Alkaline nickel-metal hydride battery

Abstract

The invention relates to an alkaline nickel-metal hydride battery. An electrode group of the alkaline nickel-metal hydride battery comprises a partition plate, a positive electrode and a negative electrode, the positive electrode is composed of a conductive positive electrode current collector and a positive electrode active layer coated on the surface of the positive electrode current collector, and the positive electrode active layer comprises a positive electrode active material and a positive electrode additive. The negative electrode is composed of a conductive negative electrode current collector and a negative electrode active layer coated on the surface of the negative electrode current collector, and the negative electrode active layer comprises a negative electrode active material and a negative electrode additive. The molar concentration of hydroxyl in the alkaline electrolyte of the alkaline nickel-metal hydride battery is 8-10 mol / L, and the alkaline electrolyte comprises sodium hydroxide with the molar concentration of 7-8 mol / L, lithium hydroxide with the molar concentration of 0-3 mol / L and potassium hydroxide with the molar concentration of 0-2 mol / L.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, in particular to an alkaline nickel-hydrogen battery. Background Art

[0002] This section provides background information related to the present application which does not necessarily constitute prior art.

[0003] The preparation process of the positive electrode used in the existing alkaline nickel-hydrogen battery is generally as follows: first, nickel hydroxide particles, a binder and water as the positive electrode active material are mixed to prepare a positive electrode slurry; then, the positive electrode slurry is filled into a collector composed of a foamed nickel sheet with a three-dimensional network skeleton structure; then, a positive electrode sheet is formed through a drying process of the positive electrode slurry and a rolling process of the collector to densify the positive electrode slurry; finally, the positive electrode is manufactured by cutting the positive electrode sheet into a specified size.

[0004] Although the positive electrode used in the existing alkaline nickel-hydrogen battery can be filled with active materials at a high density, the conductivity of the nickel hydroxide particles as the active material is relatively low, so the utilization rate of the active material is low. In order to solve this technical problem, the existing technical solution includes: adding a small amount of cobalt compound as a conductive agent to the active material with nickel hydroxide particles as the main component, the cobalt compound is dissolved in the alkaline electrolyte as cobalt acid ions, and is evenly dispersed on the surface of the nickel hydroxide. Then, the above cobalt acid ions are oxidized by the highly conductive cobalt hydroxide oxide when the alkaline nickel-hydrogen battery starts to charge, forming a conductive network connecting the active materials to each other and between the active materials and the collector. As a result, the conductivity between the active materials and between the active materials and the collector is improved, and the utilization rate of the active materials is improved. However, this technical solution has the following technical problems:

[0005] 1. When an alkaline nickel-hydrogen battery is repeatedly placed in a deep discharge state during the charge and discharge cycle (in the present invention, if the alkaline nickel-hydrogen battery is discharged to below the lower limit of its usable voltage range, the alkaline nickel-hydrogen battery is in a deep discharge state), the stability of cobalt relative to the reduction reaction is greatly damaged. As the number of deep discharge repetitions increases, the conductive network is gradually destroyed and its range gradually increases. Accompanying this, the conductivity of the active material decreases, and the utilization rate of the active material also gradually decreases. Therefore, even if the alkaline nickel-hydrogen battery that has been repeatedly deeply discharged is recharged, it is difficult to restore to the initial charge capacity.

[0006] 2. When an alkaline nickel-metal hydride battery in a deeply discharged state is left for a long time, the potential of the positive electrode reaches below the reduction potential of the cobalt hydroxide oxide, which will cause the cobalt hydroxide oxide that forms the conductive network to be reduced and dissolved. Moreover, if the reduction and dissolution of the cobalt hydroxide oxide occur, the above-mentioned conductive network will be partially destroyed, so the conductivity of the positive electrode is reduced, resulting in damage to the charging acceptance capacity, and the utilization rate of the positive electrode active material is reduced. Therefore, even if the battery is charged again, it is difficult to restore the charging capacity to the initial capacity value. Here, if the degree of recovery of the charging capacity after deep discharge is expressed as capacity recovery, the higher the capacity recovery, the closer the charging capacity reaches to the initial capacity when charging after deep discharge.

[0007] The existing alkaline nickel-hydrogen batteries also have the following technical problems: the alkaline nickel-hydrogen batteries in the fully charged state (in the present invention, if the alkaline nickel-hydrogen battery is charged to the upper limit of its usable voltage range at room temperature, the alkaline nickel-hydrogen battery is in the fully charged state) have the problem of reduced discharge characteristics under large currents and capacity loss after being placed for a long time, especially in a high temperature environment. The reasons for this technical problem are speculated to include:

[0008] 1. When alkaline nickel-hydrogen batteries are placed for a long time, the alkaline electrolyte in the alkaline nickel-hydrogen batteries will cause the negative electrode of the alkaline nickel-hydrogen batteries to be oxidized (especially when the alkaline nickel-hydrogen batteries are placed for a long time in a high temperature environment, the corrosiveness of the alkaline electrolyte will become stronger, making the negative electrode of the alkaline nickel-hydrogen batteries more easily oxidized in a high temperature environment), especially the negative electrode alloy materials containing rare earth elements. Rare earth elements are easily oxidized in alkaline solution to form hydroxides. The hydroxides on the surface of the negative electrode will hinder the electrochemical reaction of the negative electrode, resulting in increased impedance, causing the polarization of the alkaline nickel-hydrogen battery to increase during the subsequent charge and discharge process and reach the cut-off voltage ahead of time, causing capacity loss.

[0009] 2. When alkaline nickel-hydrogen batteries are stored for a long time, metal ions such as manganese (Mn) or aluminum (Al) in the hydrogen-absorbing alloy dissolved in the alkaline electrolyte in the positive electrode of the alkaline nickel-hydrogen battery invade from the segregation part of the cobalt compound layer formed on the surface of nickel hydroxide, destroying the good conductive network and reducing the discharge characteristics of the alkaline nickel-hydrogen battery under large current. Summary of the invention

[0010] In view of the technical problems existing in the existing alkaline nickel-hydrogen batteries, the present invention aims to provide an alkaline nickel-hydrogen battery to overcome the technical problems existing in the existing alkaline nickel-hydrogen batteries.

[0011] Compared with the existing alkaline nickel-hydrogen batteries, the alkaline nickel-hydrogen batteries provided by the present invention can simultaneously achieve the following technical effects: (1) reducing the self-discharge of the fully charged alkaline nickel-hydrogen batteries during long-term storage; (2) avoiding the problem of reduced discharge characteristics of the fully charged alkaline nickel-hydrogen batteries under large current during long-term storage; (3) improving the open circuit voltage of the fully charged alkaline nickel-hydrogen batteries; (4) improving the capacity recovery of the deeply discharged alkaline nickel-hydrogen batteries after long-term storage; (5) improving the durability of the alkaline nickel-hydrogen batteries to repeated deep discharge during the charge and discharge cycle.

[0012] To achieve the above object, the present invention adopts the following technical scheme: an alkaline nickel-hydrogen battery, wherein an electrode group and an alkaline electrolyte are contained in a container in a sealed state, the electrode group includes a separator, a positive electrode and a negative electrode, and the separator is between the positive electrode and the negative electrode. As a material for the separator, a material obtained by imparting a hydrophilic functional group to a non-woven fabric made of polyamide fiber or a non-woven fabric made of polyolefin fiber such as polyethylene or polypropylene can be used.

[0013] The alkaline nickel-hydrogen battery also meets the following requirements:

[0014] 1. The positive electrode is composed of a conductive positive electrode collector and a positive electrode active layer coated on the surface of the positive electrode collector, wherein the positive electrode active layer includes a positive electrode active material and a positive electrode additive;

[0015] 2. The positive electrode active material includes nickel hydroxide in which at least one of magnesium and aluminum is solid-dissolved, and the positive electrode additive includes at least one of zinc oxide, titanium oxide and cobalt hydroxide;

[0016] 3. The negative electrode is composed of a conductive negative electrode collector and a negative electrode active layer coated on the surface of the negative electrode collector, and the negative electrode active layer includes a negative electrode active material and a negative electrode additive;

[0017] 4. The negative electrode active material includes a hydrogen storage alloy material capable of storing and releasing hydrogen, and the negative electrode additive is aluminum fluoride (AlF 3 ), calcium fluoride (CaF 2 ) or yttrium fluoride (YF 3 )

[0018] 5. Hydroxide (OH) in alkaline electrolyte - ) has a molar concentration of 8-10 mol / L, and the alkaline electrolyte includes sodium hydroxide (NaOH) with a molar concentration of 7-8 mol / L, lithium hydroxide (LiOH) with a molar concentration of 0-3 mol / L, and potassium hydroxide (KOH) with a molar concentration of 0-2 mol / L.

[0019] The negative electrode additive can improve the stability and capacity of the negative electrode active material and improve the interface performance of the negative electrode active material, thereby improving the performance of the alkaline nickel-hydrogen battery. Preferably, the amount of the negative electrode additive added is 0.1-5 parts by mass relative to 100 parts by mass of the negative electrode active material.

[0020] The cobalt hydroxide in the positive electrode additive helps to improve the conductivity between the positive electrode active materials. Preferably, the amount of cobalt hydroxide added is 0.5-5 parts by mass relative to 100 parts by mass of the positive electrode active material.

[0021] Among them, zinc oxide in the positive electrode additive can inhibit the expansion of the positive electrode during the charge and discharge cycle, which helps to improve the cycle life characteristics of the battery. Preferably, the addition amount of zinc oxide is 0.3-5 parts by mass relative to 100 parts by mass of the positive electrode active material.

[0022] Among them, the titanium oxide in the positive electrode additive can absorb hydrogen ions and hydroxide ions in the electrolyte, improve the electrochemical activity of the positive electrode surface, and thus improve the discharge capacity and cycle life of the alkaline nickel-hydrogen battery. Preferably, the addition amount of titanium oxide is 0.01-5 parts by mass relative to 100 parts by mass of the positive electrode active material.

[0023] Among them, preferably, the average particle size of the positive electrode active material is within the range of 8-20 μm. The use of small-diameter particles with an average particle size of less than 20 μm can increase the surface area of ​​the positive electrode active material, increase the electrode reaction area of ​​the positive electrode, and achieve high output power of the battery, but small-diameter particles are prone to agglomeration, so the average particle size of the positive electrode active material is greater than 8 μm. More preferably, the average particle size of the positive electrode active material is 10-16 μm.

[0024] The inventor unexpectedly discovered during the research process that in order to reduce the self-discharge of a fully charged alkaline nickel-hydrogen battery during long-term storage and simultaneously increase the open circuit voltage of the fully charged alkaline nickel-hydrogen battery, the content of KOH in the alkaline electrolyte must be reduced as much as possible without reducing the electrical performance of the alkaline nickel-hydrogen battery. Based on this discovery, the inventor avoided the negative impact on the electrical performance of the alkaline nickel-hydrogen battery caused by reducing the content of KOH in the alkaline electrolyte by improving the positive electrode active layer and the negative electrode active layer.

[0025] In one or more embodiments, the positive electrode active layer further includes a positive electrode binder. As the positive electrode binder, for example, carboxymethyl cellulose, methyl cellulose, PTFE (polytetrafluoroethylene) dispersion, HPC (hydroxypropyl cellulose) dispersion, etc. can be used.

[0026] In one or more embodiments, the particles of the positive electrode active material used in the alkaline nickel-hydrogen battery provided by the present invention have a core-shell structure. More specifically, the particles of the positive electrode active material include a core and a coating layer, the core is nickel hydroxide in which at least one of magnesium and aluminum is solid-dissolved, and the coating layer is nickel hydroxide in which at least one of magnesium and aluminum is solid-dissolved. The positive electrode active material satisfies: (1) when the solid solution amount of magnesium contained in the core is A and the solid solution amount of magnesium contained in the coating layer is B, the relationship B>A≥0 is satisfied; (2) when the solid solution amount of aluminum contained in the core is C and the solid solution amount of aluminum contained in the coating layer is D, the relationship C>D≥0 is satisfied.

[0027] In one or more embodiments, the negative electrode active layer further includes a conductive additive and a negative electrode binder. The negative electrode binder may be a hydrophilic or hydrophobic polymer, and the conductive additive may be a carbon material such as carbon black or graphite.

[0028] It should be noted that the method for forming the hydrogen storage alloy material used in the alkaline nickel-hydrogen battery provided by the present invention is not particularly limited. For example, plasma arc melting method, high-frequency melting (casting mold) method, mechanical alloying method (mechanical alloying method), mechanical milling method, rapid cooling and solidification method (specifically, roller spinning method, melt dragging method, direct casting and rolling method, rotating liquid medium spinning method, injection molding method, gas atomization method, wet spraying method, sputtering method, rapid solidification thin strip grinding method, gas jet sputtering method, melt extraction method, injection molding method, rotating electrode method, etc.). Mechanical alloying method and mechanical grinding method are effective synthesis methods, and the size and crystal shape of the hydrogen storage alloy material prepared by this method are easy to control. In addition to using the rapid solidification method alone, it can also be used in combination with the mechanical alloying method.

[0029] In one or more embodiments, the hydrogen storage alloy material used in the negative electrode active material is an AB type structure hydrogen storage alloy. More specifically, the hydrogen storage alloy material is a rare earth-Mg-Ni series hydrogen storage alloy containing rare earth elements, Mg, and Ni. The rare earth-Mg-Ni series hydrogen storage alloy is a hydrogen storage alloy having a general formula: Ln 1-x Mg x (Ni 1-y T y ) z The invention relates to a hydrogen storage alloy, wherein Ln represents at least one element selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ca, Sr, Sc, Y, Yb, Er, Ti, Zr and Hf, T represents at least one element selected from V, Nb, Ta, Cr, Mo, Fe, Al, Ga, Zn, Sn, In, Cu, Si, P and B, and the subscripts x, y and z represent numbers satisfying 0<x≤1, 0≤y≤0.5 and 2.5≤z≤4.5 respectively.

[0030] In one or more embodiments, the hydrogen storage alloy material used in the negative electrode active material contains La, Mg, Ni, Co, Al and element M, and the hydrogen storage alloy material satisfies: (1) the molar ratio a of Mg relative to the sum of La and Mg is 0.01≤a≤0.5; (2) the molar ratio b of Ni relative to the sum of La and Mg is 2≤b≤4; (3) the molar ratio c of Co relative to the sum of La and Mg is 0.01≤c≤0.75; (4) the molar ratio d of Al relative to the sum of La and Mg is 0.01≤d≤0.05; (5) the element M is at least one selected from Y, Zr and Sn, and the content of the element M is 0.01%-0.4% of the weight of the hydrogen storage alloy material. The hydrogen storage alloy material containing element M can prevent the reduction of conductivity at low temperature and further improve the high temperature storage characteristics, so that the hydrogen storage alloy material can be used in a wider temperature range. For example, when element M is Y, the hydrogen storage alloy material has a strong affinity for oxygen and can reduce adjacent oxides. However, it is unexpectedly found that when the content of element M in the hydrogen storage alloy material exceeds 0.4wt%, element M may replace the constituent elements in the hydrogen storage alloy material, thereby causing the capacity of the hydrogen storage alloy material to decrease and the durability to deteriorate due to the introduction of lattice defects.

[0031] The alkaline nickel-hydrogen battery provided by the present invention can suppress the destruction of its conductive network during the charge and discharge cycle, and the effect of suppressing the destruction of the conductive network can be basically maintained even when repeated deep discharge is performed. Therefore, the battery of the present invention has excellent durability relative to repeated deep discharge.

[0032] The alkaline nickel-hydrogen battery provided by the present invention has excellent storage stability for a long time in a wide range of ambient temperatures, which is specifically manifested in low self-discharge and low capacity loss.

[0033] The following describes the invention in conjunction with specific embodiments. DETAILED DESCRIPTION

[0034] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0035] The alkaline nickel-hydrogen batteries described in the embodiments of the present invention are all cylindrical batteries of AA size. More specifically, the alkaline nickel-hydrogen batteries described in the embodiments of the present invention all satisfy the following structure:

[0036] 1. Alkaline nickel-hydrogen batteries have a bottomed cylindrical case with an open top. The case is conductive, and its bottom wall serves as a negative terminal.

[0037] 2. A conductive circular plate-shaped cover plate and a ring-shaped insulating seal member surrounding the cover plate are arranged in the opening of the shell, and the cover plate and the insulating seal member are fixed to the opening edge of the shell by riveting the opening edge of the shell. That is, the cover plate and the insulating seal member cooperate with each other to hermetically seal the opening of the shell.

[0038] 3. The shell contains an electrode group wound into a spiral shape, which includes a positive electrode, a negative electrode and a separator. The separator is located between the positive electrode and the negative electrode to physically isolate the positive electrode and the negative electrode. The outermost periphery of the electrode group is formed by a part of the negative electrode (the outermost peripheral part), and the outermost peripheral part of the negative electrode is in contact with the inner peripheral wall of the shell to achieve electrical connection between the negative electrode and the shell.

[0039] 4. In the housing, a positive electrode tab is arranged between one end of the electrode group and the cover plate, one end of the positive electrode tab is connected to the positive electrode, and the other end is connected to the cover plate. Therefore, the positive electrode is electrically connected to the positive electrode terminal of the cover plate through the positive electrode tab. In addition, a circular insulating member is arranged between the cover plate and the electrode group. Moreover, the positive electrode tab extends through the slit provided in the insulating member. In addition, a circular insulating member is also arranged between the electrode group and the bottom of the housing.

[0040] 5. An alkaline electrolyte is injected into the shell, and the alkaline electrolyte allows the charge and discharge reaction to proceed between the positive electrode and the negative electrode.

[0041] In the embodiment of the present invention, the positive electrode is composed of a conductive positive electrode collector and a positive electrode active layer coated on the surface of the positive electrode collector. The positive electrode active layer includes a positive electrode active material and a positive electrode additive. The positive electrode collector has a surface density of about 600 g / m 2 , nickel foam with a porosity of 95% and a thickness of about 2 mm.

[0042] The positive electrode of the alkaline nickel-hydrogen battery provided in the embodiment of the present invention is manufactured by the following method: first, prepare a positive electrode slurry containing a positive electrode active material, a positive electrode additive, water and a binder; fill the positive electrode slurry into nickel foam and dry it; after drying, roll and cut in sequence to obtain a positive electrode. The particles of the positive electrode active material have a core-shell structure, including a core and a coating layer, the core is nickel hydroxide with a solid solution of magnesium and aluminum, and the coating layer is nickel hydroxide with a solid solution of magnesium and aluminum. Based on the total weight of the core, the content of magnesium in the core is 0.1% and the content of aluminum is 0.1%; based on the total weight of the coating layer, the content of magnesium in the coating layer is 0.01% and the content of aluminum is 0.01%. The method for making the positive electrode active material is as follows:

[0043] Step 1: weigh nickel sulfate, magnesium sulfate and aluminum sulfate (by controlling the mass ratio of nickel sulfate, magnesium sulfate and aluminum sulfate, the content of solid-dissolved magnesium and the content of solid-dissolved aluminum in the kernel can be regulated), and add them to a 1 mol / L sodium hydroxide aqueous solution containing ammonium ions to prepare a mixed aqueous solution. While stirring the obtained mixed aqueous solution, 10 mol / L sodium hydroxide aqueous solution is slowly added to the mixed aqueous solution to react, and the pH is controlled to be stable at 13-14 during the reaction process to generate a core particle with nickel hydroxide as the main body and solid-dissolved magnesium and aluminum.

[0044] Step 2: The obtained core particles are washed three times with 10 times amount of pure water, and then dehydrated and dried. In addition, the obtained core particles are formed into a spherical shape with an average particle size of about 10 μm.

[0045] Step 3: Put the obtained core particles into an ammonia solution, maintain the pH in the reaction at 9-10, and add an aqueous solution containing nickel sulfate, magnesium sulfate and aluminum sulfate (by controlling the mass ratio of nickel sulfate, magnesium sulfate and aluminum sulfate, the content of solid-dissolved magnesium and the content of solid-dissolved aluminum in the coating layer can be regulated), thereby forming a coating layer with nickel hydroxide as the main body and solid-dissolved magnesium and aluminum on the surface of the core particles, and the thickness of the coating layer is about 3μm. Then, the composite particles are washed with water and dried at 60°C. Thus, a positive electrode active material is obtained.

[0046] In the embodiment of the present invention, the negative electrode is composed of a conductive negative electrode collector and a negative electrode active layer coated on the surface of the negative electrode collector, the negative electrode active layer includes a negative electrode active material and a negative electrode additive, the negative electrode active material is a hydrogen storage alloy material, the crystal structure of the hydrogen storage alloy material is Ce2Ni7 type determined by X-ray diffraction measurement (XRD measurement), and the composition of the hydrogen storage alloy material is Nd determined by radio frequency plasma emission spectrometry (ICP) 0.32 Sm 0.55 Mg 0.10 Ni 3.27 Al 0.15 Co 0.03 Y 0.01 . The hydrogen storage alloy material is obtained by, for example, the following method: first, weighing and mixing metal raw materials according to the conditions of achieving the specified composition, melting the mixture in, for example, an induction melting furnace to form an ingot; subjecting the obtained ingot to a heat treatment of heating at 900-1200°C in an inert atmosphere for 5-24 hours; finally, crushing the ingot, and screening and classifying it into the desired particle size (particle size distribution having an average particle size of 45 μm) to obtain the hydrogen storage alloy material. The negative electrode collector is a nickel-plated steel plate having a thickness of 60 μm.

[0047] The negative electrode of the alkaline nickel-hydrogen battery provided in the embodiment of the present invention is manufactured by the following method: first, the negative electrode active material, the negative electrode additive, the conductive aid, the binder and water are mixed to prepare the negative electrode slurry; the obtained negative electrode slurry is coated on the negative electrode collector and dried; after drying, rolling and cutting are performed in sequence to obtain the negative electrode.

[0048] The separator of the alkaline nickel-hydrogen battery provided in the embodiment of the present invention is made of a closed-loop non-woven fabric of polypropylene fibers with sulfonic acid groups, with a thickness of 0.1 mm and a surface density of 40 g / m 2 .

[0049] The positive electrode and negative electrode prepared according to the above method are wound into a spiral shape with a separator between them to form an electrode group. The electrode group thus obtained is housed in a shell. Next, a predetermined amount of alkaline electrolyte is injected into the shell. Then, the shell containing the electrode group and the alkaline electrolyte is sealed by a cover plate having a positive terminal, thereby obtaining an alkaline nickel-hydrogen battery described in an embodiment of the present invention.

[0050] The alkaline nickel-hydrogen batteries provided in the embodiments of the present invention have a relatively high open circuit voltage, which can effectively reduce the occurrence of self-discharge, can maintain a relatively large amount of electric energy even when left unused for a long time, have excellent capacity recovery performance, and have excellent charge and discharge performance.

[0051] The differences between the alkaline nickel-hydrogen batteries provided in Examples 1-4 are shown in Table 1.

[0052] The specific preparation method of the alkaline nickel-hydrogen battery provided in Example 1 of the present invention is as follows:

[0053] Step 1: prepare a mixed powder by mixing the positive electrode active material, zinc oxide and cobalt hydroxide in a mass ratio of 100:3:2. Prepare a positive electrode slurry by mixing the mixed powder with a hydroxypropyl cellulose solution (the hydroxypropyl cellulose solution is used as a binder, and the content of hydroxypropyl cellulose in the hydroxypropyl cellulose solution is 0.2%) in a mass ratio of 2:1.

[0054] Step 2: Fill the positive electrode slurry into the nickel foam and then dry it.

[0055] Step 3: After the positive electrode slurry filled in the nickel foam is dried, it is subjected to a rolling process (the volume density after the rolling process is about 2.9 g / cm 3 ), and then cut it according to the specified size to obtain the AA size positive electrode.

[0056] Step 4: Add 0.2 parts by mass of sodium polyacrylate, 0.2 parts by mass of carboxymethyl cellulose, 0.5 parts by mass of styrene-butadiene rubber dispersion (the solid content of styrene-butadiene rubber in the styrene-butadiene rubber dispersion is 50%), 0.5 parts by mass of graphite, 50 parts by mass of water, and 0.5 parts by mass of aluminum fluoride (AlF 3 ), 0.5 parts by mass of calcium fluoride (CaF 2 ) and 0.5 parts by mass of yttrium fluoride (YF 3 ), to obtain a mixture, and knead the mixture at room temperature to obtain a negative electrode slurry.

[0057] Step five, the negative electrode slurry is coated on both end surfaces of the nickel-plated steel plate by a coating process, and then dried. After the negative electrode slurry is dried, it is rolled and cut in sequence to obtain a negative electrode of AA size.

[0058] Step six, the prepared positive electrode and negative electrode are wound into a spiral shape with a separator in between to form an electrode group, the electrode group is placed in an AA-sized cylindrical shell, and then 2.2g of alkaline electrolyte is injected, and then the opening of the shell is sealed with a cover plate, etc., to assemble into an AA-sized alkaline nickel-hydrogen battery with a nominal capacity of 2000mAh.

[0059] Step 7: After charging the alkaline nickel-hydrogen battery at 20°C with a charging current of 0.1C for 16 hours, the battery is discharged with a discharge current of 0.2C until the battery voltage reaches 1.0V, and this initial activation treatment is repeated twice. Thus, an alkaline nickel-hydrogen battery in a usable state is obtained.

[0060] The only difference between the alkaline nickel-hydrogen battery provided in Comparative Example 1 and the alkaline nickel-hydrogen battery provided in Example 1 is that the positive electrode active material in the alkaline nickel-hydrogen battery provided in Comparative Example 1 is spherical nickel hydroxide.

[0061] The only difference between the alkaline nickel-hydrogen battery provided in Comparative Example 2 and the alkaline nickel-hydrogen battery provided in Example 1 is that the positive electrode active material in the alkaline nickel-hydrogen battery provided in Comparative Example 2 is spherical nickel hydroxide in which zinc and cobalt are solid-dissolved, and the content of zinc and cobalt is 0.1% based on the total weight of the positive electrode active material.

[0062] The differences between the alkaline nickel-hydrogen batteries provided in Comparative Examples 3-8 and the alkaline nickel-hydrogen battery provided in Example 1 are shown in Table 2.

[0063] Table 1

[0064]

[0065]

[0066] Table 2

[0067]

[0068] The alkaline nickel-hydrogen batteries provided in Examples 1-4 and the alkaline nickel-hydrogen batteries provided in Comparative Examples 1-8 were subjected to the following tests. The test results are shown in Tables 3 and 4.

[0069] 1. Measurement of initial capacity

[0070] The alkaline nickel-hydrogen battery that has completed the initial activation treatment is charged at a constant current and constant voltage at a charging current of 0.1C in an atmosphere at 20°C, and then discharged at a current of 1.0C in the same atmosphere until the battery voltage reaches 1.0V. The discharge capacity of the alkaline nickel-hydrogen battery at this time is measured and the discharge capacity at this time is taken as the initial capacity.

[0071] 2. Room temperature storage performance test

[0072] Alkaline nickel-hydrogen batteries are charged at a constant current and constant voltage of 0.1C in an atmosphere of 20°C to make them fully charged. A high-precision DC voltmeter is used to measure the OCV (open circuit voltage) of the fully charged alkaline nickel-hydrogen batteries, and a multimeter is used to measure the CCV (closed circuit voltage) of the fully charged alkaline nickel-hydrogen batteries.

[0073] The alkaline nickel-hydrogen battery was stored in an atmosphere of 20°C. On the 30th day of storage, the OCV (open circuit voltage) and CCV (closed circuit voltage) of the alkaline nickel-hydrogen battery were measured; on the 60th day of storage, the OCV (open circuit voltage) and CCV (closed circuit voltage) of the alkaline nickel-hydrogen battery were measured, and then the alkaline nickel-hydrogen battery was discharged at a current of 3.0C until the battery voltage reached 1.0V, and the discharge capacity A of the alkaline nickel-hydrogen battery at this time was measured. The capacity retention rate A was obtained according to the following calculation formula: Capacity retention rate A (%) = (discharge capacity A / initial capacity) × 100. The value of the capacity retention rate A indicates whether the alkaline nickel-hydrogen battery in the fully charged state has a problem of reduced discharge characteristics under large current during long-term storage.

[0074] 3. High temperature storage performance test

[0075] Alkaline nickel-hydrogen batteries are charged at a constant current and constant voltage of 0.1C in an atmosphere of 20°C to make them fully charged. A high-precision DC voltmeter is used to measure the OCV (open circuit voltage) of the fully charged alkaline nickel-hydrogen batteries, and a multimeter is used to measure the CCV (closed circuit voltage) of the fully charged alkaline nickel-hydrogen batteries.

[0076] The alkaline nickel-hydrogen battery was stored in an atmosphere of 60°C. On the 60th day of storage, the alkaline nickel-hydrogen battery was discharged at a current of 1.0C until the battery voltage reached 1.0V. The discharge capacity B of the alkaline nickel-hydrogen battery at this time was measured, and the capacity retention rate B was obtained according to the following calculation formula: capacity retention rate B (%) = (discharge capacity B / initial capacity) × 100. The value of the capacity retention rate B indicates the severity of the self-discharge problem of the fully charged alkaline nickel-hydrogen battery when placed in a high temperature environment for a long time.

[0077] 4. Charge and discharge cycle stability test

[0078] In an atmosphere of 20°C, the alkaline nickel-hydrogen battery is charged at a charging current of 1.0C, placed for 30 minutes after charging, and then discharged at a current of 1.0C until the battery voltage reaches 1.0V. After discharging, the battery is placed for 30 minutes before charging again. The above charging and discharging is cycled for 200 weeks, and the discharge capacity C of the alkaline nickel-hydrogen battery at the 200th week is measured. The capacity retention rate C is obtained according to the following calculation formula: Capacity retention rate C (%) = (discharge capacity C / initial capacity) × 100. The value of the capacity retention rate C indicates the charge and discharge cycle stability of the alkaline nickel-hydrogen battery.

[0079] 5. Capacity recovery rate test after deep discharge

[0080] The alkaline nickel-hydrogen battery was charged at a constant current and constant voltage at a charging current of 0.1C at an atmosphere of 20°C, so that the alkaline nickel-hydrogen battery was in a fully charged state. Then, a 2Ω resistor was connected between the positive terminal and the negative terminal of the alkaline nickel-hydrogen battery, and it was placed at an atmosphere of 20°C for 15 days. Then, the battery was charged at a charging current of 1.0C at an atmosphere of 20°C, and then discharged at a current of 1.0C in the same atmosphere until the battery voltage reached 1.0V, and the discharge capacity D of the alkaline nickel-hydrogen battery was measured, and the capacity recovery rate was obtained according to the following calculation formula: Capacity recovery rate (%) = (discharge capacity D / initial capacity) × 100.

[0081] According to Table 3 and Table 4, it can be judged that the alkaline nickel-hydrogen battery provided by the present invention can simultaneously achieve the following technical effects: (1) reducing the self-discharge of the fully charged alkaline nickel-hydrogen battery during long-term storage in a high-temperature environment; (2) avoiding the problem of reduced discharge characteristics of the fully charged alkaline nickel-hydrogen battery under high current during long-term storage; (3) improving the open circuit voltage of the fully charged alkaline nickel-hydrogen battery; (4) improving the capacity recovery of the deeply discharged alkaline nickel-hydrogen battery after long-term storage.

[0082] Table 3

[0083]

[0084] Table 4

[0085]

[0086]

[0087] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An alkaline nickel-hydrogen battery, wherein an electrode group and an alkaline electrolyte are contained in a container in a sealed state, the electrode group comprises a separator, a positive electrode and a negative electrode, the separator is between the positive electrode and the negative electrode, and the battery is characterized in that: The positive electrode is composed of a positive electrode collector having conductivity and a positive electrode active layer coated on the surface of the positive electrode collector, wherein the positive electrode active layer includes a positive electrode active material and a positive electrode additive, wherein the positive electrode active material includes nickel hydroxide in which at least one of magnesium and aluminum is solid-dissolved, and the positive electrode additive includes at least one of zinc oxide, titanium oxide and cobalt hydroxide; The negative electrode is composed of a conductive negative electrode collector and a negative electrode active layer coated on the surface of the negative electrode collector, wherein the negative electrode active layer includes a negative electrode active material and a negative electrode additive, wherein the negative electrode active material includes a hydrogen storage alloy material capable of storing and releasing hydrogen, and the negative electrode additive is at least one of aluminum fluoride, calcium fluoride or yttrium fluoride; The molar concentration of hydroxide in the alkaline electrolyte is 8-10 mol / L, and the alkaline electrolyte includes sodium hydroxide with a molar concentration of 7-8 mol / L, lithium hydroxide with a molar concentration of 0-3 mol / L, and potassium hydroxide with a molar concentration of 0-2 mol / L.

2. The alkaline nickel-hydrogen battery according to claim 1, characterized in that The amount of the negative electrode additive added is 0.1-5 parts by mass relative to 100 parts by mass of the negative electrode active material.

3. The alkaline nickel-hydrogen battery according to claim 1, characterized in that: The positive electrode additive includes the cobalt hydroxide, and the added amount of the cobalt hydroxide is 0.5-5 parts by mass relative to 100 parts by mass of the positive electrode active material.

4. The alkaline nickel-hydrogen battery according to claim 1, characterized in that: The positive electrode additive includes zinc oxide, and the added amount of zinc oxide is 0.3-5 parts by mass relative to 100 parts by mass of the positive electrode active material.

5. The alkaline nickel-hydrogen battery according to claim 1, characterized in that: The positive electrode additive includes titanium oxide, and the addition amount of the titanium oxide is 0.01-5 parts by mass relative to 100 parts by mass of the positive electrode active material.

6. The alkaline nickel-hydrogen battery according to claim 1, characterized in that The average particle size of the positive electrode active material particles is in the range of 8-20 μm.

7. The alkaline nickel-hydrogen battery according to claim 6, characterized in that: The particles of the positive electrode active material include a core and a coating layer, the core is nickel hydroxide in which at least one of magnesium and aluminum is solid-dissolved, the coating layer is nickel hydroxide in which at least one of magnesium and aluminum is solid-dissolved, and the positive electrode active material satisfies: When the solid solution amount of magnesium contained in the core is A and the solid solution amount of magnesium contained in the coating layer is B, the relationship of B>A≥0 is satisfied; When the solid solution amount of aluminum contained in the core is C and the solid solution amount of aluminum contained in the coating layer is D, C>D≥0 is satisfied.

8. The alkaline nickel-hydrogen battery according to claim 1, characterized in that The hydrogen storage alloy material contains La, Mg, Ni, Co, Al and element M, and the hydrogen storage alloy material satisfies: The molar ratio a of Mg to the sum of La and Mg is 0.01≤a≤0.5; The molar ratio b of Ni relative to the sum of La and Mg is 2≤b≤4; The molar ratio c of Co relative to the sum of La and Mg is 0.01≤c≤0.75; The molar ratio d of Al to the sum of La and Mg is 0.01≤d≤0.05; The element M is at least one selected from Y, Zr and Sn, and the content of the element M is 0.01%-0.4% by weight of the hydrogen storage alloy material.

Images