Boric Acid Modified Binder for 3D Electrode Bonding in Li-Ion Batteries
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Solution Overview
Problem
Conventional emulsion-type binders used in lithium-ion batteries lack the formation of an effective three-dimensional bonding network, leading to poor expansion inhibition and performance issues during the cycling process.
Innovation Solution
A boric acid derivative modified binder is developed, which forms a copolymer with specific monomers and functional monomers to create a three-dimensional network through dehydration condensation reactions, enhancing bonding strength and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional emulsion-type binders (SBR or styrene-acrylate) are used, then the binder provides basic bonding function between active material layers and substrate, but the adhesive films formed are elastomers with only van der Waals force and no chemical interaction between particles, resulting in poor expansion inhibition during cycling
Solution Approach 1:
The patent uses composite materials by combining conventional emulsion-type binder with boric acid derivative crosslinking agent. The boric acid derivative modifies the binder to form a three-dimensional bonding network through chemical crosslinking, transforming the simple elastomer into a composite structure with enhanced bonding performance and expansion inhibition capability
Solution Approach 2:
The patent changes the chemical parameter of the binder by introducing boric acid derivative groups that enable chemical crosslinking. This transforms the physical bonding (van der Waals force) into chemical bonding, fundamentally changing the bonding mechanism and creating a stable three-dimensional network structure
2Strength
If emulsion-type binders with cross-linking are used, then some bonding strength is achieved, but without effective three-dimensional network formation, the expansion inhibition remains poor
Solution Approach 1:
The patent transitions from two-dimensional surface bonding to three-dimensional network bonding by introducing crosslinking agents that form bonds in the third dimension (depth). This creates a spatial three-dimensional bonding network that provides both strength and structural stability, preventing expansion in all directions during cycling
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 modified binder significantly improves the cycle performance and low-temperature performance of lithium-ion batteries, reducing expansion rates and prolonging cycle life while maintaining high cycle capacity retention.
Implementation Method 1
forms a copolymer with specific monomers and functional monomers to create a three-dimensional network through dehydration condensation reactions, enhancing bonding strength and mechanical stability
Data Source
AI summary
The present application provides a boric acid derivative modified binder and a lithium-ion battery including the binder. Surfaces of emulsion particles of the binder are rich in boric acid groups (—B(OH)2). When the binder is applied to an electrode piece of the battery, the boric acid groups can be subjected to a dehydration condensation reaction with —OH in sodium carboxymethyl cellulose dispersant, or with —OH in a functional monomer during the drying process of the electrode piece, to form a three-dimensional network, increasing the bonding force and greatly improving the peeling strength of the electrode piece. The binder can also significantly improve the cycle performance of the lithium-ion battery, thereby prolonging the cycle life of the lithium-ion battery.