Non-flammable Lithium Battery Electrolyte with High-Concentration Salt
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving non-flammability and maintaining battery characteristics when using high concentrations of ester phosphate as an electrolyte solution, due to issues with corrosion reactions and the need for film additives that deteriorate performance.
Innovation Solution
Incorporating a high-concentration lithium salt (1.5 mol/L or more) with 100% ester phosphate in the electrolyte solution, without the need for film-forming additives, to create a non-flammable electrolyte that enhances discharge capacity and rate characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ester phosphate is mixed at 20% or more to make the electrolyte non-flammable, then safety is improved, but discharge capacity is extremely reduced
Solution Approach 1:
The patent changes the concentration parameter of lithium salt from conventional levels to 1.5 mol/L or higher, which fundamentally alters the electrolyte's properties. This parameter change enables the system to achieve both non-flammability and high discharge capacity (100 mAh/g or more), resolving the contradiction between safety and productivity that previously existed at lower lithium salt concentrations.
2Duration of action of stationary object
If film additives such as VC or VEC are added to improve cycle characteristic, then cycle stability is improved, but non-flammable effect is deteriorated and secondary reactions are caused
Solution Approach 1:
The patent extracts and eliminates film-forming additives (VC, VEC, etc.) from the electrolyte system. By removing these additives entirely and relying on high-concentration lithium salt (1.5 mol/L or more) combined with ester phosphate, the system achieves both good cycle characteristics and maintained non-flammability, resolving the contradiction between cycle stability and safety.
Solution Approach 2:
The high-concentration lithium salt electrolyte system is self-sufficient and does not require external film-forming additives to achieve cycle stability. The system's own components (lithium salt and ester phosphate) work together to provide both long cycle life and non-flammability, eliminating the need for additives that would compromise safety.
3Productivity
If LiTFSI salt is used as electrolyte due to high stability and ionic conductance, then electrochemical performance is improved, but corrosion reaction with aluminum collector occurs
Solution Approach 1:
The patent uses a composite electrolyte system combining LiTFSI salt with ester phosphate in high concentration (1.5 mol/L or more). This composite formulation maintains the high ionic conductance and electrochemical stability of LiTFSI while the ester phosphate component suppresses corrosion reactions with aluminum collectors, resolving the contradiction between performance and harmful side reactions.
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
This approach results in a safer, non-flammable lithium secondary battery with improved discharge capacity and rate characteristics, while avoiding the drawbacks of film additives and corrosion reactions.
Implementation Method 1
it was impossible to use this salt as the electrolyte for lithium-ion secondary batteries since the LiTFSI salt causes corrosion reaction with 1 an aluminum collector
Implementation Method 2
LiTFSI salt having excellent characteristics such as high stability to heat, high solubility, and high ionic conductance
Implementation Method 3
studies have been made to improve the safety furthermore, by using ester phosphate known as an organic solvent having a high non-flammable effect
Data Source
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AI summary
An object of this invention is to provide a highly safe secondary battery employing a non-flammable electrolyte solution. The secondary battery has a positive pole comprising an oxide for storing and releasing lithium ions, a negative pole comprising a carbon material for storing and releasing lithium ions, and an electrolyte solution. The electrolyte solution comprises 1.5 mol/L or more of a lithium salt, or 1.0 mol/L or more of a lithium salt and 20% by volume or more of a phosphate ester derivative.