Boron Derivative Electrolyte for Lithium Battery Thermal Runaway
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to thermal runaway and capacity degradation caused by the decomposition of aromatic compounds used as additives, which compromise safety and storage characteristics at high and low temperatures.
Innovation Solution
An electrolyte for lithium secondary batteries containing a boron derivative, specifically represented by certain chemical formulas, is used, which improves high-temperature and low-temperature characteristics by forming a stable solid electrolyte interphase layer and maintaining chemical stability, along with additional additives like lithium difluoro(oxalato)borate and vinylene carbonate to enhance lifespan and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aromatic compounds are added to the electrolyte to suppress thermal runaway, then safety is improved, but the additive decomposes during charge and discharge processes leading to capacity degradation and storage characteristic deterioration
Solution Approach 1:
The patent changes the chemical structure parameter of the additive from aromatic compounds to boron derivative compounds with specific molecular structures (containing B-O bonds and aromatic rings). This structural parameter change provides both thermal runaway suppression capability and resistance to decomposition during charge-discharge cycles, resolving the contradiction between safety and lifespan.
Solution Approach 2:
The patent uses composite electrolyte formulations combining boron derivative additives with specific lithium salts and carbonate solvents. This composite approach creates synergistic effects where the boron derivative provides thermal stability while the overall composition maintains electrochemical stability and capacity retention over extended cycles.
2Quantity of substance
If capacity density is increased to meet miniaturization demands, then energy density is improved, but thermal runaway risk increases
Solution Approach 1:
The boron derivative compound acts as an intermediary substance between the electrodes and electrolyte. It forms protective interface layers that mediate the interaction, allowing high capacity density operation while preventing direct harmful reactions that lead to thermal runaway. The additive serves as a buffer that enables high energy density without proportionally increasing thermal risk.
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 ensures high capacity retention, low thickness change rate, and improved stability at high temperatures, maintaining excellent discharge capacity and lifespan characteristics, with a capacity recovery rate of 75% or more and a thickness increase rate of 1-20% when exposed to high temperatures for extended periods.
Implementation Method 1
improves high-temperature and low-temperature characteristics by forming a stable solid electrolyte interphase layer
Implementation Method 2
a non-aqueous lithium ion battery, which is capable of preventing over-charge current and a thermal runaway phenomenon caused by the over-charge current by using an aromatic compound such as biphenyl
Implementation Method 3
a method of improving safety of a battery by adding a small amount of an aromatic compound such as biphenyl, 3-chlorothiophene, or the like, to increase an internal resistance by electrochemical neutralization in an abnormal over-voltage state
Data Source
AI summary
Provided are an electrolyte for a lithium secondary battery and a lithium secondary battery containing the same.