Lithium-Ion Battery Electrolyte Additives for Low-Temperature Power
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving high power performance while maintaining long cycle and storage life, as existing solutions to improve cycle and storage life often compromise power performance, and high voltage leads to increased side reactions and gas generation, affecting safety.
Innovation Solution
An electrolyte comprising an organic solvent, lithium salt, trifluoromethanesulfonate silyl compound, lithium fluorophosphate compound, and cyclic phosphonitrile compound, which decreases impedance at the electrode interface, inhibits gas generation, and enhances cycle and high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stable solid electrolyte interface (SEI) film is formed to protect the negative electrode, then cycle life and storage life are improved, but interface impedance increases and power performance decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific composite additive system containing silyl compound, lithium fluorophosphate compound, and cyclic phosphonitrile compound. This compositional parameter change modifies the SEI film properties to achieve both stability and low impedance
Solution Approach 2:
The patent uses a composite additive system combining three different types of compounds (silyl compound, lithium fluorophosphate compound, and cyclic phosphonitrile compound) that work synergistically to form an optimized SEI film with both protective stability and low resistance characteristics
2Use of energy by moving object
If voltage is increased to improve energy density, then energy density is improved, but side reactions increase and gas generation increases, worsening cycle life and storage life
Solution Approach 1:
The patent applies preliminary anti-action by having the composite additive system pre-form a protective interface layer on the electrode surfaces before high voltage operation begins. This pre-formed layer prevents oxidative side reactions at high voltage, thereby maintaining cycle life and storage life even when energy density is improved through voltage increase
3Reliability
If positive additive is used to form protective layer on positive active material, then side reactions are inhibited, but power performance decreases
Solution Approach 1:
The patent merges the functions of negative electrode protection and positive electrode protection into a single composite additive system. The combination of silyl compound, lithium fluorophosphate compound, and cyclic phosphonitrile compound works synergistically to form optimized interface layers on both electrodes simultaneously, achieving protection without the power performance penalty of separate additives
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 significantly improves power performance, cycle life, high-temperature storage performance, and safety of lithium-ion batteries by reducing impedance and gas generation, while maintaining power performance.
Implementation Method 1
The three types of compounds can cooperate to act on the electrode interface of the lithium-ion battery, so as to significantly decrease the impedance of the SEI film on the surface of the negative electrode
Implementation Method 2
The three types of compounds can also significantly inhibit the gas generation during the cycle process and the storage process of the lithium-ion battery
Data Source
AI summary
The present disclosure provides an electrolyte and a lithium-ion battery. The electrolyte comprises: an organic solvent; a lithium salt dissolved in the organic solvent; and an additive. The additive comprises trifluoromethanesulfonate silyl compound, lithium fluorophosphate compound and cyclic phosphonitrile compound. The electrolyte of the present disclosure can significantly decrease the low temperature resistance of the lithium-ion battery, and improve the power performance of the lithium-ion battery, and the electrolyte of present disclosure can also significantly inhibit the gas generation during the cycle process and the storage process of the lithium-ion battery, and significantly improve the cycle performance, the high temperature storage performance and the safety performance of the lithium-ion battery.