Non-Aqueous Battery Electrolyte for HF and PF5 Scavenging
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Solution Overview
Problem
Lithium ion batteries face degradation issues due to the decomposition of lithium salts at high temperatures, leading to increased resistance and reduced capacity, primarily caused by the formation of HF and PF5, which affect the passivation ability of the SEI and result in self-discharge.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries that includes a Lewis base compound capable of scavenging HF and PF5, preventing their decomposition and subsequent metal dissolution from the positive electrode, thereby maintaining the passivation ability of the SEI and reducing resistance and improving capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LiPF6 lithium salt is used as electrolyte salt, then good ionic conductivity is achieved, but HF and PF5 are produced by pyrolysis at high temperatures which degrade the film and cause metal dissolution
Solution Approach 1:
A Lewis base compound is introduced as an intermediary substance that selectively reacts with and scavenges HF and PF5 generated from LiPF6 decomposition. The Lewis base acts as a mediator between the harmful decomposition products and the electrode film, preventing direct contact and damage between HF/PF5 and the film structure, thus maintaining film integrity while allowing LiPF6 to provide ionic conductivity.
Solution Approach 2:
The harmful decomposition products HF and PF5 are converted from detrimental factors into beneficial ones by having them react with the Lewis base compound. The reaction between Lewis base and HF/PF5 transforms these harmful substances into harmless or less harmful compounds, effectively eliminating their damaging effects on the electrode film while preserving the original LiPF6 functionality.
2Reliability
If HF and PF5 attack the film, then metal dissolution occurs and resistance increases, but the film's passivation ability is degraded
Solution Approach 1:
The Lewis base compound is pre-introduced into the electrolyte system to perform preliminary neutralization of HF and PF5 before they can attack the film. This preventive action occurs continuously during battery operation, maintaining the film's passivation ability by eliminating the acidic attack mechanism before damage can accumulate.
Solution Approach 2:
The Lewis base compound serves as a protective intermediary layer chemically bound to or in close proximity to the film surface, intercepting HF and PF5 molecules and preventing them from reaching and degrading the film structure, thus preserving passivation ability while allowing ionic transport.
3Reliability
If the SEI passivation ability is insufficient, then additional electrolyte decomposition occurs causing self-discharge, but capacity is reduced
Solution Approach 1:
The Lewis base compound acts as a protective intermediary that strengthens the SEI film's passivation ability by neutralizing acidic components that would otherwise degrade the SEI structure. This intermediary protection prevents electrolyte decomposition and self-discharge events, maintaining energy retention while preserving SEI functionality.
Solution Approach 2:
The Lewis base compound provides beforehand cushioning protection to the SEI film by pre-neutralizing HF and PF5, creating a protective chemical environment that cushions the SEI against future degradation attacks, preventing self-discharge and capacity loss before they can occur.
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 use of the Lewis base compound in the electrolyte solution effectively suppresses the degradation of the film on the electrode surfaces, reducing metal dissolution and electrolyte decomposition, resulting in a lithium secondary battery with lower resistance and improved capacity characteristics.
Implementation Method 1
the additive includes a compound represented by Formula 1... R1 to R3 are each independently a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms
Data Source
AI summary
A non-aqueous electrolyte solution for a lithium secondary battery and a lithium secondary battery including the same are disclosed herein. In some embodiments, a non-aqueous electrolyte solution for a lithium secondary battery, includes a lithium salt, an organic solvent, and an additive, wherein the additive includes a compound represented by Formula 1.