Lewis Base Electrolyte Additive for High-Temperature Li-Ion Stability
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Solution Overview
Problem
Lithium-ion batteries experience performance degradation due to the decomposition of lithium salts at high temperatures, leading to increased resistance and capacity loss, primarily caused by the formation of Lewis acid materials like PF5, which degrade the solid electrolyte interphase (SEI) and cause self-discharge.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries incorporating a Lewis base compound, represented by Formula 1, which scavenges decomposition products such as PF5 by forming a robust film on the electrodes, thereby preventing further degradation and improving high-temperature storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium salt (LiPF6) is used as electrolyte component, then ionic conductivity is improved, but decomposition products (PF5) are generated at high temperature causing SEI degradation and capacity loss
Solution Approach 1:
A nitrogen-containing compound (Formula 1) is introduced as an intermediary substance that selectively binds to PF5 decomposition products through Lewis base-Lewis acid interaction. This mediator prevents PF5 from attacking and degrading the SEI film on electrode surfaces, thereby maintaining battery reliability at high temperatures while preserving the ionic conductivity benefits of LiPF6.
Solution Approach 2:
The invention converts the harmful effect of PF5 generation into a beneficial scavenging mechanism. The nitrogen-containing compound intentionally allows PF5 to form and then captures it through strong coordination bonding, transforming the decomposition issue into a controlled scavenging process that protects the SEI film and improves high-temperature stability.
2Quantity of substance
If high temperature storage is performed, then battery capacity increases initially, but decomposition reactions accelerate causing resistance increase and capacity degradation
Solution Approach 1:
The nitrogen-containing compound is pre-introduced into the electrolyte solution to establish a protective chemical environment before high-temperature storage begins. This preliminary anti-action ensures that when temperature increases accelerate decomposition reactions, the scavenger is already in position to neutralize PF5 and other decomposition products, preventing SEI degradation and maintaining composition stability.
3Ease of operation
If SEI film is degraded by Lewis acid materials, then electrode passivation ability decreases, but this causes additional electrolyte decomposition and electron consumption
Solution Approach 1:
The nitrogen-containing compound acts as a protective intermediary that binds to Lewis acid materials (PF5) before they can attack the SEI film. By intercepting these harmful species, the compound preserves the SEI's passivation ability and prevents the cascade of additional electrolyte decomposition reactions that would otherwise consume electrons and reduce battery efficiency.
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 stabilizes the SEI, reduces electrode resistance, and enhances cycle performance by scavenging thermal decomposition products, leading to improved high-temperature durability and capacity retention of lithium secondary batteries.
Implementation Method 1
Since a compound represented by Formula 1, which is used as an electrolyte solution additive for a lithium secondary battery of the present invention, as a Lewis base material, includes a nitrogen element having an unshared electron pair, it may easily bond with a Lewis acid, and thus it may effectively scavenge a decomposition product of a lithium salt in an electrolyte solution.
Implementation Method 2
A non-aqueous electrolyte solution for lithium secondary batteries incorporating a Lewis base compound, represented by Formula 1, which scavenges decomposition products such as PF5 by forming a robust film on the electrodes
Implementation Method 3
an electrolyte solution that becomes a medium for transferring lithium ions
Implementation Method 4
a side reaction caused by deterioration of the electrolyte solution at high temperatures, particularly deterioration due to decomposition of a lithium salt
Data Source
AI summary
The present disclosure relates to an electrolyte solution additive for a lithium secondary battery, a non-aqueous electrolyte solution for a lithium secondary battery comprising the same, and a lithium secondary battery. Specifically, the electrolyte solution additive for a lithium secondary battery of the present disclosure is a compound based on a Lewis base, and may effectively suppress the dissolution of transition metals from a positive electrode by removing by-products generated by the decomposition of a lithium salt.