CN-122000445-A - Preparation method and application of low-temperature-resistant and high-voltage-resistant ether electrolyte

CN122000445ACN 122000445 ACN122000445 ACN 122000445ACN-122000445-A

Abstract

A preparation method and application of low temperature resistant and high voltage resistant ether electrolyte belong to the technical field of lithium metal battery electrolyte. The invention aims to solve the problems of poor adaptability and poor weather resistance of the traditional commercial ester-based electrolyte to a lithium metal battery. A low temperature resistant and high voltage resistant ether electrolyte comprises lithium difluorosulfimide, lithium difluorooxalato borate, ethylene glycol diethyl ether and 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether. A low temperature resistant and high voltage resistant ether electrolyte is applied to a lithium metal battery. The invention solves the problems of poor suitability and poor weather resistance of the traditional commercial ester-based electrolyte to the lithium metal battery, obviously improves the circulation rate stability of the ether-based electrolyte in high-pressure and wide-temperature environments, and is suitable for the fields of electric automobiles, high-power energy storage equipment and the like with strict requirements on quick charge performance.

Inventors

CHEN MINGHUA
Jiang tengfei
LI YU
ZHANG JIAWEI
WANG FAN
LIANG XINQI
LIU XIN

Assignees

哈尔滨理工大学

Dates

Publication Date: 20260508
Application Date: 20260303

Claims (10)

1. The preparation method of the low-temperature-resistant and high-voltage-resistant ether electrolyte is characterized by comprising the following steps of: 1. Molecular sieves are respectively added into lithium difluorosulfimide, lithium difluorooxalato borate, ethylene glycol diethyl ether and 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether for physical dehydration, obtaining physically dehydrated lithium bis (fluorosulfonyl) imide, lithium difluoro (oxalato) borate, ethylene glycol diethyl ether and 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether; 2. And uniformly mixing physically dehydrated lithium difluorosulfimide, lithium difluorooxalato borate, ethylene glycol diethyl ether and 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether in a glove box filled with argon at room temperature, and stirring to obtain the low-temperature-resistant and high-voltage-resistant ether-based electrolyte.
2. The preparation method of the low-temperature-resistant and high-voltage-resistant ether-based electrolyte is characterized in that the molar ratio of lithium difluorosulfonimide, lithium difluorooxalato borate, ethylene glycol diethyl ether and 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether in the low-temperature-resistant and high-voltage-resistant ether-based electrolyte is (0.5-0.9): (0.1-0.5): 2:3.
3. The method for preparing the low-temperature-resistant and high-voltage-resistant ether-based electrolyte according to claim 2, wherein the molar ratio of lithium difluorosulfonimide, lithium difluorooxalato borate, ethylene glycol diethyl ether and 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether in the low-temperature-resistant and high-voltage-resistant ether-based electrolyte is 0.9:0.1:2:3.
4. The method for preparing the low-temperature-resistant and high-voltage-resistant ether-based electrolyte according to claim 2, wherein the molar ratio of lithium difluorosulfonimide, lithium difluorooxalato borate, ethylene glycol diethyl ether and 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether in the low-temperature-resistant and high-voltage-resistant ether-based electrolyte is 0.7:0.3:2:3.
5. The method for preparing the low-temperature-resistant and high-voltage-resistant ether-based electrolyte according to claim 2, wherein the molar ratio of lithium difluorosulfonimide, lithium difluorooxalato borate, ethylene glycol diethyl ether and 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether in the low-temperature-resistant and high-voltage-resistant ether-based electrolyte is 0.5:0.5:2:3.
6. The method for preparing the low-temperature-resistant and high-voltage-resistant ether electrolyte according to claim 1, wherein the stirring time in the second step is 8-12 h.
7. The use of a low temperature, high voltage resistant ether electrolyte as defined in claim 1, wherein the use of a low temperature, high voltage resistant ether electrolyte in lithium metal batteries.
8. The use of the low temperature and high voltage resistant ether electrolyte according to claim 7, wherein the lithium metal battery is assembled by the following method: 1. Preparing an electrode: ① . Mixing an active material, a conductive agent and a binder, and grinding in a mortar to obtain mixed electrode powder; The active material in the first ① step is NCM811, the conductive agent is Super P, and the binder is polyvinylidene fluoride; ② . Adding N-methyl pyrrolidone into the mixed electrode powder, stirring to obtain electrode slurry, uniformly coating the electrode slurry on a copper foil with the coating thickness of 80-120 mu m, pre-drying the copper foil coated with the electrode slurry in a vacuum oven at 80 ℃ for 1-3 h, and drying the copper foil in the vacuum oven at 120 ℃ for 10-12 h to obtain NCM811 pole pieces; 2. NCM811// Li battery assembly: And stacking the cathode battery shell, the elastic sheet, the gasket, the lithium sheet, the PP diaphragm, the NCM811 pole piece and the anode battery shell in sequence, respectively dripping 30 mu L of electrolyte on two sides of the diaphragm, and sealing by a button battery sealing machine to obtain the NCM811// Li battery assembly.
9. The application of the low-temperature-resistant and high-voltage-resistant ether-based electrolyte according to claim 8, wherein the mass ratio of the active material to the conductive agent to the binder in the first ① is 0.4:0.05:0.05, the grinding time in the first ① is 40-60 min, the mass ratio of the active material in the first ① to the N-methylpyrrolidone in the second ② is 0.4:2, the stirring speed in the first ② is 500-1000 rpm, and the stirring time is 4-6 h.
10. The application of the low-temperature-resistant and high-voltage-resistant ether electrolyte is characterized in that the diameter of a lithium sheet in the second step is 14mm, the diameter of an NCM811 pole piece in the second step is 12mm, the diameter of a PP diaphragm in the second step is 19mm, the elastic sheet in the second step is made of stainless steel, and the gasket in the second step is made of stainless steel.

Description

Preparation method and application of low-temperature-resistant and high-voltage-resistant ether electrolyte Technical Field The invention belongs to the technical field of lithium metal battery electrolytes, and particularly relates to a preparation method and application of a low-temperature-resistant and high-voltage-resistant ether-based electrolyte. Background With the global energy structure transformation, the fields of electric automobiles, energy storage systems, mobile equipment, low-altitude economy and the like are rapidly developed. These leading-edge technology industries place unprecedented stringent demands on energy density, power density, safety, and cycle life for electrochemical energy storage systems. However, the energy density of the lithium ion battery currently taking the dominant role in the market gradually approaches the theoretical limit, and it is difficult to meet the requirement of future technology iteration. Therefore, the development of the next generation battery system with higher energy density has become a necessary way to support the national energy strategy and lead the industry upgrade. In this context, lithium metal batteries are generally regarded as the most potential breakthrough direction due to their extremely high theoretical specific capacity and lowest electrochemical potential of the negative electrode material. However, the market for laboratory industrialization is fraught with thorns, the core bottleneck of which is the lack of a "universal" electrolyte that can "tame" high-activity lithium metal cathodes and "match" high-voltage anodes at the same time. Traditional commercial carbonate electrolytes are unstable at the high voltages required for high energy density batteries and are not compatible with lithium metal cathodes, resulting in severe interfacial side reactions and lithium dendrite growth, leading to safety risks and rapid capacity fade. And the ether electrolyte which can stably coexist with lithium metal cannot withstand the severe environment of the high-voltage positive electrode due to the poor oxidation resistance, so that the improvement of the energy density of the battery is greatly limited. The pair of sharp contradictions lead the lithium metal battery to be trapped into the dilemma of 'having high energy density but not high power output and long service life guarantee' for a long time especially in the application scene of pursuing extremely fast charging. The existing electrolyte modification strategy is often focused on local repair of a single interface, and the inherent contradiction between a solvated structure and interface dynamics is difficult to be coordinated fundamentally. Particularly, under the condition of high-rate charge and discharge, the energy barrier of the lithium ions for removing the solvation shell at the electrode interface becomes a fast control step for restricting ion migration, and the fast charge performance limit of the battery is directly determined. Disclosure of Invention The invention aims to solve the problems of poor adaptability and poor weather resistance of the traditional commercial ester-based electrolyte to a lithium metal battery, and provides a preparation method and application of a low-temperature-resistant and high-voltage-resistant ether-based electrolyte. When the invention happens, in order to solve the technical problems, the invention develops a new way, and from the essence of regulating and controlling the solvation structure of the electrolyte, the direct correlation between the solvation entropy and the performance is quantized and established by constructing a high-entropy electrolyte system. The innovative high-entropy design actively guides anions into a solvation shell layer of lithium ions, not only remarkably reduces key desolvation energy barriers and realizes ultra-fast migration of lithium ions, so that the battery can still stably work under the extreme multiplying power of 20 ℃, but also builds a firm and stable interface protection layer on the surfaces of the positive electrode and the negative electrode through preferential decomposition of the anions. The high-quality positive electrode passivation layer (CEI) effectively resists oxidation corrosion under high voltage, and the excellent negative electrode passivation layer (SEI) inhibits growth of lithium dendrites, so that century problems of high-voltage compatibility and lithium metal stability are solved simultaneously. The invention has the important significance that the invention not only provides a specific electrolyte formula, but also provides a brand-new electrolyte design mode, successfully breaks through the traditional style of the lithium metal battery between high voltage and high multiplying power performance, and lays a solid material foundation and scientific theoretical support for the practical application of the next generation high-power lithium metal battery facing the key fields of lo