Li-Ion Electrolyte Composition for Stable Silicon Anode SEI
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Solution Overview
Problem
Conventional lithium-ion battery electrolytes are inefficient and unstable, particularly when used with silicon-based anodes, leading to poor cycle life and safety concerns due to large volume changes and unstable solid electrolyte interphase formation.
Innovation Solution
Development of new electrolyte compositions that include ether and sulfonamide solvents with higher oxidation potentials, which form stable and electronically insulating solid electrolyte interphase (SEI) layers on silicon anodes and cathodes, enhancing electrochemical stability and compatibility with high-voltage cathodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional carbonate-based electrolytes are used with silicon-based anodes, then initial capacity can be achieved, but cycle life deteriorates due to unstable solid electrolyte interphase formation and large volume changes
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by replacing conventional carbonate-based solvents with ether-based solvents (such as dimethoxyethane, diglyme, triglyme) and sulfonamide-based solvents (such as N-methyl-2-pyrrolidone, N,N-dimethylformamide). This parameter change fundamentally alters the electrolyte's interaction with silicon anodes, enabling stable SEI formation that accommodates volume changes during cycling, thereby resolving the contradiction between cycle life and electrolyte stability.
Solution Approach 2:
The patent employs composite electrolyte formulations combining multiple ether-based and sulfonamide-based solvents with lithium salts (such as LiPF6, LiBF4). This composite approach creates a synergistic effect where the ether and sulfonamide components work together to form a robust solid electrolyte interphase on silicon anodes, simultaneously improving cycle life and maintaining electrolyte stability under varying operating conditions.
2Quantity of substance
If silicon-based anodes with large volume changes are used, then energy density improves, but safety deteriorates due to unstable solid electrolyte interphase and potential dendrite formation
Solution Approach 1:
The patent modifies the electrolyte's physical and chemical parameters by using ether-based solvents with higher dielectric constants and sulfonamide-based solvents with superior thermal stability. These parameter changes enable the electrolyte to maintain stability during the large volume expansions and contractions of silicon anodes, preventing dendrite formation and improving safety while preserving the high energy density benefits of silicon-based materials.
3Power
If conventional electrolytes are used with high-voltage cathodes, then voltage capacity increases, but electrochemical stability deteriorates due to oxidation at high potentials
Solution Approach 1:
The patent changes the electrochemical window parameters of the electrolyte by selecting ether-based solvents and sulfonamide-based solvents that possess higher oxidation potentials compared to conventional carbonates. This parameter change expands the electrochemical stability window, enabling the electrolyte to remain stable at high voltages (above 4.3V) and allowing the battery to operate with high-voltage cathodes while maintaining electrochemical 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
The new electrolyte compositions significantly improve cycle life, energy density, safety, and thermal stability, reducing gassing and electrolyte consumption, while maintaining compatibility with both high-capacity silicon anodes and high-voltage cathodes.
Implementation Method 1
form stable and electronically insulating solid electrolyte interphase (SEI) layers on silicon anodes and cathodes
Implementation Method 2
electrolyte in contact with the first electrode, the second electrode, and the separator
Data Source
AI summary
New electrolyte compositions for lithium-ion energy storage devices with silicon-based electrode materials having improved stability. The electrolyte compositions may be used in an energy storage device comprising a first electrode and a second electrode, where 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 the electrolyte composition.