High-Temperature Lithium Battery Electrolyte for Gas-Suppressing SEI Films
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Solution Overview
Problem
Existing lithium secondary battery electrolytes face challenges in achieving optimal high-temperature performance, including gas production and reduced cycle life due to insufficient formation of a stable solid electrolyte interface film (SEI) and instability under extreme conditions.
Innovation Solution
A high-temperature lithium secondary battery electrolyte composed of a diisocyanate compound and a bicyclic sulfate compound forms a flexible, thin, and uniform SEI film on the negative electrode, passivating the positive electrode surface, thereby inhibiting gas production and improving high-temperature cycling and storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte formulations are used, then the battery can operate at normal temperatures, but gas production increases and cycle life decreases under high-temperature conditions
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by introducing specific additives (cyclic carboxylate compound at 0.01-5 wt% and sulfur-containing compound at 0.01-5 wt%) to change the properties of the SEI film formed on electrodes, making it more stable and less prone to decomposition at high temperatures, thereby reducing gas production and improving reliability
Solution Approach 2:
The patent creates a composite electrolyte system by combining multiple components (cyclic carbonate, chain carbonate, lithium salt, cyclic carboxylate compound, and sulfur-containing compound) that work synergistically to form a composite SEI film with enhanced stability and protective properties against high-temperature degradation
2Reliability
If conventional electrolyte formulations are used, then the battery can function under normal conditions, but the SEI film becomes unstable and decomposes under high-temperature conditions
Solution Approach 1:
The patent changes the compositional parameters of the electrolyte by adding specific compounds that modify the SEI film formation process, resulting in a film with altered chemical stability parameters that prevent decomposition at elevated temperatures during cycling
Solution Approach 2:
The cyclic carboxylate and sulfur-containing compounds act as intermediary substances that facilitate the formation of a stable SEI film by participating in the initial film formation process and creating a protective barrier that prevents direct contact between the electrolyte and electrode, thereby stabilizing the interface under high-temperature cycling conditions
3Productivity
If the electrolyte uses volatile and flammable solvents to achieve high conductivity, then charging efficiency is improved, but safety hazards increase under extreme conditions
Solution Approach 1:
The patent modifies the physical and chemical parameters of the electrolyte system by introducing additives that alter the flammability characteristics while maintaining ionic conductivity through optimized composition ratios of safe solvents and functional additives
4Reliability
If the electrolyte viscosity is reduced to improve ion conduction, then conductivity increases, but the stability of the electrolyte composition under high temperature decreases
Solution Approach 1:
The patent optimizes the viscosity parameter of the electrolyte by selecting appropriate solvent combinations and adding specific compounds that maintain low viscosity for good ion conduction while simultaneously providing thermal stability to prevent decomposition at high temperatures
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 synergistic effect of diisocyanate and bicyclic sulfate compounds enhances the high-temperature storage performance and cycle life of lithium secondary batteries by reducing gas production and maintaining structural integrity under high-temperature conditions.
Implementation Method 1
The lithium ion battery electrolyte can form a stable solid electrolyte interphase (SEI) film on the surface of an electrode material by adding a first type of isocyanate additive and a second type of film-forming additive
Implementation Method 2
F atoms can not only form a film at an electrode interface, but also reduce the intermolecular force, thereby reducing the viscosity of the electrolyte and improving the conductivity of the electrolyte
Implementation Method 3
when the battery is used under overcharge or overdischarge or under extreme conditions, short circuits or fire may be caused inside the battery due to heat generation
Data Source
AI summary
The invention relates to the technical field of secondary batteries, specifically to a high-temperature lithium secondary battery electrolyte and a battery cell. The high-temperature lithium secondary battery contains an additive composition consisting of a diisocyanate compound and a bicyclic sulfate compound.