Lithium Battery Electrolyte Additive for HF and PF5 Scavenging
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Solution Overview
Problem
Lithium secondary batteries face performance deterioration due to side reactions caused by decomposition products of lithium salts, leading to increased resistance and reduced capacity, especially at high temperatures, as a result of incomplete SEI film formation and decomposition of electrolytes.
Innovation Solution
An electrolyte for lithium secondary batteries incorporating a specific additive represented by Formula 1, which reacts with decomposition by-products of lithium salts, such as HF and PF5, to suppress side reactions and maintain battery performance by forming a stable SEI film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium salt is used as electrolyte component, then ionic conductivity is improved, but decomposition products cause side reactions leading to increased resistance and reduced capacity
Solution Approach 1:
A nitrogen-containing heterocyclic compound is introduced as an intermediary substance that reacts with decomposition products (HF, PF5) generated from lithium salts. This intermediary captures the harmful by-products through chemical reaction, preventing them from attacking the SEI film and causing side reactions, thus maintaining battery performance stability
Solution Approach 2:
The invention converts harmful decomposition products into beneficial effects by having the nitrogen-containing heterocyclic compound react with HF and PF5 to form stable complexes. The harmful by-products that would otherwise damage the SEI film are transformed into stable reaction products that no longer cause harm, effectively turning a detrimental process into a protective mechanism
2Ease of manufacture
If SEI film is incompletely formed, then initial battery setup is simpler, but additional electrolyte decomposition occurs causing self-discharge and reduced capacity
Solution Approach 1:
The nitrogen-containing heterocyclic compound is pre-added to the electrolyte formulation before battery assembly. This preliminary inclusion ensures that when lithium salts decompose during initial charging cycles, the heterocyclic compound is already present to capture HF and PF5 by-products, protecting the SEI film formation process and preventing subsequent electrolyte decomposition that would cause self-discharge
3Productivity
If high temperature operation is permitted, then energy utilization is improved, but salt decomposition accelerates causing increased resistance
Solution Approach 1:
The nitrogen-containing heterocyclic compound serves as a thermal stability intermediary that becomes increasingly active at elevated temperatures. As temperature rises and accelerates lithium salt decomposition, the heterocyclic compound reacts more rapidly with generated HF and PF5, maintaining protection effectiveness throughout the operating temperature range and preventing temperature-induced resistance increase
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 effectively prevents self-discharge and resistance increase in lithium secondary batteries by removing decomposition products, enhancing high-temperature safety and capacity properties.
Implementation Method 1
an additive which reacts with a by-product generated by decomposition of a lithium salt
Implementation Method 2
stably form an SEI film and maintain the same
Implementation Method 3
the passivation capability of the film is reduced
Data Source
Figure 1
AI summary
An electrolyte for a lithium secondary battery and a lithium secondary battery including the same are disclosed herein. In some embodiments, an electrolyte includes a lithium salt, an additive containing a compound represented by Formula 1, and an organic solvent.