Non-Aqueous Electrolyte Additive for SEI Stability at High Temperature
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Solution Overview
Problem
Existing lithium secondary batteries face issues with high-temperature storage stability and lifespan due to the generation of Lewis acids like PF5 from lithium salts, leading to decomposition of the organic solvent and destruction of the solid electrolyte interface layer (SEI) at the negative electrode.
Innovation Solution
A non-aqueous electrolyte comprising a lithium salt, an organic solvent, and a compound represented by Chemical Formula 1, which includes a functional group capable of acting as a Lewis base to remove Lewis acids, thereby preventing solvent decomposition and enhancing the SEI layer durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 lithium salt is used in the electrolyte, then electrochemical performance is improved, but at high temperature Lewis acid (PF5) is generated causing solvent decomposition and SEI layer destruction
Solution Approach 1:
The patent introduces a cyclic carboxylate compound as an intermediary substance that mediates between the LiPF6 lithium salt and the organic solvent. This compound preferentially reacts with the lithium salt to form a stable complex, preventing the generation of Lewis acid (PF5) that would otherwise decompose the solvent and destroy the SEI layer. The cyclic carboxylate acts as a protective intermediary that maintains the benefits of LiPF6 while eliminating its harmful high-temperature effects.
2Temperature
If high temperature operation is permitted, then battery power and speed are improved, but thermal decomposition of lithium salt occurs generating harmful Lewis acids
Solution Approach 1:
The patent applies preliminary anti-action by introducing the cyclic carboxylate compound that preemptively binds to the lithium salt before thermal decomposition can occur. This compound is specifically selected to have high affinity for the lithium salt, forming a stable complex that prevents the thermal decomposition pathway leading to Lewis acid generation. The cyclic carboxylate acts in advance to neutralize the potential harmful effect, allowing higher operating temperatures without the generation of harmful Lewis acids.
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 non-aqueous electrolyte improves high-temperature storage characteristics and lifespan of lithium secondary batteries by preventing solvent decomposition and reinforcing the SEI layer, thus enhancing battery durability.
Implementation Method 1
the compound included in the non-aqueous electrolyte solution according to the present disclosure can play a role in removing the Lewis acid generated from the lithium salt when the lithium secondary battery is exposed to high temperatures
Implementation Method 2
preventing the decomposition of the organic solvent caused by the Lewis acid generated from the lithium salt
Implementation Method 3
since the compound represented by the specific Chemical Formula has a low LUMO energy level, it can participate in the formation reaction of the SEI layer of the negative electrode
Data Source
AI summary
The present invention relates to a non-aqueous electrolyte comprising a lithium salt; an organic solvent; and a compound represented by Chemical Formula 1, wherein the invention can control moisture in the lithium secondary battery in which the non-aqueous electrolyte is used, suppress by-product formation according to moisture control, and improve the durability of the solid electrolyte layer, thereby improving the durability thereof,wherein L1 and L2 are each independently a single bond or an alkylene group having 1 to 5 carbon atoms, and R1 is hydrogen or an alkyl group having 1 to 5 carbon atoms.