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CN-122000496-A - Mixed water-based electrolyte containing long-chain fatty acid zinc salt and application thereof

CN122000496ACN 122000496 ACN122000496 ACN 122000496ACN-122000496-A

Abstract

The invention is suitable for the technical field of electrochemical energy storage, and provides a mixed water-based electrolyte containing long-chain fatty acid zinc salt and application thereof, wherein the mixed water-based electrolyte comprises a solvent and zinc salt, the solvent is a mixture of deionized water and a nonaqueous organic solvent, the zinc salt comprises long-chain fatty acid zinc salt and other zinc salts, the concentration of the long-chain fatty acid zinc salt is 0.5-2mol/L, the concentration of the other zinc salt is 0-5mol/L, the structural formula of the long-chain fatty acid zinc salt is shown as follows, zn (R-COO) 2 , wherein R represents a hydrophobic long-carbon chain organic group, and the total number of carbon atoms is 6-C-30. The invention introduces long-chain fatty acid zinc, which is used as zinc salt to supplement Zn 2+ concentration, and also is used as interface modifier due to its unique molecular structure (long hydrophobic carbon chain and hydrophilic carboxyl).

Inventors

  • LU JUN
  • Lv Yanqun
  • HUANG CHENYUE
  • ZHAO MING

Assignees

  • 浙江大学

Dates

Publication Date
20260508
Application Date
20260409

Claims (10)

  1. 1. The mixed water-based electrolyte containing the zinc salt of the long-chain fatty acid is characterized by comprising a solvent and zinc salt, wherein the solvent is a mixture of deionized water and a nonaqueous organic solvent, the zinc salt comprises zinc salt of the long-chain fatty acid and other zinc salts, the concentration of the zinc salt of the long-chain fatty acid is 0.5-2 mol/L, the concentration of the other zinc salts is 0-5mol/L, and the structural formula of the zinc salt of the long-chain fatty acid is shown as follows: Zn(R-COO) 2 ; Wherein R represents a hydrophobic long carbon chain organic group, and the total number of carbon atoms is more than or equal to 6 and less than or equal to 30.
  2. 2. The mixed aqueous electrolyte containing zinc long-chain fatty acid salt according to claim 1, wherein the zinc long-chain fatty acid salt is zinc straight-chain long-chain fatty acid, and the structural formula is as follows: Zn[CH 3 -(CH 2 ) n -COO] 2 ; Wherein n is an integer and represents the number of repeated units of methylene, and the value range is more than or equal to 4 and less than or equal to 28; if the chain contains double bonds, the hydrocarbon ratio in the structural formula is correspondingly adjusted to be C n H 2n-1 .
  3. 3. The mixed aqueous electrolyte containing zinc long-chain fatty acid according to claim 1, wherein the zinc long-chain fatty acid salt is a zinc branched-chain long-chain fatty acid, and has the following structural formula: Zn[C(R 1 )(R 2 )(R 3 ) -COO] 2 ; Wherein R 1 、R 2 、R 3 is hydrogen or different alkyl groups, and the sum of the carbon atoms of R 1 、R 2 、R 3 is more than or equal to 4.
  4. 4. The mixed aqueous electrolyte containing zinc long-chain fatty acid according to claim 1, wherein the zinc long-chain fatty acid salt is a functionalized zinc long-chain fatty acid, and has the following structural formula: Zn[R 4 -X-COO] 2 ; Wherein R 4 represents a long-chain alkylene or alkenylene skeleton, X represents a polar functional group other than carboxyl, and at least one of hydroxyl, epoxy, amino, double bond and ketocarbonyl is selected.
  5. 5. The mixed aqueous electrolyte containing a zinc salt of a long-chain fatty acid according to claim 1, wherein the zinc salt of a long-chain fatty acid is at least one compound selected from the group consisting of zinc octoate, zinc decanoate, zinc laurate, zinc myristate, zinc palmitate, zinc stearate, zinc arachidate, zinc behenate, zinc lignocerate, zinc oleate, zinc linoleate, zinc linolenate, zinc erucate, zinc 2-ethylhexanoate, zinc isostearate, zinc neodecanoate, zinc 12-hydroxystearate, zinc ricinoleate, zinc undecenoate, and isomers thereof.
  6. 6. The mixed aqueous electrolyte containing zinc salt of long-chain fatty acid according to claim 1, wherein the other zinc salt is at least one selected from the group consisting of zinc sulfate, zinc chloride, zinc bromide, zinc iodide, zinc triflate, zinc acetate, zinc nitrate, zinc perchlorate, zinc tetrafluoroborate, and zinc bistrifluoromethylsulfonyl imide.
  7. 7. The mixed aqueous electrolyte containing zinc salt of long-chain fatty acid according to claim 1, wherein the nonaqueous organic solvent is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol dimethyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetradiethylene glycol dimethyl ether, diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, methylethyl carbonate, methyl acetate, methyl propionate, ethyl acetate, ethyl propionate, propyl acetate, propyl propionate, ethylene carbonate, propylene carbonate, butylene carbonate, γ -butyrolactone, butylene carbonate, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, dimethyl methylphosphonate, acetonitrile, sulfolane, methyl ethyl sulfone, dimethylformamide, dimethylacetamide, dimethyldimethoxysilane, methyltriethoxysilane, tetraethylorthosilicate, dimethyldiethoxysilane, methyltrimethoxysilane; the volume of the nonaqueous organic solvent accounts for 0-95 vol% of the total volume of the electrolyte.
  8. 8. Use of a mixed aqueous electrolyte comprising zinc salts of long-chain fatty acids according to any one of claims 1 to 7 for the preparation of an electrochemical energy storage device.
  9. 9. The use of claim 8, wherein the electrochemical energy storage device is one of an aqueous zinc ion battery, an aqueous zinc metal battery, a zinc-air battery, a zinc-flow battery, a hybrid zinc ion supercapacitor.
  10. 10. The use of claim 8, wherein the electrochemical energy storage device further comprises a positive electrode, a negative electrode, and a separator.

Description

Mixed water-based electrolyte containing long-chain fatty acid zinc salt and application thereof Technical Field The invention belongs to the technical field of electrochemical energy storage, and particularly relates to a mixed water-based electrolyte containing zinc salts of long-chain fatty acids and application thereof. Background With the aggravation of energy crisis, development of efficient, safe and low-cost electrochemical energy storage technology is urgent. The water-based battery adopting water as a solvent has the advantages of intrinsic safety, high ionic conductivity, environmental friendliness in manufacturing, low cost and the like, is a hot spot in the next-generation large-scale energy storage technology, and particularly is a water-based zinc ion battery, a water-based zinc-based flow battery and the like, because the metal zinc has high theoretical specific capacity (820 mAh/g) and low oxidation-reduction potential (-0.76V vs. SHE), and has great commercialization prospect. However, conventional aqueous electrolytes (e.g., zinc sulfate, zinc triflate aqueous solutions) present serious challenges in that the thermodynamic stability window of water molecules is narrow, and the solvated shell of zinc ions contains a large amount of water ([ Zn (H 2O)6]2+) ] which is very prone to hydrogen evolution reaction at the interface of the negative electrode, resulting in increased internal pressure of the battery, increased pH value and accumulation of insulating byproducts, and meanwhile, there is a serious "tip effect" in the zinc deposition process, and due to uneven electric field distribution, zinc ions tend to deposit at the protrusions to form dendrites and finally pierce the membrane to cause short circuit, and in addition, the conventional inorganic zinc salts or short-chain organic zinc salts are extremely strong in polarity, cannot effectively construct a hydrophobic interface layer, and are difficult to fundamentally block contact of water molecules with the negative electrode. The prior art has mostly addressed the above problems by adding trace amounts of organic additives, but the additives are not only consumed, but they do not provide capacity contribution and effective conductance of zinc ions. Disclosure of Invention The embodiment of the invention aims to provide a mixed water-based electrolyte containing zinc salts of long-chain fatty acids, and aims to solve the problems in the prior art. The embodiment of the invention is realized in such a way that the mixed water-based electrolyte containing the zinc salt of the long-chain fatty acid comprises a solvent and the zinc salt, wherein the solvent is a mixture of deionized water and a nonaqueous organic solvent, the zinc salt comprises the zinc salt of the long-chain fatty acid and other zinc salts, the concentration of the zinc salt of the long-chain fatty acid is 0.5-2mol/L, the concentration of the other zinc salt is 0-5mol/L, and the structural formula of the zinc salt of the long-chain fatty acid is shown as follows: Zn(R-COO)2; Wherein R represents a hydrophobic long carbon chain organic group, and the total number of carbon atoms is more than or equal to 6 and less than or equal to 30. Another object of the embodiment of the invention is to provide an application of the mixed water-based electrolyte containing zinc salt of long-chain fatty acid in preparing an electrochemical energy storage device. According to the embodiment of the invention, long-chain fatty acid zinc is introduced into a water-based electrolyte, the long-chain fatty acid zinc salt belongs to typical amphiphilic molecules, anions (R-COO -) of the long-chain fatty acid zinc salt are tightly arranged on the surface of a zinc-philic metal negative electrode by using polar carboxyl head parts as anchoring sites through chemical bonding (coordination bonds) or electrostatic adsorption, and hydrophobic long-chain tail parts of the long-chain fatty acid zinc salt are extended to the electrolyte side vertically or obliquely and form a compact ordered hydrophobic barrier through self-assembly, so that a large number of free water molecules and solvated water molecules in the bulk phase are effectively 'displaced' out of an electric double layer inner layer, thereby cutting off the active water supply of hydrogen evolution reaction, and doubly inhibiting water decomposition and electrode corrosion from thermodynamic and kinetic aspects; van der Waals forces between long chain molecules form a flexible lattice structure that allows desolvated Zn 2+ to pass smoothly, but effectively blocks larger sized solvent molecular clusters, anionic clusters, or macromolecular byproducts from contacting the electrode surface; more importantly, the ordered molecular array homogenizes the local electric field distribution on the surface of the electrode, eliminates the electric field concentration effect caused by the roughness of the surface of the electrode, induces zinc ions