Sulfonylimide Additives for Stable SEI in Si Anode Li-Ion Cells
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Solution Overview
Problem
Conventional lithium-ion battery technologies face challenges with silicon-based anodes and high-voltage cathodes due to issues like large volumetric expansion, unstable solid-electrolyte interphase, and electrolyte decomposition, leading to reduced cycling life and capacity retention.
Innovation Solution
The use of symmetrical or asymmetrical alkylsulfonyl imide or cyclic alkylene sulfonylimide salts as electrode and electrolyte additives forms stable, electronically insulating but ionically conducting solid-electrolyte interphase layers on silicon anodes and cathodes, enhancing electrochemical stability and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional electrolytes and electrode materials are used in silicon-based anodes, then high capacity can be achieved, but volumetric expansion and unstable solid-electrolyte interphase lead to reduced cycling life
Solution Approach 1:
The patent applies preliminary action by introducing electrolyte additives (fluorinated cyclic carbonates and chain carbonates) that pre-form stable solid-electrolyte interphase layers on the silicon anode surface before cycling begins. This preliminary SEI formation prevents subsequent electrolyte decomposition and stabilizes the electrode-electrolyte interface, thereby extending cycling life while maintaining high capacity
Solution Approach 2:
The patent employs parameter changes by modifying the electrolyte composition with specific fluorinated cyclic carbonate additives (containing CF3 groups) and chain carbonate additives at controlled concentrations (0.1-10 wt%). These compositional changes alter the properties of the formed SEI layer, making it more stable and less prone to decomposition, thus resolving the contradiction between high capacity and cycling stability
2Quantity of substance
If high-voltage cathodes are used to increase energy density, then capacity is improved, but electrolyte decomposition occurs leading to reduced reliability
Solution Approach 1:
The patent uses fluorinated cyclic carbonate and chain carbonate additives as intermediary substances that form protective interfacial layers on both electrodes. These intermediary SEI and CEI layers act as barriers that prevent direct contact between the high-voltage cathode and the bulk electrolyte, thereby preventing electrolyte decomposition while allowing ion transport, thus enabling high energy density with maintained reliability
3Quantity of substance
If silicon-based anodes are used to increase capacity, then energy density is improved, but large volumetric expansion causes mechanical failure and reduced cycling life
Solution Approach 1:
The patent applies preliminary action by having the electrolyte additives form stable solid-electrolyte interphase layers on the silicon anode surface before significant volumetric expansion occurs. This pre-formed SEI layer acts as a protective coating that accommodates the expansion and contraction of silicon during cycling, preventing mechanical failure and maintaining structural integrity, thus enabling high capacity with improved mechanical stability
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
This approach improves the cycle life, energy density, safety, and thermal stability of lithium-ion batteries by reducing electrolyte consumption and gassing, while minimizing capacity fade and transition metal ion dissolution.
Implementation Method 1
forms stable, electronically insulating but ionically conducting solid-electrolyte interphase layers on silicon anodes and cathodes
Implementation Method 2
electronically insulating but ionically conducting solid-electrolyte interphase layers
Implementation Method 3
ionically conducting solid-electrolyte interphase layers
Data Source
AI summary
Electrode or electrolyte additives for energy storage devices comprising symmetrical or asymmetrical alkylsulfonyl imide or cyclic alkylene sulfonylimide salts are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, and an electrolyte composition. Symmetrical or asymmetrical alkylsulfonyl imide or cyclic alkylene sulfonylimide salts may serve as additives to the electrodes or to the electrolyte composition, or both.