Lewis Base Electrolyte Additives for SEI Stability in Li-Ion Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion batteries face issues with increased resistance and capacity degradation due to the decomposition of electrolytes at high temperatures, leading to self-discharge and loss of passivation ability of the solid electrolyte interphase (SEI) film.
Innovation Solution
A non-aqueous electrolyte for lithium secondary batteries containing a Lewis base compound as an additive, which scavenges decomposition products like HF and PF5, forming a stable SEI film and maintaining passivation ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lithium salt (e.g., LiPF6) is used in the electrolyte, then the battery achieves good electrochemical performance, but the lithium salt decomposes at high temperature to generate acids (HF, PF5) that deteriorate the SEI film and cause self-discharge
Solution Approach 1:
A Lewis base compound is introduced as an intermediary substance that selectively reacts with acidic decomposition products (HF, PF5) generated from lithium salt. This intermediary captures the harmful acids through coordinate bonding, preventing them from attacking the SEI film while allowing the lithium salt to continue functioning as the primary electrolyte component
Solution Approach 2:
The invention converts the harmful acidic decomposition products into beneficial coordinated complexes. The Lewis base compound reacts with HF and PF5 to form stable adducts, transforming these harmful substances into benign species that no longer attack the SEI film or cause self-discharge
2Stability of the object's composition
If the SEI film is formed on the electrode surface, then it provides passivation ability to prevent electrolyte decomposition, but the film deteriorates due to acid attack from lithium salt decomposition
Solution Approach 1:
The Lewis base compound acts as a protective intermediary that preferentially binds to acidic species before they can reach and attack the SEI film. This creates a chemical buffer zone that protects the passivation layer from acid-induced deterioration
Solution Approach 2:
The Lewis base compound provides beforehand cushioning by pre-capturing acidic decomposition products through rapid coordinate bonding. This preemptive action cushions the SEI film from direct acid attack, maintaining its passivation ability throughout battery operation
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 solution enhances battery performance by reducing self-discharge and maintaining capacity, improving initial efficiency and high-temperature storage characteristics.
Implementation Method 1
a non-aqueous electrolyte additive which is a Lewis base compound, reacts rapidly with an acid and has an excellent effect of forming an SEI film and an excellent effect of scavenging decomposition products generated in a non-aqueous electrolyte
Implementation Method 2
it has an excellent effect of forming an SEI film and an excellent effect of scavenging decomposition products generated in a non-aqueous electrolyte
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed is a non-aqueous electrolyte containing a Lewis base compound added thereto. The non-aqueous electrolyte can scavenge HF and PF5 generated as decomposition products of lithium salt (LiPF6) to maintain the passivation ability of an SEI film during high-temperature storage. In addition, the non-aqueous electrolyte can provide a lithium secondary battery with improved battery performance by improving the self-discharge phenomenon caused by the elution from a positive electrode and the breakage of the SEI film at a negative electrode. In addition, the non-aqueous electrolyte can provide a secondary battery with improved initial efficiency by forming an initial coating film well to inhibit additional electrolyte decomposition.