AU2012208932A1

AU2012208932A1 - Ion-exchange battery with a plate configuration

Info

Publication number: AU2012208932A1
Application number: AU2012208932A
Authority: AU
Inventors: Pu Chen
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-01-21
Filing date: 2012-01-20
Publication date: 2013-05-09
Also published as: WO2012097456A1

Abstract

A rechargeable battery with a plate structure consists of a cathode electrode, an anode electrode and an electrolyte. The cathode electrode includes a current collector, cathode active materials, a binder and a conductive agent. The cathode active material is preferably selected from lithium and/or sodium intercalation compounds. The anode electrode includes an electrode plate, which is electrically conductive and electrochemically inert. The electrolyte consists of a solution of metal salts. The solution can consist of water, ethanol, methanol or mixture thereof. The metal salts consist of at least one of metal ion, which can be reduced and deposited onto the surface of the anode plate during charging, and oxidized and dissolved into the electrolyte during discharging.

Description

WO 2012/097456 PCT/CA2012/050032 1 ION-EXCHANGE BATTERY WITH A PLATE CONFIGURATION 2 CROSS REFERENCE TO RELATED APPLICATIONS 3 [0001] The present application claims priority under the Paris Convention to US 4 Application Number 61/434,959, filed January 21, 2011, the entire contents of which are 5 incorporated herein by reference. 6 FIELD OF THE INVENTION 7 [0002] The present invention relates to a secondary battery. In particular, the invention 8 relates to an ion exchange secondary battery having a plate configuration. 9 BACKGROUND OF THE INVENTION 10 [0003] Since the invention of lead-acid batteries, the energy storage and conversion 11 industry has entered the "secondary battery times". As known in the art, a "secondary 12 battery", also referred to as a rechargeable battery, is a battery wherein the internal 13 electrochemical reactions are reversible. Various kinds of secondary batteries are applied in 14 different fields depending on their specific requirements. For example, portable electronic 15 devices require a battery with a high energy density as in lithium ion (Li-ion) batteries, 16 electric tools require a high power output as in Li-ion, Ni-MH, and Ni-Cd batteries, and large 17 energy storage applications (such as a UPS), motor start-up batteries, wind power/solar 18 energy storage devices all require batteries with low cost and long service life. 19 [0004] Lead-acid batteries have been occupying the majority of the battery market 20 share, especially among energy storage fields for several decades. But this fact should not 21 conceal many disadvantages of the lead-acid batteries, in particular, the lead pollution 22 problem associated with its manufacture, battery recall and recycle after use, short service 23 life (typically 2 years), and low energy density. It is necessary to find a new battery, which 24 comes with low cost, long service life, environment friendly and good safety characteristics, 25 to replace the present lead-acid batteries. Although the current Li-ion and Ni-MH batteries 26 have better performance than lead-acid batteries in energy density, power density, service 27 life and environment aspects, they still cannot replace the lead-acid batteries mainly 28 because of the cost. 1 WO 2012/097456 PCT/CA2012/050032 1 [0005] To solve this problem, many researchers turned to aqueous Li-ion battery, hoping 2 to use water based electrolytes in place of organic electrolytes and drastically reduce the 3 cost of Li-ion batteries, and also to solve the safety problem with Li-ion batteries. In 1994, 4 Jeff Dahn et al. presented an aqueous battery with LiMn 2 0 4 as the cathode material, 5 vanadium oxide such as V0 2 as the anode material, and a water solution of lithium salts as 6 the electrolyte [LI W., DAHN J.R., WAINWRIGHT D.S., Science, 264 (1994), 1115]. Up to 7 now, all reported aqueous Li-ion batteries used the same principle as the Li-ion battery, 8 based on an embedded type structure on both positive and negative electrodes, such as 9 LiMn 2 04/VO 2 , LiNio 81 Coo 19 0 2 /LiV 3 0 8 , LiMn 2 04/TiP 2 0 7 , LiMn 2 04/LiTi 2 (PO4) 3 , and 10 LiCoO 2 /LiV 3 0 8 . A further example of such batteries is provided in US Patent Number 11 7,189,475. However, all these batteries have a low energy density and poor cycle life, 12 because of the decomposition of the intercalation anode materials during charging and 13 discharging in the aqueous solution (i.e. water). 14 [0006] A need exists for an improved aqueous secondary battery that can replace 15 current lead-acid batteries. 16 SUMMARY OF THE INVENTION 17 [0007] Accordingly to one aspect, the invention provides a rechargeable battery 18 consisting of a cathode electrode, an anode electrode and an electrolyte. 19 [0008] In one aspect, the invention provides a rechargeable battery comprising a shell 20 and a cover, the shell containing: 21 [0009] - at least one cathode plate, comprising a current collector, a cathode active 22 material, a binder and a conductive agent; 23 [0010] - at least one anode plate comprising an electrically conductive and 24 electrochemically inert material; 25 [0011] - an electrolyte comprising a solution of at least one metal salt, wherein the 26 metal is capable of being reduced and deposited onto the surface of the anode during 27 charging of the battery and oxidized and dissolved into the electrolyte during discharging of 28 the battery. 2 WO 2012/097456 PCT/CA2012/050032 1 BRIEF DESCRIPTION OF THE DRAWINGS 2 [0012] The features of the invention will become more apparent in the following detailed 3 description in which reference is made to the appended drawings wherein: 4 [0013] Figure 1 shows a schematic of a cathode electrode according to one aspect of 5 the invention. 6 [0014] Figure 2 shows a schematic of an anode electrode according to one aspect of the 7 invention. 8 [0015] Figure 3 shows a schematic of a cover of the battery according to one aspect of 9 the invention. 10 [0016] Figure 4 shows a schematic of a cathode electrode according to the embodiment 11 illustrated in Example 1. 12 [0017] Figure 5 shows a schematic of the anode electrode according to the embodiment 13 illustrated in Example 1. 14 [0018] Figure 6 shows a schematic of the battery structure according to the embodiment 15 illustrated in Example 1. 16 [0019] Figure 7 shows the charge and discharge curve of the battery of Example 1. 17 [0020] Figure 8 shows the cyclability curve of the battery in Example 1. 18 DETAILED DESCRIPTION OF THE INVENTION 19 [0021] The terms "comprise", "comprises", "comprised" or "comprising" may be used in 20 the present description. As used herein (including the specification and/or the claims), these 21 terms are to be interpreted as specifying the presence of the stated features, integers, steps 22 or components, but not as precluding the presence of one or more other feature, integer, 23 step, component or a group thereof as would be apparent to persons having ordinary skill in 24 the relevant art. 25 [0022] In one aspect, the present invention relates to a structure design of a novel 26 secondary battery, based on the principle of ion-exchange in the electrolyte. Such battery is 27 referred to herein as an Ion-Exchange Battery (IEB). 3 WO 2012/097456 PCT/CA2012/050032 1 [0023] In one aspect of the present invention, as illustrated in the accompanying figures, 2 there is provided a battery 300 having a plate structure comprising a positive electrode or 3 cathode 310, a negative electrode or anode 320, an electrolyte 340 and separator 330. 4 [0024] As shown in Figure 1, the positive electrode 310 comprises a current collector 5 311, cathode active materials 312, at least one binder 313 and at least one conductive agent 6 or material 314. In a preferred embodiment of the invention, the cathode active materials 7 312 comprise lithium (Li) and/or sodium (Na) intercalation cathode materials. 8 [0025] A negative electrode 320 according to an aspect of the invention is illustrated in 9 Figure 2. As shown, the negative electrode 320 generally comprises an electrically 10 conductive and electrochemically inert plate 321 with a plating or coating layer 322. 11 [0026] The electrolyte according to one aspect of the invention comprises a solution, 12 preferably an aqueous solution, of metal salts. The solvent may comprise water, ethanol, 13 methanol or mixtures thereof. The metal salts comprise at least one sort of metal ion, which 14 can be reduced and deposited onto the surface of the anode plate 322 during charging, and 15 oxidized and dissolved into the electrolyte during discharging. 16 [0027] As illustrated in Figure 6, the electrodes 310, 320 of the invention preferably have 17 a generally plate shape, and are preferably electrically separated from each other by a 18 separator 330. In a preferred embodiment of the invention, the separator 330 comprises a 19 generally porous membrane. The electrodes 310, 320 and separator 330 are packed in a 20 shell 380, casing or other such container as will be known to persons skilled in the art. The 21 shell 380 may, for example, be formed of a plastic or metal material. A cover 360 is 22 preferably provided on the shell 380, in order to separate the internal components of the 23 battery from the external environment. In a preferred embodiment, the cover 360 may be 24 insulative. The cathode current collector 311 and the negative (anode) electrode 320 are 25 connected through the cover 360 with the output circuit, 316 and 326. 26 [0028] In another aspect, as shown in Figure 3, the cathode current collector 311 may 27 penetrate through the cover 360. In such case, a cap 3116 may be provided over the 28 exposed ends of the collectors 311. Various materials may be used to form the cap 3116. 29 For example, the cap 3116 may be formed from graphite, conductive plastics, Pb, Sn or an 30 alloy of such metals. 31 [0029] In one preferred embodiment, as shown in Figure 6, the battery may be provided 32 with a pressure limiting, or pressure relief means, as known in the art, which serves to 4 WO 2012/097456 PCT/CA2012/050032 1 prevent a pressure buildup inside the battery 300. In one aspect, the pressure relief means 2 comprises a pressure relief valve 370. The valve 370 may be provided at any location on 3 the battery as would be apparent to persons skilled in the art. In one aspect, the valve 370 4 may be located on the cover 360 as shown in Figure 6. 5 [0030] The lithium ion intercalation compounds of the cathode active material may 6 comprise layered structure compounds, spinel structure compounds or olivine structure 7 compounds. The layered structure compounds may be represented by the compositional 8 formula LijxMyM'zM" 0

O

2 +n, where each of M, M', M" represents an element selected from Ni, 9 Mn, Co, Mg, Ti, Cr, V, Zn, Zr, Si, Al, and where x, y, z, c, n individually satisfy the following 10 relationships: 0< x 50.5, 0< y :1, 0s z 51, 0 sc <1, and -0.25 n 50.2. The spinel structure 11 compounds may be represented by the compositional formula LilxMnyMzOk, where M is at 12 least one element selected from Na, Li, Co, Mg, Ti, Cr, V, Zn, Zr, Si, Al, and where x, y, z, k 13 individually satisfy the following relationships: 0< x 50.5, 15 y $2.5, 0s z 50.5, and 35 k 56. 14 The olivine structure compounds may be represented by the compositional formula LixM 15 yM'y(X'O4),, where: M is an element selected from Fe, Mn, V, Co; M' is at least one element 16 selected from Mg, Ti, Cr, V, Al, Co; X' is selected from S, P and Si; and, x, y and n 17 individually satisfy the following relationships: 0< x 52, 05 y 50.6, 15 n :51.5. 18 [0031] According to one embodiment, the invention comprises a LiMn 2 0 4 /Zn battery with 19 LiMn 2 0 4 as the cathode active material, tin plated copper film/foil as the anode, and 5 mol/L 20 ZnCl 2 as the electrolyte. In such example, during charging, Li+ ions deintercalate from the 21 spinel crystal lattice of LiMn 2 0 4 , while trivalent manganese is oxidized to tetravalent 22 manganese with an accompanying electron output. In this example of the invention, 23 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 24 and are deposited on the anode surface. When the battery is charging (as shown in Figure 25 2), the reaction at the cathode is LiMn 2 0 4 -xe--> Li+ + Lil-xMn 2 0 4 , and the reaction at the 26 anode is Zn 2 + + xe--> (x / 2) Zn. The discharging process reverses these reactions. 27 [0032] In the current lithium battery industry, almost all cathode materials are doped, 28 coated, or modified by various methods. For example, LiMn 2 0 4 is no longer able to 29 represent the general formula of a "lithium manganese oxide" that is widely used. Strictly, 30 the general formula of the material should be according to the general formula of the spinel 31 structure compound that the present invention involves. However, doping, coating and other 32 modifications cause the chemical formula of the material to be more complex, so the formula 33 LiMn 2 0 4 should include the cathode materials of a variety of modifications, and be consistent 5 WO 2012/097456 PCT/CA2012/050032 1 with the general formula of the spinel structure compounds, as described in the present 2 invention. The chemical formula of LiFePO 4 , and other materials described herein, will be 3 understood to include the materials of a variety of modifications and to be consistent with the 4 general formulae of layered structure, spinel structure or olivine structure compounds. 5 [0033] In one aspect of the invention, the cathode active material comprises a material 6 that can reversibly intercalate-deintercalate. Such compounds include those that are able to 7 intercalate-deintercalate lithium, sodium and other ions. When the cathode active material is 8 a lithium ion intercalation-deintercalation compound, it can preferably be selected from, for 9 example, LiMn 2 0 4 , LiFePO 4 , LiCoO 2 , LiMxPO 4 , LiMxSiOy (where M is a metal with a variable 10 valence, x) and other compounds. When the cathode active material is a sodium ion 11 intercalation-deintercalation compounds, it can be, for example, NaVPO 4 F. 12 [0034] The cathode current collector of the invention may be selected from a stainless 13 steel mesh or foil, graphite plate or foil, carbon fiber or a combination thereof. The thickness 14 of the collector is between 0.01 mm and 50 mm. 15 [0035] The anode electrode 320 of the invention may comprise a flat or porous plate 16 with a thickness between 0.001 mm and 5 mm. The plate may comprise a material selected 17 from carbon based materials, stainless steel, and metals or metal combinations, alloys etc., 18 and combinations thereof. The plate forming the anode is preferably electroplated or coated 19 by one of C, Sn, In, Ag, Pb, Co, and Zn. 20 [0036] In one embodiment, the separator 330 is preferably a porous membrane having a 21 pore size between 0.01 and 1000 microns and a porosity of 20 - 95%. 22 [0037] In one aspect, the electrolyte of the present ion-exchange battery contains at 23 least one sort of metal ion chosen from: Zn, Ni, Fe, Cr, Cu and Mn and combinations thereof. 24 In operation of the battery of the invention, the metal ion of the electrolyte is reduced and 25 deposited onto the surface of the anode during the charging phase. During the discharge 26 phase, the above reaction/process is reversed. That is, during discharge, the metal 27 deposited on the surface of the anode is oxidized and returned to its ionic state in the 28 electrolyte solution. The solvent of the electrolyte is preferably water or an aqueous solution. 29 For example, the solvent may comprise water, ethanol, methanol, or any mixture thereof. In 30 one aspect, the concentration of the metal dissolved in the solvent may be 0.5-15 mol/L. 31 [0038] According to one embodiment of the invention, the electrolyte comprises an 32 aqueous solution comprising LiCI, Li 2

SO

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

)

2 or any 6 WO 2012/097456 PCT/CA2012/050032 1 combination thereof. In one aspect, the electrolyte comprises a solution containing 1 mol/L 2 LiCI, or Li 2

SO

4 , LiNO 3 , and 4 mol/L ZnCl 2 , or ZnSO 4 , or Zn(NO 3

)

2 . 3 [0039] To accelerate the rate of ion exchange, additional Li or Na salts may be added to 4 the electrolyte. In such case, these salts may be added to any desired concentration, such 5 as 1-15 mol/L. 6 [0040] Without being restricted to any particular theory, the working principle of the 7 present ion-exchange battery is described below: during the charging process, Li/Na ions 8 within the cathode deintercalate into the electrolyte while, simultaneously, the metal ions 9 contained in the electrolyte are reduced and deposited onto the surface of the anode. The 10 discharging process reverses these reactions. Thus, according to the invention, an ion 11 exchange process takes place in the electrolyte. For this reason, the battery is termed an 12 ion-exchange battery (IEB). 13 [0041] Again, without limiting the invention in any way, the principle of the battery of the 14 invention is: when charging, the cathode active material reacts, where Li (HOST)- e--> Li + + 15 (HOST), and the anode presents Mx+ + xe--> M. Li (HOST) is a lithium ion intercalation 16 compound; M is a metal; MX+ is the ionic state of M. If the cathode active material is a 17 sodium ion intercalation compound, the cathode active material reacts with Na (HOST)-e--> 18 Na ++ (HOST), and the anode presents Mx+ + xe--> M when charging. 19 [0042] As shown in Figure 6, the present invention also provides a battery pack, 20 comprising a number of plate ion-exchange battery units 300 connected in parallel. For 21 example, 2 to 10 such units may be connected. However, the invention is not intended to be 22 limited to any specific number of units. 23 [0043] According to the present description, the invention provides plate shaped ion 24 exchange batteries having a number of suitable combinations of the cathodes, anodes and 25 electrolytes. 26 [0044] As described herein, the present invention comprises new battery system, 27 wherein the cathode active material comprises ion intercalation/deintercalation compounds. 28 The electrochemical reversibility of the cathode relies on the intercalation (during charging of 29 the battery) and deintercalation (during discharging of the battery) of ions to/from the 30 cathode active material. The electrochemical reversibility of the anode relies on a metal ion 31 being reduced (during charging of the battery) and oxidized (during discharging of the 32 battery) on the surface of the anode plate. 7 WO 2012/097456 PCT/CA2012/050032 1 [0045] In a preferred embodiment, the electrolyte of the invention contains both the 2 deintercalated ions of the cathode active material and the ion that deposits/dissolves to/from 3 the anode surface. 4 [0046] As discussed above, the cathode of the invention comprises at least a cathode 5 current collector, one or more cathode active materials, one or more binders, and one or 6 more conductive agents. The cathode current collector preferably comprises a composite 7 material that may use carbon based conductive materials. Different carbon or carbon 8 composite materials have different electrical properties. For example, graphite and 9 conductive carbon fibre are both good electronic conductors, and also have excellent 10 structural strength. As such, these materials can be used as a cathode current collector in 11 the present invention. In addition, by mixing the conductive carbon black and a binder, such 12 as PVDF (polyvinylidene fluoride), polyethylene, polypropylene, uniformly and heat treating, 13 the conductive material can be made with both good electronic conductivity and flexibility. 14 Such a conductive material is found to have suitable properties for use as a cathode 15 collector for the invention. 16 [0047] In a preferred embodiment, the cathode active material are mixed with the 17 cathode conductive agent and binder uniformly, and are then coated onto the current 18 collector. To obtain a desired energy density, the current collector should not be too thick; 19 the preferred range of the thickness is between 0.01 mm - 5 mm. To facilitate electrolyte 20 infiltration and to ensure good mobility of intercalation ions, the coating of the cathode active 21 material should not be thick, and the preferred range of such thickness is between 0.1 mm 22 10 mm. As mentioned above, a cathode structure according to the invention is shown in 23 Figure 1. 24 [0048] The anode structure consists mainly of an anode plate. In principle, any material 25 that has good conductivity and sufficient chemical stability can be used as the anode plate. 26 For example, Al, Fe, Ni, Cu, Ag, Cd, W, Au, Pb, Sn, stainless steel and graphite, and 27 combinations of same, can be used for making an anode plate according to the invention. 28 Considering conductive resistance, structural strength and weight, the preferred thickness of 29 the anode plate should be between 0.005 - 1 mm. 30 [0049] To protect the anode plate, improve the overpotential of hydrogen evolution on 31 the surface of the plate, and enhance the current efficiency of the anode, the anode surface 32 is preferably covered with a layer of metal or metal oxide by a process such as plating, 33 coating, etc. The material for the plating or coating is selected from at least one of Sn, Ag, 8 WO 2012/097456 PCT/CA2012/050032 1 Pb, Co, Zn, and their oxide powders. The thickness of the plating or coating is preferably 2 between 0 - 0.1 mm. As mentioned above, an anode structure according to the invention is 3 shown in Figure 2. 4 [0050] The cathode of the battery is preferably porous, made of powder, and has a high 5 current discharge capability. But the anode, which comprises a plate or foil of carbon or of 6 the aforementioned metals, is flat, and its specific area may be limited. For example, if the 7 surface of the anode is porous, the specific area will be high and, as such, the anode would 8 have better electrochemical properties and a higher current discharge capability. 9 [0051] The present inventor has found that using metal foam as the anode substrate, 10 and further plating suitable material thereon, can improve the discharge performance of the 11 anode. For example, an anode comprised of a nickel foam material with silver plated 12 thereon was found to have better discharge performance than nickel foam itself. 13 [0052] The electrolyte of the invention preferably includes at least one kind of metal ion 14 that proceeds with reduction-oxidation reactions on the surface of the anode during charge 15 and discharge, respectively. For example, with LiMn 2 0 4 as the cathode active material, the 16 electrolyte preferably contains Zn 2 * ions, and the zinc salt may be chosen from the sulfate or 17 chloride. In such case, the preferred concentration of Zn2+ in the electrolyte is about 4 - 6 18 mol/L. 19 [0053] The cathode, anode, separator membrane and electrolyte can be placed in a 20 special container, such as discussed above and as shown in the appended figures. As will 21 be understood, the cathode and anode need to be connected to an external circuit, to 22 provide an electron conducting channel. 23 [0054] In one embodiment of the invention, as illustrated in Figure 3, the current 24 collectors 311 of the cathodes extend externally of the shell 380 and run across the battery 25 cover 360. It will be understood that the apertures in the cover 360 through with the current 26 collectors 311 extend are preferably sealed in a suitable manner. In the illustrated 27 embodiment, the anodes 320 also extend through the cover 360 and run across same to 28 connect with the external circuit. As shown in Figure 3, the anode plate can be connected to 29 the external circuit wires by welding or other methods inside or outside the battery. 30 [0055] As shown in Figure 3 and as discussed above, the portions of the cathode 31 current collectors 311 extending through the battery cover 360 are preferably sealed with a 32 protective cover or cap 3116 that has good electrical conductivity and is chemically stable. 9 WO 2012/097456 PCT/CA2012/050032 1 The role of the protective cap 3116 is to prevent water in the electrolyte of the battery from 2 evaporating out through the opening through which the cathode current collectors extend. In 3 the result, the caps 3116 aid in preventing the corrosion of the external circuit wires and the 4 cathode current collectors. The preferred materials of the protective caps 3116 are 5 impermeable graphite, conductive plastics, lead alloy, etc. Various materials having the 6 aforementioned properties will be apparent to persons skilled in the art. 7 [0056] As will be understood by persons skilled in the art, all features described herein 8 can be replaced by features that can provide the same, equal or similar purposes. 9 Therefore, unless otherwise stated, the features disclosed herein are only the general 10 features of equal or similar examples. 11 [0057] As will be understood by persons skilled in the art after having reviewed the 12 present description, the main advantages offered by the present invention include one or 13 more of: 1) desirable qualitative characteristics such a battery providing good 14 electrochemical performance, environmental safety, and/or low-cost; 2) a battery having a 15 simple structure, which facilitates manufacturing time/cost and provides high reliability; and 16 3) a battery that can be widely used, including replacing the current lead-acid batteries. 17 [0058] Examples 18 [0059] Aspects of the present invention are described below by means of various 19 illustrative examples. The examples contained herein are not intended to limit the invention 20 in any way but to illustrate same in more detail. It should be understood that the 21 experiments in the following examples, unless otherwise indicated, are in accordance with 22 conditions as would be known to persons skilled in the art or the conditions recommended 23 by manufacturers. Unless indicated otherwise, all percentages, ratios, proportions referred 24 to in the examples are calculated by weight. 25 [0060] Example 1 26 [0061] The cathode active material LiMn 2 0 4 , conductive carbon black and SBR (styrene 27 butadiene rubber milk) were mixed uniformly in accordance with the proportion of 85:10:5, 28 and then the mixture was added into water to make slurry. The cathode current collector 29 comprised a graphite plate with a thickness of 1 mm; the slurry was coated onto the graphite 30 plate and dried at 105 OC for 10 hours. The active material coated on each graphite plate 31 was 5 g, and the total amount of the cathode active material was 20 g, with a theoretical 32 capacity of 2000 mAh. The configuration of the cathode is shown in figure 4. 10 WO 2012/097456 PCT/CA2012/050032 1 [0062] The anode of the battery comprised a copper foil with a thickness of 0.1 mm, and 2 had the configuration as shown in Figure 5. The size of the anode substrate was slightly 3 larger than that of the cathode, so that the full capacity of the cathode could be used and the 4 current distribution at the edge of the anode would be uniform. The copper foil was covered 5 by a certain thickness of plating/coating to enhance the adhesion properties of metal 6 reduced from metal ions in the electrolyte. In this example, the surface of the copper foil 7 was coated with a layer of tin by plating, and the thickness of the tin plating was about 0.01 8 mm. 9 [0063] The separator membrane of the battery was a non-woven material with a 10 thickness of 0.1 mm. 11 [0064] The battery was formed with five anode plates and four cathode plates in 12 alternating fashion. The adjacent anode and cathode electrodes were separated by a layer 13 of the non-woven membrane. The assembled electrodes were placed in a plastic battery 14 shell, and then 20 ml of electrolyte was injected. The cathode current collector and anode 15 plate was allowed to extend through the battery cover, and were sealed by a binder. 16 [0065] The electrolyte comprised a water solution containing 4 mol/L LiCI and 4.5 mol/L 17 ZnCI. When charging, Li+ ions deintercalated from the cathode and dissolved into the 18 electrolyte with electron output through the current collector; meanwhile Zn2+ ions in the 19 electrolyte were reduced and electrodeposited on the surface of the anode. For maintaining 20 the concentration of Zn2+ in the electrolyte after charging, the amount of Zn2+ in the 21 electrolyte was chosen to be more than the amount of Zn on the anode plate after charging. 22 In this example, 0.09 mol Zn2+ was provided in the electrolyte. This amount was based on a 23 calculation that, at 2 Ah, there would be 0.035 mol Zn2+ consumed during charging. The 24 concentration of Zn2+ in the electrolyte after charging is 2.75 mol/L. 25 [0066] Small amounts of gas would be expected to be generated during charging. Such 26 gas is due to decomposition of water to hydrogen and oxygen. Some of this gas can be 27 expected to diffuse to the opposite electrode and be converted back to water. Nevertheless, 28 an anti-explosion valve (pressure valve) would be provided on the battery cover to prevent 29 the explosion caused by the inner pressure of the battery. It is also expected that the gas 30 generation resulted in the charge-discharge current efficiency of the battery to be less than 31 100%. The voltage-capacity curve of the first charge and discharge is shown in Figure 7, 32 wherein the y axis shows voltage and the x axis shows time. As shown in Figure 7, the 11 WO 2012/097456 PCT/CA2012/050032 1 charge voltage of this battery is about 2V on average and the discharge voltage is about 2 1.8V. As shown in Table 1, the first charge-discharge current efficiency is 93%. 3 [0067] As shown in Figure 8, the discharge capacity of the above battery shows no 4 decay after 100 cycles. 5 [0068] Example 2 6 [0069] A battery was made according to a method similar to that of Example 1. 7 However, in this case, the anode plate comprised a tin plated nickel foam, of the same size 8 as the anode plate of Example 1. Using nickel foam as the skeleton for the anode provides 9 an increased specific area than a metal plate/foil, and the tin plating provides a better 10 interface for the electrodeposition of Zn. The performance of the battery according to this 11 example is shown in Table 1. 12 [0070] Example 3 13 [0071] A battery was made according to a method similar to that of Example 1. 14 However, in this case, the anode plate comprised 316L stainless steel. The thickness of the 15 stainless steel plate was 0.5 mm. The surface of the stainless steel was passivated with 16 concentrated sulfuric acid and then sanded rough with abrasive paper. The performance of 17 the battery according to this example is shown in Table 1. 18 [0072] Table 1 First cycle Discharge capacity Average discharge Example Columbic retention after 100 voltage at 1C efficiency cycles 1 93% 99% 1.75 2 90% 95% 1.68 3 91% 94% 1.75 19 20 21 [0073] Although the invention has been described with reference to certain specific 22 embodiments, various modifications thereof will be apparent to those skilled in the art 23 without departing from the purpose and scope of the invention as outlined in the claims 12 WO 2012/097456 PCT/CA2012/050032 1 appended hereto. Any examples provided herein are included solely for the purpose of 2 illustrating the invention and are not intended to limit the invention in any way. Any drawings 3 provided herein are solely for the purpose of illustrating various aspects of the invention and 4 are not intended to be drawn to scale or to limit the invention in any way. The disclosures of 5 all prior art recited herein are incorporated herein by reference in their entirety. 6 7 8 13

Claims

1. A rechargeable battery comprising a shell and a cover, the shell containing: - at least one cathode plate, comprising a current collector, a cathode active material, a binder and a conductive agent; - at least one anode plate comprising an electrically conductive and electrochemically inert material; - an electrolyte comprising a solution of at least one metal salt, wherein the metal is capable of being reduced and deposited onto the surface of the anode during charging of the battery and oxidized and dissolved into the electrolyte during discharging of the battery.

2. The rechargeable battery according to claim 1, wherein the cathode active material comprises a lithium intercalation compound, a sodium intercalation compound or mixtures thereof.

3. The rechargeable battery according to claim 1, wherein adjacent cathodes and anodes are separated by a separator.

4. The rechargeable battery according to claim 1, further comprising a cover to close the shell.

5. The rechargeable battery according to claim 4, wherein ends of the current collectors and the anodes extend through the cover.

6. The rechargeable battery according to claim 5, wherein said ends of the current collectors extending through the cover are provided with sealing caps. 14 WO 2012/097456 PCT/CA2012/050032

7. The rechargeable battery according to any one of claims 1 to 6, further comprising at least one pressure relief valve to limit the pressure inside the battery.

8. The rechargeable battery according to any one of claims 1 to 6, wherein the at least one cathode current collector has a thickness of between 0.01 mm and 10 mm, and the at least one anode has a thickness of between 0.001 mm and 5 mm.

9. The rechargeable battery according to claim 2, wherein said lithium ion intercalation compound comprises a layer structure compound, a spinel structure compound or an olivine structure compound.

10 The rechargeable battery according to claim 9, wherein said layer structure compound is represented by the formula LijxMyM'zM" 0 O 2 +n, 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 0<xs0.5, Oys1, 0szs1, 0scs1, and 0.2:ns0.2.

11. The rechargeable battery according to claim 9, wherein said spinel structure compound is represented by the formula LilxMnyMzOk, 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 0<xs0.5, 15ys2.5, 0szs0.5, and 3:5k6.

12. The rechargeable battery according to claim 9, wherein said olivine structure compound is represented by the formula LixM 1 yM'y(X'O4),, 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 0<xs2, 05y:0.6, and 1:5ns1.5.

13. The rechargeable battery according to any one of claims 1 to 12, wherein the anode comprises: a carbon-based material; stainless steel; metals electroplated or coated by at least one of C, Sn, In, Ag, Pb, Co, and Zn; or, combinations thereof. 15 WO 2012/097456 PCT/CA2012/050032

14. The rechargeable battery according to claim 13, wherein the thickness of the anode is between 0.005-1 mm.

15. The rechargeable battery according to claim 3, wherein the separator comprises a porous membrane with a pore diameter between 0.001 and 1000 microns.

16. The rechargeable battery according to any one of claims 1 to 15, wherein the electrolyte contains at least one metal ion selected from the group comprising Zn, Ni, Fe, Cr, Cu and Mn.

17. The rechargeable battery according to claim 16, wherein the concentration of the metal ion is 0.5-15 mol/L.

18. The rechargeable battery according to claim 16, wherein the electrolyte comprises an aqueous solution.

19. The rechargeable battery according to claim 18, wherein the electrolyte comprises a solution of water, ethanol, methanol or a combination thereof.

20. The rechargeable battery according to any one of claims 1 to 19, wherein the battery comprises 2 to 10 pairs of the cathodes and anodes, each of said cathode and anode pairs being connected in parallel to form a battery pack. 16