Low-temperature aqueous zinc-ion battery electrolyte, preparation method and application thereof

Abstract

This invention provides a low-temperature aqueous zinc-ion battery electrolyte, its preparation method, and its application. The low-temperature aqueous zinc-ion battery electrolyte comprises a zinc salt, water, and a diluent; the diluent is one of tetrahydrofuran, methyl tert-butyl ether, cyclopentyl methyl ether, dioxane, and ethylene glycol diether; the zinc salt is one of zinc sulfate heptahydrate, zinc gluconate, zinc acetate, zinc trifluoromethanesulfonate, and zinc chloride; and the water is deionized water. This aqueous zinc-ion battery electrolyte exhibits excellent interfacial stability, high and low temperature performance, and cycle performance. Batteries prepared using this aqueous zinc-ion battery electrolyte exhibit high coulombic efficiency, excellent cycle stability, excellent high and low temperature cycle performance, and excellent cycle discharge performance.

Description

Technical Field

[0001] This invention belongs to the field of secondary energy storage battery technology, specifically relating to a low-temperature aqueous zinc-ion battery electrolyte, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries dominate large-scale smart grids and portable energy storage systems due to their high energy density, mature manufacturing processes, and excellent lightweight performance. However, Earth's lithium resources are finite, and the use of lithium-ion batteries for large-scale energy storage faces challenges related to high cost, safety, and the environment. Therefore, given the multiple challenges facing existing energy storage technologies, developing new energy storage technologies has become a critical issue that urgently needs to be addressed in the energy sector.

[0003] Aqueous zinc-ion batteries are characterized by their high theoretical capacity (820mAh g). -1 Or 5854mAh cm -3 With its high ionic conductivity (typically 10 to 100 times that of organic electrolytes), low cost, and stability, reversibility, and non-toxicity in aqueous electrolyte systems, aqueous batteries are considered promising candidates for large-scale energy storage. However, the widespread application of aqueous batteries in low-temperature environments remains challenging. At low temperatures (e.g., -40°C), hydrogen bonding interactions lead to the solidification of the aqueous electrolyte, resulting in the degradation of Zn. 2+ Ion diffusion and desolvation kinetics are extremely slow, leading to a deterioration in rate performance. Furthermore, anodic corrosion and dendrite growth exacerbate the cycling stability of ZIBs, resulting in severe degradation of electrochemical performance. Therefore, designing aqueous batteries capable of stable operation at low temperatures is crucial.

[0004] Current common electrolyte solutions mainly involve high-concentration electrolytes, the introduction of small-molecule additives, or organic cosolvents. However, these methods all face significant challenges. High-concentration electrolytes are costly and suffer from serious problems such as incomplete zinc salt dissociation and increased electrolyte viscosity, severely impacting ionic conductivity and limiting charging rate and power density. Using small-molecule additives or organic cosolvents, however, involves them acting as the main ligands in the solvation sheath via electron donor mechanisms, increasing the desolventizing energy barrier at the interface and battery polarization losses, thus affecting the kinetics of low-temperature zinc anode deposition. Therefore, the design of low-temperature electrolytes still requires further exploration. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a low-temperature aqueous zinc-ion battery electrolyte and its application. The aqueous zinc-ion battery prepared by this method incorporates a diluent to create localized cation-anion aggregation chemistry, which disrupts hydrogen bonds and effectively inhibits water crystallization. This promotes high ion mobility of the electrolyte at temperatures below zero degrees Celsius, resulting in excellent interfacial stability, high and low temperature performance, and cycle performance. Batteries prepared using this aqueous zinc-ion battery electrolyte exhibit high coulombic efficiency, excellent cycle stability, excellent high and low temperature cycle performance, and excellent cycle discharge performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a low-temperature aqueous zinc-ion battery electrolyte, comprising the following components: zinc salt, water, and diluent;

[0008] The diluent is one of tetrahydrofuran, methyl tert-butyl ether, cyclopentyl methyl ether, dioxane, and ethylene glycol diether;

[0009] In some embodiments, the zinc salt is one of zinc sulfate heptahydrate, zinc gluconate, zinc acetate, zinc trifluoromethanesulfonate, and zinc chloride.

[0010] In some embodiments, the concentration of the zinc salt in the low-temperature aqueous zinc-ion battery electrolyte is 0.5–3 mol / L;

[0011] In some embodiments, the diluent accounts for 10%-50% of the total solvent;

[0012] In some embodiments, the water is deionized water:

[0013] In some embodiments, the deionized water accounts for 50%-90% of the total solvent.

[0014] A second aspect of the present invention provides a method for preparing the low-temperature aqueous zinc-ion battery electrolyte described in the first aspect, comprising the following steps:

[0015] The inorganic zinc salt and deionized water are mixed to prepare a basic electrolyte;

[0016] The diluent is added to the base electrolyte to prepare the low-temperature aqueous zinc-ion battery electrolyte.

[0017] A third aspect of the present invention provides an aqueous zinc-ion battery, comprising an electrolyte, wherein the electrolyte is the low-temperature aqueous zinc-ion battery electrolyte described in the above-described technical solution or the low-temperature aqueous zinc-ion battery electrolyte prepared by the preparation method described in the above-described technical solution.

[0018] The low-temperature aqueous zinc-ion battery electrolyte provided by this invention reconfigures Zn by introducing a diluent. 2+ Coordination environment. System characterization shows that diluent molecules preferentially occupy the bulk electrolyte region rather than participate in the internal solvation sheath, driving anionic substitution of Zn. 2+ The surrounding two H2O molecules coordinate and establish local cation-anion aggregation. This rationally designed structure solves several problems simultaneously: the hydrogen bond breaking ability of the diluent effectively inhibits water crystallization while maintaining ion mobility at sub-zero temperatures; the desolvation kinetics are improved due to reduced water coordination leading to local cation-anion aggregation; and the enhanced Zn... 2+ - Cation-cation interactions promote preferential anion decomposition, forming a rapidly diffusing, ZnF2-rich, dominant interface. Batteries prepared using this low-temperature aqueous zinc-ion battery electrolyte exhibit high coulombic efficiency, excellent cycle stability, excellent high and low temperature cycle performance, and excellent cycle discharge performance. Furthermore, the preparation process of this low-temperature aqueous zinc-ion battery electrolyte is simple, the raw materials are readily available, and it is environmentally friendly, making it suitable for large-scale production and showing broad market application prospects in zinc-ion batteries, zinc-ion energy storage devices, and other fields. Attached Figure Description

[0019] Figure 1 The Zn||Zn symmetric battery assembled using the electrolytes in Example 1 and Comparative Example 1 in this invention operates at 30°C with a capacity of 2 mAh·cm⁻¹. -2 The specific capacity and long-cycle performance at a current density of 2 mA·cm⁻² are shown in the figure.

[0020] Figure 2 The Zn||Zn symmetric battery assembled using the electrolytes in Example 1 and Comparative Example 1 in this invention operates at -40°C and 1 mAh·cm⁻¹. -2 Specific capacity and 1 mA·cm -2 Long-cycle performance at current density;

[0021] Figure 3 The Zn||Zn symmetric cells assembled using the electrolytes in Example 1 and Comparative Example 1 in this invention exhibit a 1 mAh·cm⁻¹ capacity at 30°C and -40°C. -2 Specific capacity and 1mAh·cm -2 SEM image of the zinc anode surface after cycling for 100 hours under the specified current density;

[0022] Figure 4 The Zn||Cu half-cell assembled using the electrolytes in Example 1 and Comparative Example 1 in this invention is tested at 30°C and 1 mAh·cm⁻¹. -2 Specific capacity and 1mAh·cm -2 Coulomb efficiency plot under current density conditions;

[0023] Figure 5 The Zn||Cu half-cell assembled using the electrolytes in Example 1 and Comparative Example 1 in this invention operates at -40°C and 1 mAh·cm⁻¹. -2 Specific capacity and 1mAh·cm -2 Coulomb efficiency plot under current density conditions;

[0024] Figure 6 The Zn||NVO battery assembled using the electrolytes in Example 1 and Comparative Example 1 in this invention is tested at 30°C and at 1 A·g -1 Long-cycle performance under current density conditions;

[0025] Figure 7 The Zn||NVO battery assembled using the electrolytes in Example 1 and Comparative Example 1 in this invention is tested at -40°C at 1 A·g -1 The long-cycle performance diagram under the given current density conditions. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the embodiments described in this invention are merely preferred embodiments and are not intended to limit the scope of the invention.

[0027] Example 1

[0028] The low-temperature aqueous zinc-ion battery electrolyte provided in this embodiment is obtained by a preparation method including the following process:

[0029] Zinc trifluoromethanesulfonate was dissolved in water to prepare an aqueous solution of zinc trifluoromethanesulfonate with a concentration of 1.5 mol / L. Then, 1.5 mL of cyclopentyl methyl ether was added to 10 mL of the zinc trifluoromethanesulfonate aqueous solution and stirred evenly to obtain the electrolyte for the low-temperature aqueous zinc-ion battery.

[0030] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, zinc foil as the positive and negative electrodes, and a glass fiber membrane as the separator, a Zn||Zn symmetric cell was assembled. The Zn||Zn symmetric cell was then tested using the LAND battery testing system.

[0031] (1) At 30℃, 2mAh·cm -2 Specific capacity and 2mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0032] (2) At -40℃, 1mAh·cm -2 Specific capacity and 1 mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0033] The zinc anode of the cycled Zn||Zn symmetric battery was tested using scanning electron microscopy (SEM). The Zn||Zn symmetric battery was subjected to a 1 mAh·cm⁻¹ temperature. -2 Specific capacity and 1mAh·cm -2 The zinc anode was subjected to SEM testing after cycling for 100 hours under the specified current density to analyze the zinc deposition morphology.

[0034] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for an aqueous zinc-ion battery, copper foil as the positive electrode, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||Cu half-cell was assembled. The Zn||Cu half-cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 mAh·cm⁻¹ -2 Specific capacity and 1 mA·cm -2 The coulombic efficiency of the Zn||Cu half-cell was tested at a current density of [value missing].

[0035] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, sodium vanadate hydrate (NaV3O8·1.5H2O, NVO) as the positive electrode material, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||NVO full cell was assembled. The Zn||NVO full cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 A·g -1 The long-cycle performance of Zn||NVO full cells was tested under the current density conditions.

[0036] Example 2

[0037] The low-temperature aqueous zinc-ion battery electrolyte provided in this embodiment is obtained by a preparation method including the following process:

[0038] Zinc trifluoromethanesulfonate was dissolved in water to prepare an aqueous solution of zinc trifluoromethanesulfonate with a concentration of 1.5 mol / L. Then, 2 mL of cyclopentyl methyl ether was added to 10 mL of the zinc trifluoromethanesulfonate aqueous solution and stirred evenly to obtain the electrolyte for the low-temperature aqueous zinc-ion battery.

[0039] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, zinc foil as the positive and negative electrodes, and a glass fiber membrane as the separator, a Zn||Zn symmetric cell was assembled. The Zn||Zn symmetric cell was then tested using the LAND battery testing system.

[0040] (1) At 30℃, 2mAh·cm -2 Specific capacity and 2mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0041] (2) At -40℃, 1mAh·cm -2 Specific capacity and 1 mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0042] The zinc anode of the cycled Zn||Zn symmetric battery was tested using scanning electron microscopy (SEM). The Zn||Zn symmetric battery was subjected to a 1 mAh·cm⁻¹ temperature. -2 Specific capacity and 1mAh·cm -2 The zinc anode was subjected to SEM testing after cycling for 100 hours under the specified current density to analyze the zinc deposition morphology.

[0043] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for an aqueous zinc-ion battery, copper foil as the positive electrode, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||Cu half-cell was assembled. The Zn||Cu half-cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 mAh·cm⁻¹ -2 Specific capacity and 1 mA·cm -2 The coulombic efficiency of the Zn||Cu half-cell was tested at a current density of [value missing].

[0044] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, sodium vanadate hydrate (NaV3O8·1.5H2O, NVO) as the positive electrode material, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||NVO full cell was assembled. The Zn||NVO full cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 A·g -1 The long-cycle performance of Zn||NVO full cells was tested under the current density conditions.

[0045] Example 3

[0046] The low-temperature aqueous zinc-ion battery electrolyte provided in this embodiment is obtained by a preparation method including the following process:

[0047] Zinc trifluoromethanesulfonate was dissolved in water to prepare an aqueous solution of zinc trifluoromethanesulfonate with a concentration of 1.5 mol / L. Then, 2.5 mL of cyclopentyl methyl ether was added to 10 mL of the zinc trifluoromethanesulfonate aqueous solution and stirred evenly to obtain the electrolyte for the low-temperature aqueous zinc-ion battery.

[0048] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, zinc foil as the positive and negative electrodes, and a glass fiber membrane as the separator, a Zn||Zn symmetric cell was assembled. The Zn||Zn symmetric cell was then tested using the LAND battery testing system.

[0049] (1) At 30℃, 2mAh·cm -2 Specific capacity and 2mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0050] (2) At -40℃, 1mAh·cm -2 Specific capacity and 1 mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0051] The zinc anode of the cycled Zn||Zn symmetric battery was tested using scanning electron microscopy (SEM). The Zn||Zn symmetric battery was subjected to a 1 mAh·cm⁻¹ temperature. -2 Specific capacity and 1mAh·cm -2 The zinc anode was subjected to SEM testing after cycling for 100 hours under the specified current density to analyze the zinc deposition morphology.

[0052] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for an aqueous zinc-ion battery, copper foil as the positive electrode, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||Cu half-cell was assembled. The Zn||Cu half-cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 mAh·cm⁻¹ -2 Specific capacity and 1 mA·cm -2 The coulombic efficiency of the Zn||Cu half-cell was tested at a current density of [value missing].

[0053] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, sodium vanadate hydrate (NaV3O8·1.5H2O, NVO) as the positive electrode material, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||NVO full cell was assembled. The Zn||NVO full cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 A·g -1 The long-cycle performance of Zn||NVO full cells was tested under the current density conditions.

[0054] Example 4

[0055] The low-temperature aqueous zinc-ion battery electrolyte provided in this embodiment is obtained by a preparation method including the following process:

[0056] Zinc trifluoromethanesulfonate was dissolved in water to prepare an aqueous solution of zinc trifluoromethanesulfonate with a concentration of 1.5 mol / L. Then, 3 mL of cyclopentyl methyl ether was added to 10 mL of the zinc trifluoromethanesulfonate aqueous solution and stirred evenly to obtain the electrolyte for the low-temperature aqueous zinc-ion battery.

[0057] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, zinc foil as the positive and negative electrodes, and a glass fiber membrane as the separator, a Zn||Zn symmetric cell was assembled. The Zn||Zn symmetric cell was then tested using the LAND battery testing system.

[0058] (1) At 30℃, 2mAh·cm -2 Specific capacity and 2mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0059] (2) At -40℃, 1mAh·cm -2 Specific capacity and 1 mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0060] The zinc anode of the cycled Zn||Zn symmetric battery was tested using scanning electron microscopy (SEM). The Zn||Zn symmetric battery was subjected to a 1 mAh·cm⁻¹ temperature. -2 Specific capacity and 1mAh·cm -2 The zinc anode was subjected to SEM testing after cycling for 100 hours under the specified current density to analyze the zinc deposition morphology.

[0061] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for an aqueous zinc-ion battery, copper foil as the positive electrode, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||Cu half-cell was assembled. The Zn||Cu half-cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 mAh·cm⁻¹ -2 Specific capacity and 1 mA·cm -2 The coulombic efficiency of the Zn||Cu half-cell was tested at a current density of [value missing].

[0062] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, sodium vanadate hydrate (NaV3O8·1.5H2O, NVO) as the positive electrode material, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||NVO full cell was assembled. The Zn||NVO full cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 A·g -1 The long-cycle performance of Zn||NVO full cells was tested under the current density conditions.

[0063] Example 5

[0064] The low-temperature aqueous zinc-ion battery electrolyte provided in this embodiment is obtained by a preparation method including the following process:

[0065] Zinc trifluoromethanesulfonate was dissolved in water to prepare a zinc trifluoromethanesulfonate aqueous solution with a concentration of 1.5 mol / L. Then, 3.5 mL of cyclopentyl methyl ether was added to 10 mL of the zinc trifluoromethanesulfonate aqueous solution and stirred evenly to obtain the low-temperature aqueous zinc-ion battery electrolyte.

[0066] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, zinc foil as the positive and negative electrodes, and a glass fiber membrane as the separator, a Zn||Zn symmetric cell was assembled. The Zn||Zn symmetric cell was then tested using the LAND battery testing system.

[0067] (1) At 30℃, 2mAh·cm -2 Specific capacity and 2mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0068] (2) At -40℃, 1mAh·cm -2 Specific capacity and 1 mA·cm -2 The long-cycle performance of Zn||Zn symmetric cells was tested at a current density.

[0069] The zinc anode of the cycled Zn||Zn symmetric battery was tested using scanning electron microscopy (SEM). The Zn||Zn symmetric battery was subjected to a 1 mAh·cm⁻¹ temperature. -2 Specific capacity and 1mAh·cm -2 The zinc anode was subjected to SEM testing after cycling for 100 hours under the specified current density to analyze the zinc deposition morphology.

[0070] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for an aqueous zinc-ion battery, copper foil as the positive electrode, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||Cu half-cell was assembled. The Zn||Cu half-cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 mAh·cm⁻¹ -2 Specific capacity and 1 mA·cm -2 The coulombic efficiency of the Zn||Cu half-cell was tested at a current density of [value missing].

[0071] Using the aforementioned low-temperature aqueous zinc-ion battery electrolyte as the electrolyte for the aqueous zinc-ion battery, sodium vanadate hydrate (NaV3O8·1.5H2O, NVO) as the positive electrode material, zinc foil as the negative electrode, and a glass fiber membrane as the separator, a Zn||NVO full cell was assembled. The Zn||NVO full cell was tested using the LAND battery testing system at -40℃ and 30℃ respectively: at 1 A·g -1The long-cycle performance of Zn||NVO full cells was tested under the current density conditions.

[0072] Comparative Example 1

[0073] Compared to the low-temperature aqueous zinc-ion battery electrolyte in Example 1, no diluent was added, and all other test conditions were exactly the same.

[0074] Test Results and Analysis

[0075] Figure 1 and Figure 2 The figures show the long-cycle performance of Zn||Zn symmetric cells assembled using the electrolytes in Example 1 and Comparative Example 1 at 30°C and -40°C, respectively. The results show that at 30°C, the current density is 2 mA cm⁻¹. -2 The capacity is 2mAh cm -2 Under the conditions described, the battery assembled using the electrolyte in Comparative Example 1 was extremely unstable, with an initial polarization as high as 280mV and very drastic polarization voltage fluctuations, resulting in short-circuit failure in less than 300 hours. In contrast, the battery assembled using the electrolyte in Example 1 exhibited a long cycle life exceeding 1500 hours, nearly six times that of the electrolyte in Comparative Example 1, and maintained a low overpotential of 50mV throughout. At a low temperature of -40°C, the current density was 1 mA cm⁻¹. -2 The capacity is 1mAh cm -2 Under the specified conditions, the battery assembled using the electrolyte in Example 1 achieved an ultra-long cycle life of 1400 hours and consistently maintained a low overpotential below 80 mV. In contrast, the battery assembled using the electrolyte in Comparative Example 1 exhibited a very high overpotential and failed to function properly. The excellent performance at low temperatures may be attributed to the introduction of cyclopentyl methyl ether, which disrupts the hydrogen bond network structure of water, thereby lowering the freezing point of the electrolyte and aiding in the formation of a stable SEI.

[0076] Figure 3 The Zn||Zn symmetric cells assembled using the electrolytes in Example 1 and Comparative Example 1 in this invention exhibit a 1 mAh·cm⁻¹ capacity at 30°C and -40°C. -2 Specific capacity and 1mAh·cm -2SEM images of the zinc anode surface after 100 hours of cycling under the specified current density were obtained. The results showed that, regardless of room temperature or low temperature, the Zn anode of the battery assembled using the electrolyte in Comparative Example 1 exhibited significant corrosion after 100 hours of cycling. Numerous zinc dendrites and moss-like zinc deposits were visible on the zinc surface, along with numerous micropores, indicating severe hydrogen evolution reaction and corrosion. In stark contrast, the Zn anode of the battery assembled using the electrolyte in Example 1 showed a very smooth zinc surface without dendrites after 100 hours of cycling, exhibiting no significant corrosion. This is attributed to the stable SEI induced by the solvation structure of anion and cation aggregation, which promotes uniform zinc deposition, thereby inhibiting uneven nucleation and dendrite growth, as well as the formation of byproducts.

[0077] Figure 5 and Figure 6 The figures show the coulombic efficiency of the Zn||Cu half-cells assembled using the electrolytes in Example 1 and Comparative Example 1 at 30°C and -40°C, respectively. The results indicate that the battery assembled using the electrolyte in Example 1 achieves the optimal coulombic efficiency at 30°C (1 mAh·cm⁻¹). -2 Specific capacity and 1mAh·cm -2 After 1200 cycles under the specified current density, the average electroplating (CE) reached 99.74%. In contrast, the Zn plating / stripping CE of the battery assembled using the electrolyte in Comparative Example 1 was lower, at only 81.23%, and the battery failed after the 100th cycle. Even at a low temperature of -40°C, the battery assembled using the electrolyte in Example 1 had an initial CE of 97.4%, and after 1000 cycles, the average CE remained as high as 99.86%, demonstrating its excellent plating / stripping reversibility.

[0078] Figure 6 and Figure 7 The figures show the long-cycle performance of Zn||NVO batteries assembled using the electrolytes in Example 1 and Comparative Example 1 at 30°C and -40°C, respectively. The results indicate that at 30°C, 1A g... -1 At a current density of [value missing], the battery assembled using the electrolyte in Example 1 maintained 85.37% capacity retention after 1000 cycles, with an average coulombic efficiency approaching 100%. At -40°C, 1 A g [value missing] -1 At the specified current density, the battery assembled using the electrolyte in Example 1 retained 90.91% of its capacity after 2000 cycles. In contrast, the battery assembled using the electrolyte in Comparative Example 1 failed due to short circuit in less than 350 hours. This is attributed to the disruption of the hydrogen bond network of water by cyclopentyl methyl ether, while simultaneously forming a stable SEI, promoting uniform zinc deposition and thus improving the low-temperature performance of the electrolyte.

Claims

1. A low-temperature aqueous zinc-ion battery electrolyte, characterized in that, It includes the following components: zinc salt, water, and diluent; The diluent is one of tetrahydrofuran, methyl tert-butyl ether, cyclopentyl methyl ether, dioxane, and ethylene glycol.

2. The low-temperature aqueous zinc-ion battery electrolyte according to claim 1, characterized in that, The zinc salt is one of zinc sulfate heptahydrate, zinc gluconate, zinc acetate, zinc trifluoromethanesulfonate, and zinc chloride.

3. The low-temperature aqueous zinc-ion battery electrolyte according to claim 2, characterized in that, The concentration of the zinc salt in the low-temperature aqueous zinc-ion battery electrolyte is 0.5–3 mol / L.

4. The low-temperature aqueous zinc-ion battery electrolyte according to claim 3, characterized in that, The diluent accounts for 10%-50% of the total solvent.

5. The low-temperature aqueous zinc-ion battery electrolyte according to claim 4, characterized in that, The water is deionized water.

6. The low-temperature aqueous zinc-ion battery electrolyte according to claim 5, characterized in that, The proportion of deionized water in the total solvent is 50%-90%.

7. A method for preparing the low-temperature aqueous zinc-ion battery electrolyte according to any one of claims 1-6, characterized in that, Includes the following steps: The inorganic zinc salt and deionized water are mixed to prepare a basic electrolyte; The diluent is added to the base electrolyte to prepare the low-temperature aqueous zinc-ion battery electrolyte.

8. An aqueous zinc-ion battery, characterized in that, Includes an electrolyte, wherein the electrolyte is the low-temperature aqueous zinc-ion battery electrolyte according to any one of claims 1-6 or the low-temperature aqueous zinc-ion battery electrolyte prepared by the preparation method according to claim 7.

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