Electrolyte Additive for Stable Lithium Battery Films
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Solution Overview
Problem
Conventional techniques fail to stably form surface films on both anode and cathode electrodes of secondary batteries, leading to deterioration in charge/discharge efficiency, cycle life, and safety due to internal stress and uneven film formation, which results in reduced capacity and increased resistance over time.
Innovation Solution
Incorporating a linear disulfonate compound in the electrolyte solution for secondary batteries, along with cyclic monosulfonates and cyclic sulfonates with two sulfonyl groups, to form stable films on both anode and cathode electrodes, preventing decomposition of electrolyte components and enhancing film stability and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surface film is formed by chemical reaction at the electrode interface with liquid electrolyte, then a protective film can be formed on the anode surface, but the film becomes contaminated with byproducts leading to uneven film formation and reduced reliability
Solution Approach 1:
The patent introduces a solid electrolyte interface (SEI) layer as an intermediary between the lithium anode and the liquid electrolyte. This SEI layer acts as a mediator that prevents direct harmful reactions between lithium metal and water/hydrofluoric acid in the electrolyte, while still allowing lithium ion transport. The SEI layer forms a protective barrier that eliminates contamination issues associated with direct chemical reaction methods.
Solution Approach 2:
The patent changes the physical state parameter of the electrolyte interface by forming a solid-like SEI layer from the liquid electrolyte components. This parameter change from liquid to solid interface creates a more stable and uniform film structure that prevents contamination while maintaining ionic conductivity.
2Reliability
If lithium metal is exposed to air for surface film formation, then a surface film can be created, but uneven film formation occurs and lithium metal exposure leads to safety problems
Solution Approach 1:
The patent applies preliminary action by pre-forming a stable SEI layer on the lithium anode surface before the battery is assembled and filled with electrolyte. This preliminary film formation occurs in a controlled manner during initial charging cycles, preventing subsequent harmful reactions with moisture and ensuring uniform protection from the start.
Solution Approach 2:
The lithium anode itself serves to form the protective SEI layer through controlled decomposition of electrolyte components during initial charging. The system uses its own resources (electrolyte and lithium potential) to create the protective film without external intervention, ensuring proper adhesion and uniformity.
3Duration of action of stationary object
If conventional additives are used in electrolyte solution, then some film formation can occur, but stable films on both anode and cathode cannot be formed simultaneously leading to reduced cycle life
Solution Approach 1:
The patent employs a dual-function additive system where certain compounds serve multiple purposes: they form protective films on both the anode and cathode, maintain electrolyte stability, and enable long-term cycling. The combination of cyclic carbonates, chain carbonates, and specific additives creates a universal solution that addresses multiple interface issues simultaneously.
Solution Approach 2:
The electrolyte solution uses a composite formulation combining multiple solvent types (cyclic and chain carbonates) with specific additive compounds. This composite electrolyte system creates synergistic effects that enable stable film formation on both electrodes, improving overall battery reliability and cycle life beyond what single-component systems can achieve.
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 approach results in improved charge/discharge efficiency, extended cycle life, and high capacity retention, while suppressing the increase in resistance during storage, thereby enhancing the overall performance and safety of lithium secondary batteries.
Implementation Method 1
a linear disulfonate compound... to form stable films on both anode and cathode electrodes, preventing decomposition of electrolyte components
Implementation Method 2
an additive for electrolyte solution... enhancing the overall performance and safety of lithium secondary batteries
Data Source
AI summary
There is provided a lithium secondary battery which has excellent characteristics such as energy density and electromotive force and is excellent in cycle life and storage stability. An electrolyte solution for secondary battery comprising at least an aprotic solvent having an electrolyte dissolved therein and a compound represented by the general formula (1).