Lithium-Ion Battery Electrolyte for Cycle Retention and Thermal Stability
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Solution Overview
Problem
Lithium-ion batteries face challenges in maintaining high cycling capacity retention, preventing battery expansion, and improving post-cycle high-temperature resistance, which can lead to thermal runaway.
Innovation Solution
An electrolyte comprising compounds of Formula I, II, or III, along with fluorinated additives, forms a stable protective layer on the electrodes, enhancing cycle performance and thermal stability by using diglycolic anhydride and trinitrile or ether-trinitrile compounds, and incorporating silicon-containing materials with carbon layers to stabilize the negative electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in lithium-ion batteries, then the batteries can operate with basic performance, but the cycling capacity retention rate decreases and the battery expands during cycles
Solution Approach 1:
The patent introduces a film-forming additive as an intermediary substance in the electrolyte that mediates between the electrode and the electrolyte. This additive forms a stable protective film on the electrode surface, preventing direct harmful interactions and reducing battery expansion while maintaining good cycling capacity retention rate.
Solution Approach 2:
The patent modifies the electrolyte composition by adding specific compounds (cyclic carboxylic acid anhydride and chain nitrile) to change the chemical parameters of the electrolyte system. These parameter changes enable the formation of stable protective films that improve cycling performance and reduce expansion.
2Reliability
If conventional electrolytes are used, then the battery structure remains simple, but the post-cycle high-temperature resistance is poor and thermal runaway occurs
Solution Approach 1:
The patent applies preliminary anti-action by having the film-forming additive proactively form a protective film on the electrode surface before thermal runaway can occur. This pre-formed film acts as a barrier that prevents the chain reaction leading to thermal runaway, thereby improving post-cycle high-temperature resistance.
Solution Approach 2:
The patent converts the potentially harmful interaction between electrolyte and electrode at high temperatures into a beneficial protective mechanism. The film-forming additive undergoes controlled decomposition to form a stable protective layer that prevents catastrophic thermal runaway, transforming a harmful thermal process into a beneficial protective action.
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 cycling capacity retention and high-temperature stability of lithium-ion batteries, preventing thermal runaway and battery expansion, thereby ensuring safety and performance.
Implementation Method 1
An electrolyte comprising compounds of Formula I, II, or III, along with fluorinated additives, forms a stable protective layer on the electrodes
Data Source
AI summary
The present application provides an electrolyte and an electrochemical device. The electrolyte comprises diglycolic anhydride and a trinitrile compound, with which the cycle performance and the high-temperature stability under over-discharge conditions of lithium-ion batteries are significantly improved.