CN117728047A - Double-salt-double-solvent electrolyte for high-reversibility water-based zinc ion battery and preparation method thereof - Google Patents

Abstract

The invention discloses a double-salt-double-solvent electrolyte for highly reversible aqueous zinc ion batteries and a preparation method. In the electrolyte, the solvent is a mixed solvent of water and ether, and the electrolyte is zinc acetate plus zinc tetrafluoroborate salt or Zinc trifluoromethanesulfonate salt. The battery based on dual salt-dual solvent electrolyte has a high zinc anode average Coulombic efficiency (CE) of 99.8% at a high zinc anode depth of discharge (DOD _Zn ) of 60%. The design of the dual-salt-dual-solvent electrolyte solves the problems of zinc corrosion and slow zinc deposition kinetics in traditional aqueous single-component zinc salt electrolytes, and can achieve a highly reversible "stripping-deposition" process of zinc metal anodes. The application of dual salt-dual solvent electrolytes can effectively improve the comprehensive electrochemical performance of aqueous zinc-ion batteries based on vanadium-manganese-based oxides or organic cathodes.

Description

A kind of double salt-dual solvent electrolyte for highly reversible aqueous zinc ion battery and its preparation method

Technical field

The invention relates to an aqueous zinc metal battery electrolyte and a preparation method, in particular to a double salt-double solvent electrolyte for highly reversible aqueous zinc ion batteries and a preparation method thereof.

Background technique

Safe, efficient, green and sustainable energy storage systems and technologies are current research hotspots in the energy field, especially large-scale grid energy storage equipment that requires higher security. Among the many current energy storage batteries, lithium-ion batteries occupy a major share of the market due to their high energy density and working voltage. However, the cost of lithium-ion batteries is increasing due to the shortage of lithium sources, and the commonly used organic electrode liquids can easily cause more serious accidents when thermal runaway occurs, causing losses to the environment and personal and property safety. To solve this problem, researchers use safer aqueous electrolytes to replace the current organic electrolytes to develop a new generation of energy storage systems and technologies. Among many aqueous ion battery systems, zinc metal has the advantages of high abundance, low cost, high theoretical capacity (820mAh g ^-1 ), and low redox potential (-0.762vs.SHE), making aqueous zinc ion batteries The field has gradually become a hot spot of concern in the scientific research community and industry.

However, a major challenge limiting the commercialization of aqueous zinc metal batteries or zinc-ion batteries is the low utilization rate of zinc metal anodes and the reversibility of its electrochemical "stripping-deposition" process, which is mainly due to the presence of zinc in the aqueous electrolyte environment. Factors such as negative electrode corrosion and zinc dendrite growth cause zinc-ion batteries to be unable to perform deep charge-discharge cycles and cause short-circuit failure. In recent years, many studies have shown that using electrolyte to regulate the interface between zinc and electrolyte is a very effective strategy to reduce zinc anode corrosion and inhibit zinc dendrites. This is because changing the interface electrolyte environment will affect the reactivity of water and zinc ions. Mass transfer method. Studies have shown that adding non-aqueous solvents to the electrolyte can limit the activity of water molecules to inhibit corrosion. However, the multi-element solvent system formed by mixing this non-aqueous solvent with water will reduce the conductivity of the electrolyte and slow down the charge transfer kinetics. Considering that the anion solvation process of different electrolyte salts will affect the interface electrolyte composition and charge transfer kinetics, the charge transfer in the electrolyte can be promoted by diversifying electrolyte salts in multi-component solvents. This strategy can not only solve the zinc anode corrosion problem caused by traditional aqueous electrolytes, but also solve the problem of slow charge transfer kinetics in multi-element solvents.

Contents of the invention

Purpose of the invention: The present invention aims to provide a double salt-double solvent electrolyte for aqueous zinc ion batteries that is used to improve the reversibility of the electrochemical "stripping-deposition" process of zinc anodes; another purpose of the present invention is to provide a The preparation method of double salt-dual solvent electrolyte is described.

Technical solution: the double-salt-dual-solvent electrolyte for the highly reversible aqueous zinc ion battery of the present invention, the solvent is a mixed solvent of water and ether, and the electrolyte is zinc acetate plus zinc tetrafluoroborate salt or trifluoromethanesulfonic acid Zinc salt.

Preferably, the molar concentration of zinc tetrafluoroborate or zinc trifluoromethanesulfonate is 0.5-2 mol/kg, the molar concentration range of zinc acetate is 0.1-0.5 mol/kg, and the molar ratio of water to ether is 1-120. :1.

Preferably, the ether solvent is ethylene glycol dimethyl ether, diglyme, triglyme or tetraglyme.

The invention relates to a preparation and design method of a double salt-double solvent electrolyte that can realize a highly reversible zinc negative electrode, and includes the following steps:

(1) Dissolve zinc tetrafluoroborate or zinc trifluoromethanesulfonate into a mixed solvent of water and ether to form a single salt-double solvent electrolyte;

(2) Dissolve the zinc acetate salt into the single salt-dual solvent electrolyte to form a double salt-dual solvent electrolyte.

Preferably, the zinc tetrafluoroborate salt in step (1) is zinc tetrafluoroborate hydrate, with a purity of ≥99%; the zinc trifluoromethanesulfonate salt is anhydrous zinc trifluoromethanesulfonate, with a purity of ≥98%; the water is deionized water; the purity of the ether solvent is ≥99%.

Preferably, the optimal ratio of the solvent and the optimal concentration configuration of the electrolyte are obtained through tests of zinc metal corrosion resistance and zinc negative electrode reversibility. The zinc metal corrosion resistance is an electrolyte immersion zinc metal test; the zinc negative electrode is reversible. The performance test is a zinc-copper battery cycle test under high discharge depth. Zinc and copper are high-purity metal foils with a purity of ≥99.99%.

Preferably, the zinc acetate salt is anhydrous zinc acetate or zinc acetate hydrate, with a purity of ≥99%; the molar concentration of zinc acetate is less than the molar concentration of zinc tetrafluoroborate or zinc triflate.

The dual salt-dual solvent electrolyte prepared as described above can not only improve the reversibility of the zinc negative electrode but also be suitable for the positive electrode of various types of aqueous zinc ion batteries.

Beneficial effects: Compared with existing electrolyte types, the present invention has the following significant advantages: (1) The double salt-double solvent electrolyte suppresses the corrosiveness of the zinc salt electrolyte of a single water solvent at low concentrations, and at the same time The problem of slow zinc deposition kinetics of a single zinc salt is solved; (2) the double salt-dual solvent electrolyte maintains an average zinc anode Coulombic efficiency of up to 99.8% at a high zinc anode discharge depth (DOD _Zn ) of 60% ( CE); (3) The prepared double salt-dual solvent electrolyte can be used in various organic polymers and inorganic vanadium-based and manganese-based oxide cathode materials for aqueous zinc-ion batteries.

Description of the drawings

Figure 1 is a physical picture of zinc metal after immersion in a single salt-single solvent electrolyte obtained in Example 1 as a comparison;

Figure 2 is a physical picture of a zinc metal foil soaked in the single salt-double solvent electrolyte obtained in Example 1;

Figure 3 is a physical picture of a zinc metal foil soaked in the double salt-double solvent electrolyte obtained in Example 1;

Figure 4 shows the cycle performance of the zinc-copper battery with a single salt-single solvent electrolyte obtained in Example 1 as a comparison at 20% discharge depth;

Figure 5 shows the cycle performance of the zinc-copper battery with single salt-dual solvent electrolyte obtained in Example 1 at 20% discharge depth;

Figure 6 shows the cycle performance of the zinc-copper battery with double salt-dual solvent electrolyte obtained in Example 1 at 20% discharge depth;

Figure 7 shows the cycle performance of the zinc-copper battery with the single salt-double solvent electrolyte obtained in Example 1 at 60% discharge depth;

Figure 8 shows the cycle performance of the zinc-copper battery with double salt-dual solvent electrolyte obtained in Example 1 at 60% discharge depth;

Figure 9 shows the performance of Zn-PANI batteries with different electrolytes in Example 1;

Figure 10 shows the performance of Zn-VO ₂ batteries with different electrolytes in Example 1;

Figure 11 shows the performance of Zn-MnO ₂ batteries with different electrolytes in Example 1.

Detailed ways

The technical solution of the present invention will be further described below with reference to the accompanying drawings.

Example 1

(1) Using water/tetraethylene glycol dimethyl ether mixture as the solvent, prepare a zinc tetrafluoroborate electrolyte with a molar concentration of 1 mol/kg, in which the molar ratio of water to tetraethylene glycol dimethyl ether is 40:1 A single salt-dual solvent electrolyte was obtained. At the same time, for experimental control, pure water was used as the solvent, and a zinc tetrafluoroborate electrolyte with a molar concentration of 1 mol/kg was prepared to obtain a single salt-single solvent electrolyte.

(2) Add zinc acetate with a molar concentration of 0.2 mol/kg into the single salt-dual solvent electrolyte in step (1) and dissolve to obtain a double salt-dual solvent electrolyte.

(3) Use the single salt-double solvent electrolyte obtained in step (1), the control single salt-single solvent electrolyte, and the double salt-double solvent electrolyte obtained in step (2) for anti-corrosion of zinc metal To test the reversibility and reversibility of the zinc anode, zinc and copper metal foils with a thickness of 30 μm were used to test the cycle performance of the zinc-copper battery with the above electrolyte at 20% and 60% of the negative electrode discharge depth.

(4) The physical picture of zinc metal soaked in the single salt-single solvent electrolyte for 48 hours as a control is shown in Figure 1; the physical picture of zinc metal soaked in the single salt-double solvent electrolyte for 48 hours is shown in Figure 2 ; The physical picture of zinc metal soaked in double salt-dual solvent electrolyte for 48 hours is shown in Figure 3.

(5) Under the test of 20% zinc negative electrode discharge depth, the cycle performance of the zinc-copper battery with single salt-single solvent electrolyte as a control is shown in Figure 4. The average CE of 7 cycles is about 95.174%; single salt -The cycle performance of the zinc-copper battery with dual-solvent electrolyte is shown in Figure 5. The average CE of 250 cycles is about 99.596%; the cycle performance of the zinc-copper battery with dual-salt-dual-solvent electrolyte is shown in Figure 6. The average CE of 250 cycles is about 99.838%; under the test of 60% zinc negative electrode discharge depth, the cycle performance of the zinc-copper battery with single salt-double solvent electrolyte is shown in Figure 7. The average CE of 20 cycles is about 99.09 %; The cycle performance of the zinc-copper battery with double salt-dual solvent electrolyte is shown in Figure 8. The average CE of 150 cycles is about 99.80%.

Example 2

(1) Using water/tetraethylene glycol dimethyl ether mixture as the solvent, prepare a zinc tetrafluoroborate electrolyte with a molar concentration of 1 mol/kg, in which the molar ratio of water to tetraethylene glycol dimethyl ether is 80:1 A single salt-dual solvent electrolyte was obtained. At the same time, for experimental control, pure water was used as the solvent, and a zinc tetrafluoroborate electrolyte with a molar concentration of 1 mol/kg was prepared to obtain a single salt-single solvent electrolyte.

(2) Add zinc acetate with a molar concentration of 0.3 mol/kg into the single salt-dual solvent electrolyte in step (1) and dissolve to obtain a double salt-dual solvent electrolyte.

(3) Use the single salt-double solvent electrolyte obtained in step (1), the control single salt-single solvent electrolyte, and the double salt-double solvent electrolyte obtained in step (2) for anti-corrosion of zinc metal To test the reversibility and reversibility of the zinc anode, zinc and copper metal foils with a thickness of 30 μm were used to test the cycle performance of the zinc-copper battery with the above electrolyte at 20% and 60% of the negative electrode discharge depth.

(4) The physical picture of zinc metal soaked in the single salt-single solvent electrolyte for 48 hours as a control is similar to Figure 1; the physical picture of zinc metal soaked in the single salt-double solvent electrolyte for 48 hours is similar to Figure 2; The physical picture of zinc metal soaked in salt-dual solvent electrolyte for 48 hours is similar to Figure 3.

(5) Under the test of 20% zinc negative electrode discharge depth, the cycle performance of the zinc-copper battery with single salt-single solvent electrolyte as a control is shown in Figure 4. The average CE of 7 cycles is about 95.174%; single salt -The cycle performance of the zinc-copper battery with dual-solvent electrolyte is similar to Figure 5, with an average CE of about 99.597% for 250 cycles; the cycle performance of the zinc-copper battery with dual-salt-dual-solvent electrolyte is similar to Figure 6, with 250 cycles The average CE of the cycle is about 99.812%; under the test of 60% zinc negative electrode discharge depth, the cycle performance of the zinc-copper battery with single salt-dual solvent electrolyte is similar to Figure 7, the average CE of 18 cycles is about 98.737%; double The cycle performance of the zinc-copper battery with salt-dual solvent electrolyte is similar to Figure 8, with an average CE of approximately 99.788% for 100 cycles.

Example 3

(1) Using water/tetraethylene glycol dimethyl ether mixture as the solvent, configure a zinc tetrafluoroborate electrolyte with a molar concentration of 1.5 mol/kg, in which the molar ratio of water to tetraethylene glycol dimethyl ether is 40: 1. Obtain a single salt-dual solvent electrolyte. At the same time, for experimental control, pure water was used as the solvent and a zinc tetrafluoroborate electrolyte with a molar concentration of 1.5 mol/kg was prepared to obtain a single salt-single solvent electrolyte.

(2) Add zinc acetate with a molar concentration of 0.2 mol/kg into the single salt-dual solvent electrolyte in step (1) and dissolve to obtain a double salt-dual solvent electrolyte.

(3) Use the single salt-double solvent electrolyte obtained in step (1), the control single salt-single solvent electrolyte, and the double salt-double solvent electrolyte obtained in step (2) for anti-corrosion of zinc metal To test the reversibility and reversibility of the zinc anode, zinc and copper metal foils with a thickness of 30 μm were used to test the cycle performance of the zinc-copper battery with the above electrolyte at 20% and 60% of the negative electrode discharge depth.

(4) The photo of zinc metal soaked in the single salt-single solvent electrolyte for 48 hours as a control is similar to Figure 1; the photo of zinc metal soaked in the single salt-double solvent electrolyte for 48 hours is similar to Figure 2; double salt- The photo of zinc metal soaked in dual-solvent electrolyte for 48 hours is similar to Figure 3.

(5) Under the test of 20% zinc negative electrode discharge depth, the cycle performance of the zinc-copper battery with a single salt-single solvent electrolyte as a control is similar to Figure 4. The average CE of 4 cycles is about 94.764%; single salt- The cycle performance of the zinc-copper battery with dual-solvent electrolyte is similar to Figure 5, with an average CE of about 99.582% for 200 cycles; the cycle performance of the zinc-copper battery with dual-salt-dual-solvent electrolyte is similar to Figure 6, with 200 cycles The cycle average CE is about 99.796%; under the test of 60% zinc anode discharge depth, the cycle performance of the zinc-copper battery with single salt-double solvent electrolyte is similar to Figure 7, the average CE of 25 cycles is about 98.74%; double The cycle performance of the zinc-copper battery with salt-dual solvent electrolyte is similar to Figure 8, with an average CE of approximately 99.793% for 100 cycles.

Battery application examples

Assemble an aqueous zinc-ion battery, use the electrolyte prepared in Example 1 as the electrolyte; use three materials as positive electrode materials: polyaniline (PANI), vanadium dioxide (VO ₂ ) and manganese dioxide (MnO ₂ ). When preparing the positive electrode, mix the active material, conductive agent Ketjen Black and binder polytetrafluoroethylene (PTFE) in a mass ratio of 7:2:1, add N-methylpyrrolidone (NMP) and grind A uniform slurry is obtained, and then the slurry is scraped onto a stainless steel mesh and dried in a drying oven at 60°C to obtain a positive electrode loading mass of approximately 7 to 10 mg cm ^-2 . Zinc foil with a thickness of 10 μm and a density of 13 mg cm ^-2 was used as the negative electrode, and glass fiber was used as the separator. CR2032 button batteries of Zn-PANI, Zn-VO ₂ and Zn-MnO ₂ with different electrolytes were assembled and charged and discharged at a constant current. test.

The performance of the Zn-PANI battery using double salt-dual solvent as electrolyte for 400 cycles at a current density of 0.5A g ^-1 is shown in Figure 9. The triangular pattern represents the battery performance of a single salt-single solvent electrolyte, the circular pattern represents the battery performance of a single salt-dual solvent electrolyte, and the solid square pattern represents the battery performance of a dual salt-dual solvent electrolyte. In addition, the performance of the Zn-VO ₂ battery using double salt-double solvent as electrolyte for 100 cycles at a current density of 0.5A g ^-1 is shown in Figure 10. Zn-VO 2 battery using double salt-double solvent as electrolyte The performance of -MnO ₂ battery for 60 cycles at a current density of 0.1A g ^-1 is shown in Figure 11. From the comparison of cycle performance results, it can be concluded that the battery using double salt-dual solvent as the electrolyte has higher capacity and better stability, which benefits from the stability of the double salt-dual solvent electrolyte to the zinc anode and the zinc Efficiently improve the "stripping-deposition" kinetics of the negative electrode.

Claims (10)

1. A double salt-dual solvent electrolyte for highly reversible aqueous zinc ion batteries, characterized in that in the electrolyte, the solvent is a mixed solvent of water and ether, and the electrolyte is zinc acetate plus zinc tetrafluoroborate salt or trifluoroborate. Zinc salt of fluoromethanesulfonate. 2. The double salt-dual solvent electrolyte for highly reversible aqueous zinc ion batteries according to claim 1, wherein the molar concentration of zinc tetrafluoroborate or zinc trifluoromethanesulfonate is 0.5 to 2 mol/ kg. 3. The double-salt-dual-solvent electrolyte for highly reversible aqueous zinc ion batteries according to claim 1, characterized in that the zinc acetate molar concentration range is 0.1 to 0.5 mol/kg. 4. The double-salt-dual-solvent electrolyte for highly reversible aqueous zinc-ion batteries according to claim 1, wherein the molar ratio of water to ether is 1 to 120:1. 5. The double salt-dual solvent electrolyte for highly reversible aqueous zinc ion batteries according to claim 1, wherein the ether solvent is ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or triethylene glycol. Dimethyl ether or tetraethylene glycol dimethyl ether. 6. The double-salt-dual-solvent electrolyte for highly reversible aqueous zinc ion batteries according to claim 1, characterized in that the zinc tetrafluoroborate salt is zinc tetrafluoroborate hydrate with a purity of ≥99%; the trifluoride The zinc methylsulfonate salt is anhydrous zinc triflate, with a purity of ≥98%; the zinc acetate is anhydrous zinc acetate or zinc acetate hydrate, with a purity of ≥99%. 7. The double-salt-dual-solvent electrolyte for highly reversible aqueous zinc-ion batteries according to claim 1, characterized in that the water is deionized water and the purity of the ether solvent is ≥99%. 8. A method for preparing a double salt-dual solvent electrolyte for a highly reversible aqueous zinc ion battery according to any one of claims 1 to 7, characterized in that it includes the following steps: (1) Dissolve zinc tetrafluoroborate or zinc trifluoromethanesulfonate into a mixed solvent of water and ether to form a single salt-double solvent electrolyte; (2) Dissolve zinc acetate into a single salt-dual solvent electrolyte to form a double salt-dual solvent electrolyte. 9. An aqueous zinc ion battery, characterized by comprising the double salt-dual solvent electrolyte according to any one of claims 1 to 7. 10. The aqueous zinc ion battery according to claim 9, wherein the positive electrode material is polyaniline, vanadium dioxide or manganese dioxide.