Carbonate Electrolyte for SiOx Anodes Under Hot Lamination
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Solution Overview
Problem
The hot lamination process used in manufacturing lithium-ion batteries with lithiated silicon oxide anodes causes solvent swelling and evaporation, leading to poor cyclability and performance.
Innovation Solution
An electrolyte comprising a lithium salt and a cosolvent mixture of cyclic and linear carbonate-containing solvents is used, which provides thermal stability and suppresses swelling during the lamination process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear carbonate solvents (such as dimethyl carbonate) are used in the electrolyte, then the electrolyte provides good ionic conductivity and low viscosity, but the solvents swell and evaporate during hot lamination process, resulting in poor cyclability
Solution Approach 1:
The patent changes the physical and chemical parameters of the electrolyte by replacing linear carbonate solvents with cyclic carbonate solvents (ethylene carbonate, propylene carbonate, fluoroethylene carbonate) that have higher boiling points and greater thermal stability. This parameter change allows the electrolyte to withstand the hot lamination process temperatures without swelling or evaporation, thereby improving cyclability while maintaining ionic conductivity
Solution Approach 2:
The patent employs a composite electrolyte formulation combining cyclic carbonate solvents with specific lithium salts (LiPF6, LiTFSI, LiFSI, LiBOB) and additive compounds. This composite material approach creates an electrolyte system that leverages the thermal stability of cyclic carbonates while maintaining the beneficial ionic conductivity properties, resolving the contradiction between stability and conductivity
2Productivity
If hot lamination process is used for manufacturing pouch cells, then the batteries can be manufactured efficiently, but the process causes solvent evaporation and swelling, leading to poor battery performance
Solution Approach 1:
The patent modifies the electrolyte composition to use cyclic carbonate solvents with higher boiling points and thermal stability, enabling the battery to withstand the hot lamination process temperatures (typically 80-100°C) without solvent evaporation or swelling. This parameter change allows efficient hot lamination manufacturing while maintaining battery performance and cyclability
3Use of energy by moving object
If lithiated silicon oxide is used in the anode active layer, then the battery achieves high energy density and fast recharging capability, but the combination with linear carbonate electrolytes results in poor cyclability
Solution Approach 1:
The patent creates a compatible composite system by pairing lithiated silicon oxide anode with a specifically formulated electrolyte containing cyclic carbonate solvents (ethylene carbonate, propylene carbonate, fluoroethylene carbonate) and lithium salts. This composite material combination resolves the incompatibility between high-capacity silicon oxide anodes and traditional linear carbonate electrolytes, enabling both high energy density and good cyclability
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 electrolyte enhances the fast charge capability, extends DC fast charge cycle life, and maintains low temperature discharge capacity, while allowing for high temperature lamination without solvent evaporation.
Implementation Method 1
the cyclic carbonate-containing solvent comprises a 5-membered cyclic ring with a carbonate moiety, that has a boiling point greater than 200° C. and a melting point less than 50° C.
Implementation Method 2
The hot lamination process however, causes swelling of the solvents and evaporation of the dimethyl carbonate, which results in poor cyclability for the lithium-ion battery.
Implementation Method 3
the cyclic carbonate-containing solvent has a boiling point greater than 225° C. and a melting point less than −25° C.
Data Source
AI summary
In an embodiment, an electrolyte includes a lithium salt and a cosolvent, where the cosolvent comprises a cyclic carbonate-containing solvent and a linear carbonate-containing solvent. In an embodiment, a battery includes an anode, a cathode, an electrolyte and a separator. The anode includes an anode current collector and an anode active layer. The anode active layer comprises a lithiated silicon oxide or a combination of lithiated silicon oxide and carbon present in an amount of 20 wt % or greater, based on a total weight of the anode active layer. The cathode includes a cathode current collector and a cathode active layer. The electrolyte includes a lithium salt and a cosolvent that includes a cyclic carbonate-containing solvent and a linear carbonate-containing solvent.