Sulfonylimide Electrolyte Additives for Stable Silicon Anode Interfaces
Find Innovative SolutionsGenerate Solutions
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 to form stable, electronically insulating but ionically conducting solid-electrolyte interphase layers on silicon anodes and cathodes, enhancing mechanical strength and reducing electrolyte decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anodes are used to increase energy density, then capacity is improved, but volumetric expansion occurs leading to reduced cycling life
Solution Approach 1:
The patent applies preliminary action by pre-forming a stable solid-electrolyte interphase layer on the silicon anode surface before cycling begins. This is achieved through using fluorinated cyclic carbonate electrolyte additives that react during initial cycles to create a protective interface layer that accommodates subsequent volume changes, preventing electrode disintegration and maintaining cycling life despite silicon's expansion characteristics
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorinated cyclic carbonate additives with specific molecular structures. These parameter changes in electrolyte composition enable the formation of a stable SEI layer with different properties than conventional electrolytes, allowing the layer to remain intact during silicon's volumetric expansion and contraction cycles
2Quantity of substance
If conventional electrolytes are used with high-voltage cathodes, then energy density is improved, but electrolyte decomposition occurs reducing reliability
Solution Approach 1:
The patent uses fluorinated cyclic carbonate electrolyte additives as intermediary substances that form a protective interface layer between the high-voltage cathode and the bulk electrolyte. This intermediary SEI layer acts as a mediator that prevents direct contact and decomposition reactions between the electrolyte and cathode at high voltages, enabling stable operation at elevated voltages while maintaining energy density
Solution Approach 2:
The patent employs fluorinated cyclic carbonate additives that undergo controlled oxidation at the cathode interface during initial cycles. This accelerated oxidation process forms a stable, highly oxidized SEI layer that is resistant to further decomposition at high voltages, creating a protective barrier that enables reliable high-voltage operation
3Quantity of substance
If silicon anodes expand volumetrically during cycling, then capacity is improved, but mechanical strength of the interface deteriorates
Solution Approach 1:
The patent creates a flexible, thin film solid-electrolyte interphase layer on the silicon anode surface that can accommodate volumetric expansion and contraction. This film structure maintains mechanical integrity through cycling by forming a compliant interface that flexes with silicon volume changes rather than cracking, preserving both capacity and mechanical strength
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 cycling stability and energy density of lithium-ion batteries by forming a stable interface that mitigates volume changes and electrolyte decomposition, leading to increased calendar life and safety while reducing gassing and electrolyte consumption.
Implementation Method 1
form stable, electronically insulating but ionically conducting solid-electrolyte interphase layers on silicon anodes and cathodes
Implementation Method 2
forming a stable interface that mitigates volume changes
Implementation Method 3
reducing electrolyte decomposition
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.