Low-temperature zinc-nickel battery electrolyte and preparation method thereof

Abstract

The invention belongs to the field of energy storage, relates to a low-temperature zinc-nickel battery electrolyte and a preparation method thereof, and belongs to the technical field of electrochemical energy storage. The electrolyte takes water as a solvent and consists of an alkaline component, a zinc source and a low-temperature structure regulation additive, and low-temperature crystallization and polarization are reduced by improving a water phase structure and an electrode / electrolyte interface reaction. Under the condition of optimal proportioning, the zinc-nickel battery can be stably charged and discharged under the conditions of 40 DEG C and 2C, and the specific capacity of a low-concentration system is improved from about 95 mAh / g to about 154 mAh / g, and the improvement amplitude is about 62%; the specific capacity of a high-concentration system is increased from about 82 mAh / g to about 123 mAh / g under the conditions of 40 DEG C and 10 DEG C, the maximum capacity is increased by about 50%, a low-temperature discharge platform is more stable, voltage polarization is reduced, and the cycle retention rate is increased. The electrolyte is simple in formula, the process is easily compatible with an existing zinc-nickel battery production line, and the electrolyte is suitable for energy storage and communication scenes in cold and severe cold areas.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, specifically relating to an aqueous zinc-nickel battery electrolyte suitable for low-temperature environments and its application in zinc-nickel secondary batteries. Background Technology

[0002] Lithium-ion batteries are widely used due to their high energy density and long cycle life. However, they mainly use organic electrolytes, which present problems such as flammability, high risk of thermal runaway, high raw material costs, and significant performance degradation at low temperatures, limiting their use in cold regions and high-safety scenarios. In contrast, aqueous zinc-nickel batteries use water as a solvent, have abundant and lower-cost raw materials, non-flammable electrolytes with high ionic conductivity at room temperature, and are also environmentally friendly and have good power output. They are considered to have the potential to replace organic electrolyte lithium-ion batteries and lead-acid batteries in some energy storage, grid peak shaving, communication base stations, and start-stop power supplies.

[0003] However, at -40 °C, the aqueous hydrogen bond network tends to become ordered, making it prone to crystallization and ice formation, leading to increased viscosity and decreased conductivity. Traditional zinc-nickel electrolytes exhibit phenomena such as intensified polarization, decreased discharge plateau, and capacity decay. Existing methods, such as increasing alkali / salt concentration, introducing organic co-solvents, or polymeric additives, can improve low-temperature performance to some extent, but they easily introduce problems such as increased risk of system crystallization, limited interfacial stability, complex formulations, and reduced environmental friendliness. It is still difficult to achieve stable operation under extremely cold conditions while ensuring system simplicity and safety. Therefore, in this invention, we apply the concepts of electrolyte structure regulation and ion solvation adjustment to optimize the low-temperature performance of zinc-nickel systems. By introducing specific inorganic salt additives into traditional alkaline zinc-nickel electrolytes, we synergistically regulate the aqueous phase structure and electrode / electrolyte interface processes, thereby alleviating low-temperature crystallization and polarization problems and improving the battery's capacity output and cycle stability at low temperatures. Summary of the Invention

[0004] This invention addresses the problems of electrolyte crystallization, increased polarization, and rapid capacity decay in aqueous zinc-nickel batteries at low temperatures such as -40°C. It proposes an aqueous zinc-nickel battery electrolyte suitable for low-temperature environments, its preparation method, and its applications. By introducing a structure-regulating additive that is stable in strong alkalis and highly water-soluble into a conventional alkaline zinc-nickel electrolyte, low-temperature crystallization and polarization are reduced without altering the existing electrode system, thereby improving the battery's low-temperature capacity output and cycle stability.

[0005] The technical solution adopted in this invention is as follows: an aqueous zinc-nickel battery electrolyte for low-temperature environments, using water as a solvent, comprising an alkaline substrate, a zinc source, and a low-temperature structure regulating additive; wherein, the alkaline substrate is an aqueous solution of one or more hydroxides selected from KOH, NaOH, LiOH, RbOH, and CsOH, and ZnO is added to form a zincate equilibrium; the low-temperature structure regulating additive is an inorganic salt that is stable under strongly alkaline conditions and has good water solubility, and its cation is selected from Li + Na + K + 、Rb + Cs + One or more of the following, wherein the anion is selected from Cl. - ,Br - I - NO3 - SCN - ClO4 - BF4 - One or more of these can be used as a single salt or in combination; The preparation method of the low-temperature zinc-nickel battery electrolyte includes the following steps: Step 1: Using deionized water as a solvent, dissolve the alkaline substrate to obtain an alkaline base solution of the target concentration; the alkaline substrate is selected from one or more of KOH, NaOH, LiOH, RbOH, and CsOH, and the total alkali concentration is 1.0 to 6.0 mol / L, calculated as the sum of the molar concentrations of hydroxides; Step 2: Add zinc oxide (ZnO) to the alkaline base solution and stir until it is saturated or nearly saturated, while maintaining the presence of undissolved solid phase to maintain a stable solid-liquid equilibrium; the concentration of ZnO is 10–80 g / L. Step 3: Add a low-temperature structure regulating additive that is chemically stable and water-soluble in a strongly alkaline aqueous system to the target concentration at 25℃, and stir until the electrolyte is clear and transparent; the total concentration of the low-temperature structure regulating additive is 0.05~2.00mol / L, derived from Li + Na + K + 、Rb + Cs + Cations and Cl - ,Br - I - NO3 - SCN - ClO4 - BF4 - The anions can be randomly paired or combined, with a molar ratio of 10:1 to 1:10; CsCl, LiCl, NaClO4, and LiCl / CsCl can be selected. Step 4: Based on the electrolyte prepared above, using Ni(OH)2 as the positive electrode and zinc foil as the negative electrode, the two electrodes are clamped with PEEK electrode clips and immersed in the electrolyte to form an open zinc-nickel battery, which is used for the assembly and testing of button and pouch zinc-nickel batteries.

[0006] Furthermore, the alkaline component is mainly KOH, with a KOH concentration of 1.0–6.0 mol / L; when CsOH is further included, the CsOH concentration is 0.1–2.0 mol / L, and the total alkaline concentration of KOH and CsOH, calculated by summing the molar concentrations of each hydroxide, is 2.0–6.0 mol / L; the low-temperature structure regulating additive is a cesium halide salt.

[0007] Furthermore, the alkaline substrate is any combination of the following, based on the molar concentration of each hydroxide: (1) 2.0 mol / L KOH; (2) 6.0 mol / L KOH; (3) 2.0 mol / L KOH + 1.0 mol / L CsOH; (4) 2.0 mol / L CsOH; (5) 2.0 mol / L KOH + 1.0 mol / L NaOH; (6) 2.0 mol / L KOH + 0.5 mol / L LiOH + 0.5 mol / L CsOH; (7) 2.0 mol / L KOH + 0.5 mol / L NaOH + 0.5 mol / L CsOH.

[0008] Furthermore, the low-temperature structure regulating additive for cesium halide salts is cesium chloride (CsCl) at a concentration of 0.5 mol / L.

[0009] Furthermore, the low-temperature structure regulating additive can be selected from any of the following single salt or compound systems, and has the following concentrations respectively, with the total concentration being the sum of the molar concentrations of each salt: (1) CsBr 0.50 mol / L; (2) LiCl 0.30 mol / L + CsCl 0.20 mol / L; (3) CsCl 0.25 mol / L + CsBr 0.25 mol / L.

[0010] Furthermore, in step 3, the total concentration of the low-temperature structure-regulating additive is 0.3–0.8 mol / L.

[0011] Furthermore, the working temperature range of the electrolyte is −60 to 25°C.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1) The discharge plateau is more stable and polarization is reduced at low temperatures: The low-temperature constant current charge-discharge (GCD) curve shows that the discharge plateau rises and maintains better performance, and the voltage hysteresis is reduced; 2) Significantly improved rate performance: In the low-temperature rate test from 0.5 to 1 to 2 to 5 to 10°C, the battery capacity retention rate of the electrolyte system of this invention is significantly higher than that of the control system without the addition of low-temperature structure regulation additives. 3) Enhanced cycle stability: In constant current cycle tests at −40℃, the battery capacity decay rate is reduced and the voltage fluctuation during cycling is smaller, demonstrating better operational stability; 4) Simple implementation and good process compatibility: The raw materials for the formula are readily available and the preparation steps are simple. It is directly compatible with the existing zinc-nickel battery production process, which is conducive to its application in scenarios such as energy storage and start-stop power supply in cold and frigid regions. Attached Figure Description

[0013] Figure 1 The comparison curves show the cycling performance of zinc-nickel batteries assembled using electrolyte 1 (2.0 mol / L KOH, saturated ZnO) and electrolyte 1 (2.0 mol / L KOH + 0.5 mol / L CsCl, saturated ZnO) at -40℃ under 2C conditions.

[0014] Figure 2 The rate performance comparison curves of zinc-nickel batteries assembled using the electrolyte of Comparative Example 1 and the electrolyte of Example 1 under −40℃ conditions are shown in the range of 0.5→1→2→5→10C.

[0015] Figure 3 A comparison of the constant current charge-discharge curves of zinc-nickel batteries assembled using the electrolyte of Comparative Example 1 and the electrolyte of Example 1 under 2C conditions at −40℃.

[0016] Figure 4 The comparison curves show the cycling performance of zinc-nickel batteries assembled using electrolyte 2 (6.0 mol / L KOH, saturated ZnO) and electrolyte 2 (6.0 mol / L KOH + 0.5 mol / L CsCl, saturated ZnO) at -40℃ under 2C conditions.

[0017] Figure 5 The rate performance comparison curves of zinc-nickel batteries assembled using the electrolytes of Comparative Example 2 and Example 2 at −40℃ under conditions of 0.5→1→2→5→10C.

[0018] Figure 6 A comparison of the constant current charge-discharge curves of zinc-nickel batteries assembled using the electrolytes of Comparative Example 2 and Example 2 at -40°C under 2C conditions.

[0019] Figure 7The comparison curves show the cycle performance of zinc-nickel batteries assembled using the electrolyte of Comparative Example 3 (2.0 mol / L KOH + 1.0 mol / L CsOH, saturated ZnO) and the electrolyte of Example 3 (2.0 mol / L KOH + 1.0 mol / L CsOH + 0.5 mol / L CsCl, saturated ZnO) at -40℃ under 2C conditions.

[0020] Figure 8 The rate performance comparison curves of zinc-nickel batteries assembled using the electrolytes of Comparative Example 3 and Example 3 at −40℃ under conditions of 0.5→1→2→5→10C.

[0021] Figure 9 A comparison of the constant current charge-discharge curves of zinc-nickel batteries assembled using the electrolytes of Comparative Example 3 and Example 3 at -40°C under 2C conditions.

[0022] Figure 10 The comparison curves show the cycle performance of zinc-nickel batteries assembled using the electrolyte of Comparative Example 1 (2.0 mol / L KOH, saturated ZnO) and the electrolyte of Example 4 (2.0 mol / L KOH + 0.30 mol / L LiCl + 0.20 mol / L CsCl, saturated ZnO) at -40℃ under 2C conditions.

[0023] Figure 11 The rate performance comparison curves of zinc-nickel batteries assembled using the electrolytes of Comparative Example 1 and Example 4 at −40℃ under conditions of 0.5→1→2→5→10C.

[0024] Figure 12 A comparison of the constant current charge-discharge curves of zinc-nickel batteries assembled using the electrolytes of Comparative Example 1 and Example 4 at -40°C under 2C conditions. Detailed Implementation

[0025] This invention introduces a certain concentration of inorganic salt low-temperature structure-regulating additives into traditional alkaline zinc-nickel electrolytes to adjust the aqueous hydrogen bonding network and ion solvation structure, thereby simultaneously improving the electrolyte's conductivity and electrode / electrolyte interface kinetics under extremely cold conditions. Specifically, CsCl is used as a representative structure-disrupting cesium salt additive. 0.5 mol / L CsCl is introduced into 2.0 mol / L and 6.0 mol / L KOH systems, respectively, allowing the electrolyte to maintain good fluidity and ion migration ability near −40°C, thus improving the low-temperature capacity output and rate performance of zinc-nickel batteries.

[0026] The electrolyte uses deionized water as a solvent, and the alkaline component is selected from one or more of KOH, NaOH, LiOH, RbOH, and CsOH, with a total alkaline concentration of 1.0–6.0 mol / L. ZnO is added at the preparation temperature until the zincate is saturated or nearly saturated, allowing a small amount of undissolved solid phase to maintain solid-liquid equilibrium. If necessary, a low-temperature structure-regulating additive that is chemically stable under strongly alkaline conditions and has good water solubility is introduced. Its cations are selected from Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺, and its anions are selected from Cl⁻, Br⁻, I⁻, NO₃⁻, SCN⁻, ClO⁻, BF⁻, etc., and can be used as a single salt or in combination. A zinc-nickel battery is assembled based on the above electrolyte formulation, including a Ni(OH)₂ positive electrode, a metallic zinc negative electrode, a separator, and the electrolyte. Cyclic performance, rate performance, and constant current charge-discharge behavior are tested at −40°C.

[0027] Comparative Example 1 (2.0 mol / L KOH electrolyte) Potassium hydroxide (KOH) was dissolved in deionized water to prepare an alkaline solution with a concentration of 2.0 mol / L. The solution was stirred at room temperature until completely dissolved to obtain a 2.0 mol / L KOH alkaline base solution. Zinc oxide (ZnO) powder was added in batches to the base solution at approximately 25°C while stirring until the solution reached saturation or near-saturation of zincate. A small amount of undissolved solid phase was allowed to remain to maintain a stable solid-liquid equilibrium. No additional low-temperature structure-regulating additives were added to obtain the electrolyte of Comparative Example 1 (denoted as 2.0 mol / L KOH).

[0028] Comparative Example 2 (6.0 mol / L KOH electrolyte) A 6.0 mol / L alkaline solution was prepared by dissolving KOH in deionized water and stirring at room temperature until completely dissolved, yielding a 6.0 mol / L KOH alkaline base solution. ZnO powder was added in batches to this base solution at approximately 25°C, and the mixture was stirred until the solution reached zincate saturation or near-saturation, allowing a small amount of undissolved solid phase to remain. No structure-modifying additives were added, resulting in the electrolyte of Comparative Example 2 (denoted as 6.0 mol / L KOH).

[0029] Example 1 (2.0 mol / L KOH + 0.5 mol / L CsCl electrolyte) This embodiment introduces CsCl as a low-temperature structure-regulating additive based on Comparative Example 1. Specifically, a 2.0 mol / L alkaline solution is prepared by dissolving KOH in deionized water. ZnO is added at approximately 25°C until saturation or near saturation is achieved, allowing a small amount of undissolved solid phase to remain. Subsequently, solid cesium chloride (CsCl) is added to the zinc-containing alkaline solution at (25±2)°C to achieve a CsCl concentration of 0.50 mol / L. The solution is stirred until it becomes clear and transparent, yielding the electrolyte of Example 1 (denoted as 2.0 mol / L KOH + 0.5 mol / L CsCl).

[0030] Example 2 (6.0 mol / L KOH + 0.5 mol / L CsCl electrolyte) This example introduces CsCl based on Comparative Example 2. Specifically, a 6.0 mol / L alkaline solution is prepared by dissolving KOH in deionized water. ZnO is added at approximately 25°C until saturation or near saturation is achieved, allowing a small amount of undissolved solid phase to remain. CsCl is then added to the zinc-containing alkaline solution at (25±2)°C to achieve a CsCl concentration of 0.50 mol / L. The solution is stirred until it becomes clear and transparent, yielding the electrolyte of Example 2 (denoted as 6.0 mol / L KOH + 0.5 mol / L CsCl).

[0031] Comparative Example 3 (2.0 mol / L KOH + 1.0 mol / L CsOH electrolyte) Using deionized water as solvent, a mixed alkaline solution was prepared with 2.0 mol / L KOH and 1.0 mol / L CsOH. The solution was stirred at room temperature until completely dissolved to obtain a mixed alkaline solution. ZnO powder was added in batches to the solution at approximately 25 °C while stirring until the solution reached zincate saturation or near-saturation. A small amount of undissolved solid phase was allowed to remain to maintain a stable solid-liquid equilibrium. No additional low-temperature structure-regulating additives were added to obtain the electrolyte of Comparative Example 3 (denoted as 2.0 mol / L KOH + 1.0 mol / L CsOH).

[0032] Example 3 (2.0 mol / L KOH + 1.0 mol / L CsOH + 0.5 mol / L CsCl electrolyte) This embodiment introduces CsCl as a low-temperature structure-regulating additive based on Comparative Example 3. Specifically, a mixed alkaline solution of 2.0 mol / L KOH + 1.0 mol / L CsOH was prepared according to Comparative Example 3, and ZnO was added until saturated or nearly saturated, allowing a small amount of undissolved solid phase to remain; then, under the condition of maintaining (25±2)℃, solid CsCl was added to the above zinc-containing mixed alkaline solution to make the CsCl concentration 0.50 mol / L, and stirred until the solution was clear and transparent, to obtain the electrolyte of Example 3 (denoted as 2.0 mol / L KOH + 1.0 mol / L CsOH + 0.5 mol / L CsCl).

[0033] Example 4 (2.0 mol / L KOH + 0.30 mol / L LiCl + 0.20 mol / L CsCl electrolyte) This embodiment introduces a LiCl / CsCl compound as a low-temperature structure-regulating additive based on Comparative Example 1. Specifically, a 2.0 mol / L KOH solution was prepared according to Comparative Example 1, and ZnO was added until saturated or nearly saturated, allowing a small amount of undissolved solid phase to remain. Subsequently, LiCl and CsCl were added to the above zinc-containing alkaline solution at (25±2)℃, so that the LiCl concentration was 0.30 mol / L and the CsCl concentration was 0.20 mol / L (total concentration 0.50 mol / L). The solution was stirred until it became clear and transparent, resulting in the electrolyte of Example 4 (denoted as 2.0 mol / L KOH + 0.30 mol / L LiCl + 0.20 mol / L CsCl).

[0034] Battery assembly and testing conditions The electrolytes prepared in the comparative examples and embodiments described above were used for the assembly and testing of zinc-nickel batteries. The positive electrode used a nickel-based electrode sheet with Ni(OH)₂ as the active material, and the negative electrode used polished and activated zinc foil. A porous separator was placed between the positive and negative electrodes. The entire assembly was placed in a PEEK electrode holder and completely immersed in the electrolyte to be tested, forming a two-electrode zinc-nickel battery. The battery was first activated and cycled at room temperature, then placed in a −40 °C environment for constant current charge-discharge cycle testing at 2C. Rate performance testing was then conducted at 0.5→1→2→5→10C, and constant current charge-discharge curves at representative rates (e.g., 2C) were recorded.

[0035] The electrolytes of Comparative Example 1 and Example 1 were applied to the above-mentioned zinc-nickel batteries, respectively, and subjected to 2C constant current cycling, 0.5–10C rate testing, and 2C constant current charge-discharge testing at −40°C. The results are as follows: Figures 1-3As shown, the curve for Comparative Example 1 corresponds to 2.0 mol / L KOH, and the curve for Example 1 corresponds to 2.0 mol / L KOH + 0.5 mol / L CsCl.

[0036] from Figure 1 As can be seen, under conditions of −40℃ and 2C, the reversible capacity of the zinc-nickel battery using the electrolyte of Comparative Example 1 is relatively low, only 95 mAh / g. However, after using the electrolyte of Example 1, the initial 2C discharge capacity is significantly improved, reaching 154 mAh / g. The capacity retention during cycling is better, and the capacity decay rate is slowed down. Figure 2 The results show that in the low-temperature rate test of 0.5 to 10C, the capacity of Comparative Example 1 decreased significantly in the medium and high rate range (especially 2C and above), while Example 1 maintained a higher discharge capacity at the same rate, maintaining 123 mAh / g at 5C current density and 86 mAh / g at 10C current density, with the overall rate curve rising horizontally. Figure 3 In Example 1, the discharge plateau of the 2C constant current charge-discharge curve under electrolyte conditions is significantly higher and the plateau segment is smoother than that of Comparative Example 1, while the charge-discharge voltage difference and polarization are reduced. Overall... Figures 1-3 It can be seen that the addition of 0.5 mol / L CsCl to the 2.0 mol / L KOH system improves the low-temperature conductivity of the electrolyte and the kinetic behavior of the electrode interface, significantly enhancing the capacity output, rate performance, and cycle stability of the zinc-nickel battery under −40℃ conditions.

[0037] The electrolytes of Comparative Example 2 and Example 2 were applied to the above-mentioned zinc-nickel batteries, and the same 2C cycle test, 0.5–10C rate test, and 2C constant current charge-discharge test were performed at −40 °C. The results are as follows: Figures 4-6 As shown, the curve for Comparative Example 2 corresponds to 6.0 mol / L KOH, and the curve for Example 2 corresponds to 6.0 mol / L KOH + 0.5 mol / L CsCl.

[0038] Depend on Figure 4 It can be seen that in the high-alkali concentration 6.0 mol / L KOH system, Comparative Example 2 already has a certain capacity output and cycling stability under −40℃ and 2C conditions, with an initial capacity of 178 mAh / g; Example 2 under the same conditions has a slightly improved initial specific capacity compared to Comparative Example 2, reaching 182 mAh / g, indicating that the introduction of CsCl into the high-alkali system can further improve the low-temperature performance. Figure 5The results show that in the rate test of 0.5 to 10C, the discharge capacity of Comparative Example 2 decreased significantly at rates above 5C, maintaining 132 mAh / g at 5C current density and 82 mAh / g at 10C current density. Example 2 maintained a higher capacity in the medium and high rate range, with a slower rate curve decay. It could still maintain 153 mAh / g at 5C current density and even as high as 123 mAh / g at 10C current density. Figure 6 In Example 2, the discharge plateau of the 2C constant current charge-discharge curve under electrolyte conditions decreased in degree of downward shift, and the charge-discharge voltage difference decreased, indicating that the low-temperature interface polarization and charge transfer resistance were further reduced.

[0039] The electrolytes of Comparative Example 3 and Example 3 were applied to the above-mentioned zinc-nickel batteries, respectively. 2C constant current cycling, 0.5–10C rate testing, and 2C constant current charge-discharge testing were conducted at −40 °C. The results are as follows: Figures 7-9 As shown. The curve for Comparative Example 3 corresponds to 2.0 mol / L KOH + 1.0 mol / L CsOH, and the curve for Example 3 corresponds to 2.0 mol / L KOH + 1.0 mol / L CsOH + 0.5 mol / L CsCl. (From...) Figures 7-9 It is evident that the introduction of CsCl into the mixed alkali system improves the capacity output and voltage plateau stability of the battery at low temperatures, and slows down the rate decay, indicating that this low-temperature structure regulation strategy is also applicable to mixed alkali systems containing CsOH.

[0040] The electrolytes of Comparative Example 1 and Example 4 were applied to the above-mentioned zinc-nickel batteries, respectively, and subjected to 2C constant current cycling, 0.5–10C rate testing, and 2C constant current charge-discharge testing at −40 °C. The results are as follows: Figures 10-12 As shown. The curve for Comparative Example 1 corresponds to 2.0 mol / L KOH, and the curve for Example 4 corresponds to 2.0 mol / L KOH + 0.30 mol / L LiCl + 0.20 mol / L CsCl. (From...) Figures 10-12 It is evident that, even with reduced CsCl content and the introduction of LiCl compound, the battery's low-temperature performance is still improved compared to the system without low-temperature structure regulation additives, indicating that the compound salt system is feasible as a low-temperature structure regulation additive.

[0041] A comparison of the results of Comparative Examples 1 and 2 with those of Examples 1 and 2 shows that, within the concentration range defined in the claims, using CsCl as a representative low-temperature structure-regulating additive improves capacity output, rate performance, and cycle stability at −40 °C in KOH-ZnO-based aqueous zinc-nickel battery electrolytes at different alkaline concentrations. Specifically, in the 2.0 mol / L KOH system, the battery specific capacity at −40 °C and 2C increased from approximately 95 mAh / g to approximately 154 mAh / g, an increase of approximately 62%; in the 6.0 mol / L KOH system, the specific capacity at −40 °C and 10C increased from approximately 82 mAh / g to approximately 123 mAh / g, an increase of approximately 50%. Furthermore, the CsCl-containing electrolytes in both systems exhibited a higher and more stable low-temperature discharge plateau and lower voltage polarization in 2C constant current charge-discharge tests, and their capacity retention in cycle tests was also superior to the corresponding examples. Furthermore, Example 3 shows that this strategy is also applicable to mixed alkali systems containing CsOH, and Example 4 shows that under the condition of reducing the amount of CsCl and introducing LiCl compound, the low-temperature performance can still be improved compared with the system without additives, indicating that both single salt and compound salt systems are feasible to implement.

[0042] The above results demonstrate that the low-temperature structure regulation strategy proposed in this invention can effectively improve the capacity output and service life of aqueous alkaline zinc-nickel batteries in frigid environments, providing a reliable electrolyte solution for their engineering applications.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements within the theoretical and methodological principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An aqueous zinc-nickel battery electrolyte for low-temperature environments, using water as a solvent, comprising an alkaline base, a zinc source, and a low-temperature structure-regulating additive; wherein, The alkaline substrate is an aqueous solution of one or more hydroxides selected from KOH, NaOH, LiOH, RbOH, and CsOH, with ZnO added to form a zincate equilibrium; The low-temperature structure-regulating additive is an inorganic salt that is stable and highly water-soluble under strongly alkaline conditions, and its cation is selected from Li. + Na + K + 、Rb + Cs + One or more of the following, wherein the anion is selected from Cl. - ,Br - I - NO3 - SCN - ClO4 - BF4 - One or more of these can be used alone or in combination.

2. A method for preparing an aqueous zinc-nickel battery electrolyte for low-temperature environments as described in claim 1, the method comprising the following steps: Step 1: Using deionized water as a solvent, dissolve the alkaline substrate to obtain an alkaline base solution of the target concentration; the alkaline substrate is selected from one or more of KOH, NaOH, LiOH, RbOH, and CsOH, and the total alkali concentration is 1.0 to 6.0 mol / L, calculated as the sum of the molar concentrations of hydroxides; Step 2: Add zinc oxide (ZnO) to the alkaline base solution and stir until it is saturated or nearly saturated, while maintaining the presence of undissolved solid phase to maintain a stable solid-liquid equilibrium; the concentration of ZnO is 10–80 g / L. Step 3: Add a low-temperature structure regulating additive that is chemically stable and water-soluble in a strongly alkaline aqueous system to the target concentration at 25℃, and stir until the electrolyte is clear and transparent; the total concentration of the low-temperature structure regulating additive is 0.05~2.00mol / L, derived from Li + Na + K + 、Rb + Cs + Cations and Cl - ,Br - I - NO3 - SCN - ClO4 - BF4 - The anions can be randomly paired or combined, with a molar ratio of 10:1 to 1:

10. Step 4: Based on the electrolyte prepared above, using Ni(OH)2 as the positive electrode and zinc foil as the negative electrode, the two electrodes are clamped with PEEK electrode clips and immersed in the electrolyte to form an open zinc-nickel battery, which is used for the assembly and testing of button and pouch zinc-nickel batteries.

3. The method for preparing an aqueous zinc-nickel battery electrolyte for low-temperature environments as described in claim 2, characterized in that, The alkaline component is mainly KOH, with a KOH concentration of 1.0–6.0 mol / L; when CsOH is further included, the CsOH concentration is 0.1–2.0 mol / L, and the total alkaline concentration of KOH and CsOH, calculated by summing the molar concentrations of each hydroxide, is 2.0–6.0 mol / L; the low-temperature structure regulating additive is a cesium halide salt.

4. The method for preparing an aqueous zinc-nickel battery electrolyte for low-temperature environments as described in claim 2, characterized in that, The alkaline substrate is any combination of the following, expressed in terms of the molar concentration of each hydroxide: (1) 2.0 mol / L KOH; (2) 6.0 mol / L KOH; (3) 2.0 mol / L KOH + 1.0 mol / L CsOH; (4) 2.0 mol / L CsOH; (5) 2.0 mol / L KOH + 1.0 mol / L NaOH; (6) 2.0 mol / L KOH + 0.5 mol / L LiOH + 0.5 mol / L CsOH; (7) 2.0 mol / L KOH + 0.5 mol / L NaOH + 0.5 mol / L CsOH.

5. The method for preparing an aqueous zinc-nickel battery electrolyte for low-temperature environments as described in claim 2, characterized in that, The low-temperature structure modulator for cesium halide salts is cesium chloride (CsCl) at a concentration of 0.5 mol / L.

6. The method for preparing the aqueous zinc-nickel battery electrolyte for low-temperature environments as described in claim 2, characterized in that, The low-temperature structure-regulating additive can be selected from any of the following single salts or compound systems, and each has the following concentrations, with the total concentration being the sum of the molar concentrations of each salt: (1) CsBr 0.50 mol / L; (2) LiCl 0.30 mol / L + CsCl 0.20 mol / L; (3) CsCl 0.25 mol / L + CsBr 0.25 mol / L.

7. The method for preparing an aqueous zinc-nickel battery electrolyte for low-temperature environments as described in claim 2, characterized in that, In step 3, the total concentration of the low-temperature structure-regulating additive is 0.3–0.8 mol / L.

8. The method for preparing an aqueous zinc-nickel battery electrolyte for low-temperature environments as described in claim 2, characterized in that, The electrolyte operates in the temperature range of −60 to 25°C.

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