Polyurethane Gel Electrolyte Coating for Silicon Anode Volume Change
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Solution Overview
Problem
Lithium ion batteries (LIBs) face challenges due to significant volume changes in electrodes during charging and discharging, leading to structural damages, pulverization of active materials, and instability of the solid electrolyte interface (SEI) layer, which affects battery cycle life and performance.
Innovation Solution
A polyurethane gel polymer electrolyte (GPE) coating is applied to the electrodes, which is formed by reacting an isocyanate and a polyol. This elastic and stretchable coating improves electrode adhesion strength, reduces thickness change during cycling, and maintains electrode integrity by restricting pulverized particles and conductive carbon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon is used as anode active material to achieve high theoretical specific capacity, then battery energy density is improved, but electrode structural stability deteriorates due to large volume changes during cycling
Solution Approach 1:
A flexible polymer coating layer is applied to the silicon anode particles. This coating layer acts as a protective shell that can accommodate the large volume expansion and contraction of silicon during lithium insertion and extraction, preventing particle pulverization and maintaining electrode structural integrity while allowing high specific capacity to be achieved
Solution Approach 2:
The anode is designed as a composite structure combining silicon active material with a polymer coating matrix. This composite approach allows the silicon to provide high specific capacity while the polymer matrix provides mechanical stability and structural support, resolving the contradiction between energy density and structural stability
2Stability of the object's composition
If binder additives are used to restrict physical expansion of electrode, then electrode structural stability is improved, but mechanical properties deteriorate and coating polymer amount becomes excessive
Solution Approach 1:
The polymer coating's mechanical properties are optimized by adjusting formulation parameters such as polymer molecular weight, crosslinking density, and coating thickness. This allows the coating to provide sufficient structural stability while maintaining appropriate mechanical flexibility and using a reasonable amount of polymer material
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 polyurethane GPE coating significantly enhances the cycling stability and long-term performance of lithium ion batteries by maintaining electrode integrity and preventing further degradation due to volume changes, thereby improving battery cycle life and capacity retention.
Implementation Method 1
a polyurethane gel polymer electrolyte (GPE) coating... which is formed by reacting an isocyanate and a polyol
Implementation Method 2
This elastic and stretchable coating improves electrode adhesion strength, reduces thickness change during cycling
Data Source
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AI summary
The present disclosure relates generally to a coated electrode for use in preparation of lithium ion batteries and methods of preparing such. More particularly, the present disclosure relates to a polymer coating composition for coating electrodes of the lithium ion batteries (LIBs). The polymer coating composition comprises a polyurethane gel polymer electrolyte (GPE) formed by a reaction of an isocyanate and a polyol.