Silicon-Anode Electrolyte Composition for Stable SEI and Low Gas Generation
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Solution Overview
Problem
Lithium-ion batteries with silicon-based anodes and high-voltage cathodes face challenges such as unstable solid electrolyte interphase layers, oxidative instability of conventional electrolytes, and inferior cycle life, leading to reduced energy density and safety concerns due to issues like gas generation and volume swelling in high FEC-containing electrolytes.
Innovation Solution
An electrolyte system comprising a sulfonate or carboxylate salt-based compound, a linear carbonate, and a cyclic carbonate, which stabilizes the solid electrolyte interphase, reduces electrolyte reactions, and enhances thermal stability, thereby improving the electrochemical performance and safety of silicon-based anode batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high FEC-containing electrolyte is used, then initial capacity is improved, but gas generation and volume swelling occur leading to reduced safety
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing sulfonate or carboxylate salt-based compounds with specific molecular structures (containing S=O or C=O groups) to replace high FEC-containing electrolytes. This parameter change achieves both high initial capacity and prevents gas generation/volume swelling by forming stable SEI layers that prevent electrolyte decomposition.
Solution Approach 2:
The patent creates a composite electrolyte system combining sulfonate or carboxylate salt-based compounds with linear carbonates and cyclic carbonates. This composite material approach allows the electrolyte to simultaneously provide high ionic conductivity for capacity while the sulfonate/carboxylate groups form protective interfaces that prevent gas generation and volume expansion.
2Quantity of substance
If silicon-based anode material is used, then energy density is improved, but volumetric expansion during lithiation leads to disintegration and reduced cycling life
Solution Approach 1:
The patent applies beforehand cushioning by having the sulfonate or carboxylate salt-based electrolyte compounds pre-form stable solid electrolyte interphase (SEI) layers on the silicon anode surface before significant expansion occurs. These pre-formed protective layers accommodate the volumetric expansion during lithiation without disintegrating, thus preserving the silicon structure and maintaining cycling life while enabling high energy density.
Solution Approach 2:
The patent changes the chemical parameters of the electrolyte interface by introducing sulfonate or carboxylate groups that form SEI layers with different mechanical and chemical properties compared to conventional electrolytes. These modified SEI layers have higher elasticity and stability, allowing them to withstand the 300% volumetric expansion of silicon during lithiation without failing, thus enabling long cycling life at high energy density.
3Power
If conventional non-aqueous electrolyte is used, then electrochemical performance is achieved, but oxidative instability occurs at voltages beyond 4.5 V leading to accelerated decay
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by incorporating sulfonate or carboxylate salt-based compounds with high oxidation resistance. These compounds have higher electrochemical stability windows that prevent oxidative decomposition at voltages beyond 4.5 V, allowing the battery to achieve high power electrochemical performance while maintaining reliability and preventing accelerated capacity decay.
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 proposed electrolyte system improves the cycle life and thermal stability of silicon-based anode batteries, reducing capacity fade and gas generation, while increasing the safety and energy density of lithium-ion batteries.
Implementation Method 1
an unstable solid electrolyte interphase (SEI) layer can develop on the surface of the cycled anodes. As the active material expands and contracts during each charge-discharge cycle, unreacted Si surfaces in the active material can subsequently be exposed to the liquid electrolyte and form thicker SEI layers.
Implementation Method 2
The proposed electrolyte system improves the cycle life and thermal stability of silicon-based anode batteries, reducing capacity fade and gas generation
Implementation Method 3
oxidative instability of the conventional non-aqueous electrolyte takes place at voltages beyond 4.5 V, which can lead to accelerated decay of cycling performance
Implementation Method 4
enhances thermal stability, thereby improving the electrochemical performance and safety of silicon-based anode batteries
Implementation Method 5
An electrolyte system comprising a sulfonate or carboxylate salt-based compound, a linear carbonate, and a cyclic carbonate, which stabilizes the solid electrolyte interphase, reduces electrolyte reactions, and enhances thermal stability
Data Source
AI summary
Electrolytes and electrolyte additives for energy storage devices comprising sulfonate or carboxylate salt 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 a sulfonate or carboxylate salt based compound.