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CN-122000458-A - Chlorine-free simple magnesium salt electrolyte for magnesium-sulfur battery and preparation method and application thereof

CN122000458ACN 122000458 ACN122000458 ACN 122000458ACN-122000458-A

Abstract

The invention belongs to the technical field of electrochemical energy storage batteries, and particularly relates to a chlorine-free simple magnesium salt electrolyte for a magnesium-sulfur battery, and a preparation method and application thereof. The electrolyte comprises magnesium salt, ionic liquid, organic ether solvent, amine solvent and organic phosphine additive. According to the invention, the solvation structure is regulated and controlled through the multicomponent synergistic effect, so that the compatibility of the electrolyte with a sulfur anode and a magnesium cathode is improved, and the electrochemical performance of the magnesium-sulfur battery is improved. Specifically, the amine solvent is used as a strong polar solvent to improve the solubility of magnesium polysulfide, so that the diffusion and redox transformation kinetics of the magnesium polysulfide are promoted, the organic phosphine compound is used as an additive to effectively improve the specific discharge capacity and voltage platform of the magnesium-sulfur battery, meanwhile, the ionic liquid is added to improve the stability of a magnesium cathode/electrolyte interface, the transmission capacity of Mg 2+ is enhanced, and the overpotential of magnesium deposition/dissolution is reduced. In addition, the electrolyte does not contain chloride ions, so that the corrosion problem caused by the chloride ions is avoided.

Inventors

  • TAN SHUANGSHUANG
  • ZENG HONG
  • Li Hongai
  • LI LINGJIE
  • DIAO JIANG
  • PAN FUSHENG

Assignees

  • 重庆大学
  • 重庆新型储能材料与装备研究院

Dates

Publication Date
20260508
Application Date
20251225

Claims (10)

  1. 1. The chlorine-free simple magnesium salt electrolyte for the magnesium-sulfur battery is characterized by comprising magnesium salt, ionic liquid, organic ether solvent, amine solvent and organic phosphine compound.
  2. 2. The chlorine-free simple magnesium salt electrolyte for magnesium-sulfur battery according to claim 1, wherein, The magnesium salt is selected from magnesium bis (trifluoromethylsulfonyl) imide and/or magnesium trifluoromethylsulfonate, and/or The ionic liquid is selected from one or more of pyrrolidine ionic liquid, piperidine ionic liquid or quaternary ammonium salt ionic liquid, and/or The organic ether solvent is selected from one or more of ethylene glycol dimethyl ether, tetrahydrofuran, ethylene glycol formal, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether or 1, 3-dioxolane, and/or The amine solvent is selected from one or more of 2-ethoxyethylamine, 2-methoxyethylamine, 2-dimethoxyethylamine or 2, 2-diethoxyethylamine; The organic phosphine compound is selected from one or more of triphenylphosphine oxide, triphenyl phosphate or (aminoethyl) diphenyl phosphine oxide.
  3. 3. The chlorine-free simple magnesium salt electrolyte for magnesium sulphur batteries according to claim 2 wherein the ionic liquid is selected from one or more of 1-ethyl-1-methylpyrrolidine triflate, 1-butyl-1-methylpyrrolidine triflate, 1-ethyl-1-methylpyrrolidine bistrifluoromethylsulfonylimine salt, 1-butyl-1-methylpyrrolidine bistrifluoromethylsulfonylimine salt, 1-ethyl-1-methylpiperidine triflate or N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bistrifluoromethylsulfonylimine salt.
  4. 4. The chlorine-free simple magnesium salt electrolyte for magnesium-sulfur battery according to claim 2, wherein, The ionic liquid is 1-butyl-1-methyl pyrrole trifluoro methanesulfonate, The organic ether solvent is ethylene glycol dimethyl ether, The amine solvent is 2-ethoxyethylamine, The organic phosphine compound is triphenylphosphine oxide.
  5. 5. The chlorine-free simple magnesium salt electrolyte for a magnesium-sulfur battery according to any one of claim 1 to 4, wherein, The molar concentration of the magnesium salt is 0.1mol/L to 1mol/L, and/or The concentration of the ionic liquid is 0.1mol/L to 1mol/L, and/or The volume of the organic ether solvent is 0<v percent (not more than 90 percent) of the total volume of the organic ether solvent and the amine solvent, and/or The molar concentration of the organic phosphine compound is 0.01mol/L to 0.2mol/L.
  6. 6. The chlorine-free simple magnesium salt electrolyte for magnesium-sulfur battery according to claim 5, wherein, The concentration of the ionic liquid is 0.5mol/L, and/or The volume of the organic ether solvent is 71% of the total volume of the organic ether solvent and the amine solvent, and/or The molar concentration of the organic phosphine compound was 0.05mol/L.
  7. 7. The method for preparing the chlorine-free simple magnesium salt electrolyte for the magnesium-sulfur battery according to any one of claims 1 to 6, which is characterized by comprising the step of mixing magnesium salt, ionic liquid, organic ether solvent, amine solvent and organic phosphine compound to obtain the chlorine-free simple magnesium salt electrolyte for the magnesium-sulfur battery.
  8. 8. The preparation method according to claim 7, characterized in that the preparation method comprises: (1) Dissolving magnesium salt into an organic ether solvent to obtain a magnesium salt solution; (2) And adding an amine solvent, an organic phosphine compound and an ionic liquid into the magnesium salt solution, and mixing to obtain the chlorine-free simple magnesium salt electrolyte for the magnesium-sulfur battery.
  9. 9. Magnesium-sulfur battery characterized by comprising the chlorine-free simple magnesium salt electrolyte for magnesium-sulfur battery according to any one of claims 1 to 6.
  10. 10. The magnesium sulfur battery of claim 9, wherein the magnesium sulfur battery further comprises a positive electrode, a negative electrode, and a battery separator, wherein, The preparation material of the positive electrode is selected from one or more of sulfur-carbon composite material, sulfur metal compound composite material or sulfur polymer composite material, and/or The preparation material of the negative electrode is selected from one or more of metal magnesium, magnesium alloy or magnesium-based composite material, and/or The battery separator is selected from glass fiber film separators.

Description

Chlorine-free simple magnesium salt electrolyte for magnesium-sulfur battery and preparation method and application thereof Technical Field The invention belongs to the technical field of electrochemical energy storage batteries, and particularly relates to a chlorine-free simple magnesium salt electrolyte for a magnesium-sulfur battery, and a preparation method and application thereof. Background With the continuous upgrading of global energy demands and the increasing prominence of environmental problems, the development of a novel battery energy storage system with high efficiency, low cost and environmental friendliness has become a research hotspot in the energy field. Magnesium-sulfur (Mg-S) batteries are considered to be one of the electrochemical energy storage technologies with great potential for the next generation because of the remarkable advantages of extremely high theoretical energy density (3221 wh·l -1 and 1684wh·kg -1), low raw material cost, high safety of metallic magnesium negative electrodes, and the like, and have been widely paid attention to in academia and industry in recent years. However, the practical application of magnesium-sulfur batteries still faces a number of key technical bottlenecks. Early developed grignard reagent electrolyte has stronger nucleophilicity, can chemically react with sulfur positive electrode, and causes rapid decay of battery capacity and self-discharge. Meanwhile, polysulfide formed in the discharging process of the magnesium-sulfur battery has limited solubility in the traditional ether electrolyte, mainly undergoes solid phase conversion reaction, and has slow reduction kinetics and low specific capacity. Second, soluble polysulfide intermediates migrate to the magnesium anode during discharge (i.e., a "shuttling effect") and exacerbate anode corrosion and passivation. Aiming at the problems, the prior art mainly adopts two electrolyte systems, namely a chlorine-containing non-nucleophilic electrolyte (such as Mg (HMDS) 2/MgCl2/AlCl3, MACC and the like), wherein although better magnesium deposition/dissolution reversibility can be realized, the existence of chloride ions is easy to corrode a current collector (such as aluminum foil), the specific discharge capacity of a sulfur positive electrode is not high, and the other electrolyte system is a boron-based magnesium salt ether electrolyte which is not corrosive, but is difficult to promote the reduction and conversion kinetics of magnesium polysulfide and has quite high price. In contrast, simple magnesium salt electrolytes, such as non-nucleophilic Mg (TFSI) 2/ether solvent systems, are inexpensive, but generally passivate the metal magnesium foil without introducing chloride ions, preventing uniform deposition and dissolution of Mg 2+, resulting in an inability of the magnesium sulfur cell to function properly. Therefore, the development of a novel electrolyte system which has high compatibility with chlorine-free and sulfur, high Mg 2+ transmission dynamics and good negative electrode interface stability has important significance for promoting the practical process of the magnesium-sulfur battery. Disclosure of Invention Based on the above, the invention aims to provide a chlorine-free simple magnesium salt electrolyte for a magnesium-sulfur battery, and a preparation method and application thereof. In order to achieve the above purpose, the present invention may adopt the following technical scheme: the invention provides a chlorine-free simple magnesium salt electrolyte for a magnesium-sulfur battery, which comprises magnesium salt, ionic liquid, organic ether solvent, amine solvent and organic phosphine compound. Preferably, in the chlorine-free simple magnesium salt electrolyte for the magnesium-sulfur battery, the magnesium salt is selected from magnesium bis (trifluoromethylsulfonyl) imide and/or magnesium trifluoromethylsulfonate, and/or the ionic liquid is selected from one or more combinations of pyrrolidine ionic liquid, piperidine ionic liquid or quaternary ammonium salt ionic liquid, and/or the organic ether solvent is selected from one or more combinations of ethylene glycol dimethyl ether, tetrahydrofuran, ethylene glycol formal, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether or1, 3-dioxolane, and/or the amine solvent is selected from one or more combinations of 2-ethoxyethylamine, 2-methoxyethylamine, 2-dimethoxyethylamine or 2, 2-diethoxyethylamine, and the organic phosphine compound is selected from one or more combinations of triphenylphosphine oxide, triphenyl phosphate or (aminoethyl) diphenyl phosphine oxide. More preferably, in the chlorine-free simple magnesium salt electrolyte for the magnesium-sulfur battery, the ionic liquid is selected from one or more of 1-ethyl-1-methylpyrrolidine triflate, 1-butyl-1-methylpyrrolidine triflate, 1-ethyl-1-methylpyrrolidine bis (trifluoromethylsulfonyl) imide salt, 1-ethyl-1-methylpiperidine triflate or N, N-die