Lithium Battery Electrolyte Overcharge Protection via CHB and 2-FBP Additives
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to high-temperature overcharge, which can lead to explosion, and existing solutions like protection circuits and thermal choking mechanisms are inefficient or impractical, especially under high voltage/high current conditions, while conventional electrolyte additives like cyclohexyl benzene (CHB) and 2-fluoro biphenyl (2-FBP) do not provide sufficient overcharge-prevention properties.
Innovation Solution
A secondary battery electrolyte is developed by adding 3 to 5% by weight of cyclohexyl benzene (CHB) and 0.2 to 1.5% by weight of 2-fluoro biphenyl (2-FBP, which undergoes electrochemical polymerization and exothermic oxidation reactions to inhibit lithium ion migration and generate heat, effectively blocking pores and preventing overcharge reactions without causing significant battery performance deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protection circuit is mounted to prevent battery explosion, then safety is improved, but additional installation space is required which limits miniaturization
Solution Approach 1:
The patent extracts the safety function from an external protection circuit and integrates it into the electrolyte composition itself through the CHB and 2-FBP additives, which provide overcharge-prevention properties intrinsically without requiring additional installation space
Solution Approach 2:
The electrolyte additives automatically provide overcharge protection when abnormal high voltage occurs, with CHB undergoing exothermic oxidation reaction to generate heat and block pores, and 2-FBP forming protective films, creating a self-regulating safety mechanism without external control
2Reliability
If CHB is added to electrolyte to prevent explosion, then overcharge safety is improved, but oxidative decomposition leads to gas evolution and battery swelling
Solution Approach 1:
The patent introduces 2-FBP as an intermediary substance that forms protective films on electrode surfaces, mediating between the overcharge conditions and CHB's exothermic oxidation reaction, thereby suppressing gas-generating side reactions while maintaining the safety benefits of CHB
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 combination of CHB and 2-FBP significantly enhances overcharge-prevention properties and high-temperature safety under high voltage/high current conditions, preventing battery explosion and maintaining performance by controlling oxidative decomposition and internal resistance, thus ensuring reliable operation and safety.
Implementation Method 1
CHB, used as an electrolyte additive, undergoes electrochemical polymerization, which results in increased internal resistance of the battery, thereby increasing a stability of the battery
Implementation Method 2
the resulting heat elevates an internal temperature of the battery within a short period of time to thereby block pores of a separator
Implementation Method 3
2-fluoro biphenyl (2-FBP), which undergoes electrochemical polymerization and exothermic oxidation reactions to inhibit lithium ion migration and generate heat
Data Source
AI summary
Provided is a secondary battery electrolyte having improved high temperature properties and overcharge-prevention properties, particularly improved overcharge-prevention properties under high voltage/high current conditions, in conjunction with a minimized deterioration of the battery performance, by adding 3 to 5% by weight of cyclohexyl benzene (CHB) and 0.2 to 1.5% by weight of 2-fluoro biphenyl (2-FBP) as overcharge-preventing additives to an electrolyte of a lithium secondary battery.