CN-122025811-A - High-temperature electrolyte additive, electrolyte and lithium ion battery

CN122025811ACN 122025811 ACN122025811 ACN 122025811ACN-122025811-A

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a high-temperature electrolyte additive, an electrolyte and a lithium ion battery. The high-temperature electrolyte additive comprises a first additive and a second additive, wherein the first additive has the general formula: Wherein R 1 、R 2 、R 3 is independently selected from any one of hydrogen, halogen and substituted or unsubstituted alkyl with 1-5 carbon atoms, and the general formula of the second additive is as follows: . Wherein R 4 is selected from any one of hydrogen and halogen, and R 5 is selected from any one of hydrogen and C1-C3 alkyl. Solves the problem of poor high-temperature stability of the existing electrolyte.

Inventors

YANG JIAMING
LIU XUHUA
GU YI
LU XIAOLIN
LI XIAOCHEN
Guan Jianian
TAN JUNJIE
WANG WENHUA
LU ZHEMIN
HUANG CHUNYAN

Assignees

西安热工研究院有限公司
华能上海石洞口发电有限责任公司

Dates

Publication Date: 20260512
Application Date: 20260204

Claims (10)

1. A high temperature electrolyte additive, comprising a first additive and a second additive; The first additive has the general formula: ; wherein R 1 、R 2 、R 3 is independently selected from any one of hydrogen, halogen, substituted or unsubstituted alkyl with 1-5 carbon atoms; The second additive has the general formula: ; Wherein R 4 is selected from any one of hydrogen and halogen, and R 5 is selected from any one of hydrogen and C1-C3 alkyl.
2. The high temperature electrolyte additive of claim 1 wherein the first additive is selected from one of the following formulas: 、。
3. A high temperature electrolyte additive according to claim 1 wherein the second additive is selected from one of the following formulas: 、、。
4. an electrolyte comprising an organic solvent, a lithium salt and an electrolyte additive, the electrolyte additive comprising other auxiliary additives and the electrolyte composite additive of any one of claims 1-3; The electrolyte comprises, by weight, 0.2% -0.5% of a first additive, 0.5% -1% of a second additive, 3% -5% of other auxiliary additives, 10% -14% of lithium salt and the balance of an organic solvent, wherein the total mass of the electrolyte is 100%.
5. An electrolyte as in claim 4, wherein the lithium salt comprises at least one of lithium hexafluorophosphate and lithium bis-fluorosulfonyl imide.
6. An electrolyte according to claim 4, wherein the other auxiliary additives include sulfur-containing additives, lithium salt additives and carbonate additives.
7. An electrolyte according to claim 4, wherein the sulfur-containing additive is added to the electrolyte in an amount of 0.5% to 1.5%, the lithium salt additive is added to the electrolyte in an amount of 0.5% to 0.8%, and the carbonate additive is added to the electrolyte in an amount of 1.2% to 3.5%, based on 100% of the total mass of the electrolyte.
8. An electrolyte according to claim 4 wherein the sulfur-containing additive is 1, 3-propenesulfonic acid lactone or vinyl sulfate, the lithium salt additive comprises at least one of lithium difluorophosphate and lithium bisoxalato borate, and the carbonate additive comprises vinylene carbonate and fluoroethylene carbonate.
9. The electrolyte of claim 8, wherein the ethylene carbonate is added to the electrolyte in an amount of 0.2% to 0.5% and the fluoroethylene carbonate is added to the electrolyte in an amount of 1% to 3%.
10. The lithium ion battery comprises a positive electrode and a negative electrode, and is characterized by further comprising the electrolyte as claimed in any one of claims 4-9, wherein the lithium ion battery adopts a formation process cooperatively matched with a bifunctional electrolyte additive, and specifically comprises the following steps: 1) A pre-charging stage, wherein the temperature is 25-35 ℃, the current is charged to 3.0V at 0.02-0.05 ℃, and the additive molecules are promoted to be uniformly adsorbed on the surface of the electrode; 2) A constant-current charging stage, wherein the temperature is 30-40 ℃, the current is charged to 4.2V at 0.1-0.2 ℃, and the orderly progress of the interface reaction of the additive is accelerated; 3) And in the constant voltage charging stage, the temperature is 35-45 ℃, and the voltage is kept at 4.2V until the current is reduced to 0.01 ℃ so as to perfect the densification of the interface film.

Description

High-temperature electrolyte additive, electrolyte and lithium ion battery Technical Field The invention belongs to the technical field of lithium ion batteries, and particularly relates to a high-temperature electrolyte additive, an electrolyte and a lithium ion battery. Background With the rapid development of new energy automobiles, energy storage systems and portable electronic devices, high-energy density lithium ion batteries are becoming a mainstream market demand. The ternary layered anode material has high specific capacity and voltage platform, so that the energy density of the battery is obviously improved, and the ternary layered anode material becomes a core choice of a power battery. However, the problem of performance degradation of ternary batteries in high temperature environments is increasingly pronounced and becomes a key bottleneck limiting their large-scale application. The high temperature condition accelerates the side reaction inside the battery, on one hand, the interface reaction between the electrolyte and the high-activity positive electrode is aggravated, so that the interface membrane (CEI membrane) of the cathode electrolyte is thickened and the interface impedance is increased, on the other hand, the transition metal ions are dissolved out and migrate to the negative electrode, the structure of the solid electrolyte interface membrane (SEI membrane) is destroyed, and the electrolyte is continuously decomposed. These reactions not only cause irreversible capacity decay, but also are more likely to trigger thermal runaway chain reactions, severely threatening the safety of the battery system. Especially in tropical/subtropical areas and high power fast charging scenarios, cycle life dips and safety risks caused by high temperatures have become industry pain points. In addition, the existing lithium ion battery formation process mostly adopts a single constant-current or constant-voltage mode, and the formation process is not effectively matched with the reaction characteristics of electrolyte additives. The traditional formation process is difficult to regulate and control the reaction rate and the distribution uniformity of the additive on the surface of the electrode, so that the reaction of the additive is insufficient, the formation of an interfacial film has defects, such as overhigh porosity and uneven thickness, and even if a high-performance electrolyte additive is added, the effect of the additive cannot be fully exerted, thereby further exacerbating the performance attenuation of the battery in a high-temperature environment. Therefore, the high-temperature stability of the ternary battery is improved, not only is an electrolyte additive system optimized, but also a formation process matched with the additive is constructed, and the safety bottleneck can be fundamentally broken through and the application scene can be expanded by combining the electrolyte additive system with the additive. Disclosure of Invention The invention aims to provide a high-temperature electrolyte additive, an electrolyte and a lithium ion battery, which solve the problem of poor high-temperature stability of the existing electrolyte. The invention is realized by the following technical scheme: The invention discloses a high-temperature electrolyte additive, which comprises a first additive and a second additive; The first additive has the general formula: ; wherein R 1、R2、R3 is independently selected from any one of hydrogen, halogen, substituted or unsubstituted alkyl with 1-5 carbon atoms; The second additive has the general formula: ; Wherein R 4 is selected from any one of hydrogen and halogen, and R 5 is selected from any one of hydrogen and C1-C3 alkyl. Further, the first additive is selected from one of the following structural formulas: 、。 further, the second additive is selected from one of the following structural formulas: 、、。 the invention discloses an electrolyte, which comprises an organic solvent, lithium salt and an electrolyte additive, wherein the electrolyte additive comprises other auxiliary additives and the electrolyte composite additive; The electrolyte comprises, by weight, 0.2% -0.5% of a first additive, 0.5% -1% of a second additive, 3% -5% of other auxiliary additives, 10% -14% of lithium salt and the balance of an organic solvent, wherein the total mass of the electrolyte is 100%. Further, the lithium salt includes at least one of lithium hexafluorophosphate and lithium difluorosulfonimide. Further, other auxiliary additives include sulfur-containing additives, lithium salt additives, and carbonate additives. Further, the addition amount of the sulfur-containing additive in the electrolyte is 0.5% -1.5%, the addition amount of the lithium salt additive in the electrolyte is 0.5% -0.8%, and the addition amount of the carbonate additive in the electrolyte is 1.2% -3.5% calculated by 100% of the total mass of the electrolyte. Further, the sulfur-containing additive