Electrolyte for zinc battery, preparation method of electrolyte and zinc battery

Abstract

The invention relates to an electrolyte for a zinc battery, a preparation method of the electrolyte and the zinc battery. The electrolyte for the zinc battery comprises alkali, a corrosion inhibitor, zinc oxide, an additive and deionized water, the additive comprises o-vanillin and lignosulfonate; the corrosion inhibitor comprises phosphate and borate; the mass percentage of the alkali in the electrolyte for the zinc battery is 20-40%; the mass percentage of the phosphate in the electrolyte for the zinc battery is 1%-3%; the mass percentage content of the borate in the electrolyte for the zinc battery is 3%-12%; the zinc oxide is in a saturated state in the electrolyte for the zinc battery. According to the scheme provided by the invention, the zinc battery can present excellent cycle performance and low-temperature discharge performance.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrolyte for zinc batteries, a preparation method thereof, and a zinc battery. Background Art

[0002] Zinc batteries are widely used in consumer electronics, new energy vehicles, energy storage and other fields due to their high safety, high energy density and environmental friendliness. However, when zinc batteries are charged, zinc ions are converted into zinc elements, which are unevenly deposited on the surface of the negative electrode to form branched crystals called dendrites. These zinc dendrites can pierce the diaphragm, causing the positive and negative electrodes to connect, resulting in a short circuit in the battery and deteriorating the battery's cycle performance.

[0003] In the related technology, a large number of additives have been used in electrolytes to improve the cycle life of batteries, such as phosphate additives and borate additives. These additives can inhibit the disordered growth of zinc dendrites and reduce the risk of battery short circuit. However, the cycle life improved by these additives is limited and still cannot fully meet the needs. At the same time, these additives will also affect the kinetic performance of the battery, resulting in the degradation of the low-temperature discharge performance of the battery.

[0004] Therefore, it is urgent to develop an electrolyte for zinc batteries that can effectively improve the cycle performance and low-temperature discharge performance of the battery. Summary of the invention

[0005] In order to solve or partially solve the problems existing in the related art, the present application provides an electrolyte for a zinc battery and a preparation method thereof, and a zinc battery, which can effectively improve the cycle performance and low-temperature discharge performance of the zinc battery.

[0006] The first aspect of the present application provides an electrolyte for a zinc battery, wherein the electrolyte for a zinc battery comprises an alkali, a corrosion inhibitor, zinc oxide, an additive and deionized water; the additive comprises o-vanillin and lignin sulfonate; the corrosion inhibitor comprises phosphate and borate; The mass percentage of the alkali in the zinc battery electrolyte is 20% to 40%; The mass percentage of the phosphate in the zinc battery electrolyte is 1% to 3%; The mass percentage of the borate in the zinc battery electrolyte is 3% to 12%; The zinc oxide is in a saturated state in the zinc battery electrolyte.

[0007] In the above-mentioned zinc battery electrolyte, the lignin sulfonate comprises sodium lignin sulfonate and / or calcium lignin sulfonate.

[0008] The electrolyte for zinc batteries as described above, wherein the mass percentage of o-vanillin in the electrolyte for zinc batteries is 0.1% to 0.5%.

[0009] In the zinc battery electrolyte as described above, the mass percentage of the lignin sulfonate in the zinc battery electrolyte is 0.1% to 0.5%.

[0010] The electrolyte for zinc battery as described above, wherein the alkali includes at least one of potassium hydroxide and sodium hydroxide; and / or the phosphate includes at least one of disodium hydrogen phosphate, sodium dihydrogen phosphate and dipotassium hydrogen phosphate; and / or the borate includes potassium borate and / or sodium borate.

[0011] The electrolyte for zinc batteries as described above, wherein the mass ratio of the electrolyte for zinc batteries is: 20% to 40% alkali, 1% to 3% phosphate, 3% to 12% borate, 0.1% to 0.5% o-vanillin, 0.1% to 0.5% lignin sulfonate, and the balance is deionized water; zinc oxide is added in an appropriate amount to saturation.

[0012] A second aspect of the present invention provides a method for preparing an electrolyte for a zinc battery, comprising the following steps: adding alkali, phosphate, borate, o-vanillin, and lignin sulfonate into deionized water and mixing to obtain a mixed solution; Adding zinc oxide into the mixed solution until saturated to obtain an electrolyte for a zinc battery; Among them, the mass percentage of the alkali in the zinc battery electrolyte is 20%~40%; the mass percentage of the phosphate in the zinc battery electrolyte is 1%~3%; the mass percentage of the borate in the zinc battery electrolyte is 3%~12%.

[0013] In the method for preparing the electrolyte for zinc batteries as described above, the mass percentage of o-vanillin in the electrolyte for zinc batteries is 0.1% to 0.5%.

[0014] In the method for preparing the zinc battery electrolyte as described above, the mass percentage of the lignin sulfonate in the zinc battery electrolyte is 0.1% to 0.5%.

[0015] In the method for preparing the electrolyte for zinc battery as described above, the lignin sulfonate comprises sodium lignin sulfonate and / or calcium lignin sulfonate.

[0016] A third aspect of the present application provides a zinc battery, which includes the zinc battery electrolyte as described above or the zinc battery electrolyte prepared according to the method for preparing the zinc battery electrolyte as described above.

[0017] The technical solution provided by the present application may include the following beneficial effects: o-vanillin and lignin sulfonate are added to the zinc battery electrolyte of the present application and the mass percentage of each component in the zinc battery electrolyte is controlled. The alkali, sustained-release agent and zinc oxide in the zinc electrolyte are used as the basis to ensure the solubility of zinc ions and the stability of the electrolyte, while avoiding direct contact between the zinc electrode and the electrolyte, thereby ensuring the battery's cycle performance and low-temperature discharge performance; at the same time, o-vanillin and lignin sulfonate can act synergistically on the basis of an alkaline electrolyte containing an alkali, a sustained-release agent and zinc oxide. On the one hand, o-vanillin includes an aldehyde group, a phenolic hydroxyl group and a methoxy group. These groups enable o-vanillin to accept electrons on the surface of the zinc negative electrode to undergo a reduction reaction, reducing the generated Organic matter can form a protective film on the surface of the zinc negative electrode, blocking the direct contact between the electrolyte and the zinc element, reducing the dissolution of the zinc element at the negative electrode in the electrolyte, thereby reducing the hydrogen evolution reaction of the electrolyte, improving the stability of the electrolyte, and then reducing the self-discharge of the battery and improving the cycle performance of the battery; on the other hand, lignin sulfonate can also participate in the formation of the protective film, which can improve the ion mobility of the protective film. At the same time, lignin sulfonate can improve the ionic conductivity of the electrolyte and reduce the viscosity of the electrolyte, which is beneficial to increase the diffusion rate and migration number of zinc ions in the protective film and the electrolyte, thereby helping to uniformly deposit zinc on the zinc negative electrode during charging, reducing the generation of zinc dendrites, and thereby improving the cycle life and low-temperature discharge performance of the battery.

[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] To make the present invention easy to understand, the present invention will be described in detail below. However, before describing the present invention in detail, it should be understood that the present invention is not limited to the specific embodiments described. It should also be understood that the terms used herein are only for describing specific embodiments and are not intended to be limiting.

[0020] Where a numerical range is provided, it is understood that each intervening value between the upper and lower limits of the range and any other specified or intervening values ​​in the specified range is encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included in the smaller ranges and are also encompassed within the present invention, subject to any explicitly excluded limits in the specified ranges. Where a specified range includes one or two limits, ranges excluding either or both of those included limits are also encompassed within the present invention.

[0021] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. Although any methods and materials or equivalent methods and materials described herein can also be used in the practice or testing of the present invention, preferred methods and materials are now described.

[0022] In the related art, when zinc batteries are charged, zinc ions are converted into zinc elements, which are unevenly deposited on the surface of the negative electrode to form dendrites, which can pierce the diaphragm, causing the positive and negative electrodes to be connected, resulting in a short circuit in the battery and deteriorating the battery's cycle performance. Currently, a large number of additives have been used in electrolytes to improve the cycle life of batteries, such as phosphate additives and borate additives. These additives can inhibit the disordered growth of zinc dendrites and reduce the risk of battery short circuits. However, the cycle life improved by these additives is limited and still cannot fully meet the demand. At the same time, these additives will also affect the battery's kinetic performance, resulting in the degradation of the battery's low-temperature discharge performance.

[0023] In response to the above problems, an embodiment of the present application provides an electrolyte for a zinc battery, which includes an alkali, a corrosion inhibitor, zinc oxide, an additive and deionized water; the additive includes o-vanillin and lignin sulfonate; the corrosion inhibitor includes phosphate and borate; the mass percentage of the alkali in the zinc battery electrolyte is 20%~40%; the mass percentage of the phosphate in the zinc battery electrolyte is 1%~3%; the mass percentage of the borate in the zinc battery electrolyte is 3%~12%; and zinc oxide is saturated in the zinc battery electrolyte.

[0024] In the zinc battery system, the active materials of the negative electrode are generally zinc and zinc oxide. During the discharge process, zinc loses electrons at the negative electrode and becomes zinc ions that enter the electrolyte; during the charging process, zinc ions in the electrolyte gain electrons on the surface of the negative electrode to generate zinc. During the charging process, the zinc on the negative electrode will be dissolved into the electrolyte, and electrons will be released during the dissolution of the zinc, causing a small amount of hydrogen ions ionized in the electrolyte to tend to gain electrons on the surface of the zinc electrode, resulting in hydrogen evolution reaction, causing the battery to self-discharge. At the same time, the dissolution of zinc causes the ionic conductivity of the electrolyte to decrease and the viscosity to increase. The transfer of zinc ions in the electrolyte to the negative electrode surface is limited, and zinc ions will be over-concentrated in a local area, causing the current density in the area to increase abnormally, promoting the formation of zinc dendrites.

[0025] The present application does not limit the specific selection of alkali, and it can be selected according to actual needs. When alkali is added to the electrolyte, zinc can react with hydroxide ions to form zincate complexes, increase the solubility of zinc ions, avoid precipitation or other irreversible reactions of zinc ions in the electrolyte, and improve the stability of the electrolyte. In addition, the presence of alkali can increase the concentration of negative ions in the electrolyte, reduce the occurrence of hydrogen evolution side reactions, improve the ion mobility of the electrolyte, reduce electrode polarization, and improve the cycle life and low-temperature discharge performance of the battery. The mass percentage of alkali in the zinc battery electrolyte of the present application is 20% to 40%, for example, the mass percentage of alkali in the electrolyte can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38% or 40%, etc.

[0026] The corrosion inhibitors of the present application include phosphates and borates. The present application does not limit the specific selection of phosphates and borates, and can be selected according to actual needs. When phosphates and borates are added to the electrolyte, phosphates and borates can form a protective film on the surface of the zinc negative electrode, isolating zinc from the corrosive electrolyte, inhibiting the dissolution of zinc element, and slowing down the corrosion of the zinc electrode. Moreover, the protective film can prevent zinc ions from forming zinc dendrites due to excessive local concentration, thereby improving the stability of the battery. At the same time, it can buffer the pH value of the electrolyte to prevent side reactions caused by excessive pH fluctuations, and can also improve the electrolyte ion conductivity, thereby improving the battery's cycle performance and low-temperature discharge performance. The mass percentage of phosphate in the electrolyte of the present application is 1% to 3%. For example, the mass percentage of phosphate in the electrolyte can be 1%, 1.5%, 2%, 2.5% or 3%, etc. The mass percentage of the borate in the electrolyte of the present application is 3% to 12%. For example, the mass percentage of the borate in the electrolyte can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11% or 12%.

[0027] The zinc oxide in the electrolyte of the present application can form a protective film on the surface of the zinc electrode, reduce the direct contact between the zinc electrode and the electrolyte, make the deposition of zinc ions orderly, inhibit the dendrite phenomenon caused by the uneven deposition of zinc ions, and can change the solvation state of zinc ions and stabilize the pH value of the electrolyte. At the same time, zinc oxide may play a catalytic role on the electrode surface, reduce the activation energy of the electrode reaction, accelerate the rate of the electrode reaction, and improve the cycle performance and low-temperature discharge performance of the battery. The sum of the mass percentages of alkali, phosphate, borate, o-vanillin, lignin sulfonate and water in the electrolyte of the present application is 100%, and zinc oxide is saturated in the mixed solution of alkali, phosphate, borate, o-vanillin, lignin sulfonate and water.

[0028] The o-vanillin of the present application is 3-methoxy-2-hydroxybenzaldehyde. The lignin sulfonate of the present application is a high molecular polymer that can be efficiently dissolved in an aqueous solution.

[0029] The zinc battery electrolyte of the present application adds o-vanillin and lignin sulfonate and controls the mass percentage of each component in the zinc battery electrolyte. The alkali, sustained-release agent and zinc oxide in the zinc electrolyte are used as the basis to ensure the solubility of zinc ions and the stability of the electrolyte, while avoiding direct contact between the zinc electrode and the electrolyte, thereby ensuring the cycle performance and low-temperature discharge performance of the battery; at the same time, o-vanillin and lignin sulfonate can act synergistically on the basis of the alkaline electrolyte containing alkali, sustained-release agent and zinc oxide. On the one hand, o-vanillin includes aldehyde group, phenolic hydroxyl group and methoxy group, and these groups enable o-vanillin to accept electrons on the surface of the zinc negative electrode to undergo reduction reaction, and the organic matter generated by reduction can be on the surface of the zinc negative electrode. On the other hand, lignin sulfonate can participate in the formation of the protective film at the same time, improve the ion mobility of the protective film, and at the same time, lignin sulfonate can improve the ionic conductivity of the electrolyte and reduce the viscosity of the electrolyte, which is beneficial to improve the diffusion rate and migration number of zinc ions in the protective film and the electrolyte, thereby facilitating the uniform deposition of zinc on the zinc negative electrode during charging, reducing the generation of zinc dendrites, and thus improving the cycle life and low-temperature discharge performance of the battery.

[0030] In a specific embodiment, the lignin sulfonate includes sodium lignin sulfonate and / or calcium lignin sulfonate. When the lignin sulfonate is selected from sodium lignin sulfonate and calcium lignin sulfonate, the lignin sulfonate can be efficiently dissolved in the electrolyte, participate in the construction of the protective film on the surface of the zinc negative electrode, improve the ion mobility in the protective film, and further improve the ion conductivity of the electrolyte, reduce the generation of zinc dendrites, thereby improving the battery's cycle performance and low-temperature discharge performance, and can avoid the lignin sulfonate from reacting with other components in the electrolyte, avoiding the generation of side reactions. The present application does not specifically limit the number average molecular weight of the lignin sulfonate, which can be selected according to actual needs. For example, the number average molecular weight of sodium lignin sulfonate can be selected as 535.5, which can make the sodium lignin sulfonate fully dissolved in the electrolyte, improve the ion mobility of the protective film and the ion conductivity of the electrolyte, and improve the battery's cycle performance and low-temperature discharge performance.

[0031] In a specific embodiment, the mass percentage of o-vanillin in the electrolyte is 0.1% to 0.5%, for example, the mass percentage of o-vanillin in the electrolyte can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, etc. When the mass percentage of o-vanillin is within the above range, o-vanillin can better reduce the dissolution of zinc in the electrolyte, reduce the probability of hydrogen evolution reaction in the electrolyte, and better improve the stability of the electrolyte, thereby making the battery cycle performance better.

[0032] In a specific embodiment, the mass percentage of lignin sulfonate in the electrolyte is 0.1% to 0.5%, for example, the mass percentage of lignin sulfonate in the electrolyte can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, etc. When the mass percentage of lignin sulfonate is within the above range, lignin sulfonate can better improve the ion mobility of the protective film and the ion conductivity of the electrolyte, so that the diffusion rate and migration number of zinc ions in the protective film and the electrolyte are higher, thereby improving the cycle life and low-temperature discharge performance of the battery.

[0033] In a specific embodiment, the base includes at least one of potassium hydroxide and sodium hydroxide. When the base is selected from the above compounds, the ionic conductivity and zinc ion complexing ability of the electrolyte are higher, and the stability of the electrolyte is better, which is conducive to further improving the cycle performance and low temperature performance of the battery.

[0034] In a specific embodiment, the phosphate includes at least one of disodium hydrogen phosphate, sodium dihydrogen phosphate and dipotassium hydrogen phosphate. When the phosphate is selected from the above compounds, when the pH value of the electrolyte changes during the charge and discharge process of the zinc battery, the phosphate can maintain the relative stability of the pH through its own hydrolysis and the movement of the ionization equilibrium, reducing the problems of zinc dendrite growth, hydrogen evolution reaction and the formation of basic zincate caused by pH fluctuations. At the same time, the phosphate ions of the phosphate can interact with the zinc ions, affecting the solvation structure of the zinc ions to a certain extent, making the deposition of zinc ions in the electrolyte more uniform, inhibiting the growth of zinc dendrites, and helping to improve the cycle stability and low temperature performance of the battery.

[0035] In a specific embodiment, the borate includes potassium borate and / or sodium borate. Potassium borate and sodium borate can be adsorbed on the surface of the zinc electrode to form an interface layer, inhibit the growth of zinc dendrites caused by the decomposition of water, and make the deposition of zinc on the electrode surface more uniform. In addition, potassium ions and sodium ions can be used as electrostatic shielding cations to improve the deposition morphology of zinc ions in aqueous solution, reduce the local aggregation of zinc ions on the electrode surface, and inhibit the growth of zinc dendrites. At the same time, it can also stabilize the pH value of the electrolyte, optimize the solvation structure of zinc ions, improve the ionic conductivity of the electrolyte, and inhibit the hydrogen evolution reaction, thereby extending the cycle life of the battery to a greater extent and improving the low-temperature discharge performance of the battery.

[0036] In a specific embodiment, the mass ratio of the electrolyte is: 20% to 40% alkali, 1% to 3% phosphate, 3% to 12% borate, 0.1% to 0.5% o-vanillin, 0.1% to 0.5% lignin sulfonate, and the balance is deionized water; zinc oxide is added in an appropriate amount until saturated. The sum of the mass percentages of alkali, phosphate, borate, o-vanillin, lignin sulfonate and water in the electrolyte is 100%, and zinc oxide is saturated in the mixture of alkali, phosphate, borate, o-vanillin, lignin sulfonate and water. When the mass ratio of the electrolyte is within the above range, alkali, borate, phosphate, o-vanillin, lignin sulfonate and zinc oxide can better play their roles, better inhibit the dissolution and corrosion of zinc element, prevent the formation of zinc dendrites, improve the stability of the zinc electrode, and increase the migration rate of zinc ions in the protective film and the electrolyte, thereby improving the cycle life and low-temperature discharge performance of the zinc battery.

[0037] The second aspect of the present application provides a method for preparing an electrolyte for a zinc battery, comprising the following steps: S1. Add alkali, phosphate, borate, o-vanillin and lignin sulfonate into deionized water and mix to obtain a mixed solution; wherein the mass percentage of alkali in the zinc battery electrolyte is 20% to 40%; the mass percentage of phosphate in the zinc battery electrolyte is 1% to 3%; and the mass percentage of borate in the zinc battery electrolyte is 3% to 12%; S2. Add zinc oxide to the mixed solution until it is saturated to obtain an electrolyte for a zinc battery.

[0038] Specifically, deionized water is mixed with 20% to 40% of alkali, 1% to 3% of phosphate, 3% to 12% of borate, o-vanillin, and lignin sulfonate, and the mixture is evenly mixed to obtain a mixed solution; zinc oxide is then slowly added to the mixed solution and mixed until the zinc oxide in the mixed solution is saturated to obtain an electrolyte for a zinc battery.

[0039] The saturation of zinc oxide in the mixed solution of the present application means that under certain conditions of temperature, pressure, etc., a maximum amount of zinc oxide has been dissolved in the mixed solution, and no more zinc oxide can be dissolved.

[0040] The present application does not limit the specific parameters of mixing, which can be selected according to actual needs, for example, stirring treatment can be selected.

[0041] The preparation method of the zinc battery electrolyte of the present application can evenly distribute o-vanillin, lignin sulfonate and other components in the electrolyte, which is conducive to the full play of the effects of o-vanillin, lignin sulfonate and other components, so that the hydrogen evolution reaction of the electrolyte is reduced, the diffusion rate and migration number of zinc ions in the electrolyte are increased, the generation of zinc dendrites is reduced, and the cycle life of the zinc battery is extended. In addition, the preparation method is simple, efficient, easy to operate, and is conducive to the industrial preparation of the electrolyte.

[0042] In a specific embodiment, the mass percentage of o-vanillin in the electrolyte for zinc batteries is 0.1% to 0.5%. For example, the mass percentage of o-vanillin in the electrolyte can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%.

[0043] In a specific embodiment, the mass percentage of lignin sulfonate in the zinc battery electrolyte is 0.1% to 0.5%, for example, the mass percentage of lignin sulfonate in the electrolyte can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%.

[0044] In a specific embodiment, the mass percentage of alkali in the electrolyte is 20%~40%, for example, the mass percentage of alkali in the electrolyte can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38% or 40%; the mass percentage of phosphate in the electrolyte is 1%~3%, for example, the mass percentage of phosphate in the electrolyte can be 1%, 1.5%, 2%, 2.5% or 3%; the mass percentage of borate in the electrolyte is 3%~12%, for example, the mass percentage of borate in the electrolyte can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11% or 12%; the balance is deionized water.

[0045] The third aspect of the present application provides a zinc battery comprising the above zinc battery electrolyte, which has excellent cycle performance and low-temperature discharge performance.

[0046] In a specific embodiment, the zinc battery includes a positive electrode and a negative electrode. The negative electrode of the zinc battery of the present application includes a composite material of zinc metal and zinc oxide. Preferably, the negative electrode is a plate-shaped material. When the negative electrode is a composite material of zinc metal and zinc oxide, during the charging process of the zinc battery, zinc ions obtain electrons and are reduced to zinc element at the negative electrode and deposited, and during the discharging process of the zinc battery, the zinc element loses electrons and becomes zinc ions and enters the electrolyte, thereby realizing the charging and discharging function of the zinc battery.

[0047] In a specific embodiment, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on the positive electrode current collector, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes nickel hydroxide (Ni(OH) 2 ), yttrium trioxide Y 2 O 3 , nickel powder, etc. When the positive electrode active material is selected from the above compounds, the nickel in the positive electrode active material undergoes a valence change during the charge and discharge process, thereby realizing the charge and discharge function of the zinc battery.

[0048] In the embodiments of the present application, there is no particular limitation on the type of the positive electrode current collector, which can be any known material suitable for use as a positive electrode current collector. In one embodiment, the positive electrode current collector includes nickel foam.

[0049] In a specific embodiment, the zinc battery also includes a diaphragm. The embodiment of the present application has no particular restrictions on the material and shape of the diaphragm, as long as it does not significantly damage the effect of the present application. It may include a polypropylene composite diaphragm or a polyethylene composite diaphragm, etc., and can be specifically configured as needed.

[0050] In a specific embodiment, the zinc battery may include an outer package, which can be used to encapsulate the electrode assembly and the electrolyte.

[0051] In a specific embodiment, the outer packaging of the zinc battery can be a hard shell, such as a hard plastic shell, a steel shell, etc. The outer packaging of the secondary battery can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed.

[0052] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape.

[0053] Hereinafter, the present application will be further described in detail through specific embodiments.

[0054] Example 1 1. Preparation of electrolyte At room temperature and pressure, o-vanillin, lignin sulfonate, potassium hydroxide, disodium hydrogen phosphate and potassium borate are added to deionized water and mixed to obtain a mixed solution, and then zinc oxide is added to the mixed solution until saturated to obtain an electrolyte; Among them, the mass percentage of o-vanillin is 0.3%, the mass percentage of lignin sulfonate is 0.3%, the mass percentage of potassium hydroxide is 30%, the mass percentage of disodium hydrogen phosphate is 2%, and the mass percentage of potassium borate is 5%.

[0055] 2. Preparation of negative electrode sheet The required negative electrode slurry is prepared according to 70% zinc oxide, 8% zinc powder, 1% bismuth oxide, 0.1% indium oxide, 1% PA66 fiber, and 19.9% ​​glue (composed of 2% CMC aqueous solution, 60% PTFE aqueous solution, and 38% 5040), coated on both sides on the inclined copper mesh, and then dried, rolled, and cut to obtain the negative electrode sheet.

[0056] 3. Preparation of positive electrode According to 72.5wt% of nickel hydroxide with cobalt coating on the surface, 3.5wt% of Ni powder, 0.75wt% of Y 2 O 3 (yttrium trioxide), 2wt% CMC, 1.5wt% xanthan gum, 0.75wt% PTFE, and the rest pure water are uniformly mixed to obtain positive electrode slurry, the slurry is filled and pressed into nickel foam and dried, and then rolled and cut to obtain positive electrode sheets.

[0057] 4. Production of zinc battery The positive and negative electrode sheets and the separator prepared above are wound, the electrode assembly is put into the shell, and the alkali is injected and sealed to complete the preparation of the zinc battery.

[0058] The preparation methods of the zinc batteries provided in Examples 2 to 24 and Comparative Examples 1 to 12 are substantially the same as that in Example 1, and the specific parameters are shown in Table 1.

[0059] Comparative Example 13 The preparation method of the zinc battery of this comparative example is substantially the same as that of Example 1, except that zinc oxide is not added to the electrolyte for the zinc battery.

[0060] Table 1

[0061] Test example Zinc battery performance test: Battery activation method: Charge the zinc battery at 0.05C for 10h, let it sit for 10min, and then discharge it at 0.05C to 1.3V; then charge it at 0.1C for 10h, let it sit for 10min, and then discharge it at 0.1C to 1.3V; then charge it at 0.2C to 1.9V, switch to constant voltage charging until the current is ≤0.01C, and then discharge it at 0.2C to 1.3V; (taking 2A1400 model battery as an example, the theoretical capacity is 1400mAh, and 0.2C is 280mAh).

[0062] Cycle performance test: Charge the activated zinc battery to 1.9V at 1C constant current and constant voltage, leave it for 10 minutes, switch to constant voltage charging until the current is less than 0.01C, leave it for 10 minutes, and then discharge it to 1.2V at 1C. Perform multiple charge and discharge cycles under the above conditions, and record the number of cycles when the capacity retention rate drops to 60%. There are 5 batteries in each group.

[0063] Capacity retention rate (%) = discharge capacity corresponding to the number of cycles (mAh) / discharge capacity of the third cycle (mAh) × 100%, see Table 2.

[0064] Low temperature discharge performance test: Fully charge the battery at 0.2C at 25℃, let it stand for 10min, discharge it at 0.2C to 1.3V at 25℃, repeat the charge and discharge for 3 weeks, record the discharge capacity at 0.2C in the third week and use it as the initial capacity. Fully charge the battery at 0.2C at 25℃, let it stand for 10min, transfer the battery to a -10℃ oven, leave it for 4h, and after the battery is completely cooled to -10℃, discharge it at 0.2C to 1.1V, and record the discharge capacity.

[0065] -10℃ discharge capacity retention rate (%) = (discharge capacity) / (initial capacity) × 100%. The results are recorded in Table 2.

[0066] Table 2

[0067] As can be seen from Table 2, according to the comparison between Examples 1 to 13 and Comparative Examples 1 to 3, when o-vanillin and lignin sulfonate act synergistically, the cycle performance and low-temperature discharge performance of the battery are better.

[0068] According to the comparison between Examples 1 to 7 and Comparative Examples 1 to 2, when the mass percentage of o-vanillin is in the range of 0.1% to 0.5%, o-vanillin can reduce the hydrogen evolution reaction of the electrolyte and reduce the generation of zinc dendrites, which is beneficial to improving the cycle performance and low-temperature discharge performance of the battery.

[0069] According to the comparison between Examples 1, 8 to 13 and Comparative Examples 1 and 3, it can be seen that when the mass percentage of lignin sulfonate is in the range of 0.1% to 0.5%, lignin sulfonate can increase the diffusion rate and migration number of zinc ions in the protective film and the electrolyte, thereby improving the cycle performance and low-temperature discharge performance of the battery.

[0070] According to the comparison between Examples 1 and 14, when the lignin sulfonate is selected as sodium lignin sulfonate or calcium lignin sulfonate, the lignin sulfonate can be efficiently dissolved in the electrolyte, participate in the construction of the protective film on the surface of the zinc negative electrode, and improve the cycle life and low-temperature discharge performance of the battery.

[0071] According to the comparison of Examples 1 and 15 and Comparative Example 4, when potassium hydroxide or sodium hydroxide is selected as the alkali, it is beneficial to form a zincate complex, increase the solubility of zinc ions, and at the same time increase the concentration of negative ions in the electrolyte, reduce the occurrence of hydrogen evolution side reactions, and improve the cycle life and low-temperature discharge performance of the battery.

[0072] According to the comparison between Examples 1, 16, and 17 and Comparative Examples 5 and 6, it can be seen that when the mass percentage of alkali in the electrolyte is 20% to 40%, the stability of the electrolyte is higher and the hydrogen evolution reaction is less, so that the cycle performance and low-temperature discharge performance of the battery are better.

[0073] According to the comparison of Examples 1, 18 and 19, it can be seen that when the phosphate is selected as disodium hydrogen phosphate, sodium dihydrogen phosphate or dipotassium hydrogen phosphate, the cycle performance and low-temperature discharge performance of the battery are better.

[0074] According to the comparison between Examples 1, 20, 21 and Comparative Examples 7, 8, 9, it can be seen that when the mass percentage of phosphate in the electrolyte is 1%~3%, the phosphate can better buffer the pH change of the electrolyte, inhibit the growth of zinc dendrites to a greater extent, and further improve the cycle performance and low-temperature discharge performance of the battery.

[0075] According to the comparison between Examples 1 and 22, it can be seen that when the borate is selected from potassium borate or sodium borate, the battery has excellent cycle performance and low-temperature discharge performance.

[0076] According to the comparison between Examples 1, 23, and 24 and Comparative Examples 10 to 12, when the mass percentage of borate in the electrolyte is 3% to 12%, it is beneficial to maintain the stability of the pH value of the electrolyte, improve the electronic conductivity of the electrolyte, inhibit the hydrogen evolution reaction, and make the battery cycle performance and low-temperature discharge performance better.

[0077] According to the comparison between Example 1 and Comparative Example 13, it can be seen that when zinc oxide is added to the electrolyte, the cycle performance and low-temperature discharge performance of the battery are better.

[0078] 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. An electrolyte for a zinc battery, characterized in that: The zinc battery electrolyte comprises alkali, corrosion inhibitor, zinc oxide, additives and deionized water; the additives comprise o-vanillin and lignin sulfonate; the corrosion inhibitor comprises phosphate and borate; The mass percentage of the alkali in the zinc battery electrolyte is 20% to 40%; The mass percentage of the phosphate in the zinc battery electrolyte is 1% to 3%; The mass percentage of the borate in the zinc battery electrolyte is 3% to 12%; The zinc oxide is in a saturated state in the zinc battery electrolyte.

2. The zinc battery electrolyte according to claim 1, characterized in that: The lignin sulfonate includes sodium lignin sulfonate and / or calcium lignin sulfonate.

3. The zinc battery electrolyte according to claim 1, characterized in that: The mass percentage of the o-vanillin in the zinc battery electrolyte is 0.1% to 0.5%.

4. The zinc battery electrolyte according to claim 1, characterized in that: The mass percentage of the lignin sulfonate in the zinc battery electrolyte is 0.1% to 0.5%.

5. The zinc battery electrolyte according to claim 1, characterized in that: The alkali comprises at least one of potassium hydroxide and sodium hydroxide; and / or, The phosphate includes at least one of disodium hydrogen phosphate, sodium dihydrogen phosphate and dipotassium hydrogen phosphate; and / or, The borate includes potassium borate and / or sodium borate.

6. The zinc battery electrolyte according to claim 4, characterized in that: The mass ratio of the electrolyte for the zinc battery is: 20% to 40% alkali, 1% to 3% phosphate, 3% to 12% borate, 0.1% to 0.5% o-vanillin, 0.1% to 0.5% lignin sulfonate, and the balance is deionized water; zinc oxide is added in an appropriate amount to saturation.

7. A method for preparing an electrolyte for a zinc battery, characterized in that: The following steps are involved: adding alkali, phosphate, borate, o-vanillin, and lignin sulfonate into deionized water and mixing to obtain a mixed solution; Adding zinc oxide into the mixed solution until saturated to obtain an electrolyte for a zinc battery; Among them, the mass percentage of the alkali in the zinc battery electrolyte is 20%~40%; the mass percentage of the phosphate in the zinc battery electrolyte is 1%~3%; the mass percentage of the borate in the zinc battery electrolyte is 3%~12%.

8. The method for preparing the zinc battery electrolyte according to claim 7, characterized in that: The mass percentage of o-vanillin in the zinc battery electrolyte is 0.1% to 0.5%; And / or, the mass percentage of the lignin sulfonate in the zinc battery electrolyte is 0.1% to 0.5%.

9. The method for preparing the zinc battery electrolyte according to claim 7, characterized in that: The lignin sulfonate includes sodium lignin sulfonate and / or calcium lignin sulfonate.

10. A zinc battery, characterized in that: The invention relates to a zinc battery electrolyte comprising the zinc battery electrolyte according to any one of claims 1 to 6 or the zinc battery electrolyte prepared by the method for preparing the zinc battery electrolyte according to any one of claims 7 to 9.

Images