A two-phase electrolyte zinc ion battery

Abstract

The application provides a dual-phase electrolyte zinc ion battery. The dual-phase electrolyte zinc ion battery comprises a zinc metal negative electrode, a dual-phase electrolyte, a diaphragm and a positive electrode. The dual-phase electrolyte comprises a negative electrode side organic-rich phase electrolyte and a positive electrode side aqueous electrolyte. The application makes up for the deficiency of a single electrolyte, suppresses the hydrogen evolution reaction of the zinc metal negative electrode, improves the coulomb efficiency and cycle life of the battery, and does not lose the positive electrode kinetics. The application is simple to prepare, easy to industrialize and has application prospects in the energy storage technology field.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to a long-life biphase electrolyte zinc-ion battery. Background Technology

[0002] With global pollution becoming increasingly prominent, the development of renewable energy sources such as hydropower, wind power, and solar power, as well as the transformation of the energy structure, are inevitable trends. However, renewable energy is susceptible to seasonal, weather, and geographical factors, resulting in discontinuous and unstable power generation, leading to the curtailment of hydropower, wind power, and solar power. Energy storage technology is an effective way to achieve peak shaving and frequency regulation, and can improve the grid's ability to absorb renewable energy. Among them, electrochemical energy storage technology has advantages such as low investment, high efficiency, and flexible use, and has become a research focus for researchers in recent years. Large-scale energy storage needs to meet the conditions of safety, reliability, low cost, and environmental friendliness. Aqueous zinc-ion batteries, which use zinc metal as the negative electrode, manganese dioxide and other oxides as the positive electrode, and zinc salt aqueous solution as the electrolyte, are a type of secondary battery that can well meet the above requirements and has recently become a focus of attention, possessing significant research value.

[0003] However, the application of aqueous zinc-ion batteries still faces many challenges, including dendrite growth and hydrogen evolution corrosion on the zinc metal anode, which shorten battery life and reduce zinc utilization. In recent years, researchers have developed various strategies to address these issues, such as surface coatings, electrolyte additives, and mixed electrolytes. These strategies have effectively mitigated dendrite growth and hydrogen evolution corrosion, but they still cannot fully meet the needs of practical applications. Exploring new solutions is of great significance for the large-scale application of zinc-ion batteries. Summary of the Invention

[0004] To address the issues of short cycle life and low coulombic efficiency in aqueous zinc-ion batteries, this invention provides a two-phase electrolyte zinc-ion battery. This battery features an increased cycle life of the zinc metal negative electrode, a reduced hydrogen evolution corrosion rate, and minimal impact on the positive electrode kinetics. The battery is also simple to manufacture and inexpensive.

[0005] Technical solution of the present invention

[0006] A two-phase electrolyte zinc-ion battery, the battery comprising a zinc metal negative electrode, a two-phase electrolyte, a separator, and a positive electrode.

[0007] The zinc metal negative electrode includes zinc foil or zinc powder.

[0008] The biphase electrolyte is prepared based on the principles of salting-out effect and salt-dissolution effect, and its components include hydrophilic salts, deionized water, organic solvents, and amphiphilic salts.

[0009] The hydrophilic salt is zinc sulfate, with a molar concentration of 1.8–2.2 mol·L⁻¹. -1 .

[0010] The organic solvent is one or more of N-methylpyrrolidone, acetonitrile, methanol, ethanol, tetramethylurea, tetrahydrofuran, and methyl ethyl carbonate, and the volume ratio of the organic solvent to deionized water is 3:7 to 5:5.

[0011] The amphiphilic salt comprises one or both of zinc tetrafluoroborate and zinc bis(trifluoromethylsulfonyl)imide, with a molar concentration of 0.15–0.3 mol·L⁻¹. -1 .

[0012] The diaphragm is a double-layer diaphragm, specifically two of the following: polyethersulfone membrane, glass fiber membrane, and polypropylene membrane.

[0013] The positive electrode includes one of vanadium pentoxide (V2O5), vanadium dioxide (VO2), manganese dioxide (MnO2), and polyaniline (PANI).

[0014] The present invention has the following beneficial effects:

[0015] This invention provides a zinc-ion battery based on a two-phase electrolyte, with an organic-rich electrolyte on the negative electrode side and an aqueous electrolyte on the positive electrode side. This overcomes the thermodynamic instability of the zinc negative electrode in an aqueous electrolyte, mitigating corrosion and dendrite problems, while keeping the positive electrode kinetics unaffected. The battery of this invention improves the utilization rate of zinc metal, significantly extends the cycle life of the zinc-ion battery, and is simple, low-cost, and easy to industrialize, showing promising application prospects in the field of energy storage technology. Attached Figure Description

[0016] Figure 1 The diagram shows the cycle performance of the Zn / / Cu asymmetric battery assembled using the electrolyte in Example 1 of this invention.

[0017] Figure 2 The diagram shows the cycle performance of the Zn / / Zn symmetric battery assembled using the electrolyte in Example 1 of this invention.

[0018] Figure 3 The diagram shows the cycle performance of the Zn / / PANI full cell assembled using the electrolyte in Example 1 of this invention.

[0019] Figure 4 The diagram shows the cycle performance of the Zn / / Cu asymmetric battery assembled using the electrolyte in Example 2 of this invention.

[0020] Figure 5 The image shows the cycle performance of the Zn / / Cu asymmetric battery assembled using the electrolyte in Example 3 of this invention.

[0021] Figure 6 The circuit performance diagram shows the Zn / / Cu asymmetric battery assembled using the electrolyte in Comparative Example 1.

[0022] Figure 7 The circuit performance diagram shows the Zn / / Zn symmetric cell assembled using the electrolyte in Comparative Example 1.

[0023] Figure 8 The graph shows the cycle performance of the Zn / / PANI full cell assembled using the electrolyte in Comparative Example 1. Detailed Implementation

[0024] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0025] The cycle performance tests of the Zn / / Zn symmetric cells described in Examples 1-3 and Comparative Example 1 were conducted under the following conditions: the simulated cells used a CR2032 button cell system, wherein the electrolyte was the electrolyte described in Examples 1-3 and Comparative Example 1, the positive and negative electrodes of the symmetric cells were both 50 μm thick zinc foil, the positive electrode of the asymmetric cells was a 50 μm thick copper foil, and the positive electrode of the full cell was polyaniline (PANI).

[0026] Example 1

[0027] A two-phase electrolyte zinc-ion battery was prepared through the following experimental steps:

[0028] Electrolyte preparation: Dissolve 0.141g of zinc fluoroborate hydrate and 1.167g of zinc sulfate heptahydrate in a mixed solvent of N-methylpyrrolidone and deionized water (volume ratio 3:7), and bring the volume to 2mL. The electrolyte will separate into two layers due to density differences. The upper layer is an organic electrolyte and the lower layer is an aqueous electrolyte.

[0029] Cyclic performance simulation of Zn / / Cu asymmetric cells was performed using a CR2032 coin cell system, with effective electrode areas of 2 cm² for both positive and negative electrodes. -2 80 μL of the upper electrolyte was used to wet the glass fiber membrane (membrane thickness 300 μm). During battery assembly, the zinc foil, glass fiber membrane, and copper foil were stacked sequentially from top to bottom. The coulombic efficiency was then tested using a constant current charge-discharge method. The test conditions were as follows: discharge current was 1 mA·cm⁻¹. -2 The charging cutoff voltage is 0.6V.

[0030] The cycle performance simulation of Zn / / Zn symmetric cells used a CR2032 coin cell system, with effective electrode areas of 2 cm² for both positive and negative electrodes. -2 80 μL of the upper electrolyte was used to wet the glass fiber separator (membrane thickness 300 μm). During battery assembly, the zinc foil, glass fiber membrane, and zinc foil were stacked sequentially from top to bottom. A constant current charge-discharge test was conducted to determine its cycle life. The test conditions were as follows: current 1 mA·cm⁻¹. -2 The capacities are 1mAh·cm -2That is, it takes 2 hours to complete one cycle.

[0031] The cycle performance simulation of the Zn / / PANI full cell used a CR2032 coin cell system, with the electrolyte being the one described in this embodiment, zinc foil as the negative electrode, and polyaniline as the positive electrode. The effective area of ​​both the positive and negative electrodes was 2 cm². -2 The separator consists of a polyethersulfone (PES) membrane and a glass fiber membrane. 30 μL of the upper electrolyte is dropped onto the PES membrane (150 μm thick), and 70 μL of the lower electrolyte is dropped onto the glass fiber membrane (260 μm thick). The positive electrode is prepared by mixing active material, acetylene black, and PVDF in a mass ratio of 7:2:1 to form a slurry, which is then coated onto carbon paper and dried in a forced-air drying oven at 80°C for 6–12 hours. During battery assembly, the zinc foil, PES membrane, glass fiber membrane, and positive electrode sheet are stacked sequentially from top to bottom. The battery is subjected to a constant current (0.5 A g) test. -1 The charging and discharging tests were conducted, with a charging and discharging voltage range of 0.5 to 1.5V.

[0032] The Zn / / Cu asymmetric battery assembled using the electrolyte in this embodiment achieves a coulombic efficiency of 99.69%, the Zn / / Zn symmetric battery shows no short circuit after 700 hours of cycling, and the Zn / / PANI full cell shows no capacity decay after 300 cycles.

[0033] Example 2

[0034] In Example 1, N-methylpyrrolidone was replaced with tetramethylurea, and other conditions remained unchanged (same as in Example 1).

[0035] The Zn / / Cu asymmetric battery assembled using the electrolyte described in this embodiment has a stable coulombic efficiency of approximately 99.65%.

[0036] Example 3

[0037] In Example 1, zinc fluoroborate hydrate was replaced with zinc bis(trifluoromethanesulfonyl)imide (0.251 g), and N-methylpyrrolidone was replaced with ethyl methyl carbonate (40% by volume), while other conditions remained unchanged (same as in Example 1).

[0038] The Zn / / Cu asymmetric battery assembled using the electrolyte described in this embodiment has a stable coulombic efficiency of around 99.5%.

[0039] Comparative Example 1

[0040] Dissolve an appropriate amount of zinc sulfate in deionized water to prepare a 1M zinc sulfate solution.

[0041] The cycle performance simulation of Zn / / Zn symmetric cells used a CR2032 coin cell system, with effective electrode areas of 2 cm² for both positive and negative electrodes. -2Take 80 μL of the electrolyte to wet the glass fiber membrane (membrane thickness is 300 μm). When assembling the battery, stack the zinc foil, glass fiber membrane and zinc foil in the order from top to bottom, and perform constant current charge and discharge test to test its cycle life.

[0042] Cyclic performance simulation of Zn / / Cu asymmetric cells was performed using a CR2032 coin cell system, with effective electrode areas of 2 cm² for both positive and negative electrodes. -2 80 μL of the electrolyte was used to wet the glass fiber membrane (membrane thickness 300 μm). During battery assembly, the zinc foil, glass fiber membrane, and copper foil were stacked sequentially from top to bottom. A constant current charge-discharge test was conducted to determine its coulombic efficiency. The test conditions were as follows: discharge current was 1 mA·cm⁻¹. -2 The charging cutoff voltage is 0.6V.

[0043] The cycle performance simulation of the Zn / / PANI full cell used a CR2032 coin cell system, with the electrolyte being the one described in this embodiment, zinc foil as the negative electrode, and polyaniline as the positive electrode. The effective area of ​​both the positive and negative electrodes was 2 cm². -2 The separator consists of a polyethersulfone membrane (150 μm thick) and a glass fiber membrane (260 μm thick). 100 μL of zinc sulfate electrolyte is dropped onto the membrane, 30 μL onto the polyethersulfone membrane, and 70 μL onto the glass fiber membrane. The positive electrode is prepared by mixing active material, acetylene black, and PVDF in a mass ratio of 7:2:1 to form a slurry, which is then coated onto carbon paper and dried in a forced-air drying oven at 80°C for 6–12 hours. During battery assembly, the zinc foil, polyethersulfone membrane, glass fiber membrane, and positive electrode are stacked sequentially from top to bottom. The battery is subjected to a constant current (0.5 A g) test. -1 The charging and discharging tests were conducted, with a charging and discharging voltage range of 0.5V to 1.5V.

[0044] The Zn / / Zn symmetric cell assembled using the electrolyte described in this comparative example had a cycle life of 260 hours before short-circuiting. The Zn / / Cu asymmetric cell short-circuited after 130 cycles, with a coulombic efficiency of less than 99.5%, and the capacity of the Zn / / PANI full cell continued to decay during cycling.

Claims

1. A two-phase electrolyte zinc-ion battery, characterized in that, The battery includes a zinc metal negative electrode, a two-phase electrolyte, two separators, and a positive electrode; The biphase electrolyte is prepared based on the principles of salting out and salt dissolution. Its components include hydrophilic salts, water, organic solvents, and amphiphilic salts. The electrolyte is prepared by dissolving the hydrophilic salts and amphiphilic salts in a mixed solvent of organic solvent and water, resulting in layers. The upper layer is an organic electrolyte, and the lower layer is an aqueous electrolyte. The hydrophilic salt is zinc sulfate, and the molar concentration of the hydrophilic salt is 1.8 ~ 2.5 mol·L⁻¹. -1 ; The amphiphilic salt comprises one or both of zinc tetrafluoroborate and zinc bis(trifluoromethylsulfonyl)imide, and the molar concentration of the amphiphilic salt is 0.15 ~ 0.3 mol·L⁻¹. -1 ; The upper layer of organic electrolyte is dropped onto one membrane to obtain an organic electrolyte membrane, and the lower layer of electrolyte is dropped onto another membrane to obtain an aqueous electrolyte membrane. When assembling the battery, the zinc metal negative electrode, the organic electrolyte membrane, the aqueous electrolyte membrane, and the positive electrode are stacked in the following order from top to bottom.

2. The dual-phase electrolyte zinc-ion battery according to claim 1, characterized in that: The diaphragm consists of two diaphragms, which are one or two of polyethersulfone membranes, glass fiber membranes, and polypropylene membranes. The membrane thickness is 20~500 μm, and the amount of electrolyte impregnated or adsorbed on the membrane is 15~40 μL·cm. -2 .

3. The dual-phase electrolyte zinc-ion battery according to claim 1, characterized in that: The positive electrode is an electrode in which one or more of the following materials are active: manganese oxide, vanadium oxide, Prussian blue, and polyaniline.

4. The dual-phase electrolyte zinc-ion battery according to claim 1, characterized in that: The organic solvent is one or more of sulfolane, N-methylpyrrolidone, methanol, ethanol, tetramethylurea, tetrahydrofuran, triethyl phosphate, and methyl ethyl carbonate, and the volume ratio of the organic solvent to deionized water is 3:7 to 5:

5.

5. The dual-phase electrolyte zinc-ion battery according to claim 1, characterized in that: The zinc metal negative electrode includes zinc foil, zinc powder, or zinc sheet, with the zinc powder being adhered to the current collector by an adhesive during use.

6. The dual-phase electrolyte zinc-ion battery according to claim 1, characterized in that: The zinc-ion battery is a zinc-ion button cell.

7. The dual-phase electrolyte zinc-ion battery according to claim 1, characterized in that: The molar concentration of the hydrophilic salt is 2 ~ 2.2 mol·L⁻¹ -1 ; The molar concentration of the amphiphilic salt is 0.2 ~ 0.25 mol·L⁻¹. -1 .

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