Lithium Battery Electrolyte Additive for HF and PF5 Scavenging
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Solution Overview
Problem
The degradation of lithium ion batteries due to the formation of acids like HF and PF5 at high temperatures leads to increased resistance and reduced capacity, primarily affecting the stability and safety of the electrolyte solution.
Innovation Solution
Incorporation of a Lewis base-based compound as an additive in the non-aqueous electrolyte solution to scavenge acids like HF and PF5, forming a stable solid electrolyte interphase (SEI) on the electrode surfaces, thereby preventing further decomposition and improving high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used as a lithium salt in the electrolyte solution, then electrochemical performance is improved, but HF and PF5 are generated by pyrolysis at high temperatures which degrade the SEI film and cause self-discharge
Solution Approach 1:
The patent introduces a sulfur compound (Formula 1) as an intermediary substance that reacts with HF and PF5 to form stable adducts. This mediator approach allows the beneficial electrochemical performance of LiPF6 to be maintained while the harmful byproducts are neutralized through chemical reaction, preventing SEI film degradation and self-discharge.
Solution Approach 2:
The patent converts the harmful HF and PF5 byproducts into beneficial stable complexes through reaction with the sulfur compound. The harmful substances are transformed into harmless or beneficial products that contribute to electrolyte stability, turning the pyrolysis issue into a potential advantage by forming protective species.
2Reliability
If the SEI film is formed on electrode surfaces, then electrode protection is achieved, but the film decomposes at high temperatures due to acid byproducts leading to increased resistance and capacity loss
Solution Approach 1:
The patent applies preliminary anti-action by introducing the sulfur compound that proactively neutralizes HF and PF5 before they can attack and decompose the SEI film. This preventive approach maintains film integrity by eliminating the degrading agents in advance, rather than attempting to repair damage after it occurs.
Solution Approach 2:
The sulfur compound acts as a protective intermediary between the acidic byproducts and the SEI film. It preferentially reacts with HF and PF5, forming a protective chemical barrier that shields the vulnerable SEI film from acid attack, thereby maintaining electrode protection at high temperatures.
3Productivity
If transition metal ions dissolve from the positive electrode, then electrochemical activity increases, but resistance increases and capacity is reduced due to electrodeposition on the negative electrode
Solution Approach 1:
The sulfur compound serves as a mediator that complexes with transition metal ions in the electrolyte, preventing their migration and electrodeposition on the negative electrode. This intermediary action maintains the beneficial electrochemical activity while blocking the harmful ion transport that leads to resistance increase and capacity loss.
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 additive stabilizes the SEI, reduces electrode resistance, and enhances the battery's capacity retention and resistance to self-discharge during high-temperature storage.
Implementation Method 1
In order to ensure and maintain the passivation ability of the SEI even during high-temperature storage, it is urgent to introduce an electrolyte solution additive which may be reduction-decomposed well, or introduce an additive capable of removing the cause of degradation of a battery at high temperatures by scavenging HF and PF 5
Implementation Method 2
introduce an additive capable of removing the cause of degradation of a battery at high temperatures by scavenging HF and PF 5
Data Source
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AI summary
The present invention relates to a non-aqueous electrolyte solution additive, a non-aqueous electrolyte solution for a lithium secondary battery including the same, and a lithium secondary battery including the non-aqueous electrolyte solution, and particularly, to a non-aqueous electrolyte solution additive using a Lewis base compound capable of rapidly reacting with an acid, a non-aqueous electrolyte solution for a lithium secondary battery including the same, and a lithium secondary battery in which high-temperature storage durability is improved by including the non-aqueous electrolyte solution.