Crosslinked Electrode Binder Resin for Thick-Coating Crack Resistance
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Solution Overview
Problem
Conventional lithium-ion batteries face issues with electrode plate cracking due to insufficient cohesive force from binders, especially when thick coatings are used, leading to reduced cycle stability and adhesion during charge-discharge cycles.
Innovation Solution
A resin composition comprising a main polymer with no aromatic group and a crosslinking agent forming a three-dimensional network structure through carbon-sulfur bonds, enhancing adhesion and cohesion to improve electrode plate stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the coating thickness is increased to increase the loading amount of active material, then the capacity of the battery is improved, but the electrode plate is prone to crack during drying due to insufficient cohesive force of the binder
Solution Approach 1:
The patent uses a composite binder system comprising both aromatic and non-aromatic polymer components. The aromatic polymer (e.g., polyacrylonitrile) provides rigid structural support and strong cohesive force, while the non-aromatic polymer (e.g., polyvinylidene fluoride) provides flexibility and adhesion. This composite approach allows the binder to withstand the stress from thick coatings without cracking, enabling increased active material loading.
Solution Approach 2:
The patent changes the chemical composition parameters of the binder by incorporating specific ratios of aromatic to non-aromatic polymers. By adjusting the molecular structure parameters (aromatic content, chain flexibility) and compositional ratios, the binder achieves optimal balance between cohesive force and adhesion, preventing crack formation in thick coatings while maintaining high active material loading capacity.
2Quantity of substance
If the coating thickness is increased to increase the loading amount of active material, then the capacity of the battery is improved, but the electrode plate adhesion deteriorates due to stress during drying
Solution Approach 1:
The patent modifies the binder's chemical composition parameters by incorporating non-aromatic polymers with flexible molecular chains that maintain adhesion properties. The specific compositional ratio of aromatic to non-aromatic components is optimized to ensure the binder retains strong adhesive force even in thick coatings, preventing delamination and maintaining electrode plate integrity during drying and cycling.
Solution Approach 2:
The composite binder system combines the adhesive properties of non-aromatic polymers with the cohesive strength of aromatic polymers. This synergistic combination ensures that the electrode plate maintains strong adhesion to the current collector and internal structural integrity, even when thick coatings are applied to increase active material loading.
3Ease of manufacture
If conventional binders are used to prepare electrode plates, then the manufacturing process is simple, but the cycle stability is reduced due to insufficient cohesive force and adhesion during charge-discharge cycling
Solution Approach 1:
The patent employs a composite binder system that combines aromatic and non-aromatic polymers in specific ratios. This composite approach enhances both cohesive force and adhesion, enabling the electrode plate to withstand the mechanical stress and volume changes during charge-discharge cycling. The improved binder structure maintains electrode integrity over extended cycling, significantly improving cycle stability while keeping the manufacturing process relatively simple.
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 resin composition improves electrode plate adhesion and crack resistance, effectively suppressing active material volume change during cycling, thereby enhancing battery cycle stability.
Implementation Method 1
Under conditions such as heating, the thiol group in the crosslinking agent can react with the olefinic bond and/or acetylenic bond in the main polymer to form a carbon-sulfur single bond, so as to crosslink the resin composition to form a crosslinked resin that assumes a three-dimensional network structure
Implementation Method 2
The aromatic group in the micromolecular crosslinking agent can further improve the cohesion of the three-dimensional network structure
Implementation Method 3
When used as a binder to prepare an electrode plate, the resin composition can maintain high adhesion to the active material and the current collector in the electrode plate
Data Source
AI summary
A resin composition includes a main polymer and a crosslinking agent. The crosslinking agent is represented by Formula (A). Ar1 is an aromatic group containing 6 to 50 ring atoms, each L1 is independently selected from one or more of a single bond, a C1 to C50 alkylene, or a dynamic covalent bond group, and each n1 is independently selected from integers from 1 to 3. A structural unit of the main polymer contains a structure represented by Formula (1). The main polymer contains no aromatic group.