Electrolyte Composition for Silicon Anodes With Low High-Temperature Gas
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Solution Overview
Problem
Lithium-ion batteries using silicon negative electrode materials face issues with volume expansion, leading to interface film damage and electrolytic solution decomposition, which deteriorates battery performance, and existing additives like fluoroethylene carbonate (FEC) cause gas generation at high temperatures, risking battery failure.
Innovation Solution
An electrolytic solution comprising fluoroethylene carbonate, tris(vinyldimethylsilyl) phosphate, and optional lithium salts and isocyanate compounds, formulated to form a stable SEI film and inhibit gas generation, enhancing cycle and storage performance at various temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon negative electrode materials are used to increase energy density, then specific capacity is improved, but volume expansion occurs during cycling causing interface film damage and electrolytic solution decomposition
Solution Approach 1:
The patent introduces a specific electrolytic solution composition as an intermediary between the silicon negative electrode and the battery system. This electrolytic solution contains additives that form a stable interface film, mediating the interaction between silicon and the electrolyte to prevent direct decomposition reactions while maintaining electrochemical performance.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolytic solution by incorporating specific additives and adjusting concentration ratios. These parameter changes transform the electrolytic solution's properties to enable it to accommodate silicon's volume expansion while maintaining interface film integrity and preventing decomposition.
2Reliability
If fluoroethylene carbonate (FEC) is used as electrolytic solution additive to form stable interface film, then capacity loss is reduced and interfacial impedance is lowered, but gas generation occurs at high temperature leading to battery failure or explosion
Solution Approach 1:
The patent converts the harmful gas-generating property of FEC at high temperature into a beneficial effect by combining it with other additives. The synergistic interaction transforms FEC's instability into a mechanism that forms a more robust and thermally stable interface film, where the harmful thermal decomposition is redirected to create a protective layer rather than gas.
Solution Approach 2:
The patent creates a composite electrolytic solution system by combining FEC with specific additives. This composite formulation leverages the film-forming capability of FEC while the other components suppress its gas-generating tendency at high temperature, achieving both interface stability and thermal safety through material composition synergy.
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 solution facilitates the formation of a high-quality SEI film, reducing interfacial impedance and gas generation, resulting in improved cycle and storage performance at room and high temperatures.
Implementation Method 1
the electrolytic solution facilitates the formation of a high-quality SEI film on the surface of the negative electrode plate
Data Source
AI summary
An electrolytic solution and the use thereof. The electrolytic solution includes fluoroethylene carbonate and tris(vinyldimethylsilyl) phosphate; a mass percentage of the fluoroethylene carbonate ranges from 8% to 15%, a mass percentage of the tris(vinyldimethylsilyl) phosphate ranges from 0.5% to 2%, based on a total mass of the electrolytic solution; and a mass ratio of the tris(vinyldimethylsilyl) phosphate to the fluoroethylene carbonate ranges from 1:8 to 1:30.