Block Polymer Electrode Binder for Silicon Volume Change
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary battery electrodes face challenges with binding ability due to the large volume changes of silicon active materials during charging and discharging, leading to peeling and detachment of the electrode mixture layer, which reduces battery capacitance and durability.
Innovation Solution
A binder for secondary battery electrodes is developed, comprising a block polymer with specific structural units derived from (meth)acrylic acid, where one block has less than 30% of these units and the other block has 30% or more, enhancing the binding ability and adhesiveness to the collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binders (SBR/CMC or PVDF) are used, then the electrode can be formed, but the binding ability is insufficient leading to peeling and detachment during charging and discharging
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by incorporating specific ratios of carboxyl group-containing polymer (0.1-10 wt%) and hydroxyl group-containing polymer (0.1-10 wt%) into the SBR/CMC system. This parameter modification enhances the binding ability to silicon active material, preventing peeling and detachment during volume changes, thus improving both strength and reliability simultaneously.
Solution Approach 2:
The invention creates a composite binder system combining multiple polymer components: SBR, CMC, carboxyl group-containing polymer, and hydroxyl group-containing polymer. This composite structure provides synergistic effects where each component contributes specific functions (adhesion, flexibility, binding), resolving the contradiction between binding ability and durability that cannot be achieved with single-component binders.
2Quantity of substance
If silicon active material is used to increase capacitance, then energy density improves, but volume changes cause peeling and detachment reducing cycle characteristics
Solution Approach 1:
The invention modifies the binder composition parameters by adding carboxyl group-containing polymer and hydroxyl group-containing polymer in specific amounts (0.1-10 wt% each). These parameter changes enhance the binder's ability to accommodate silicon's volume expansion/contraction, maintaining electrode integrity during cycling while preserving the high capacitance benefits of silicon active material.
3Strength
If binder amount is increased to improve binding ability, then adhesion improves, but electrode mixture layer becomes too viscous affecting coating and drying
Solution Approach 1:
The invention changes the chemical nature of the binder components by introducing carboxyl group-containing polymer and hydroxyl group-containing polymer, which provide enhanced binding ability at low concentrations (0.1-10 wt%). This allows achieving high adhesiveness without increasing total binder amount, thus maintaining appropriate viscosity for coating and drying processes.
Data Source
AI summary
A binder for secondary battery electrodes, which enables the achievement of a secondary battery electrode that has higher binding properties than ever before contains a block polymer that has a polymer block (A) and a polymer block (B), and it is configured such that: the polymer block (A) includes less than 30% by mass of a structural unit derived from (meth)acrylic acid to a total structural units of the polymer block (A); and the polymer block (B) includes 30 mass % or more and 100 mass % or less of a structural unit derived from (meth)acrylic acid to a total structural units of the polymer block (B).