Multi-Functional Electrolyte Additives for Li-Ion Battery SEI Stability
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Solution Overview
Problem
Current electrolyte compositions for lithium ion batteries lack additives that significantly enhance electrochemical cell performance, particularly in terms of SEI stabilization, high temperature performance, and cycle life.
Innovation Solution
Development of multi-functional additive compounds containing both SEI forming and SEI modifying groups, such as organic carbonate groups covalently bonded to heteroatom functional groups like sulfonates or phosphates, which form a solid electrolyte interface and modify its properties to improve battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte compositions are used with separate SEI formers and SEI modifiers, then the electrolyte can form a basic solid electrolyte interface, but the SEI stability and high temperature performance are insufficient
Solution Approach 1:
The patent combines SEI forming and SEI modifying functional groups into a single multi-functional additive compound. This merging allows the additive to simultaneously form and modify the solid electrolyte interface, improving SEI stability and high temperature performance beyond what separate additives can achieve.
Solution Approach 2:
The multi-functional additive compound performs multiple functions: it acts as both an SEI former and an SEI modifier. This multi-functionality is achieved by incorporating both organic carbonate groups (SEI forming) and heteroatom functional groups (SEI modifying) within the same molecular structure, enabling improved battery performance across multiple parameters.
2Productivity
If conventional electrolyte compositions are used, then the battery can operate, but metal deposition occurs and cycle life is limited
Solution Approach 1:
By merging SEI forming and SEI modifying capabilities into one additive compound, the patent creates a more robust and stable solid electrolyte interface that prevents metal deposition on the lithium metal surface, thereby extending cycle life without sacrificing productivity.
3Temperature
If conventional electrolyte compositions are used, then the battery can function, but high temperature performance is poor
Solution Approach 1:
The multi-functional additive compound enhances high temperature performance while maintaining overall cell reliability. The heteroatom functional groups (sulfonates, phosphates, etc.) provide thermal stability and modify the SEI to resist degradation at elevated temperatures, while the organic carbonate groups ensure proper SEI formation.
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
These additives enhance SEI stabilization, prevent metal deposition, and improve overall cell performance, including cycle life and high temperature stability, making them suitable for various electrochemical devices like lithium ion batteries.
Implementation Method 1
SEI film formation on the negative and/or positive electrode of a lithium ion battery helps protect the electrolyte composition. A suitable film is electronically insulating and allows transport of lithium ions.
Implementation Method 2
SEI modifying additives aid in improving battery cycle life, high temperature performance, and/or low temperature performance.
Data Source
AI summary
Multi-functional additives containing at least one solid electrolyte interface (SEI) forming group and at least one SEI modifying group are advantageously employed in electrolyte compositions for electrochemical devices. The SEI forming group may comprise an organic carbonate moiety and the SEI modifying group may comprise a heteroatom functional group such as a sulfur containing organic moiety. The electrochemical devices include lithium ion batteries.