Metal hydride batteries with added hydrogen, oxygen or hydrogen peroxide

Abstract

The present invention relates to a liquid-metal hydride battery. The battery is characterized in that the battery further comprises added oxygen or hydrogen or hydrogen peroxide or a combination thereof to rebalance the electrodes and to replenish the electrolyte by reaction with the electrode materials.

Description

[0001] This application is a divisional application, with its parent application having application number 201680061821.3, application date of October 19, 2016, and invention title "Metal hydride battery with added hydrogen, oxygen or hydrogen peroxide". Technical Field

[0002] This invention primarily relates to the field of lean-liquid metal hydride batteries. The device includes a metal hydride battery in which hydrogen, oxygen, or hydrogen peroxide is added to improve performance. Furthermore, this invention specifically relates to the field of extending battery life. Background Technology

[0003] Nickel-metal hydride (NiMH) batteries exhibit long cycle life and rapid charge and discharge capabilities. During charging and discharging, the electrodes interact through an alkaline electrolyte, and hydrogen is transported between the electrodes in the form of water molecules. During discharge, hydrogen is released from the negative electrode and migrates to the positive electrode (nickel electrode), where it is intercalated. This intercalation releases energy. During charging, the hydrogen migration reverses, as... Figure 1 As shown.

[0004] Specifically, the NiMH battery is designed with a nickel electrode limited by a lean electrolyte. This is done to avoid overcharging and over-discharging of the battery pack by controlling the battery chemistry and state of charge through the gas phase.

[0005] When the battery is charged, hydrogen is transferred from nickel hydroxide to the metal hydride via water molecules in the aqueous alkaline electrolyte. During discharge, hydrogen is transferred back to the nickel hydroxide electrode as water molecules.

[0006] If the battery is charged beyond the capacity of the nickel electrode, hydrogen will still be transported through water molecules and intercalated into the metal hydride electrode. However, in this case, hydrogen will be reduced from the aqueous electrolyte, leading to the production of oxygen. Therefore, the overcharge reaction is represented as: 4OH⁻ - = 2H₂O + O₂ + 4e - (E 0 = +0.401V). Compared to flooded batteries, batteries with lean electrolytes mean that the amount of electrolyte is limited, resulting in open spaces and channels between the electrodes separated by the separator. These open channels can now transport oxygen to the metal hydride electrode, where it can recombine to form water. This recombination reaction is represented as: 2MH + O2 = 2H2O + 2M. Therefore, the metal hydride electrode has a certain overcharge capacity reserve relative to the nickel electrode.

[0007] On the other hand, if the battery is over-discharged, hydrogen will be transported to the nickel electrode. However, since the capacity of the nickel electrode is lower than that of the metal hydride electrode, hydrogen is released because the hydrogen molecules are no longer embedded in the nickel hydroxide. These hydrogen molecules may also migrate to the metal hydride electrode through open channels and recombine into water. By adding cobalt to the nickel electrode, a certain over-discharge capacity can usually be generated in the metal hydride electrode, which leads to controlled pre-charging of the metal hydride electrode during battery pack formation.

[0008] like Figure 2 As shown, for a well-functioning battery, in order to achieve stable long-term charge / discharge performance, it is important to properly balance the capacity of the nickel electrode relative to the capacity of the metal hydride electrode by utilizing an appropriate amount of overcharge and overdischarge reserves.

[0009] However, as the battery pack is used for a longer period of time, this important balance between the capacities of the two electrodes is compromised due to a variety of mechanisms.

[0010] Purpose of the invention

[0011] The main objective of this invention is to eliminate the aforementioned drawbacks and known faults of existing technologies, and to provide an improved battery. It can also be used to control electrode balance without adding cobalt, thereby reducing material costs.

[0012] The first aspect of the invention is to provide an improved battery of an initially defined type. The second aspect of the invention is to provide a battery containing cobalt hydroxide. In this battery, pre-charging of the nickel electrode by cobalt hydroxide can be regulated. In a third aspect, the invention relates to a method for preparing the battery of the invention. In a fourth aspect, the invention relates to a method for counteracting the negative effects of corrosion in metal hydride batteries. In a fifth aspect, the invention relates to a method for replenishing an alkaline electrolyte in a metal hydride battery. In a sixth aspect, the invention relates to a method for rebalancing the electrodes in a metal hydride battery. Summary of the Invention

[0013] According to the present invention, at least the aforementioned main aspects are achieved through the initially defined battery and the method for preparing the battery. Preferred embodiments of the present invention are further defined below.

[0014] According to a first aspect of the invention, an initially defined type of starved liquid battery is provided, characterized in that the casing of the battery contains added oxygen, hydrogen or hydrogen peroxide.

[0015] The battery has a housing comprising at least one battery compartment, wherein the at least one battery compartment contains a first electrode, a second electrode, a porous membrane disposed between the first and second electrodes, and an aqueous alkaline electrolyte disposed between the first and second electrodes. When the aqueous alkaline electrolyte is disposed between the first and second electrodes, it means that the electrolyte is in contact with the first and second electrodes. The membrane, the first electrode, and the second electrode are constructed to allow hydrogen and oxygen exchange by allowing gas migration between the two electrodes. The housing also includes means for adding gas or liquid into the housing. The battery further includes added oxygen or hydrogen or hydrogen peroxide or combinations thereof, thereby rebalancing the electrodes and replenishing the electrolyte by reacting with the electrode materials.

[0016] According to a second aspect of the present invention, a starved electrolyte battery is provided.

[0017] This type of lean electrolyte battery has a housing comprising at least one battery compartment, wherein the at least one battery compartment contains a first electrode, a second electrode, and an aqueous alkaline electrolyte disposed between the first and second electrodes. The first electrode is a metal hydride electrode (MH), and the second electrode is a nickel hydroxide electrode (Ni(OH)2 / NiOOH) further comprising cobalt hydroxide (Co(OH)2 / CoOOH). The housing also includes means for adding gas or liquid into the housing, and the battery further includes added hydrogen peroxide.

[0018] Therefore, this invention is based on the idea that adding oxygen, hydrogen, or hydrogen peroxide provides suitable overcharge and overdischarge reserves and refills the electrolyte, which extends battery life and increases the possible number of cycles. Without being limited by any theory, it is possible that adding oxygen from the gas or peroxide restores electrode balance, and the improved gas recombination results in reduced internal gas pressure. Therefore, the battery becomes less sensitive to unintentional overcharging or overdischarging.

[0019] Other features of the battery applicable to the first and / or second aspects of the present invention are summarized below.

[0020] In a preferred embodiment of the invention, the battery comprises a nickel hydroxide electrode (Ni(OH)2 / NiOOH).

[0021] For example, the first electrode can be a metal hydride electrode (MH) and the second electrode can be a nickel hydroxide electrode (Ni(OH)2 / NiOOH). The first electrode can be a cadmium electrode (Cd) and the second electrode can be a nickel hydroxide electrode (Ni(OH)2 / NiOOH). The first electrode can be a zinc electrode (Zn) and the second electrode can be a nickel hydroxide electrode (Ni(OH)2 / NiOOH).

[0022] The battery may include one or more battery slots, such as two or more battery slots, and a common gas space that may also include two or more battery slots.

[0023] The amount of oxygen or hydrogen added can be up to 2 moles per mole of the active metal hydroxide contents in the battery, such as Ni(OH)2 / Ni(OOH).

[0024] The amount of hydrogen peroxide added is at most 2 moles per mole of active metal hydride contents in the battery.

[0025] The first electrode can be a metal hydride electrode (MH), and the second electrode can be a nickel hydroxide electrode (Ni(OH)2 / NiOOH) that also contains cobalt hydroxide (Co(OH)2 / CoOOH). The second electrode may optionally also contain zinc hydroxide (Zn(OH)2).

[0026] The first electrode can be a metal hydride electrode (MH), and the second electrode can be a nickel hydroxide electrode (Ni(OH)2 / NiOOH) that also contains zinc hydroxide (Zn(OH)2). Optionally, the second electrode may also include cobalt hydroxide (Co(OH)2 / CoOOH).

[0027] The aqueous alkaline electrolyte may contain a mixture of lithium hydroxide, sodium hydroxide, and potassium hydroxide (LiOH, NaOH, KOH).

[0028] The first or second electrode may further include one or more of the following: cerium (Ce), lanthanum (La), praseodymium (Pr), manganese (Mn), niobium (Nb), cobalt (Co), nickel (Ni), magnesium (Mg), neodymium (Nd), titanium (Ti), zirconium (Zr), vanadium (V), chromium (Cr), tin (Sn), yttrium (Y), or aluminum (Al), such as one or more of cerium (Ce), lanthanum (La), praseodymium (Pr), manganese (Mn), niobium (Nb), nickel (Ni), magnesium (Mg), neodymium (Nd), titanium (Ti), zirconium (Zr), vanadium (V), chromium (Cr), tin (Sn), or aluminum (Al). The first electrode may preferably contain one or more of these elements.

[0029] The added hydrogen, oxygen, or hydrogen peroxide may be added individually or in sequence, or in the form of a mixture of hydrogen and oxygen, oxygen and hydrogen peroxide, or hydrogen and hydrogen peroxide.

[0030] The porous membrane can be made of polyamide or polyolefin such as polypropylene.

[0031] The second electrode can be a nickel hydroxide electrode (Ni(OH)2 / NiOOH). This nickel hydroxide electrode (Ni(OH)2 / NiOOH) may optionally also contain cobalt hydroxide (Co(OH)2 / CoOOH) and / or zinc hydroxide (Zn(OH)2).

[0032] The enclosure may include means for reducing pressure within the enclosure. The means for adding gas or liquid into the enclosure may be the same as the means for reducing pressure within the enclosure.

[0033] The enclosure may include a safety venting device configured to limit the maximum internal pressure within the enclosure.

[0034] The housing may include a single housing, or the housing may include two or more sub-housings, wherein each sub-housing is in gas communication with at least one other sub-housing via a gas pipe.

[0035] According to another aspect of the present invention, the object of the present invention can be achieved by the method for preparing the above-described battery. The method for preparing the battery includes the following steps:

[0036] a. Provides a housing, a first electrode, a second electrode, and an aqueous alkaline electrolyte, wherein the housing includes means for reducing the pressure inside the housing and means for adding gas or liquid into the housing;

[0037] b. A first electrode and a second electrode, as well as an alkaline electrolyte, are disposed within the casing to prepare a low-electrolyte battery;

[0038] c. By applying the aforementioned means of reducing pressure within the housing, the housing is emptied to generate reduced pressure; and

[0039] d. Using the aforementioned apparatus for adding gas or liquid into the enclosure, add oxygen, hydrogen, or hydrogen peroxide into the enclosure. Steps c and d may be repeated at least once, preferably twice.

[0040] According to another aspect, the object of the present invention can be achieved by a method to combat the negative effects of corrosion of metal hydride electrodes in a battery. The battery has a housing comprising at least one battery compartment, wherein the at least one battery compartment contains a first electrode, a second electrode, and an aqueous alkaline electrolyte disposed between the first and second electrodes, wherein the first electrode is a metal hydride electrode (MH) and the second electrode is a nickel hydroxide electrode (Ni(OH)₂ / NiOOH), and wherein the housing further comprises means for adding a gas or liquid into the housing. The method includes adding oxygen or hydrogen or hydrogen peroxide, or a combination thereof, into the battery at any state of charge (SOC).

[0041] According to another aspect, the object of the present invention is achieved by a method for replenishing an aqueous alkaline electrolyte within a battery. The battery has a housing comprising at least one battery compartment, wherein the at least one battery compartment contains a first electrode, a second electrode, and an aqueous alkaline electrolyte disposed between the first and second electrodes, wherein the first electrode is a metal hydride electrode (MH) and the second electrode is a nickel hydroxide electrode (Ni(OH)₂ / NiOOH), and wherein the housing further comprises means for adding a gas or liquid into the housing. The method includes adding oxygen or hydrogen or hydrogen peroxide or a combination thereof into the battery, thereby generating water within the battery through a recombination reaction between the various gases and the active electrode materials.

[0042] Before the battery reaches a state of charge (SOC) of not less than 50% or not less than 20%, oxygen, hydrogen, hydrogen peroxide, or a combination thereof may be added to the battery.

[0043] According to another aspect, the object of the present invention is achieved by a method for re-establishing balance between a first electrode and a second electrode in a battery. The battery has a housing comprising at least one battery compartment, wherein the at least one battery compartment contains a first electrode, a second electrode, and an aqueous alkaline electrolyte disposed between the first and second electrodes, wherein the first electrode is a metal hydride electrode (MH) and the second electrode is a nickel hydroxide electrode (Ni(OH)₂ / NiOOH), and wherein the housing further comprises means for adding a gas or liquid into the housing. The method includes adding oxygen or hydrogen or hydrogen peroxide, or a combination thereof, into the battery.

[0044] Further advantages and features of the invention will become apparent from the following detailed description of preferred embodiments.

[0045] All embodiments of this application are applicable to all aspects of this invention. Attached Figure Description

[0046] A more complete understanding of the above and other features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0047] Figure 1 This is a schematic diagram of a metal hydride battery;

[0048] Figure 2 The graph reveals how the electrode capacity relates to the hydrogen equilibrium pressure of the metal hydride used in the negative electrode.

[0049] Figure 3 The graph reveals the maximum pressure in each cycle;

[0050] Figure 4The graph shows the resistance every 50 cycles. Detailed Implementation

[0051] This invention is not limited to the embodiments shown above and in the accompanying drawings, which are primarily for descriptive and illustrative purposes. This patent application is intended to cover all modifications and variations of the preferred embodiments described herein. Therefore, the device can be adapted in various ways within the scope of this invention.

[0052] It should also be noted that all information relating to terms such as above, below, upper, lower, etc., should be understood / interpreted as aligning the device with the accompanying drawings, such alignment as to allow for proper reading of the reference numerals. Therefore, these terms only indicate interrelationships in the illustrated embodiments, and these relationships may change if the device of the present invention is provided with different structures / designs.

[0053] It should also be noted that even if not explicitly stated, a feature of one particular implementation can be combined with a feature of another implementation, and if such combination is possible, it should be considered obvious.

[0054] Throughout this application, unless the context otherwise requires, the term “comprising” and its variations shall be understood to implicitly include the stated number or step or the set of stated numbers or steps, but not exclude any other number or step or the set of stated numbers or steps.

[0055] The object of this invention is to provide a battery that can be rebalanced, replenished, and combat the harmful effects of corrosion, which can be achieved by adding oxygen, hydrogen, and / or hydrogen peroxide to the battery. Oxygen, hydrogen, or hydrogen peroxide can be added individually or sequentially. A lean electrolyte design means that only a minimal amount of electrolyte is available in the battery. Any loss of electrolyte will impair performance, primarily manifested as an increase in internal resistance. Electrolyte drying is a major cause of limited cycle life. The main cause of electrolyte drying is excessive internal pressure within the battery, such as… Figure 1-4 As shown, this pressure may trigger the safety valve to release oxygen or hydrogen due to misuse such as overcharging or over-discharging. Electrolyte drying can also result from electrolyte absorption into the nickel hydroxide structure or corrosion of the metal hydride alloy. The latter is particularly harmful because corrosion produces hydrogen, which cancels out the capacity balance between the nickel and metal hydride electrodes. This not only increases over-discharge reserves but also reduces overcharge capacity, leading to excessive accumulation of internal gas pressure. This increases the risk of battery pack venting and accelerates electrolyte drying. This effect is exacerbated by shifting the metal hydride operating point towards a higher equilibrium hydrogen pressure. This increases the hydrogen partial pressure, which in turn reduces the efficiency of oxygen recombination reactions. Adding oxygen to the battery pack will inhibit this development in two ways:

[0056] 1) Oxygen restores the balance between electrodes by converting the hydroxide produced in the aforementioned corrosion into water. This reduces pressure buildup during overcharging. Figure 3 )

[0057] 2) The water generated in (1) will replenish the amount of electrolyte and reduce the internal resistance. Figure 4 )

[0058] Adding only water to the battery pack reduces internal resistance but not pressure buildup because the electrode imbalance remains. On the other hand, adding hydrogen peroxide (H₂O₂) replenishes the electrolyte and re-establishes electrode balance. Sequentially adding hydrogen and oxygen allows for a controlled volume of water to be added to the electrolyte and is also a method for controlling electrode balance. Therefore, the latter is another way to regulate electrode balance, in which case cobalt does not need to be added to the nickel electrode as described above.

[0059] The battery of the present invention is a lean electrolyte battery having a casing containing at least one battery compartment. Each battery compartment contains at least two electrodes (first and second electrodes) and a porous membrane. An aqueous alkaline electrolyte and a porous membrane are disposed between the first and second electrodes. The lean electrolyte configuration allows hydrogen and oxygen to exchange through the electrolyte and the membrane, which allows gas migration between the two electrodes. The casing also includes means for adding gas or liquid into the casing, and the battery further includes added oxygen or hydrogen or hydrogen peroxide or combinations thereof. These are added to rebalance the electrodes and replenish the electrolyte by reacting with the electrode materials. The addition of oxygen, hydrogen, or hydrogen peroxide can also avoid or reduce the negative effects of corrosion. The addition of oxygen, hydrogen, or hydrogen peroxide to the battery can be carried out at any state of charge (SOC). However, it is preferred to add hydrogen at low SOC and add oxygen and hydrogen peroxide at high SOC to facilitate their absorption and sequential conversion into water, which will replenish the electrolyte.

[0060] The battery of the present invention is a starved liquid battery having a casing containing at least one battery compartment. The casing may consist of a single discrete structure providing a casing for all battery compartments, or it may comprise several sub-casings, each providing a casing for a portion of the total number of battery compartments. The battery can be of any structure, including those known in the prior art, such as cylindrical, prismatic, or bipolar structures.

[0061] Each battery case contains at least two electrodes (first and second electrodes) and a porous membrane. An aqueous alkaline electrolyte and the porous membrane are disposed between the first and second electrodes. The first electrode is a metal hydride electrode (MH), and the second electrode is a nickel hydroxide electrode (Ni(OH)2 / NiOOH) that also contains cobalt hydroxide (Co(OH)2 / CoOOH). The casing also includes means for adding gas or liquid into the casing.

[0062] A battery may contain only one battery slot, but the number of battery slots may be two or more, three or more, or four or more. When the number of battery slots is two or more, the battery may include a common gas space for all or part of the battery slots. If the housing comprises several sub-housings, the common gas space can be implemented by providing gas conduits connecting each sub-housing to at least one other sub-housing. In this way, a modular battery assembly can be achieved.

[0063] For example, a bipolar battery with a common gas space is disclosed in document WO 03 / 026042 (“A bipolar battery and biplate assembly”).

[0064] Each battery compartment contains at least two electrodes, but may contain four or more, or six or more electrodes. The electrodes are metal hydrides (MH) or metal hydroxides (MOH). The first electrode is a metal or metal alloy, and may be a metal hydride electrode (MH). The second electrode may be a nickel hydroxide electrode (Ni(OH)2 / Ni(OOH). In one embodiment, the first electrode is a cadmium electrode (Cd) and the second electrode is a nickel hydroxide electrode (Ni(OH)2 / NiOOH). In another embodiment, the first electrode is a zinc electrode (Zn) and the second electrode is a nickel hydroxide electrode (Ni(OH)2 / NiOOH). In one embodiment, the first or second electrode contains one or more of the following: cerium (Ce), lanthanum (La), praseodymium (Pr), neodymium (Nd), titanium (Ti), zirconium (Zr), vanadium (V), chromium (Cr), tin (Sn), manganese (Mn), niobium (Nb), cobalt (Co), nickel (Ni), magnesium (Mg), yttrium (Y), or aluminum (Al). Preferably, the electrode contains one or more of these elements. For example, the first electrode can be a hydrogen storage alloy known for use in NiMH batteries, such as AB5 alloy or A2 alloy. In one embodiment, the second electrode further includes cobalt or cobalt hydroxide (Co(OH)2 / CoOOH). The amount of cobalt or cobalt hydroxide can be 0-15 mol% of the electrode contents, such as 1-10 mol% or 2-5 mol%. In one embodiment, the second electrode also contains zinc or zinc hydroxide (Zn(OH)2 / CoOOH). The amount of zinc or zinc hydroxide can be 0-10 mol% of the electrode contents, such as 2-5 mol%. The second electrode may also contain cobalt hydroxide and zinc hydroxide in the above proportions. However, the second electrode may also be substantially cobalt-free or cobalt-free.

[0065] The porous membrane can be made of any suitable material, such as plastic materials like polyolefins (e.g., polyethylene, polypropylene) or polyamides, or natural polymers like cotton, nylon, or polyesters like polyethylene terephthalate, polytetrafluoroethylene, or polyvinyl chloride, or combinations thereof. The polymeric material membrane can be a nonwoven fabric. The pore size can be 10-1000 nm, such as 20-500 nm, such as 30-100 nm.

[0066] The electrolyte is an aqueous alkaline electrolyte, which may contain hydroxides of alkali metals or alkaline earth metals in addition to water. In one embodiment, the electrolyte contains potassium hydroxide. In another embodiment, the electrolyte contains lithium hydroxide. In yet another embodiment, the electrolyte contains sodium hydroxide. In one embodiment, the electrolyte contains lithium hydroxide, sodium hydroxide, and / or potassium hydroxide (LiOH, NaOH, KOH).

[0067] The device used to add gas (or remove gas, vent the casing) or liquid can be any suitable device, such as a regulator, valve or check valve.

[0068] To overcome the shortcomings of the prior art, the battery of the present invention includes added oxygen, hydrogen, or hydrogen peroxide. In one embodiment, the added hydrogen, oxygen, or hydrogen peroxide is a mixture of hydrogen and oxygen, or oxygen and hydrogen peroxide, or hydrogen and hydrogen peroxide. The addition may be repeated once or multiple times. The amounts mentioned below refer to the amount added each time or the total amount added over the entire life cycle of the battery. The amount of added oxygen or hydrogen is at most 2 mol / mol of the active metal hydroxide such as Ni(OH)2 / NiOOH in the battery contents, preferably not less than 0.001 mol / mol of the active metal hydroxide. The amount of added oxygen or hydrogen may be at most 1.5 mol / mol of the active metal hydride, or at most 3 mol. When the electrode contains cobalt hydroxide, the amount of added oxygen may be 0.1-2 mol / mol of the active cobalt hydroxide, such as 0.5-1.5 mol / mol of the active cobalt hydroxide. In one embodiment, the amount of added oxygen or hydrogen is 0.05-2 mol / mol of the active metal hydroxide, such as 1-1.5 mol. The amount of hydrogen peroxide added can be 1 mole per mole of active metal hydride. It is believed that hydrogen peroxide, similar to the addition of oxygen, will re-establish the equilibrium between the two electrodes.

[0069] The battery of the present invention can be fabricated by providing a casing, at least two electrodes, a porous membrane, and an aqueous alkaline electrolyte, and by arranging the two electrodes, electrolyte, and membrane within the casing. The casing includes facilities for adding or removing gases and liquids, and these facilities are used to vent the casing, thereby generating reduced pressure. Oxygen, hydrogen, or hydrogen peroxide is then added to the casing using these facilities. The steps of venting the casing and adding oxygen, hydrogen, or hydrogen peroxide can be repeated to obtain a more controlled environment inside the casing.

[0070] The negative effects of electrode corrosion can be reduced by adding oxygen, hydrogen, or hydrogen peroxide into the casing.

[0071] Adding oxygen, hydrogen, hydrogen peroxide, or a combination thereof to a battery causes a recombination reaction between various gases or liquids and the active electrode materials, producing water. This addition can be carried out at any state of charge (SOC). This replenishes the electrolyte in a starved electrolyte battery.

[0072] Hydrogen is preferably added at low SOC and oxygen and hydrogen peroxide at high SOC to facilitate their absorption and sequential conversion into water for addition to the electrolyte. In one embodiment, hydrogen may be added to the battery before the battery reaches a state of charge (SOC) of not less than 50% or not less than 20%. In another embodiment, oxygen or hydrogen peroxide is added to the battery when it reaches a state of charge of at least 50% or at least 75%. The addition of oxygen, hydrogen, or hydrogen peroxide may also re-establish the balance between the first and second electrodes in the battery. Hydrogen peroxide is believed to re-establish the balance between the electrodes.

Claims

1. A lean electrolyte battery comprising two or more battery cells and having a housing containing the two or more battery cells, wherein each battery cell comprises a first electrode, a second electrode, a porous membrane disposed between the first electrode and the second electrode, and an aqueous alkaline electrolyte disposed between the first electrode and the second electrode, wherein the membrane, the first electrode, and the second electrode are configured to allow hydrogen and oxygen exchange by allowing gas migration between the two electrodes, and wherein the housing further comprises means for adding gas or liquid into the housing; wherein the battery further comprises added oxygen or hydrogen peroxide or a combination thereof, thereby rebalancing the electrodes and replenishing the electrolyte by reacting with the electrode materials, wherein the battery further comprises a common gas space for the two or more battery cells, wherein oxygen or hydrogen peroxide or a combination thereof is added to the battery when the battery reaches at least 50% state of charge.

2. The battery of claim 1, wherein the first electrode is a metal hydride electrode MH and the second electrode is a nickel hydroxide electrode Ni(OH)2 / NiOOH, or wherein the first electrode is a cadmium electrode Cd and the second electrode is a nickel hydroxide electrode Ni(OH)2 / NiOOH, or wherein the first electrode is a zinc electrode Zn and the second electrode is a nickel hydroxide electrode Ni(OH)2 / NiOOH.

3. The battery of claim 1 or 2, wherein the amount of oxygen added is at most 2 moles per mole of active metal hydroxide contents in the battery.

4. The battery of claim 3, wherein the active metal hydroxide is Ni(OH)2 / Ni(OOH).

5. The battery of claim 1 or 2, wherein the amount of hydrogen peroxide added is at most 2 moles per mole of active metal hydride contents in the battery.

6. The battery of claim 1 or 2, wherein the first electrode is a metal hydride electrode MH and the second electrode is a nickel hydroxide electrode Ni(OH)2 / NiOOH, and wherein the nickel hydroxide electrode Ni(OH)2 / NiOOH further comprises cobalt hydroxide Co(OH)2 / CoOOH.

7. The battery of claim 1 or 2, wherein the aqueous alkaline electrolyte comprises a mixture of lithium hydroxide (LiOH), sodium hydroxide (NaOH), and potassium hydroxide (KOH).

8. The battery of claim 1 or 2, wherein the first or second electrode further comprises one or more of the following: cerium (Ce), lanthanum (La), praseodymium (Pr), manganese (Mn), niobium (Nb), nickel (Ni), magnesium (Mg), neodymium (Nd), titanium (Ti), zirconium (Zr), vanadium (V), chromium (Cr), tin (Sn), or aluminum (Al).

9. The battery of claim 1 or 2, wherein the added oxygen or hydrogen peroxide is added alone or in sequence, or in the form of a mixture of oxygen and hydrogen peroxide.

10. The battery of claim 1 or 2, wherein the porous separator is made of polyamide or polyolefin.

11. The battery of claim 10, wherein the polyolefin is polypropylene.

12. The battery of claim 1 or 2, wherein the second electrode is a nickel hydroxide electrode Ni(OH)2 / NiOOH, and wherein the nickel hydroxide electrode Ni(OH)2 / NiOOH optionally further comprises cobalt hydroxide Co(OH)2 / CoOOH and / or zinc hydroxide Zn(OH)2.

13. The battery of claim 1 or 2, wherein the housing includes means for reducing pressure within the housing.

14. The battery of claim 13, wherein the means for adding gas or liquid into the casing is the same as the means for reducing the pressure inside the casing.

15. The battery of claim 1 or 2, wherein the housing includes a safety venting device configured to limit maximum internal pressure within the housing.

16. The battery of claim 1 or 2, wherein the casing comprises a single casing, or wherein the casing comprises two or more sub-casings, wherein each sub-casing is in gas communication with at least one other sub-casing via a gas conduit.

17. A lean electrolyte battery comprising two or more battery cells and having a housing containing the two or more battery cells, wherein each battery cell comprises a first electrode, a second electrode, and an aqueous alkaline electrolyte disposed between the first electrode and the second electrode, wherein the first electrode is a metal hydride electrode MH and the second electrode is a nickel hydroxide electrode Ni(OH)2 / NiOOH further comprising cobalt hydroxide Co(OH)2 / CoOOH, and wherein the housing further comprises means for adding a gas or liquid to the housing; wherein the battery further comprises added oxygen or hydrogen peroxide or a combination thereof, wherein oxygen or hydrogen peroxide or a combination thereof is added to the battery when the battery reaches at least 50% state of charge.

18. A method for preparing a lean electrolyte battery comprising two or more battery cells and having a housing containing the two or more battery cells, wherein each battery cell comprises a first electrode, a second electrode, a porous membrane disposed between the first electrode and the second electrode, and an aqueous alkaline electrolyte disposed between the first electrode and the second electrode, wherein the membrane, the first electrode, and the second electrode are configured to allow hydrogen and oxygen exchange by allowing gas migration between the two electrodes, and wherein the housing further comprises means for adding gas or liquid into the housing; wherein the battery further comprises adding oxygen or hydrogen peroxide or a combination thereof to rebalance the electrodes and replenish the electrolyte by reacting with the electrode materials, wherein the battery further comprises a common gas space for the two or more battery cells, the method comprising the steps of: a. Provides a housing, a first electrode, a second electrode, and an aqueous alkaline electrolyte, wherein the housing includes means for adding gas or liquid into the housing; b. A first electrode and a second electrode, as well as an alkaline electrolyte, are disposed within the casing to prepare a low-electrolyte battery; and c. Using the aforementioned apparatus for adding gas or liquid into the enclosure, add oxygen or hydrogen peroxide or a combination thereof into the enclosure; When the battery reaches at least 50% charge, oxygen or hydrogen peroxide or a combination thereof is added to the battery.

19. The method of claim 18, wherein step c is repeated at least once.

20. The method of claim 19, wherein step c is repeated twice.

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