Secondary Battery Electrolyte With Cyclic Sulfate for SEI Stability
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving higher energy density due to lithium consumption during the formation of a solid electrolyte interface (SEI) film, which reduces coulombic efficiency and cycling performance, especially with high-specific-volume negative electrode materials.
Innovation Solution
Incorporating a lithium-rich metal oxide as a supplement at the positive electrode and adding a cyclic sulfate compound to the electrolyte solution to form protective films on both electrodes, mitigating oxygen release and oxidative decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-rich metal oxide is added as a lithium supplement at the positive electrode, then energy density is improved, but oxygen is released during delithiation which oxidizes the electrolyte solution and generates harmful substances
Solution Approach 1:
The cyclic sulfate compound acts as an intermediary substance that mediates between the lithium-rich metal oxide and the electrolyte solution. It preferentially reacts with oxygen or oxygen radicals released during delithiation of the lithium supplement, forming protective films that prevent direct contact between oxygen and the electrolyte solution, thereby eliminating the harmful oxidative decomposition while preserving the energy density benefits
Solution Approach 2:
The invention converts the harmful oxygen release into a beneficial protective mechanism. The cyclic sulfate compound utilizes the released oxygen to form stable protective films on the electrode surfaces, transforming the harmful oxidative effect into a useful film-forming effect that protects both the electrode and electrolyte from further degradation
2Reliability
If a lithium supplement is added at the positive electrode to compensate for lithium consumption, then coulombic efficiency is improved, but the complexity of the positive electrode material increases
Solution Approach 1:
The invention modifies the compositional parameters of the positive electrode by incorporating lithium-rich metal oxide in controlled amounts (1-10 mass%). This parameter change provides excess lithium to compensate for SEI formation losses, improving coulombic efficiency while maintaining manageable complexity through defined concentration ranges
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
Enhances energy density and improves coulombic efficiency and cycling performance by preventing negative electrode damage and stabilizing the SEI film.
Implementation Method 1
adding a cyclic sulfate compound to the electrolyte solution to form protective films on both electrodes
Implementation Method 2
mitigating oxygen release and oxidative decomposition
Implementation Method 3
The SEI is a good conductor of lithium ions and a poor conductor of electrons
Implementation Method 4
The SEI is a good conductor of lithium ions and a poor conductor of electrons, which inhibits the continuation of lithium consumption reaction
Data Source
Figure 1~3
Figure 4~6
AI summary
The present application relates to the technical field of batteries, and relates to a secondary battery and an electrical apparatus. The secondary battery includes a non-aqueous electrolyte solution containing a cyclic sulfate compound. The present application further relates to an electrical apparatus including the secondary battery.