Nickel-metal hydride battery electrolyte additive, electrolyte and nickel-metal hydride battery

Abstract

The invention relates to a nickel-metal hydride battery electrolyte additive, an electrolyte and a nickel-metal hydride battery. The nickel-metal hydride battery electrolyte additive comprises micron-sized boehmite, and the concentration of the micron-sized boehmite in an electrolyte is 0.15 mol / L to 1 mol / L. According to the scheme provided by the invention, the electrolyte additive micron-sized boehmite can be combined with hydroxyl in the nickel-metal hydride battery electrolyte to form aluminum hydroxide, aluminum ions can enter the positive electrode to inhibit expansion and phase transformation of the positive electrode, and aluminum hydroxide can form an aluminum hydroxide passivation film on the surface of the positive electrode and the surface of the negative electrode respectively; the aluminum hydroxide passivation film on the surface of the negative electrode can play a role in isolating electrolyte from the negative electrode, reducing contact between the negative electrode and the electrolyte and inhibiting side reaction between the negative electrode and the electrolyte, so that capacity loss of the positive electrode and the negative electrode is slowed down, stability of the positive electrode and the negative electrode is improved, and long-term high-temperature floating charge performance of the nickel-metal hydride battery is improved; and the long-term high-temperature floating charge performance of the nickel-metal hydride battery can be obviously improved at relatively low cost.

Description

Technical Field

[0001] The present application relates to the technical field of nickel-hydrogen batteries, and in particular to a nickel-hydrogen battery electrolyte additive, an electrolyte and a nickel-hydrogen battery. Background Art

[0002] Nickel-metal hydride batteries have been widely used in portable devices and energy storage backup devices due to their excellent high-rate charge and discharge performance and high safety.

[0003] In a high-temperature floating charge environment, the positive electrode material Ni(OH)2 (nickel hydroxide) of the nickel-hydrogen battery undergoes an oxygen evolution side reaction, and is accompanied by a phase transformation of β-NiOOH (a crystal structure of nickel hydroxide) to a larger γ-NiOOH (another crystal structure of nickel hydroxide) phase. In order to slow down the volume expansion of the positive electrode material during the floating charge process and enhance the conductivity of the positive electrode material, the nickel hydroxide of the related technology is plated with a layer of CoOOH (cobalt hydroxide) coating with high conductivity and high ion transport on the surface of the positive electrode material. However, the high-temperature stability of the CoOOH coating is poor, and it is easy to break, which leads to a decrease in the performance of the positive electrode. At the same time, for the hydrogen storage alloy of the negative electrode of the nickel-hydrogen battery, high temperature aggravates the corrosion and passivation of the hydrogen storage alloy in the alkaline electrolyte, resulting in a sharp decrease in the capacity and life of the nickel-hydrogen battery. Therefore, with the expansion of the application scenarios of nickel-hydrogen batteries, higher wide temperature requirements are put forward for nickel-hydrogen batteries. Among them, how to improve the long-term high-temperature floating charge performance of nickel-hydrogen batteries has become a major problem.

[0004] Related technologies improve the long-term high-temperature floating performance of nickel-hydrogen batteries by increasing the Co coating on the positive electrode and using a highly corrosion-resistant hydrogen storage alloy with high Co and Nd content on the negative electrode, thereby solving the problems that occur in nickel-hydrogen batteries during high-temperature floating charging. However, related technologies greatly increase the cost of nickel-hydrogen batteries and the effect is not good. Summary of the invention

[0005] In order to solve or partially solve the problems existing in the related art, the present application provides a nickel-hydrogen battery electrolyte additive, an electrolyte and a nickel-hydrogen battery. The electrolyte additive micron-sized boehmite can combine with the hydroxide in the nickel-hydrogen battery electrolyte to form aluminum hydroxide. The aluminum ions can enter the positive electrode to inhibit the expansion and phase transition of the positive electrode. The aluminum hydroxide can form a layer of aluminum hydroxide passivation film on the surface of the positive electrode and the surface of the negative electrode respectively. The aluminum hydroxide passivation film on the surface of the negative electrode can isolate the electrolyte from the negative electrode, reduce the contact between the negative electrode and the electrolyte, and inhibit the side reaction between the negative electrode and the electrolyte, thereby slowing down the capacity loss of the positive electrode and the negative electrode, improving the stability of the positive electrode and the negative electrode, and improving the long-term high-temperature floating charge performance of the nickel-hydrogen battery. The long-term high-temperature floating charge performance of the nickel-hydrogen battery can be significantly improved at a lower cost.

[0006] In a first aspect, the present application provides a nickel-hydrogen battery electrolyte additive, wherein the nickel-hydrogen battery electrolyte additive includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 0.15 mol / L-1 mol / L.

[0007] Preferably, the concentration of the micron-sized boehmite in the electrolyte is 0.33 mol / L-0.66 mol / L.

[0008] Preferably, the micron-sized boehmite is a spherical boehmite with a particle size of 2 μm-4 μm.

[0009] A second aspect of the present application provides a nickel-hydrogen battery electrolyte, wherein the nickel-hydrogen battery electrolyte comprises an alkaline solution and the electrolyte additive as described above.

[0010] Preferably, the alkaline solution includes one or more of potassium hydroxide, sodium hydroxide and lithium hydroxide.

[0011] Preferably, the alkaline solution comprises potassium hydroxide, sodium hydroxide and lithium hydroxide.

[0012] Preferably, the concentration of potassium hydroxide in the electrolyte is 5.5 mol / L-6 mol / L.

[0013] Preferably, the concentration of sodium hydroxide in the electrolyte is 0.35 mol / L-0.4 mol / L.

[0014] Preferably, the concentration of the lithium hydroxide in the electrolyte is 1 mol / L-1.5 mol / L.

[0015] A third aspect of the present application provides a nickel-hydrogen battery, which includes a positive electrode, a negative electrode, a separator, and the electrolyte as described above.

[0016] The technical solution provided by this application may have the following beneficial effects:

[0017] The technical solution of the present application is that the electrolyte additive micron-sized boehmite can combine with the hydroxide in the nickel-hydrogen battery electrolyte to form aluminum hydroxide, and the aluminum ions can enter the positive electrode to inhibit the expansion and phase transition of the positive electrode. The aluminum hydroxide can form a layer of aluminum hydroxide passivation film on the positive electrode surface and the negative electrode surface respectively. The aluminum hydroxide passivation film on the positive electrode surface and the negative electrode surface can play the role of isolating the electrolyte from the positive electrode and the negative electrode, reducing the contact between the positive electrode and the negative electrode and the electrolyte, and inhibiting the side reaction between the positive electrode and the negative electrode and the electrolyte, thereby slowing down the corrosion of the positive electrode and the negative electrode, slowing down the capacity loss of the positive electrode and the negative electrode, improving the stability of the positive electrode and the negative electrode, and improving the long-term high-temperature floating performance of the nickel-hydrogen battery. The nickel-hydrogen battery electrolyte additive of the embodiment of the present application can significantly improve the long-term high-temperature floating performance of the nickel-hydrogen battery at a lower cost.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. DETAILED DESCRIPTION

[0019] The embodiments of the present application will be described in more detail below. Although the embodiments of the present application are shown, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0020] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0021] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0022] The embodiment of the present application provides a nickel-hydrogen battery electrolyte additive, the electrolyte additive micron-sized boehmite can combine with the hydroxide in the nickel-hydrogen battery electrolyte to form aluminum hydroxide, aluminum ions can enter the positive electrode to inhibit the expansion and phase transition of the positive electrode, and aluminum hydroxide can form a layer of aluminum hydroxide passivation film on the positive electrode surface and the negative electrode surface respectively. The aluminum hydroxide passivation film on the positive electrode surface and the negative electrode surface can play a role in isolating the electrolyte from the positive electrode and the negative electrode, reducing the contact between the positive electrode and the negative electrode and the electrolyte, and inhibiting the side reaction between the positive electrode and the negative electrode and the electrolyte, thereby slowing down the corrosion of the positive electrode and the negative electrode, slowing down the capacity loss of the positive electrode and the negative electrode, improving the stability of the positive electrode and the negative electrode, and improving the long-term high-temperature floating performance of the nickel-hydrogen battery. The nickel-hydrogen battery electrolyte additive of the embodiment of the present application can significantly improve the long-term high-temperature floating performance of the nickel-hydrogen battery at a relatively low cost.

[0023] The technical solutions of the embodiments of the present application are described in detail below.

[0024] The embodiment of the present application provides a nickel-hydrogen battery electrolyte additive, including micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 0.15 mol / L (mole per liter)-1 mol / L.

[0025] In one embodiment, when the nickel-hydrogen battery is in a high-temperature floating charge state, the electrolyte of the nickel-hydrogen battery contacts the positive electrode material and the negative electrode material respectively, the positive electrode material Ni(OH)2 of the nickel-hydrogen battery is corroded to produce oxygen evolution side reaction and volume expansion, and the negative electrode material of the nickel-hydrogen battery is corroded to produce hydrogen evolution side reaction, resulting in a sharp decrease in the capacity and life of the nickel-hydrogen battery. Micron-sized boehmite, an electrolyte additive in the electrolyte of nickel-hydrogen batteries, can make the electrolyte contain aluminum ions. During the charging and discharging process of nickel-hydrogen batteries, the hydroxide in the electrolyte can ensure the normal electrochemical reaction in the nickel-hydrogen battery, and the aluminum ions in the electrolyte can combine with the hydroxide in the electrolyte to form aluminum hydroxide. The aluminum ions can enter the positive electrode to inhibit the expansion and phase transition of the positive electrode. The aluminum hydroxide can adhere to the surface of the positive electrode and the surface of the negative electrode respectively, forming a layer of aluminum hydroxide passivation film on the surface of the positive electrode and the surface of the negative electrode respectively. The aluminum hydroxide passivation film on the surface of the positive electrode and the surface of the negative electrode can isolate the electrolyte from the positive electrode and the negative electrode, reduce the contact between the positive electrode and the negative electrode and the electrolyte, and inhibit the side reaction between the positive electrode and the negative electrode and the electrolyte, thereby slowing down the corrosion of the positive electrode and the negative electrode, slowing down the capacity loss of the positive electrode and the negative electrode, improving the stability of the positive electrode and the negative electrode, and improving the long-term high-temperature floating charge performance of the nickel-hydrogen battery.

[0026] In one embodiment, the electrolyte of the nickel-hydrogen battery to which the electrolyte additive micron-sized boehmite is added contains aluminum ions, which can enter the positive electrode to inhibit the expansion and phase transition of the positive electrode. The aluminum ions in the electrolyte combine with the hydroxide in the electrolyte to form an aluminum hydroxide passivation film on the surface of the positive electrode and the surface of the negative electrode; the aluminum hydroxide passivation film on the surface of the positive electrode can effectively prevent (especially at high temperatures) the corrosion of the electrolyte to the positive electrode, and can delay the corrosion process of the alkaline electrolyte to the positive electrode, and inhibit the oxygen evolution side reaction and volume expansion of the positive electrode; the aluminum hydroxide passivation film on the surface of the negative electrode can effectively prevent (especially at high temperatures) the corrosion of the electrolyte to the negative electrode, and can delay the corrosion process of the alkaline electrolyte to the negative electrode. process, inhibiting the hydrogen evolution side reaction at the negative electrode; therefore, adding micron-sized boehmite, an electrolyte additive, to the electrolyte of the nickel-hydrogen battery, and the concentration of the micron-sized boehmite in the electrolyte is 0.15 mol / L-1 mol / L, which can form an aluminum hydroxide passivation film on the positive electrode surface and the negative electrode surface of the nickel-hydrogen battery respectively, thereby improving the high-temperature storage performance of the nickel-hydrogen battery; the aluminum hydroxide passivation film can inhibit the alkaline electrolyte from affecting the negative electrode, reduce the deposition of corrosion products, and make it less likely for micro short circuits to occur inside the nickel-hydrogen battery, thereby improving the self-discharge performance of the nickel-hydrogen battery; at the same time, the passivation film can change the absorption (desorption) behavior of hydrogen atoms on the negative electrode surface, inhibit the hydrogen evolution process at the negative electrode, and thereby improve the charging performance of the battery. Therefore, the embodiments of the present application can slow down the capacity loss of the positive and negative electrodes by adding the electrolyte additive micron-sized boehmite to the electrolyte, and can improve the long-term high-temperature floating performance, high-temperature storage performance, self-discharge performance and charging performance of the nickel-hydrogen battery; can increase the SOH value of the nickel-hydrogen battery at high temperature, and increase the cycle life of the nickel-hydrogen battery at high temperature, and can significantly improve the long-term high-temperature floating performance of the nickel-hydrogen battery at a relatively low cost, thereby solving the problem that the nickel-hydrogen battery is not resistant to high-temperature floating charge. In addition, the addition of micron-sized boehmite to the electrolyte has a simple process and can be applied to large-scale nickel-hydrogen battery production.

[0027] In one embodiment, an electrolyte additive is added to the electrolyte of the nickel-hydrogen battery. The electrolyte additive includes micron-sized boehmite (γ-AlOOH). The concentration of the micron-sized boehmite in the electrolyte is 0.33 mol / L-0.66 mol / L.

[0028] If the concentration of micron-sized boehmite in the electrolyte of nickel-hydrogen battery is too high, it may cause aluminum ions and hydroxide in the electrolyte to form too much aluminum hydroxide in the electrolyte, resulting in too high a concentration of aluminum hydroxide in the electrolyte, affecting the migration of ions during the charging and discharging process of the nickel-hydrogen battery, and further having a negative impact on the performance of the nickel-hydrogen battery; if the concentration of micron-sized boehmite in the electrolyte of nickel-hydrogen battery is too low, it may cause too little aluminum hydroxide content formed by aluminum ions and hydroxide in the electrolyte, and it may be impossible to form an aluminum hydroxide passivation film on the positive and negative surfaces of the nickel-hydrogen battery, respectively, and it may be impossible to play the role of inhibiting the corrosion of the negative electrode and inhibiting oxygen and hydrogen evolution. Moreover, the aluminum hydroxide passivation film cannot evenly cover the positive and negative surfaces of the nickel-hydrogen battery, which may lead to aggravated local corrosion of the positive and negative electrodes of the nickel-hydrogen battery. Therefore, it is very necessary to select an appropriate concentration of micron-sized boehmite in the electrolyte. By controlling the concentration of micron-sized boehmite in the electrolyte to 0.33mol / L-0.66mol / L, the long-term high-temperature floating performance, high-temperature storage performance, self-discharge performance and charging performance of the nickel-hydrogen battery can be effectively improved; the SOH value of the nickel-hydrogen battery at high temperature can be increased, and the cycle life of the nickel-hydrogen battery at high temperature can be increased, and the long-term high-temperature floating capacity of the nickel-hydrogen battery can be significantly improved at a lower cost. Among them, the concentration of micron-sized boehmite in the electrolyte can be 0.33mol / L, 0.35mol / L, 0.4mol / L, 0.5mol / L, 0.6mol / L, 0.66mol / L or any value in the range of 0.33mol / L-0.66mol / L.

[0029] In one embodiment, the micron-sized boehmite is a spherical boehmite with a particle size of 2 μm-4 μm, which can make the micron-sized boehmite dissolve quickly and evenly in the electrolyte.

[0030] Corresponding to the aforementioned nickel-metal hydride battery electrolyte additive embodiment, the present application also provides a nickel-metal hydride battery electrolyte and a nickel-metal hydride battery and corresponding embodiments.

[0031] The embodiment of the present application provides a nickel-metal hydride battery electrolyte, including an alkaline solution and the above-mentioned electrolyte additive.

[0032] The nickel-hydrogen battery electrolyte of the embodiment of the present application contains micron-sized boehmite, which can slow down the capacity loss of the positive and negative electrodes, and can effectively improve the long-term high-temperature floating charge performance, high-temperature storage performance, self-discharge performance and charging performance of the nickel-hydrogen battery; it can increase the SOH value of the nickel-hydrogen battery at high temperatures, increase the cycle life of the nickel-hydrogen battery at high temperatures, and can significantly improve the long-term high-temperature floating charge capability of the nickel-hydrogen battery at a relatively low cost.

[0033] In one embodiment, the alkaline solution of the nickel-metal hydride battery electrolyte includes one or more of potassium hydroxide, sodium hydroxide, and lithium hydroxide.

[0034] In one embodiment, the alkaline solution includes potassium hydroxide, sodium hydroxide, and lithium hydroxide.

[0035] In one embodiment, the concentration of potassium hydroxide in the electrolyte is 5.5 mol / L-6 mol / L. The concentration of potassium hydroxide in the electrolyte can be 5.5 mol / L, 5.6 mol / L, 5.7 mol / L, 5.8 mol / L, 5.9 mol / L, 6 mol / L or any value in the range of 5.5 mol / L-6 mol / L.

[0036] In one embodiment, the concentration of sodium hydroxide in the electrolyte is 0.35 mol / L-0.4 mol / L. The concentration of sodium hydroxide in the electrolyte can be 0.35 mol / L, 0.36 mol / L, 0.37 mol / L, 0.38 mol / L, 0.39 mol / L, 0.4 mol / L or any value in the range of 0.35 mol / L-0.4 mol / L.

[0037] In one embodiment, the concentration of lithium hydroxide in the electrolyte is 1 mol / L-1.5 mol / L. The concentration of lithium hydroxide in the electrolyte can be 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L or any value in the range of 1 mol / L-1.5 mol / L.

[0038] An embodiment of the present application provides a nickel-hydrogen battery, which includes a positive electrode, a negative electrode, a separator, and the above-mentioned electrolyte.

[0039] The positive electrode active material of the nickel-hydrogen battery of the embodiment of the present application includes nickel hydroxide, and the negative electrode active material includes a metal oxide, also known as a hydrogen storage alloy, which contains La (lanthanum), Ce (cerium), Y (yttrium), Ni (nickel), Mn (manganese), Al (aluminum), and Co (cobalt). The electrolyte includes an alkaline solution configured by the above metal hydroxides and the above nickel-hydrogen battery electrolyte additive. When charging, the negative electrode absorbs hydrogen atoms and stores them in the alloy, and the positive electrode changes from nickelous hydroxide to nickel hydroxide NiOOH and H2O; when discharging, the active hydrogen atoms are released from the alloy and converted into water, and the positive electrode changes from nickel hydroxide to nickelous hydroxide.

[0040] In one embodiment, the slurry of the positive electrode includes 70wt%-75wt% of spherical β-Ni(OH)2 (nickel hydroxide) with a surface coated with trivalent cobalt, 1wt%-4wt% of a conductive agent, 0.5wt%-1wt% of Y2O3 (yttrium trioxide) or 0.5wt%-1wt% of Yb2O3 (ytterbium trioxide), 2wt%-3wt% of a binder, 1wt%-2wt% of a suspending agent, and an appropriate amount of pure water.

[0041] In one embodiment, the conductive agent of the positive electrode includes conductive nickel powder and conductive zinc powder. Both the conductive nickel powder and the conductive zinc powder can increase the conductivity of the positive electrode. The conductive nickel powder can make the positive electrode active material nickel hydroxide cover the cobalt layer even after it is destroyed. The conductive zinc powder can play a conductive role in the early stage. The conductive zinc powder dissolves during the charge and discharge cycle, which can increase the positive electrode porosity and improve the rate performance of the nickel-hydrogen battery. At the same time, Zn ions can also inhibit the volume expansion caused by the phase change of the positive electrode, and can avoid the expansion and crushing of the active material caused by the phase change of the positive electrode.

[0042] In one embodiment, the conductive nickel powder may have a tap density of 1.5 g / cm 3 (grams per cubic centimeter) - 3g / cm 3 , spherical nickel powder with a particle size of 1μm (micrometer)-4μm.

[0043] In one embodiment, the conductive zinc powder may be nano-sized zinc powder.

[0044] In one embodiment, the binder having a dispersing and binding effect can be prepared by first preparing a binder aqueous solution when preparing the positive electrode slurry; then the binder aqueous solution and other materials of the positive electrode material are stirred evenly to prepare the positive electrode slurry. The binder aqueous solution can be a CMC aqueous solution and / or a PTFE aqueous solution. The CMC aqueous solution can be a CMC aqueous solution with a CMC mass percentage of 2%. The PTFE aqueous solution can be a PTFE aqueous solution with a PTFE mass percentage of 60%. In a specific embodiment, a polytetrafluoroethylene solid powder and pure water with a mass ratio of 3:2 can be fully stirred evenly by a magnetic stirrer to obtain a 60wt% PTFE aqueous solution.

[0045] In one embodiment, the spherical β-Ni(OH)2 and conductive nickel powder coated with trivalent cobalt on the surface of the active material have relatively high density. When the positive electrode slurry is left standing, the high-density substances will sink to the bottom. Adding the suspending agent xanthan gum to the positive electrode slurry can avoid the sinking of high-density substances when the positive electrode slurry is left standing.

[0046] In one embodiment, the negative electrode of the nickel-hydrogen battery includes 86wt%-90wt% of AB5 type hydrogen storage alloy, 0.1wt%-4wt% of conductive material, 6wt%-10wt% of binder, and 0.1wt%-0.5wt% of additives.

[0047] In one embodiment, the AB5 type hydrogen storage alloy of the negative electrode may be a low Co content AB5 type hydrogen storage alloy, the formula is La x Ce y Y z Ni 4.3 Mn 0.4 Al 0.2 Co 0.2, where x+y+z=1.

[0048] In one embodiment, the conductive material of the negative electrode may be one or more of Ni powder, copper powder, carbon black, and conductive graphite.

[0049] In one embodiment, the binder of the negative electrode is one or more of carboxymethyl cellulose, polytetrafluoroethylene emulsion, and styrene-butadiene rubber.

[0050] In one embodiment, the additive of the negative electrode can slow down the corrosion of the negative electrode, and can be yttrium oxide (Y2O3, yttrium trioxide) or ytterbium oxide (Yb2O3, ytterbium trioxide), preferably yttrium oxide.

[0051] In one embodiment, the separator of the nickel-hydrogen battery is made of sulfonated non-woven fabric with excellent liquid retention.

[0052] In one embodiment, the electrolyte of the nickel-hydrogen battery is the electrolyte including micron-sized boehmite as described above.

[0053] The following examples 1-12 and comparative examples 1-2 are used to illustrate the electrolyte containing micron-sized boehmite in the examples of the present application. Examples 1-12 and comparative examples 1-2 are only used to illustrate the present application and are not used to limit the scope of the present application.

[0054] The positive electrode, negative electrode, separator and other battery components of the nickel-hydrogen battery of Example 1-12 and Comparative Example 1-2 are the same.

[0055] Comparative Example 1:

[0056] An electrolyte is prepared, wherein the electrolyte includes potassium hydroxide, sodium hydroxide and lithium hydroxide, and no micron-sized boehmite is added, and the concentration of the micron-sized boehmite in the electrolyte is 0; wherein the concentration of potassium hydroxide in the electrolyte is 6 mol / L, the concentration of sodium hydroxide in the electrolyte is 0.4 mol / L, and the concentration of lithium hydroxide in the electrolyte is 1.5 mol / L.

[0057] To prepare a nickel-hydrogen battery, the positive electrode sheet, the negative electrode sheet, and the separator are stacked into a pole group, placed in a battery shell, sealed, and injected with electrolyte. After chemical formation, a nickel-hydrogen battery B1 is obtained.

[0058] Embodiment 1-6:

[0059] The preparation of the electrolyte and the nickel-hydrogen battery in Examples 1-6 are the same as those in Comparative Example 1, except that:

[0060] The electrolyte of Example 1 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 0.15 mol / L.

[0061] The electrolyte of Example 2 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 0.33 mol / L.

[0062] The electrolyte of Example 3 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 0.66 mol / L.

[0063] The electrolyte of Example 4 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 1 mol / L.

[0064] The electrolyte of Example 5 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 1.1 mol / L.

[0065] The electrolyte of Example 6 includes potassium hydroxide and micron-sized boehmite, the concentration of the micron-sized boehmite in the electrolyte is 0.66 mol / L, and the concentration of potassium hydroxide in the electrolyte is 6 mol / L.

[0066] The preparation of the electrolyte and the preparation of the nickel-hydrogen battery in Comparative Example 2 are the same as those in Comparative Example 1, except that:

[0067] In Comparative Example 2, the concentration of potassium hydroxide in the electrolyte is 5.5 mol / L, the concentration of sodium hydroxide in the electrolyte is 0.35 mol / L, and the concentration of lithium hydroxide in the electrolyte is 1 mol / L.

[0068] The preparation of the electrolyte and the preparation of the nickel-hydrogen battery in Examples 7-12 are the same as those in Comparative Example 2, except that:

[0069] The electrolyte of Example 7 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 0.15 mol / L.

[0070] The electrolyte of Example 8 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 0.33 mol / L.

[0071] The electrolyte of Example 9 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 0.66 mol / L.

[0072] The electrolyte of Example 10 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 1 mol / L.

[0073] The electrolyte of Example 11 includes micron-sized boehmite, and the concentration of the micron-sized boehmite in the electrolyte is 1.1 mol / L.

[0074] The electrolyte of Example 12 includes potassium hydroxide and micron-sized boehmite, the concentration of the micron-sized boehmite in the electrolyte is 0.66 mol / L, and the concentration of potassium hydroxide in the electrolyte is 5.5 mol / L.

[0075] The nickel-hydrogen batteries B1-B2 corresponding to comparative examples 1-2 and the nickel-hydrogen batteries A1-A12 corresponding to embodiments 1-12 were placed in an 80°C (degrees Celsius) oven in a fully charged state for 0.05C float charge, and were taken out every 30 days for battery discharge capacity testing. The tests are shown in Tables 1 and 2; wherein the battery discharge capacity is represented by the SOH (State Of Health) value, which is a numerical value representing the battery health state.

[0076] The SOH value calculation formula is as follows: Among them, C discharge is the discharge capacity value obtained by placing the battery in an 80°C oven for 0.05C float charge in a fully charged state after it is fully activated, and taking it out for battery discharge every 30 days; IEC capacity is the discharge capacity value obtained by charging and discharging the battery at 0.2C after it is fully activated.

[0077] The nickel-hydrogen batteries B1-B2 corresponding to comparative examples 1-2 and the nickel-hydrogen batteries A1-A12 corresponding to embodiments 1-12 were charged and discharged at 0.2C at a constant temperature of 25°C to obtain a standard capacity C IEC Then, the discharge capacities C at 1C, 2C, and 3C at a constant temperature of 25°C are obtained. nC ; Calculate the SOC at discharge rates of 1C, 2C, and 3C respectively nC , SOC with discharge rate of 1C, 2C, 3C nC As shown in Table 1 and Table 2, SOC nC =C nC / C IEC , nC is the discharge rate 1C, 2C, 3C.

[0078] SOC (State of Charge) is used to reflect the remaining capacity of the battery. Its value is defined as the ratio of the remaining capacity to the battery capacity. It is usually expressed as a percentage and its value range is 0% to 100%. When SOC = 0%, it means the battery is fully discharged, and when SOC = 100%, it means the battery is fully charged.

[0079] Table 1:

[0080]

[0081] Table 2:

[0082]

[0083]

[0084] According to the data of Comparative Example 1 and Examples 1-4 in Table 1, and the data of Comparative Example 2 and Examples 7-10 in Table 2, the SOH values ​​of the nickel-hydrogen batteries of Examples 1-4 and Examples 7-10 in which micron-sized boehmite is added to the electrolyte are better than the SOH values ​​of the nickel-hydrogen batteries of Comparative Example 1-2 in which micron-sized boehmite is not added to the electrolyte. Adding micron-sized boehmite to the electrolyte can increase the SOH value of the nickel-hydrogen battery during high-temperature float charge. The electrolyte to which micron-sized boehmite is added can significantly enhance the high-temperature float charge resistance of the nickel-hydrogen battery. Micron-sized boehmite is added to the electrolyte of the nickel-hydrogen battery so that the electrolyte of the nickel-hydrogen battery contains aluminum ions. During the charging and discharging process of the nickel-hydrogen battery, the aluminum ions in the electrolyte can enter the positive electrode to inhibit the expansion and phase transition of the positive electrode. The aluminum ions can also combine with the hydroxide in the electrolyte to form aluminum hydroxide. The aluminum hydroxide can adhere to the surface of the positive electrode and the surface of the negative electrode respectively, and form a layer of aluminum hydroxide passivation film on the surface of the positive electrode and the surface of the negative electrode respectively. The aluminum hydroxide passivation film on the surface of the positive electrode and the surface of the negative electrode can play a role in isolating the electrolyte from the positive electrode and the negative electrode, and reducing the contact between the positive electrode and the negative electrode and the electrolyte. Especially under high temperature conditions during the charging and discharging process of the nickel-hydrogen battery, the aluminum hydroxide passivation film can effectively prevent the corrosion of the electrolyte to the positive electrode and the negative electrode, and inhibit the side reaction between the positive electrode and the negative electrode and the electrolyte, thereby slowing down the corrosion of the positive electrode and the negative electrode, improving the stability of the positive electrode and the negative electrode, and improving the long-term high-temperature floating performance of the nickel-hydrogen battery. The long-term high-temperature floating performance of the nickel-hydrogen battery can be significantly improved at a lower cost.

[0085] According to the data of Example 1 and Example 2 in Table 1, and the data of Example 7 and Example 8 in Table 2, the SOH value of the nickel-hydrogen battery of Example 2 and Example 8 with a micron-level boehmite concentration of 0.33 mol / L in the electrolyte is significantly better than the SOH value of the nickel-hydrogen battery of Example 1 and Example 7 with a micron-level boehmite concentration of 0.15 mol / L in the electrolyte. The concentration of micron-level boehmite in the nickel-hydrogen battery electrolyte is too small, which may cause the aluminum hydroxide content formed by the aluminum ions and hydroxides in the electrolyte to be too small, and it is impossible to form an aluminum hydroxide passivation film on the positive electrode surface and the negative electrode surface of the nickel-hydrogen battery, respectively, and it is impossible to inhibit the corrosion of the positive electrode and the negative electrode, and inhibit the evolution of oxygen and hydrogen. Therefore, the concentration of micron-level boehmite in the nickel-hydrogen battery electrolyte is too small, and the long-term high-temperature floating charge performance of the nickel-hydrogen battery cannot be significantly improved.

[0086] According to the data of Example 4 and Example 5 in Table 1, and the data of Example 10 and Example 11 in Table 2, the SOH value of the nickel-hydrogen battery of Example 5 and Example 11 with a micron-sized boehmite concentration of 1.1 mol / L in the electrolyte is less than the SOH value of the nickel-hydrogen battery of Example 4 and Example 10 with a micron-sized boehmite concentration of 1 mol / L in the electrolyte. The concentration of micron-sized boehmite in the electrolyte of the nickel-hydrogen battery is too high, and the SOH value of the nickel-hydrogen battery deteriorates. Therefore, if the concentration of micron-sized boehmite in the electrolyte of the nickel-hydrogen battery is too high, it may cause the aluminum ions and hydroxide in the electrolyte to form too much aluminum hydroxide in the electrolyte, so that the concentration of aluminum hydroxide in the electrolyte is too high, which affects the migration of ions during the charging and discharging process of the nickel-hydrogen battery, and thus has a negative impact on the performance of the nickel-hydrogen battery.

[0087] According to the data of Example 3 and Example 6 in Table 1, and the data of Example 9 and Example 12 in Table 2, the SOH values ​​of the nickel-hydrogen batteries of Example 3 and Example 9, in which the electrolyte includes potassium hydroxide, sodium hydroxide, lithium hydroxide and micron-sized boehmite, are better than the SOH values ​​of the nickel-hydrogen batteries of Example 6 and Example 12, in which the electrolyte includes potassium hydroxide and micron-sized boehmite. Potassium hydroxide has the highest conductivity at a concentration of 6 mol / L, and the nickel-hydrogen battery has the best rate discharge capability. Sodium hydroxide in the electrolyte can improve the low-temperature rate discharge performance of the nickel-hydrogen battery and inhibit the self-discharge of the nickel-hydrogen battery. Lithium hydroxide can improve the cycle life of the nickel-hydrogen battery. The electrolyte includes potassium hydroxide, sodium hydroxide, lithium hydroxide and micron-sized boehmite. The micron-sized boehmite as an electrolyte additive can combine with hydroxide in the nickel-hydrogen battery electrolyte to form aluminum hydroxide. Aluminum ions can enter the positive electrode to inhibit the expansion and phase transition of the positive electrode. Aluminum hydroxide can form a layer of aluminum hydroxide passivation film on the positive electrode surface and the negative electrode surface respectively. The aluminum hydroxide passivation film on the negative electrode surface can isolate the electrolyte from the negative electrode, reduce the contact between the negative electrode and the electrolyte, and inhibit the side reaction between the negative electrode and the electrolyte, thereby slowing down the capacity loss of the positive electrode and the negative electrode, improving the stability of the positive electrode and the negative electrode, and improving the long-term high-temperature floating charge performance of the nickel-hydrogen battery. The long-term high-temperature floating charge performance of the nickel-hydrogen battery can be significantly improved at a lower cost.

[0088] According to the data of comparative example 1 and examples 1-4 in Table 1, and the data of comparative example 2 and examples 7-10 in Table 2, micron-sized boehmite is added to the electrolyte of the nickel-hydrogen battery. The electrolyte additive micron-sized boehmite can combine with the hydroxyl in the electrolyte of the nickel-hydrogen battery to form aluminum hydroxide. The aluminum ions can enter the positive electrode to inhibit the expansion and phase transition of the positive electrode. The aluminum hydroxide can form a layer of aluminum hydroxide passivation film on the surface of the positive electrode and the surface of the negative electrode respectively. The aluminum hydroxide passivation film on the surface of the negative electrode can isolate the electrolyte from the negative electrode, reduce the contact between the negative electrode and the electrolyte, and inhibit the side reaction between the negative electrode and the electrolyte, thereby slowing down the capacity loss of the positive electrode and the negative electrode, improving the stability of the positive electrode and the negative electrode, and improving the long-term high-temperature floating performance of the nickel-hydrogen battery. The long-term high-temperature floating performance of the nickel-hydrogen battery can be significantly improved at a lower cost; however, adding micron-sized boehmite to the electrolyte of the nickel-hydrogen battery will affect the conductivity of the electrolyte, which has a negative impact on the rate performance of the nickel-hydrogen battery. According to the SOC of comparative example 1 and examples 1-4 in Table 1 1C , SOC 2C , SOC 3C , and the SOC of Comparative Example 2 and Examples 7-10 in Table 2 1C , SOC 2C , SOC 3C , with the increase of micron-sized boehmite concentration in the electrolyte, the battery rate discharge performance gradually deteriorates. This is because the rate discharge performance of the negative electrode of the nickel-hydrogen battery is related to the charge transfer on the surface of the negative electrode hydrogen storage alloy and the internal hydrogen diffusion. Adding micron-sized boehmite to the electrolyte of the nickel-hydrogen battery, during the charging and discharging process of the nickel-hydrogen battery, the aluminum ions in the electrolyte can combine with the hydroxide in the electrolyte to form aluminum hydroxide, which can be attached to the positive and negative electrode surfaces respectively to form a layer of aluminum hydroxide passivation film on the positive and negative electrode surfaces. The aluminum hydroxide passivation film hinders the rapid transfer of charge. Adding micron-sized boehmite to the electrolyte of the nickel-hydrogen battery affects the conductivity of the electrolyte, deteriorates the ion transmission capacity of the electrolyte, and reduces the rate discharge performance of the nickel-hydrogen battery.

[0089] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A nickel-hydrogen battery electrolyte additive, characterized in that: The invention comprises micron-sized boehmite, wherein the concentration of the micron-sized boehmite in the electrolyte is 0.15 mol / L-1 mol / L.

2. The electrolyte additive according to claim 1, characterized in that: The concentration of the micron-sized boehmite in the electrolyte is 0.33 mol / L-0.66 mol / L.

3. The electrolyte additive according to claim 1, characterized in that: The micron-sized boehmite is a spherical boehmite with a particle size of 2 μm-4 μm.

4. A nickel-hydrogen battery electrolyte, characterized in that: The invention comprises an alkaline solution and an electrolyte additive as claimed in any one of claims 1 to 3.

5. The electrolyte according to claim 4, characterized in that: The alkaline solution includes one or more of potassium hydroxide, sodium hydroxide, and lithium hydroxide.

6. The electrolyte according to claim 5, characterized in that: The alkaline solution includes potassium hydroxide, sodium hydroxide and lithium hydroxide.

7. The electrolyte according to claim 6, characterized in that: The concentration of potassium hydroxide in the electrolyte is 5.5 mol / L-6 mol / L.

8. The electrolyte according to claim 6, characterized in that: The concentration of the sodium hydroxide in the electrolyte is 0.35 mol / L-0.4 mol / L.

9. The electrolyte according to claim 6, characterized in that: The concentration of the lithium hydroxide in the electrolyte is 1 mol / L-1.5 mol / L.

10. A nickel-hydrogen battery, characterized in that: The invention comprises a positive electrode, a negative electrode, a separator, and an electrolyte as claimed in any one of claims 4 to 9.

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