Crosslinked Polymer Binders for Silicon Anode Stability
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Solution Overview
Problem
Lithium ion batteries face limitations in energy and power density due to the use of graphite anodes, and silicon anodes suffer from severe degradation due to volume changes during lithiation/delithiation, requiring a more effective binder to enhance adhesion and mitigate electrode pulverization.
Innovation Solution
A covalently crosslinked binder matrix is used to hold conductive materials and electrochemical storage materials together, employing linear or branched polymers with reactive groups and a crosslinker to form a stable network that can withstand volume expansion, improving adhesion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional PVDF binder is used, then thermal stability and adhesion to graphite electrode are improved, but adhesion to silicon anode is poor
Solution Approach 1:
The patent changes the chemical parameters of the binder by using polymers with different functional groups (carboxylic acid, hydroxyl, amine, phosphoric acid, thiol) to achieve better compatibility with silicon anodes while maintaining adhesion properties
Solution Approach 2:
The patent creates a composite binder system combining polymer matrix with crosslinking agents to form a network structure that provides both mechanical strength and chemical compatibility with silicon-based anodes
2Quantity of substance
If high mass loading of electrode is needed, then energy density is improved, but electrode pulverization increases
Solution Approach 1:
The crosslinked polymer network forms a flexible, curved-boundary structure that can accommodate volume changes of spherical or irregular electrode particles, reducing stress concentration and preventing pulverization at high mass loadings
Solution Approach 2:
The crosslinked binder matrix acts as a flexible binding network that can deform with electrode volume changes during lithiation/delithiation, maintaining structural integrity and preventing particle detachment at high mass loadings
3Quantity of substance
If silicon anode is used, then specific capacity is improved, but volume change upon lithiation/delithiation causes severe electrode pulverization
Solution Approach 1:
The crosslinked polymer network is designed beforehand to provide mechanical cushioning and structural support to silicon particles, accommodating their volume expansion/contraction during cycling and preventing pulverization before it occurs
Solution Approach 2:
The patent changes the mechanical parameters of the binder system through crosslinking, creating a network with optimized elasticity and strength to accommodate the large volume changes of silicon anodes while maintaining structural stability
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 covalently crosslinked binder matrix enhances the stability and cyclability of silicon anodes, maintaining structural integrity during lithiation and delithiation, and increases the specific capacity and cyclability of electrochemical storage devices, making them suitable for high mass-loading electrodes.
Implementation Method 1
a covalently crosslinked binder matrix
Implementation Method 2
binder materials with better elasticity to help to mitigate the volume expansion
Data Source
AI summary
An electrochemical storage device including a conductive material and an electrochemical storage device material held together by a covalently crosslinked binder matrix. A method of forming an electrode for an electrochemical storage device, the method including the steps of: mixing electrochemical storage device material, conductive material, linear polymer, and crosslinker with one or more solvents, the resultant mixture forming an electrode slurry, crosslinking the linear polymer with the crosslinker to thereby create a covalently crosslinked polymer network of the polymer and crosslinker, the crosslinked polymer network physically or chemically binding together the electrochemical storage device material and the conductive material.