Zinc salt for zinc-based batteries and method of preparation and use thereof

Abstract

The application belongs to the field of electrochemistry, and particularly relates to a zinc salt for a zinc-based battery and a preparation method and application thereof. The zinc salt provided by the application is Zn[B(hfip)4]2, the zinc salt is simple to synthesize, low in price, and high in solubility in common solvents such as esters, ethers, sulfones and nitriles; the zinc salt can be used as an electrolyte material of a zinc-based battery, the zinc-based battery is a zinc ion battery, a zinc-lithium hybrid ion battery or a zinc-sodium hybrid ion battery; the zinc-based battery using the zinc salt as the electrolyte material exhibits good electrochemical performance and has an application prospect in large-scale energy storage and power batteries.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to zinc salts for zinc-based batteries, their preparation methods, and applications. Background Technology

[0002] In recent years, battery technology has developed rapidly and has been widely used in various industries. Lithium-ion batteries, in particular, have become an indispensable part of the battery field. However, with the popularization of lithium-ion batteries, some drawbacks have also been exposed, such as the low reserves of lithium and the high cost of lithium-ion batteries. These problems have hindered the development of lithium-ion batteries to some extent. However, rechargeable zinc-based batteries, due to their abundant zinc metal reserves, suitable electrochemical potential (-0.76V compared to the standard hydrogen electrode), and high theoretical capacity (820mA hg), offer a promising alternative. -1 5855mA h cm -3 Its advantages, such as high safety, have attracted attention in recent years (Nature Mater.17(2018)543-549).

[0003] Currently, water (H2O) is the commonly used electrolyte solvent in zinc batteries. However, due to the high reactivity of the zinc metal anode, it spontaneously reacts chemically with the water in the electrolyte, causing severe corrosion. Furthermore, due to the high decomposition potential of water-based solvents, water preferentially decomposes during the deposition of zinc ions onto the zinc anode, producing hydrogen gas and simultaneously increasing the pH value on the zinc anode surface. This results in the formation of an alkaline passivation layer on the zinc anode surface, hindering the free transport of zinc ions at the interface. Moreover, the electrochemical window of water-based electrolytes is relatively narrow, preventing the application of cathode materials with higher operating potentials in aqueous zinc batteries.

[0004] Against this backdrop, the idea of ​​using stable organic liquids with a wide electrochemical window as solvents for zinc battery electrolytes has begun to attract attention. However, due to the strong binding force between divalent zinc ions and anions, currently widely used zinc salts (such as zinc sulfate (ZnSO4), zinc nitrate (Zn(NO3)2), zinc chloride (ZnCl2), zinc acetate (Zn(CH3COO)2), zinc trifluoromethanesulfonate (Zn(CF3SO3)2), etc.) are almost insoluble in organic solvents. Zn(TFSI)2 (zinc bis(trifluoromethanesulfonyl)imide) has a certain solubility in organic solvents, but its high price hinders its practical application.

[0005] To address the aforementioned problems, this invention proposes a low-cost and easily synthesized zinc salt, Zn[B(hfip)4]2. This zinc salt is inexpensive, its synthesis is simple, and it exhibits high solubility in common solvents (such as esters, ethers, sulfones, and nitriles), allowing for the formulation of appropriate electrolytes as needed. Electrolytes prepared using this zinc salt are suitable for zinc batteries, zinc-lithium hybrid batteries, and zinc-sodium hybrid battery systems, demonstrating excellent electrochemical performance and showing promising application prospects in large-scale energy storage and power batteries. Summary of the Invention

[0006] The purpose of this invention is to provide a zinc salt that is simple to synthesize, inexpensive, and highly soluble in common solvents, which can be used as a zinc-based battery, as well as its preparation method and application.

[0007] The zinc salt provided by this invention for use in zinc-based batteries has the chemical name Zn[B(hfip)4]2. Its specific composition is Zn[B(C3OHF6)4]2.

[0008] This invention also provides a method for preparing the above-mentioned zinc salt Zn[B(hfip)4]2, the specific steps of which are as follows:

[0009] Step 1: Dissolve zinc borohydride in ethylene glycol dimethyl ether solvent to form a precursor solution;

[0010] Step 2: Slowly add hexafluoroisopropanol liquid dropwise to the precursor solution, while refluxing and stirring for 18-25 hours to obtain a homogeneous liquid;

[0011] Step 3: The obtained homogeneous liquid is distilled under reduced pressure to remove the solvent, yielding a white spherical solid product;

[0012] Step four: Place the white spherical solid product under vacuum to dry, and obtain the final product.

[0013] in:

[0014] The molar ratio of zinc borohydride to hexafluoroisopropanol is 1:8-9; preferably 1:8.5.

[0015] The process of slowly adding hexafluoroisopropanol should take no less than 1 hour, for example, 1-1.5 hours.

[0016] When the product is vacuum dried, the oven temperature should be set to 35-45℃, preferably 40℃.

[0017] The present invention also provides the application of the above-mentioned zinc salt in the preparation of zinc-based battery electrolytes.

[0018] The zinc-based battery is a zinc-ion battery, a zinc-lithium hybrid ion-based battery, or a zinc-sodium hybrid ion battery.

[0019] The electrolyte comprises zinc salt Zn[B(hfip)4]2 and a solvent, wherein the solvent is one or more of ester, ether, sulfone, and nitrile solvents.

[0020] For zinc-ion batteries, the zinc salt concentration in the electrolyte is 0.01 mol / L to 4 mol / L;

[0021] For zinc-lithium hybrid ion batteries, the electrolyte further includes a lithium salt; the lithium salt concentration is 0.01 mol / L to 18 mol / L.

[0022] For zinc-sodium hybrid ion batteries, the electrolyte further includes sodium salt; the zinc salt concentration is 0.01 mol / L to 4 mol / L; and the sodium salt concentration is 0.01 mol / L to 18 mol / L.

[0023] Furthermore, the lithium salt is one or more of LiPF6, LiTFSI, LiFSI, LiBOB, LiDFOB, LiTFMS, LiBF4, LiClO4, LiNO3, Li2SO4, Li3PO4, LiI, LiCl, and LiF.

[0024] Further, the sodium salt is one or more of NaPF6, NaTFSI, NaFSI, NaBOB, NaDFOB, NaTFMS, NaBF4, NaClO4, NaNO3, Na2SO4, Na3PO4, NaI, NaCl, and NaF.

[0025] Further, the ester solvent is one or more of the following: fluoroethylene carbonate, methyl ethyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate, ethyl propionate, methyl butyrate, butyl acetate, methyl propionate, propyl butyrate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, dimethyl methyl phosphate, diethyl ethyl phosphate, cumene diphenyl phosphate, and triphenyl phosphate.

[0026] The ether solvent is one or more of the following: ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dioxolane, 1,4-dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, and dimethoxymethane.

[0027] The sulfone solvent is one or more of dimethyl sulfoxide, sulfolane, methyl ethyl sulfone, dimethyl sulfone, diethyl sulfone, phenylethyl sulfone, and bis(cyanoethyl) sulfone.

[0028] The nitrile solvent is one or more of the following: acetonitrile, hexamethoxyphosphazene, butadionitrile, propionitrile, acrylonitrile, adiponitrile, glutaronitrile, octadionitrile, sebaconitrile, 1,3,6-hexanetricarbonitrile, 1,3,5-pentanetricarbonitrile, p-fluorobenzonitrile, p-methylbenzonitrile, 2-fluoroadiponitrile, 2,2-difluorobutadionitrile, tricyanobenzene, crotonitrile, trans-butenedionitrile, trans-hexenedionitrile, 1,2-di(cyanoethoxy)ethane, 1,2,3-tri(cyanoethoxy)propane, 3-(trimethylsiloxy)propionitrile, and cyclophosphonitrile.

[0029] The Zn[B(hfip)4]2 salt is significantly cheaper than the commonly used Zn(TFSI)2 salt, offering a substantial price advantage. More importantly, the Zn[B(hfip)4]2 salt is non-corrosive to common current collectors (e.g., aluminum foil, stainless steel foil), greatly ensuring battery safety during operation.

[0030] The Zn[B(hfip)4]2 salt can form a Zn-rich layer on the zinc anode surface during zinc-based battery operation. x B y O z The inorganic solid electrolyte membrane (SEI membrane) effectively promotes zinc ion conduction and inhibits zinc dendrite formation, significantly improving the utilization rate and cycle stability of the zinc metal anode. Furthermore, under high voltage, the Zn[B(hfip)4]2 anion B(hfip)4... - It can decompose on the positive electrode surface to form a positive electrode electrolyte interphase (CEI) film, effectively preventing decomposition side reactions of the electrolyte on the surface of the high-voltage positive electrode material, thereby improving the coulombic efficiency of the battery and extending its cycle life. This feature allows electrolytes containing Zn[B(hfip)4]2 salt to be compatible with high-operating-voltage positive electrode materials. Detailed Implementation

[0031] To further illustrate the technical solutions and advantages of the present invention, the present invention is described in the following specific embodiments, but the present invention is not limited to these examples.

[0032] Example 1

[0033] Ethylene glycol dimethyl ether (DME) and 1,3-dioxane (DOL) were mixed in a 1:1 volume ratio, and then Zn[B(hfip)4]2 was added to prepare a 1 mol / L solution. Sulfur (S) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (S): conductive agent (super P): binder (polyvinylidene fluoride PVDF) = 80:10:10, and coated onto the surface of carbon-coated aluminum foil to form the positive electrode sheet. Next, zinc (Zn) was used as the negative electrode material, and a glass fiber membrane was used as the separator to assemble a 2032 coin cell. After cycling 500 times at a current density of 1C at room temperature (25°C), the capacity retention rate reached 92%, and the average coulombic efficiency was 99.85% (see Table 1).

[0034] Example 2

[0035] Ethyl methyl carbonate (EMC) was used as the organic solvent, followed by the addition of Zn[B(hfip)4]2 to prepare a 1 mol / L solution. Selenium (Se) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (Se): conductive agent (super P): binder (polyvinylidene fluoride PVDF) = 80:10:10, and coated onto the surface of carbon-coated aluminum foil to form the positive electrode sheet. Next, zinc (Zn) was used as the negative electrode material, and a glass fiber membrane was used as the separator to assemble a 2032 coin cell. After cycling for 600 cycles at a current density of 1C at room temperature (25°C), the capacity retention rate reached 91.3%, and the average coulombic efficiency was 99.65% (see Table 1).

[0036] Example 3

[0037] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a weight ratio of 1:1:1 as a solvent, and then Zn[B(hfip)4]2 was added as a solute at a concentration of 0.5 mol / L. Prussian blue (Fe4[Fe(CN)6]3) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (Fe4[Fe(CN)6]3): conductive agent (super P): binder (polyvinylidene fluoride PVDF) = 70:20:10, and coated onto the surface of carbon-coated aluminum foil to form the positive electrode sheet. Next, zinc (Zn) was used as the negative electrode material, and a glass fiber membrane was used as the separator to assemble a 2032 coin cell. After cycling 900 times at a current density of 1C at room temperature (25°C), the capacity retention rate reached 89.3%, and the average coulombic efficiency was 99.75% (see Table 1).

[0038] Example 4

[0039] Acetonitrile (AN) was used as the solvent, followed by the addition of 1 mol / L Zn[B(hfip)4]2 to prepare the electrolyte. Zinc manganate (ZnMn2O4) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (ZnMn2O4): conductive agent (Super P): binder (polyvinylidene fluoride PVDF) = 80:10:10, and coated on the surface of aluminum foil to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After cycling 3000 times at a current density of 1C at room temperature (25°C), the capacity retention reached 88%, and the average coulombic efficiency reached 99.5% (see Table 1).

[0040] Example 5

[0041] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a weight ratio of 1:1:1 as a solvent, and then Zn[B(hfip)4]2 was added as a solute at a concentration of 0.5 mol / L. Manganese dioxide (MnO2) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (MnO2): conductive agent (Super P): binder (polyvinylidene fluoride PVDF) = 80:10:10, and coated on the surface of aluminum foil to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 8000 cycles at a current density of 1C at room temperature (25°C), the capacity retention reached 85%, and the average coulombic efficiency reached 99.6% (see Table 1).

[0042] Example 6

[0043] Trimethyl phosphate (TMP) was used as the solvent, followed by the addition of Zn[B(hfip)4]2 as the solute, with a concentration of 0.5 mol / L. Vanadium pentoxide (V2O5) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (V2O5): conductive agent (Super P): binder (polyvinylidene fluoride PVDF) = 80:10:10, and coated onto the surface of aluminum foil to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 6000 cycles at a current density of 0.5C at room temperature (25°C), the capacity retention reached 91%, and the average coulombic efficiency reached 99.4% (see Table 1).

[0044] Example 7

[0045] Triethyl phosphate (TEP) was used as the solvent, followed by the addition of Zn[B(hfip)4]2 as the solute, with a concentration of 0.5 mol / L. Ammonium vanadate ((NH4)2V3O8) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material ((NH4)2V3O8): conductive agent (Super P): binder (polyvinylidene fluoride PVDF) = 80:10:10, and coated onto the surface of aluminum foil to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 10,000 cycles at a current density of 2C at room temperature (25°C), the capacity retention reached 86%, and the average coulombic efficiency reached 99.3% (see Table 1).

[0046] Example 8

[0047] N,N-dimethylformamide (DMF) was used as the solvent, followed by the addition of 0.5 mol / L Zn[B(hfip)4]2 to prepare the electrolyte. Polybenzoquinone sulfide (PBQS) was used as the positive electrode active material. The molecular formula of PBQS is [C6H2O2S]. n (n is an integer greater than or equal to 1), and its structure is as follows:

[0048]

[0049] The PBQS positive electrode sheet was prepared as follows: A slurry was mixed according to the ratio of active material (PBQS): conductive agent (Ketjen Black): binder (PTFE) = 60:30:10, and pressed onto the surface of a titanium mesh to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 18,000 cycles at 25°C and a current density of 3C, the capacity retention reached 93%, and the average coulombic efficiency reached 99.5% (see Table 1).

[0050] Example 9

[0051] N,N-dimethylformamide (DMF) was used as a solvent, followed by the addition of 0.5 mol / L Zn[B(hfip)4]2 to prepare the electrolyte. Phenanthrenequinone macrocyclic trimer (PQ-MCT) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (PQ-MCT): conductive agent (Ketjen Black): binder (PTFE) = 60:30:10, and pressed onto the surface of a titanium mesh to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 20,000 cycles at 25°C and a current density of 5C, the capacity retention reached 95%, and the average coulombic efficiency reached 99.8% (see Table 1).

[0052] Example 10

[0053] Triethyl phosphate (TEP) and propylene carbonate (PC) were mixed at a volume ratio of 8:2 as a solvent, followed by the addition of 0.5 mol / L Zn[B(hfip)4]2 to prepare the electrolyte. Pyrene-4,5,9,10-tetraone (PTO) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (PTO): conductive agent (Ketjen Black): binder (PTFE) = 60:30:10, and pressed onto the surface of a titanium mesh to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 10,000 cycles at 3C at room temperature (25°C), the capacity retention reached 93%, and the average coulombic efficiency reached 99.5% (see Table 1).

[0054] Example 11

[0055] Triethyl phosphate (TMP) and propylene carbonate (PC) were mixed at a volume ratio of 1:2 as a solvent, followed by the addition of 0.5 mol / L Zn[B(hfip)4]2 to prepare the electrolyte. Polytriphenylamine (PTPAn) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (PTPAn): conductive agent (Ketjen Black): binder (PTFE) = 60:30:10, and pressed onto the surface of a titanium mesh to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 7000 cycles at 1C current density at room temperature (25°C), the capacity retention reached 90%, and the average coulombic efficiency reached 99.8% (see Table 1).

[0056] Example 12

[0057] Acetonitrile (AN) and N,N-dimethylformamide (DMF) were mixed in a 1:1 volume ratio as a solvent, followed by the addition of 1 mol / L Zn[B(hfip)4]2 to prepare the electrolyte. Polyaniline (PANI) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (PANI): conductive agent (Ketjen Black): binder (PTFE) = 60:30:10, and pressed onto the surface of a titanium mesh to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 15,000 cycles at 25°C and a current density of 5C, the capacity retention reached 89%, and the average coulombic efficiency reached 99.5% (see Table 1).

[0058] Example 13

[0059] Sulfolane sulfolane (TMS) was used as a solvent, followed by the addition of 0.75 mol / L Zn[B(hfip)4]2 to prepare the electrolyte. 4,4'-(10H-phenothiazine-3,7-diyl)bis(N,N-diphenylaniline) (PTZAN) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (PTZAN): conductive agent (Ketjen Black): binder (PTFE) = 60:30:10, and pressed onto the surface of a titanium mesh to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 6000 cycles at 3C at room temperature (25°C), the capacity retention reached 95%, and the average coulombic efficiency reached 99.1% (see Table 1).

[0060] Example 14

[0061] An electrolyte was prepared by adding a 0.75 mol / L Zn[B(hfip)4]2 solution of acetonitrile (AN) and triethyl phosphate (TEP) in a 1:1 volume ratio as the solvent. Poly(2-chloro-3,5,6-trisulfide-1,4-benzoquinone) (PCTB) was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed with the active material (PCTB): conductive agent (Ketjen Black): binder (PTFE) in a ratio of 60:30:10, and pressed onto a titanium mesh surface to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 5000 cycles at 25°C and a current density of 2C, the capacity retention reached 92%, and the average coulombic efficiency reached 99.2%.

[0062] (See Table 1).

[0063] Example 15

[0064] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a weight ratio of 1:1:1. Zn[B(hfip)4]2 and LiPF6 were then added as solutes at concentrations of 0.5 mol / L and 4 mol / L, respectively, to prepare the electrolyte. LiMn2O4 was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (LiMn2O4): conductive agent (super P): binder (polyvinylidene fluoride PVDF) = 80:10:10, and coated onto the surface of carbon-coated aluminum foil to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 1600 cycles at 1C current density at room temperature (25°C), the capacity retention reached 88%, and the average coulombic efficiency reached 99.85% (see Table 1).

[0065] Example 16

[0066] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a weight ratio of 1:1:1. Zn[B(hfip)4]2 and LiPF6 were then added as solutes at concentrations of 0.5 mol / L and 2 mol / L, respectively, to prepare the electrolyte. LiNi... 0.5 Mn 1.5 O4 is used as the positive electrode active material. The preparation of the positive electrode sheet is as follows: according to the active material (LiNi 0.5 Mn 1.5A slurry composed of O4, conductive agent (super P), and binder (polyvinylidene fluoride PVDF) in a ratio of 80:10:10 was coated onto the surface of carbon-coated aluminum foil to form the positive electrode. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 400 cycles at 1C current density at room temperature (25°C), the capacity retention reached 85%, and the average coulombic efficiency reached 99.35% (see Table 1).

[0067] Example 17

[0068] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a weight ratio of 1:1:1. Zn[B(hfip)4]2 and NaPF6 were then added as solutes at concentrations of 0.5 mol / L and 3 mol / L, respectively, to prepare the electrolyte. Na3V2(PO4)3 was used as the positive electrode active material. The positive electrode sheet was prepared as follows: a slurry was mixed according to the ratio of active material (Na3V2(PO4)3): conductive agent (super P): binder (polyvinylidene fluoride PVDF) = 80:10:10, and coated onto the surface of carbon-coated aluminum foil to form the positive electrode sheet. Next, a Zn metal sheet was used as the negative electrode. A 2032 coin cell was assembled using a Glass Fiber membrane as the separator. After 500 cycles at a current density of 0.5C at room temperature (25°C), the capacity retention reached 90%, and the average coulombic efficiency reached 99.85% (see Table 1).

[0069] Example 18

[0070] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a weight ratio of 1:1:1. Zn[B(hfip)4]2 and NaPF6 were then added as solutes at concentrations of 0.5 mol / L and 4 mol / L, respectively, to prepare the electrolyte. NaNi... 0.4 Fe 0.2 Mn 0.4 O2 is used as the positive electrode active material. The preparation of the positive electrode sheet is as follows: according to the active material (NaNi) 0.4 Fe 0.2 Mn 0.4 A slurry composed of O2, conductive agent (super P), and binder (polyvinylidene fluoride PVDF) in a ratio of 80:10:10 was coated onto the surface of carbon-coated aluminum foil to form the positive electrode. Next, a Zn metal sheet was used as the negative electrode. A Glass Fiber membrane was used as the separator to assemble a 2032 coin cell. After 800 cycles at 25°C and a current density of 0.5C, the capacity retention reached 83%, and the average coulombic efficiency reached 99.95% (see Table 1).

[0071] Table 1 Comparison of cycle performance of zinc-ion batteries using different electrode materials and electrolytes

[0072]

Claims

1. A zinc salt for use in zinc-based batteries, characterized in that, The chemical formula is Zn[B(hfip)4]2, and the specific composition is Zn[B(C3OHF6)4]2.

2. The method for preparing zinc salt as described in claim 1, characterized in that, The specific steps are as follows: Step 1: Dissolve zinc borohydride in ethylene glycol dimethyl ether solvent to form a precursor solution; Step 2: Slowly add hexafluoroisopropanol liquid dropwise to the precursor solution, while refluxing and stirring for 18-25 hours to obtain a homogeneous liquid; Step 3: The obtained homogeneous liquid is distilled under reduced pressure to remove the solvent, yielding a white spherical solid product; Step four: Place the white spherical solid product under vacuum to dry, and obtain the final product.

3. The preparation method according to claim 2, characterized in that, The molar ratio of zinc borohydride to hexafluoroisopropanol is 1:(8-9); the time for adding hexafluoroisopropanol is not less than 1 hour; during vacuum drying, the oven temperature is 35-45℃.

4. The application of the zinc salt as described in claim 1 in the preparation of zinc-based battery electrolyte; wherein the zinc-based battery is a zinc-ion battery, a zinc-lithium hybrid ion-based battery, or a zinc-sodium hybrid ion battery; wherein the electrolyte comprises the electrolyte zinc salt Zn[B(hfip)4]2 and a solvent, wherein the solvent is one or more of esters, ethers, sulfones, and nitrile solvents.

5. The application according to claim 4, characterized in that: For zinc-ion batteries, the zinc salt concentration in the electrolyte is 0.01 mol / L to 4 mol / L; For zinc-lithium hybrid ion batteries, the zinc salt concentration in the electrolyte is 0.01 mol / L to 4 mol / L; the lithium salt concentration is 0.01 mol / L to 18 mol / L. For zinc-sodium hybrid ion batteries, the concentration of zinc salt in the electrolyte is 0.01 mol / L to 4 mol / L; and the concentration of sodium salt is 0.01 mol / L to 18 mol / L.

6. The application according to claim 5, characterized in that: The lithium salt is one or more of LiPF6, LiTFSI, LiFSI, LiBOB, LiDFOB, LiTFMS, LiBF4, LiClO4, LiNO3, Li2SO4, Li3PO4, LiI, LiCl, and LiF. The sodium salt is one or more of NaPF6, NaTFSI, NaFSI, NaBOB, NaDFOB, NaTFMS, NaBF4, NaClO4, NaNO3, Na2SO4, Na3PO4, NaI, NaCl, and NaF.

7. The application according to any one of claims 4-6, characterized in that, The ester solvent is one or more of the following: fluoroethylene carbonate, methyl ethyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate, ethyl propionate, methyl butyrate, butyl acetate, methyl propionate, propyl butyrate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, dimethyl methyl phosphate, diethyl ethyl phosphate, dipropyl propyl phosphate, and triphenyl phosphate.

8. The application according to any one of claims 4-6, characterized in that, The ether solvent is one or more of the following: ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dioxolane, 1,4-dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, and dimethoxymethane.

9. The application according to any one of claims 4-6, characterized in that, The sulfone solvent is one or more of dimethyl sulfoxide, sulfolane, methyl ethyl sulfone, dimethyl sulfone, diethyl sulfone, phenylethyl sulfone, and bis(cyanoethyl) sulfone.

10. The application according to any one of claims 4-6, characterized in that, The nitrile solvent is one or more of the following: acetonitrile, hexamethoxyphosphazene, butadionitrile, propionitrile, acrylonitrile, adiponitrile, glutaronitrile, octadionitrile, sebaconitrile, 1,3,6-hexanetricarbonitrile, 1,3,5-pentanetricarbonitrile, p-fluorobenzonitrile, p-methylbenzonitrile, 2-fluoroadiponitrile, 2,2-difluorobutadionitrile, tricyanobenzene, crotonitrile, trans-butenedionitrile, trans-hexenedionitrile, 1,2-di(cyanoethoxy)ethane, 1,2,3-tri(cyanoethoxy)propane, 3-(trimethylsiloxy)propionitrile, and cyclophosphonitrile.

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