Silicon Battery Electrolyte Composition for Stable SEI and CEI
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Solution Overview
Problem
Conventional electrolytes for lithium-ion batteries with silicon-based anodes and high-voltage cathodes face challenges such as unstable solid electrolyte interphase (SEI) layers, oxidative instability, and limited cycling life, leading to reduced energy density and safety concerns.
Innovation Solution
The use of an electrolyte composition comprising an alkoxyethane-based compound, a linear carbonate, and a Li-containing salt, which forms a stable SEI layer on silicon anodes and a cathode electrolyte interphase (CEI) on high-voltage cathodes, enhancing mechanical strength, ionic conductivity, and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in lithium-ion batteries with silicon-based anodes, then the batteries can operate, but the solid electrolyte interphase (SEI) layers become unstable and cycling life is limited
Solution Approach 1:
The patent modifies the electrolyte composition by incorporating specific additives (cyclic carbonates, chain carbonates, and cyclic carboxylic acid esters) in optimized ratios. This changes the chemical parameters of the electrolyte to enable formation of stable SEI layers on silicon anodes, directly resolving the instability issue and extending cycling life while maintaining operational functionality
Solution Approach 2:
The electrolyte is formulated as a composite system combining multiple components: cyclic carbonates (10-40 wt%), chain carbonates (50-85 wt%), and cyclic carboxylic acid esters (5-20 wt%). This composite approach creates synergistic effects where each component contributes specific properties, resulting in enhanced SEI stability and extended battery cycling life compared to conventional single-component electrolytes
2Quantity of substance
If silicon-based anodes are used to increase energy density, then capacity is improved, but oxidative instability and safety concerns increase
Solution Approach 1:
The electrolyte additives act as intermediaries between the silicon anode and the oxidizing environment. The cyclic carboxylic acid esters and carbonates form protective interfacial layers that mediate the interaction, preventing direct oxidative damage to the silicon while allowing ionic transport, thus enabling high energy density operation without compromising safety
Solution Approach 2:
The electrolyte composition creates an inert chemical environment at the electrode interfaces through formation of stable SEI and CEI layers. These layers provide an inert barrier that protects the reactive silicon anode and high-voltage cathode from oxidative degradation, enabling safe operation at high energy densities
3Quantity of substance
If high-voltage cathodes are used to improve energy density, then capacity is increased, but oxidative instability increases
Solution Approach 1:
The electrolyte additives serve as intermediaries that form protective cathode electrolyte interphase (CEI) layers on high-voltage cathodes. These intermediary layers prevent direct contact between the oxidizing cathode surface and the bulk electrolyte, stabilizing the interface and enabling high-voltage operation without oxidative degradation
Solution Approach 2:
The electrolyte composition is designed to perform preliminary protective action by forming stable CEI layers on the cathode surface during initial cycles. This preliminary formation process creates a protective barrier before oxidative degradation can occur, enabling long-term stability of high-voltage cathodes
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 electrolyte system improves the cycling stability, energy density, and safety of lithium-ion batteries by reducing irreversible capacity loss, oxidative instability, and thermal issues, while increasing the calendar life and rate capability of the batteries.
Implementation Method 1
forms a stable SEI layer on silicon anodes
Implementation Method 2
forms a cathode electrolyte interphase (CEI) on high-voltage cathodes
Implementation Method 3
a Li-containing salt, which forms a stable SEI layer
Data Source
AI summary
Electrolytes and electrolyte additives for energy storage devices comprising alkoxyethane based compounds 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, an electrolyte comprising at least two electrolyte co-solvents, wherein at least one electrolyte co-solvent comprises an alkoxyethane based compound.