CN-122000467-A - Cyano electrolyte additive, electrolyte and lithium ion battery

CN122000467ACN 122000467 ACN122000467 ACN 122000467ACN-122000467-A

Abstract

The invention belongs to the technical field of lithium ion batteries, and relates to a cyano electrolyte additive, electrolyte and a lithium ion battery. The cyano electrolyte additive comprises a nitrile additive and a functional additive, wherein the structural formula of the functional additive is as follows: . The nitrile additive and the functional additive are compounded, the functional additive has cyano and triazine ring, the triazine ring chelates transition metal ions, the nitrile and the triazine ring form a film in a synergistic way, and the rigid structure of the benzene ring can enhance the thermal stability. The nitrile additive and the functional additive have cyano complementary effect, three phenyl groups in the functional additive are connected with triazine rings, the functional additive has larger structure and steric hindrance, transition metal ions on the surface of the positive electrode cannot be completely complexed, the short-chain nitrile additive has smaller structure, the space of the functional additive can be complemented, the nitrile additive and the functional additive form complementary effect in a synergistic way, and a compact interface film is formed on the surface of the positive electrode, so that the high-temperature performance is improved.

Inventors

YANG JIAMING
LIU XUHUA
LI XIAOCHEN
LU XIAOLIN
WANG WENHUA
TAN JUNJIE
JIANG HUI
ZHANG YANJUN
HUANG CHUNYAN
LU ZHEMIN

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: 20260508
Application Date: 20250908

Claims (10)

1. The cyano electrolyte additive is characterized by comprising a nitrile additive and a functional additive, wherein the structural formula of the functional additive is as follows: 。
2. A cyano electrolyte additive according to claim 1 wherein the nitrile additive comprises at least one of succinonitrile, adiponitrile, fluoroacetonitrile, 1, 2-bis (2-cyanoethoxy) ethane.
3. An electrolyte comprising a lithium salt and an electrolyte additive comprising the cyano electrolyte additive of claim 1 or 2; Calculated by the total mass of the electrolyte being 100%, the nitrile additive accounts for 0.3% -1%, the functional additive accounts for 0.3% -0.5%, and the lithium salt accounts for 12.5% -15%.
4. An electrolyte as in claim 3, wherein the electrolyte additive further comprises sulfur-containing additives, carbonate additives, and lithium salt additives.
5. The electrolyte according to claim 4, wherein the sulfur-containing additive is 0.5% -2%, the carbonate additive is 0.3% -0.5%, and the lithium salt additive is 0.3% -1% based on 100% of the total mass of the electrolyte.
6. An electrolyte according to claim 4 wherein said sulfur-containing additive comprises at least one of 1, 3-propenolactone, 1, 3-propane sultone, and vinyl sulfate; the carbonate additive comprises vinylene carbonate; the lithium salt additive comprises at least one of lithium difluorosulfimide, lithium difluorophosphate, lithium tetrafluoroborate and lithium bisoxalato borate.
7. An electrolyte as in claim 3, further comprising an organic solvent, wherein the organic solvent comprises a cyclic carbonate and a chain carbonate, wherein the chain carbonate comprises diethyl carbonate and ethylmethyl carbonate.
8. The electrolyte according to claim 7, wherein the total mass of the cyclic carbonate is 20 to 25%, the mass of the diethyl carbonate is 10 to 20%, and the mass of the methylethyl carbonate is 55 to 65% based on 100% of the total mass of the organic solvent.
9. An electrolyte according to claim 3, wherein the lithium salt is lithium hexafluorophosphate.
10. A lithium ion battery comprising a positive electrode and a negative electrode, and further comprising the electrolyte according to any one of claims 3 to 9.

Description

Cyano 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 cyano electrolyte additive, an electrolyte and a lithium ion battery. Background In the technical field of lithium ion batteries, a ternary lithium battery has high energy density and becomes a core power source of new energy automobiles, aerospace and medical instruments, but the application of the ternary lithium battery is severely restricted by performance attenuation and potential safety hazard in a high-temperature environment, and the ternary lithium battery is specifically divided into the following aspects: The material and the interface are unstable, namely the high nickel ternary material is easy to release lattice oxygen at the temperature of more than 60 ℃ to cause the layered structure to be converted into spinel/rock salt phase to lead to capacity suddenly drop, and meanwhile, high valence nickel (Ni 4+) is reacted with electrolyte to generate CO/CO 2 and other gases to cause the battery to bulge; The electrolyte is thermally decomposed, namely, the conventional lithium hexafluorophosphate (LiPF 6) base electrolyte is decomposed to generate strong corrosive phosphorus pentafluoride (PF 5) and hydrofluoric acid at the temperature of more than 75 ℃, the positive electrode material is corroded, transition metal (such as Ni 2+、Co3+) is dissolved out, and the lithium hexafluorophosphate base electrolyte migrates to a negative electrode to destroy an SEI film, so that the loss of active lithium is accelerated; the thermal runaway risk is that the initial temperature (about 170 ℃) of the ternary system thermal runaway is significantly lower than that of lithium iron phosphate (> 200 ℃) and the heat release quantity is larger. Although the prior art improves heat resistance by coating the positive electrode or adding an additive, there is still a problem of capacity fade during high temperature storage. Therefore, the development of a ternary lithium battery with high energy density and high temperature stability is urgent to break through the material interface regulation and control and electrolyte design so as to meet the rigidity requirement of the battery for high temperature storage in extreme scenes such as new energy automobiles, petroleum exploration and the like. Disclosure of Invention The invention aims to provide a cyano electrolyte additive, electrolyte and a lithium ion battery, which solve the problem of capacity attenuation of a ternary lithium battery in the high-temperature storage process in the prior art. The invention is realized by the following technical scheme: The invention discloses a cyano electrolyte additive, which comprises a nitrile additive and a functional additive, wherein the structural formula of the functional additive is as follows: 。 further, the nitrile additive includes at least one of succinonitrile, adiponitrile, fluoroacetonitrile, 1, 2-bis (2-cyanoethoxy) ethane. The invention also discloses an electrolyte, which comprises lithium salt and an electrolyte additive, wherein the electrolyte additive comprises the cyano electrolyte additive; Calculated by the total mass of the electrolyte being 100%, the nitrile additive accounts for 0.3% -1%, the functional additive accounts for 0.3% -0.5%, and the lithium salt accounts for 12.5% -15%. Further, the electrolyte additive also includes sulfur-containing additives, carbonate additives, and lithium salt additives. Further, calculated by taking the total mass of the electrolyte as 100%, the sulfur-containing additive accounts for 0.5% -2%, the carbonate additive accounts for 0.3% -0.5%, and the lithium salt additive accounts for 0.3% -1%. Further, the sulfur-containing additive includes at least one of 1, 3-propenesulfonic acid lactone, 1, 3-propane sultone, and vinyl sulfate; the carbonate additive comprises vinylene carbonate; the lithium salt additive comprises at least one of lithium difluorosulfimide, lithium difluorophosphate, lithium tetrafluoroborate and lithium bisoxalato borate. Further, the electrolyte also includes an organic solvent including a cyclic carbonate and a chain carbonate including diethyl carbonate and ethylmethyl carbonate. Further, calculated by taking the total mass of the organic solvent as 100%, the total mass of the cyclic carbonate is 20% -25%, the mass of the diethyl carbonate is 10% -20%, and the mass of the methyl ethyl carbonate is 55% -65%. Further, the cyclic carbonate includes fluoroethylene carbonate, ethylene carbonate and propylene carbonate, the mass ratio of fluoroethylene carbonate is 4%, the mass ratio of ethylene carbonate is 14% and the mass ratio of propylene carbonate is 6% based on 100% of the total mass of the organic solvent. Further, the lithium salt is lithium hexafluorophosphate. The invention also discloses a lithium ion battery, which comprises a positive electrode, a negative el