Polymer Electrolyte Additives for LiPF6 Thermal Stability
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with LiPF6 decomposing, leading to electrolyte depletion, performance deterioration at high temperatures, and safety vulnerabilities due to gas generation and potential explosions.
Innovation Solution
An electrolyte additive comprising a polymer obtained by polymerizing specific compounds as monomers, which increases electrolyte viscosity and decreases ionic conductivity at high temperatures, thereby preventing explosions and temperature rises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used as a lithium salt in the electrolyte, then the battery can achieve good electrochemical performance, but LiPF6 decomposes at high temperatures to generate gas and cause safety issues
Solution Approach 1:
The patent introduces a polymer compound as an intermediary substance that mediates between the LiPF6 lithium salt and the high-temperature environment. This polymer acts as a protective layer or stabilizing agent that prevents direct decomposition of LiPF6 at elevated temperatures, thereby maintaining both electrochemical performance and thermal stability simultaneously
Solution Approach 2:
The patent creates a composite electrolyte system by combining LiPF6 lithium salt with a polymer compound. This composite approach allows the electrolyte to benefit from the high ionic conductivity of LiPF6 while the polymer component provides thermal stability and prevents decomposition, resolving the contradiction between performance and safety
2Object-affected harmful factors
If the electrolyte viscosity is increased to suppress decomposition, then thermal stability improves, but ionic conductivity decreases affecting battery performance
Solution Approach 1:
The patent optimizes the molecular weight, composition ratio, and structural parameters of the polymer compound to achieve the right balance. By carefully controlling these parameters, the electrolyte achieves sufficient viscosity to suppress decomposition while maintaining adequate ionic conductivity for good battery performance
Solution Approach 2:
The composite electrolyte system allows the polymer component to increase viscosity for thermal stability while the LiPF6 component maintains ionic conductivity. The synergistic interaction between the two components resolves the contradiction between these opposing requirements
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 additive significantly improves the thermal stability of rechargeable lithium batteries, preventing thermal runaway and maintaining performance even at elevated temperatures.
Implementation Method 1
increases electrolyte viscosity and decreases ionic conductivity at high temperatures
Implementation Method 2
the polymer for use as the electrolyte additive according to an embodiment of the present disclosure has a function of improving high-temperature storage characteristics of a rechargeable lithium battery by having a steric hindrance function
Data Source
AI summary
An electrolyte additive for a rechargeable lithium battery includes a polymer obtained by polymerizing first compound represented by Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3 as a monomer; and second compound represented by Chemical Formula 4.