CN-115799635-B - Electrolyte, secondary battery and electric equipment

Abstract

The application discloses electrolyte, a secondary battery and electric equipment, and belongs to the field of batteries. The electrolyte includes a first additive having a chemical formula including a heterocycle and a thiourea group. The electrolyte provided by the application can improve the high-temperature storage performance, the low-temperature discharge performance and the cycle performance of the battery.

Inventors

• LIU SI
• PAN BINGXIN
• CHU CHUNBO

Assignees

• 欣旺达电动汽车电池有限公司

Dates

Publication Date

20260508

Application Date

20221130

Claims (8)

1. 1. An electrolyte, wherein the electrolyte is applied to a secondary battery, and the secondary battery comprises a high-nickel positive electrode material; the electrolyte comprises a first additive and a second additive, wherein the mass ratio of the first additive to the second additive is 1 (2-5), the chemical structural formula of the first additive comprises heterocycle and thiourea groups, and the chemical structural formula of the first additive comprises a structure shown in the formula I: (I) Wherein R 1 is selected from at least one of a halogen atom, an alkyl group having 1 to 7 carbon atoms, a cycloalkyl group having 3 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, a haloalkyl group having 1 to 12 carbon atoms; R 2 、R 3 is each independently selected from at least one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 7 carbon atoms, a cycloalkyl group having 3 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, a haloalkyl group having 1 to 12 carbon atoms; the first additive accounts for 0.1-1 wt% of the electrolyte; The second additive comprises a cyclic phosphate compound, and the chemical structural formula of the second additive comprises a structure shown as a formula II: (II) wherein R 4 is selected from S or O; R 5 、R 6 、R 7 is each independently selected from at least one of cyano, hydrogen, nitro, halogen, alkyl having 1 to 5 carbon atoms, cycloalkyl having 3 to 6 carbon atoms, alkenyl having 2 to 6 carbon atoms, alkynyl having 2 to 6 carbon atoms, aryl having 6 to 10 carbon atoms, alkoxy having 1 to 7 carbon atoms, haloalkyl having 1 to 12 carbon atoms; the second additive accounts for 0.2-2 wt% of the electrolyte.
2. 2. The electrolyte of claim 1 wherein the first additive comprises at least one of the following compounds: 。
3. 3. the electrolyte of claim 1 wherein the second additive comprises at least one of the following compounds: 。
4. 4. the electrolyte of claim 1, wherein the electrolyte comprises a lithium salt comprising lithium hexafluorophosphate and/or an auxiliary lithium salt comprising at least one of lithium difluorophosphate, lithium tetrafluoroborate, lithium bisoxalato borate, lithium difluorooxalato borate, lithium difluorobisoxalato phosphate, lithium bis (fluorosulfonyl) imide, and lithium bis (trifluoromethylsulfonyl) imide.
5. 5. The electrolyte according to claim 4, wherein the lithium hexafluorophosphate accounts for 12.0-15.0 wt% of the electrolyte.
6. 6. The electrolyte according to claim 4, wherein the auxiliary lithium salt accounts for 0.1-1.0 wt% of the electrolyte.
7. 7. A secondary battery comprising the electrolyte according to any one of claims 1 to 6.
8. 8. A powered device comprising the secondary battery as claimed in claim 7 as a power supply source of the powered device.

Description

Electrolyte, secondary battery and electric equipment Technical Field The application relates to the technical field of batteries, in particular to electrolyte, a secondary battery and electric equipment. Background The secondary battery, especially the lithium ion battery, has the advantages of high specific capacity, long cycle life, high working voltage, small volume, no memory effect and the like, and is widely applied to the fields of portable electronic equipment, electric automobiles and the like. However, with the continuous development of science and technology, higher requirements are also put on the energy density of lithium ion batteries. At present, the common positive electrode material of the lithium ion battery mainly comprises a ternary material of lithium iron phosphate and lithium nickel cobalt manganese oxide. The nickel cobalt lithium manganate ternary layered material has the advantages of high theoretical capacity, low cost, low toxicity and the like, and particularly, the high nickel of the ternary material can further remarkably improve the energy density of the lithium ion battery and improve the cruising ability of the product. However, with the increase of Ni content, the surface oxidizing property of the positive electrode material is continuously improved, so that the electrolyte is easy to be subjected to oxidative decomposition and gas production on the positive electrode surface, and meanwhile, the transition metal of the high-Ni positive electrode material is subjected to chemical reaction with the electrolyte in the high-temperature storage and circulation process, so that the transition metal dissolves out and is deposited on the interface of the negative electrode, the conductivity of the interface is also deteriorated, and the high-temperature storage performance, the low-temperature discharge performance and the circulation performance of the battery are greatly deteriorated. Disclosure of Invention The application aims to provide an electrolyte which can inhibit the oxidation reaction of the electrolyte on the surface of a positive electrode plate and reduce the dissolution of transition metal so as to solve the problems. In order to achieve the above object, the present application adopts the following technical scheme. The application provides an electrolyte, which comprises a first additive, wherein the chemical structural formula of the first additive comprises heterocycle and thiourea groups. Alternatively, in some embodiments of the application, the chemical structural formula of the first additive includes a structure as shown in formula I: Wherein R 1、R2、R3 is each independently selected from at least one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 7 carbon atoms, a cycloalkyl group having 3 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, a haloalkyl group having 1 to 12 carbon atoms. Optionally, in some embodiments of the present application, the electrolyte further includes a second additive, the second additive including a cyclic phosphate compound, the chemical structural formula of the second additive including a structure as shown in formula II: wherein R 4 is selected from S or O; R 5、R6、R7 is each independently selected from at least one of cyano, hydrogen, nitro, halogen, alkyl having 1 to 5 carbon atoms, cycloalkyl having 3 to 6 carbon atoms, alkenyl having 2 to 6 carbon atoms, alkynyl having 2 to 6 carbon atoms, aryl having 6 to 10 carbon atoms, alkoxy having 1 to 7 carbon atoms, haloalkyl having 1 to 12 carbon atoms. Optionally, in some embodiments of the application, the first additive comprises at least one of the following compounds: Optionally, in some embodiments of the application, the second additive comprises at least one of the following compounds: Optionally, in some embodiments of the present application, the first additive accounts for 0.1wt% to 1wt% of the electrolyte. Optionally, in some embodiments of the present application, the second additive accounts for 0.2wt% -2 wt% of the electrolyte, and the mass ratio of the first additive to the second additive is 1 (2-5). Alternatively, in some embodiments of the application, the electrolyte comprises a lithium salt. The lithium salt includes lithium hexafluorophosphate and/or an auxiliary lithium salt. The auxiliary lithium salt includes at least one of lithium difluorophosphate, lithium tetrafluoroborate, lithium bisoxalato borate, lithium difluorooxalato borate, lithium difluorobisoxalato phosphate, lithium bis (fluorosulfonyl) imide, and lithium bis (trifluoromethylsulfonyl) imide. Optionally, in some embodiments of the present application, the lithium hexafluorophosphate accounts for 12.0wt% to 15.0wt% of the electrolyte. The auxiliary lithium salt accounts for 0.1-1.0 wt% of the electrolyte. Alternatively, in some embod