Lithium Battery Electrolyte Stabilizing SEI for High-Temperature Operation
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining high-temperature capacity retention and safety due to the instability of the solid electrolyte interface (SEI) and side reactions between the positive electrode and electrolyte solution, leading to corrosion of the current collector under high-temperature and high-voltage conditions.
Innovation Solution
An electrolyte solution for lithium secondary batteries is developed, comprising a combination of imide lithium salts, organic solvents, and additives with sulfonate and cyclic carbonate groups, which form a stable SEI on the negative electrode and suppress side reactions at the positive electrode interface, thereby enhancing high-temperature capacity characteristics and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolyte solutions are used, then the battery can operate at high voltage, but the SEI film becomes unstable and side reactions occur at high temperature
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by introducing a specific cyclic carbonate compound with sulfonate group (Formula 1) combined with imide lithium salt. This compositional parameter change enables the formation of a stable SEI film that can withstand high-temperature conditions while maintaining electrochemical performance.
Solution Approach 2:
The electrolyte uses a composite approach by combining multiple components: imide lithium salt (first lithium salt), conventional lithium salt (second lithium salt), cyclic carbonate compound with sulfonate group (Formula 1), and other cyclic carbonate compounds. This composite electrolyte system works synergistically to form a robust SEI film that provides both stability and ionic conductivity at high temperatures.
2Quantity of substance
If conventional electrolyte solutions are used, then the battery can achieve high capacity, but side reactions cause current collector corrosion at high voltage and temperature
Solution Approach 1:
The cyclic carbonate compound with sulfonate group (Formula 1) acts as an intermediary substance that reacts preferentially with the electrode surfaces to form a protective SEI film. This intermediary layer prevents direct contact between the conventional electrolyte components and the current collector, thereby eliminating corrosion while maintaining ionic transport for capacity delivery.
Solution Approach 2:
The electrolyte composition is designed to perform preliminary protective action by forming a stable SEI film during initial cycles and throughout operation. This pre-formed protective layer prevents subsequent harmful side reactions and corrosion attacks on the current collector, enabling sustained high-voltage operation without degradation.
3Reliability
If the SEI film is formed to suppress lithium ion reactions, then negative electrode protection is improved, but the film must be robust enough to prevent corrosion at positive electrode under high voltage
Solution Approach 1:
The cyclic carbonate compound with sulfonate group (Formula 1) and imide lithium salt combination serves multiple functions simultaneously: it forms protective SEI on the negative electrode, prevents corrosion on the positive electrode, maintains ionic conductivity, and provides thermal stability. This multi-functional additive system simplifies the overall electrolyte design while achieving comprehensive protection for both electrodes.
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 proposed electrolyte solution effectively stabilizes the SEI and reduces electrode corrosion, improving the battery's high-temperature capacity retention and safety by forming a robust film on both electrodes, thus maintaining performance under extreme conditions.
Implementation Method 1
the lithium ions react with the carbon negative electrode to form Li2CO3, LiO, or LiOH, and thus, a film is formed on a surface of the negative electrode. The film is referred to as 'solid electrolyte interface (SEI)'
Implementation Method 2
Charge and discharge of the lithium secondary battery is performed while a process of intercalating and deintercalating lithium ions dissolved from a lithium metal oxide positive electrode into and out of a negative electrode is repeated
Data Source
AI summary
An electrolyte solution for a lithium secondary battery, and a lithium secondary battery including the same are disclosed herein. In some embodiments, an electrolyte solution includes a first lithium salt, a second lithium salt, an organic solvent, and an additive including a compound represented by Formula 1, wherein the first lithium salt is an imide lithium salt.