil is 100 pm, and the thickness of the tin layer is 5 pm. Other thicknesses of these materials will be apparent to persons skilled in the art in view of the description of the invention provided herein. [0043] According to one embodiment of the invention, the electrolyte comprises an aqueous solution comprising LiCI, Li 2

SO

4 , LiNO 3 , ZnCl 2 , ZnSO 4 , Zn(N0 3

)

2 or any combination thereof. In one aspect, the electrolyte comprises a solution containing 1 mol/L LiCI, or Li 2

SO

4 , LiNO 3 , and 4 mol/L ZnCl 2 , or ZnSO 4 , or Zn(N0 3

)

2 . [0044] In one aspect of the invention, a membrane may be provided with the battery structure. In such case, the membrane may comprise an organic or inorganic porous material. In one aspect, the membrane has a porosity of 20-95% and includes pores having a pore size of 0.001-100 pm. [0045] All features described can be replaced by features that can provide the same, equal or similar purpose. Therefore, unless otherwise stated, the features revealed are only the general features of equal or similar examples. [0046] As will be understood by persons skilled in the art after having reviewed the present description, the main advantages offered by the present invention include one or more of: improved cycleability; environmentally safe (due to the lack of potentially environmentally harmful components); and low cost of production. [0047] Examples [0048] Aspects of the present invention are described below by means of various illustrative examples. The examples contained herein are not intended to limit the invention in any way but to illustrate same in more detail. It should be understood that the experiments in the following examples, unless otherwise indicated, are in accordance with conditions as would be known to persons skilled in the art or the conditions recommended by manufacturers. Unless indicated otherwise, all percentages, ratios, proportions referred to in the examples are calculated by weight. 8 WO 2012/094761 PCT/CA2012/050019 [0049] Example 1 [0050] This example is divided into four sections, which illustrate the different lithium or sodium ion intercalation-deintercalation compounds used as the battery cathode active materials. As discussed above, the scope of the present invention is not intended to be limited to the specific examples provided herein. Example 1-1, 1-2, 1-3 and 1-4 serve to illustrate the principle of the invention to persons skilled in the art. [0051] Example 1-1 [0052] A cathode was prepared comprising 90% LiMn 2 0 4 as the cathode active material, 6% conductive carbon black, 2% SBR binder (styrene butadiene rubber milk), and 2% CMC (carboxymethyl cellulose sodium). The CMC was first mixed with water, followed by addition of the cathode active material and conductive carbon black. The mixture was stirred for 2 hours, and followed by addition of a SBR slurry. The mixture was then stirred for 10 minutes to form the cathode slurry. The cathode slurry was coated evenly on a 1 mm thick graphite plate, which served as the cathode current collector. The slurry was allowed to dry at 120 OC for 12 hours, to form the cathode plate. [0053] The anode electrode of the battery comprised a tin plated copper foil, wherein the thickness of the copper foil was 0.1 mm and the thickness of the tin plating was 0.005 mm 0.01 mm. The electrolyte comprised a water solution containing 4 mol/L zinc chloride and 1 mol/L lithium chloride. A non-woven membrane was used. [0054] The cathode electrode and anode electrode were assembled to form a battery, wherein the electrodes were separated with the membrane. The battery structure is shown in Figure 1. The electrolyte was injected into the battery and allowed to stand still for 12 hours. Following this, the battery was then charged and discharged with a 1.5 C rate. The voltage range of charge and discharge was 1.4 - 2.15 V (i.e., the battery was charged with constant current of 100 mAh to 2.15V, and then discharged with constant current to 1.4V, with these two steps being cycled). The first charge and discharge voltage - time curve of the battery is shown in Figure 4. As shown in Figure 5, the battery exhibited excellent cycling performance. [0055] Example 1-2 [0056] A battery was made according to a method similar to that described in Example 1-1. However, in this case, LiFePO 4 was used as the cathode active material instead of 9 WO 2012/094761 PCT/CA2012/050019 LiMn 2 0 4 . The operation voltage range of this battery was 0.8V-2V. The testing results of the cycling are shown in Figure 6 and Figure 7. Different from example 1-1, the operation voltage of this battery is lower and the average discharge voltage is around 1.2V, but it shows better cycling performance, i.e. almost no fading after 100 cycles. As illustrated by this example, although LiFePO 4 as the cathode active material instead of LiMn 2 0 4 results in a lower operation voltage, the battery of this example exhibits better cycling performance. [0057] The same principle, using LiMnPO 4 , which is of olivine structure, or other materials that have a similar structure, as the cathode active material, instead of LiMn 2 0 4 , can also form a battery according to the present invention. [0058] Example 1-3 [0059] A battery was made according to a method similar to that described in Example 1-1. However, in this case, LiMn 1

/

3 Ni 1 /3Co1/ 3 was used as the cathode active material. Different from Example 1-1, the operation voltage range of this battery was 1.3V-2.1V. This battery can also charge and discharge reversely. Because LiMn 1

/

3 Ni 1 /3Co 1

/

3 has a higher energy density than LiMn 2 0 4 , the battery of this example was found to have a higher energy density than the battery of Example 1-1. [0060] Although data concerning the charge, discharge and cycle curves of the batteries made according to the examples was obtained, such data is not provided herein for brevity. However, the different performances of certain of the batteries made according to the examples are summarized in the tables provided herein. For example, the battery performance of example 1-3 is shown in Table 1. [0061] Example 1-4 [0062] A battery was made according to a method similar to that described in Example 1-1. However, in this case, NaVPO 4 F was used as the cathode active material. The electrolyte was a water solution containing 4 mol/L zinc chloride and 1 mol/L sodium chloride. Different from example 1-1, the operation voltage range of this battery was 0.6 V 2.0 V. As will be noted, in this example, the electrolyte contained 1 mol/L sodium chloride instead of 1 mol/L lithium chloride. Although the performance of this battery was found to be not as good as that of Examples 1-1, 1-2 and 1-3, which used a lithium ion intercalation material as the cathode material, the sodium ion intercalation materials used in Example 1-4 were more easily available and less toxic, which therefore reduces the cost and environmental impact of the battery. The results of this example are shown in Table 1. 10 WO 2012/094761 PCT/CA2012/050019 [0063] Table 1. Battery performance using different cathode materials Average Discharge Cathode Anode Electrolyte Voltage discharge capacity material range (V) voltage retention after 100 cycles Example Tin plated 1M LiCI 1.3-2.1 1.4 90% 1-3 Copper foil +4M ZnCl 2 Example Tin plated 1M LiCI 0.6-2.0 1.5 76% 1-4 Copper foil +4M ZnCl 2 [0064] Example 2 [0065] Example 2 describes the performance of batteries with different anode materials. The structure of the anode of the present invention is divided into a substrate and coating/plating, and the design of the anode involves, in addition to thickness and other physical dimensions, various elements and compositions of different structures. [0066] Example 2-1 [0067] A battery was made according to a method similar to that described in Example 1-1. However, in this battery, lead plated copper foil was used as the anode material. The thickness of the copper foil was 0.1 mm and the thickness of the lead layer was 0.005 mm 0.02 mm. When charging, Zn 2 +, present in the electrolyte, was reduced to its metallic state and was deposited on the surface of the anode. When discharging, metallic zinc on the surface of the anode was oxidized to Zn2+ and dissolved into the electrolyte. The performance of this battery is shown in Table 2. [0068] Example 2-2 [0069] A battery was made according to a method similar to that described in Example 1-1. In this case, silver plated copper foil was used as the anode active material. The performance of this battery is shown in Table 2. [0070] Example 2-3 [0071] A battery was made according to a method similar to that described in Example 1-1. In this case, tin plated nickel was used as the anode active material. The performance of this battery is shown in Table 2. 11 WO 2012/094761 PCT/CA2012/050019 [0072] Example 2-4 [0073] A battery was made according to a method similar to that described in Example 1-1. In this case, tin plated copper foil was used as the anode. To form the anode, SnO and SBR were mixed evenly in a weight proportion of 5:1 to form a slurry. The slurry was then coated on the surface of the copper foil. The performance of this battery is shown in Table 2. [0074] Example 2-5 [0075] In this example, a battery was made in the same manner as described in Example 2-4. However, in this case the anode comprised a lead oxide coated copper foil. The anode was formed in the same manner as discussed in Example 2-4, with the exception of using PbO in formulating the slurry with SBR instead of SnO. The performance of this battery is shown in Table 2. [0076] Example 2-6 [0077] A battery was made according to a method similar to that described in Example 1-1. In this example, a tin plated graphite plate was used as the anode. In making this anode, a graphite plate was used as the anode substrate, and was coated with tin by plating. The thickness of the graphite substrate was 1 mm and the thickness of the tin plating layer was 50 pm. The performance of this battery is shown in Table 2. [0078] The different anodes described in Examples 2-1 to 2-6 illustrate that the anode structure is important in the battery and influences the battery performance. The plating/coating on the surface of the anode has been shown to influence the Coulomb efficiency and other performance characteristics of the battery. [0079] Table 2 Battery performance with different anode material Voltage First cycle Discharge Cathode Anode Eltrolyt range Coulomb capacity material lectrolte rt effc retention after 100 cycles Example Lead plated 1M LiCI 1.4-2.15 95% 99% 2-1 Copper foil +4M ZnCl 2 Example LiMn204 Silver plated 1.4-2.15 95% 99% 2-2 Copper foil 12 WO 2012/094761 PCT/CA2012/050019 Example Tin plated nickel 1.4-2.15 92% 99% 2-3 foil Example SnO 2 coated 1.4-2.15 97% 98% 2-4 copper foil Example PbO 2 coated 1.4-2.15 97% 94% 2-5 copper foil Example Tin plated graphite 1.4-2.15 99% 99% 2-6 [0080] Example 3 [0081] In the electrolyte of the battery, at least one kind of metal ions reacts on the surface of the anode and reduces to its metallic state during the process of charging. As will be understood, and as illustrated in this example, because of different redox potentials, using different metal ions can influence the charge-discharge voltage directly. [0082] Although the two batteries described in this example, which use other metal ions instead of Zn 2+ in the electrolyte, have low coulomb efficiencies and are of difficult practical use, the example provides illustrates that various different metal ions may be used in the battery system of the present invention. [0083] Example 3-1 [0084] A battery was made according to a method similar to that described in Example 1-1. In this example, 4 mol/L chromic nitrate was used in the electrolyte instead of zinc chloride. During the process of charging, the above mentioned lithium deintercalation reaction occurred at the cathode. However, the reaction at the anode resulted in the reduction and deposition of Cr3+ on the surface of the anode due to the change in the electrolyte. Because the redox potential of chrome is lower than that of zinc, the battery of this example was found to have a higher open circuit voltage. But the overpotential of the hydrogen evolution on chrome is lower than on zinc, so the evolution of hydrogen at the anode during the process of charging was believed to be the cause of the lower charge efficiency. [0085] The performance of this battery is shown in Table 3. 13 WO 2012/094761 PCT/CA2012/050019 [0086] Example 3-2 [0087] A battery was made according to a method similar to that described in Example 1-1. In this example, 4 mol/L manganese chloride was used instead of zinc chloride. During the process of charging, the same lithium deintercalation reaction was found to occur at the cathode. In this example, the reaction at the anode involved the reduction and deposition of Mn 2 on the surface of the anode. Because the redox potential of manganese is lower than zinc, this battery has a higher open circuit voltage. But the evolution potential of hydrogen on Mn was too low, so the evolution of hydrogen at the anode during charging was believed to be the cause of the lower charge efficiency. The performance of this battery is shown in Table 3. [0088] Table 3. Battery performance with different anode materials Cathode Voltage Average First cycle material Anode Electrolyte range discharge Columbia (V) voltage(V) efficiency 1M LiCI Example 3-1 Tin +4M 1.3-2.2 1.8 45% LiMn 2 0 4 plated Cr(NO) 3 Copper foil 1M LiCI Example 3-2 1.3-2.2 2.0 42% +4M MnCl 2 [0089] Example 4 [0090] According to one aspect of the invention, conductive carbon material is used as the cathode current collector to transmit electrons. This example serves to illustrate the use of a current collector comprising a mixture carbon and a binder (in the ratio of 0-80%). [0091] Example 4-1 [0092] A battery was made according to a method similar to that described in Example 1-1. In this case, the cathode current collector was made using carbon fibre fabric, the thickness of which was 0.1 mm. The fabric was sized to be a little bigger than the cathode active material. The performance of this battery was found to be almost the same as that of the battery of Example 1-1. 14 WO 2012/094761 PCT/CA2012/050019 [0093] Example 4-2 [0094] A battery was made according to a method similar to that described in Example 1-1. In this example, the cathode current collector was made by evenly mixing graphite, carbon black and a binder, and then forming the mixture to a plate and drying. The proportion of graphite:carbon black:binder was 6:3:1 and the thickness of the current collector plate was 1 mm. The performance of this battery was found to be almost the same as the battery of Example 1-1. [0095] Example 5 [0096] In the present example, the performance and characteristics of batteries according to the invention were compared to other batteries as known in the art. Table 4 below summarizes the results of such comparison. [0097] Table 4. Comparison of performance of present battery with known batteries Energy Cost Cycle life Environment density $/Wh 100%DOD Maintenance accept- Safety Wh/Kg ability Lead 30-40 0.1 300-500 Unnecessary Low High Ni Commercialized MH 40-60 0.5 500-1000 Unnecessary Medium High Ni- 30-40 0.3 500-1000 Unnecessary Low High Ni- 50-70 0.3- 100-500 Unnecessary High High Zn 0.5 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ VRB No -1.5 10000 Complex Medium High Immature requirement 2000_ Na- 100-150 0.6 2000 Unknown Medium Low Br- 30-100 -1 1000- Unknown Medium High Zn _ _ _ 3000 1______ 1______ Present invention 50-70 0.1 1000+ Unnecessary High High VRB: Vanadium redox battery Na-S: High temperature sodium sulphur battery [0098] Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the purpose and scope of the invention as outlined in the claims 15 WO 2012/094761 PCT/CA2012/050019 appended hereto. Any examples provided herein are included solely for the purpose of illustrating the invention and are not intended to limit the invention in any way. Any drawings provided herein are solely for the purpose of illustrating various aspects of the invention and are not intended to be drawn to scale or to limit the invention in any way. The disclosures of all prior art recited herein are incorporated herein by reference in their entirety. 16

Claims

1. A rechargeable battery, capable of charge and discharge cycles, comprising a cathode, an anode and an electrolyte, wherein: - the cathode includes a cathode active material; - the anode comprises a conductive and electrochemically inert material that does not participate in the electrochemical reaction; - the electrolyte comprises a water or alcohol solution, which includes ions of at least one dissolved metal that can be reduced to a metallic state during the charge cycle and oxidized from the metallic state to the dissolved ion state during the discharge cycle.

2. The rechargeable battery according to claim 1, wherein the electrolyte contains at least one metal ion selected from Zn, Ni, Fe, Cr, Cu, Mn and combinations thereof.

3. The rechargeable battery according to claim 2, wherein the electrolyte further contains a Li salt, a Na salt, or a combination thereof.

4. The rechargeable battery according to any one of claims 1 to 3, wherein the cathode active material is a lithium ion intercalation compound, a sodium ion intercalation compound or a combination thereof.

5. The rechargeable battery according to claim 4, wherein said lithium ion intercalation compound comprises a layer structure compound, a spinel structure compound or an olivine structure compound.

6. The rechargeable battery according to claim 5, wherein said layer structure compound is represented by the formula Lil+xMyM'zM"cO 2 +,, where: - M, M', and M" are selected from Ni, Mn, Co, Mg, Ti, Cr, V, Zn, Zr, Si, Al; and, - x, y, z, c, and n satisfy the relationship O<x<0.5, Oys1, Oszs1, Oscs1, and 0.2:ns0.2.

7. The rechargeable battery according to claim 5, wherein said spinel structure compound is represented by the formula Lil+xMnyMzOk, where: - M is selected from Na, Li, Co, Mg, Ti, Cr, V, Zn, Zr, Si, and Al; and, - x, y, z, and k satisfy the relationship O<xs0.5, 15ys2.5, Osz:0.5, and 3:5k6. 17 WO 2012/094761 PCT/CA2012/050019

8. The rechargeable battery according to claim 5, wherein said olivine structure compound is represented by the formula LixM 1 yM'y(X'O 4 ),, where: - M is selected from Fe, Mn, V, and Co; - M' is selected from Mg, Ti, Cr, V, Al, and Co; - X' is selected from S, P and Si; and, - x, y, and n satisfy the relationship O<xs2, Oy:0.6, and 1:5ns1.5.

9. The rechargeable battery according to any one of claims 1 to 8, wherein the cathode includes a current collector.

10. The rechargeable battery according to claim 9, wherein the current collector comprises a stainless steel mesh or foil, a graphite plate, a graphite foil, or carbon fibre.

11. The rechargeable battery according to any one of claims 1 to 10, wherein the anode comprises a carbon based material, stainless steel, or a metal electroplated or coated by at least one of C, Sn, In, Ag, Pb, Co, and Zn. 18