Lithium-Ion Battery Electrolyte for High-Temperature Cathode Stability
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Solution Overview
Problem
Lithium-ion batteries face unsatisfactory storage and cycling performance under high temperature, particularly with high-nickel positive electrode materials that suffer from oxidation, structural instability, and ion elution, leading to safety risks and reduced service life.
Innovation Solution
An electrolyte comprising a non-aqueous solvent with cyclosiloxane and fluoroether additives forms a synergistic interface film on the positive electrode, enhancing stability and thermal resistance by combining silicon and fluorine-containing groups to stabilize the electrode interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-nickel positive electrode materials are used to increase energy density, then the theoretical specific capacity is improved, but the storage performance and cycling performance under high temperature deteriorate due to oxidation, structural instability, and ion elution
Solution Approach 1:
The patent introduces an intermediary substance (electrolyte containing cyclosiloxane and fluoroether additives) that mediates between the high-nickel positive electrode material and the environment. This electrolyte forms a protective interface film that prevents direct contact between the electrode material and harmful substances, thereby maintaining high energy density while improving storage and cycling performance under high temperature conditions
Solution Approach 2:
The patent uses a composite electrolyte system combining cyclosiloxane and fluoroether additives with specific non-aqueous solvents and lithium salts. This composite formulation creates a synergistic effect where the cyclosiloxane forms the base protective film and the fluoroether enhances oxidation resistance, collectively stabilizing the high-nickel electrode material at elevated temperatures
2Device complexity
If conventional electrolytes are used with high-nickel positive electrode materials, then the battery structure is simple, but the positive electrode interface becomes unstable due to oxidation and ion elution at high temperature
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by incorporating specific ratios of cyclosiloxane (0.01-5 wt%) and fluoroether (0.01-5 wt%) additives. These parameter changes transform the electrolyte's properties to enable formation of a stable protective film on the positive electrode interface, preventing oxidation and ion elution without significantly complicating the overall battery structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The electrolyte significantly improves high-temperature storage and cycling performance by forming a dense, oxidation-resistant interface film, reducing volume changes and maintaining battery integrity, thereby extending the battery's service life and safety.
Implementation Method 1
the cyclosiloxane can have ring-opening polymerization reaction at high temperature to form a film on a surface of the positive electrode
Implementation Method 2
the fluoroether will preferentially form a film on a surface of the positive electrode of the lithium-ion battery, thereby inhibiting oxidative decomposition of the non-aqueous solvent
Implementation Method 3
epoxy groups, with strong electron-withdrawing properties, can capture metal ions such as cobalt and manganese, thereby inhibiting deterioration of battery performance caused by dissolution of these ions
Data Source
AI summary
This application provides an electrolyte for lithium-ion battery, a lithium-ion battery, a battery module, a battery pack, and an apparatus. The electrolyte provided in this application includes a non-aqueous solvent, and a lithium salt and an additive that are dissolved in the non-aqueous solvent, and the additive includes a cyclosiloxane and a fluoroether. This application further provides a lithium-ion battery including the foregoing electrolyte. In the electrolyte provided in this application, the cyclosiloxane and the fluoroether are used together to synergistically react on a surface of the positive electrode, combining silicon and oxygen containing groups and fluorine and oxygen containing groups to form an interface film containing silicon, oxygen, and fluorine, which not only ensures density of the interface film, but also strengthens oxidation resistance and thermal stability of the interface film, greatly improving both storage performance and cycling performance of the lithium-ion battery under high temperature.