Halogen-Free Binder Resin for Battery Electrode Adherence
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Solution Overview
Problem
Conventional binder resins for nonaqueous electrolyte secondary batteries, such as PVDF and SBR, suffer from low binding force, leading to reduced battery capacity and performance due to poor adherence between the electrode mixture layer and current collector, and the introduction of acidic groups can decrease lithium ion mobility and ionic conductivity.
Innovation Solution
A halogen-free binder resin with a vinyl cyanide monomer unit and a phosphoric acid group-containing monomer unit is developed, which provides improved thixotropy and adherence to the current collector, while maintaining electrochemical stability and reducing the amount of acidic groups to enhance lithium ion mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the amount of conduction aid is increased to enhance rate characteristics, then electron transfer ease is improved, but the amount of binder must be reduced which reduces adherence between current collector and electrode mixture layer
Solution Approach 1:
The invention changes the chemical composition parameters of the binder resin by introducing phosphoric acid groups with specific content (0.01-0.5 mol/kg) and using a vinyl cyanide-based polymer structure. This parameter change enables the binder to achieve superior adherence strength, allowing the electrode to maintain structural integrity even when conduction aid content is increased for better rate characteristics.
Solution Approach 2:
The invention creates a composite binder system by combining vinyl cyanide-based polymer chains with phosphoric acid group functionalities. This composite structure provides both strong chemical bonding capability (through phosphoric acid groups) and good electrochemical stability (through vinyl cyanide backbone), enabling simultaneous improvement of adherence and rate characteristics.
2Strength
If acidic groups are introduced into PAN-based resin to enhance binding property with current collector, then adherence is improved, but lithium ion mobility and ionic conductivity are decreased
Solution Approach 1:
The invention precisely controls the concentration parameter of phosphoric acid groups within the narrow range of 0.01-0.5 mol/kg. This parameter optimization ensures sufficient binding property with current collector while maintaining adequate lithium ion mobility. The vinyl cyanide-based polymer structure further modulates this balance through its inherent electrochemical stability and ion transport properties.
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 binder resin composition achieves excellent binding properties, improved cycle characteristics, and enhanced battery performance by maintaining the adherence and mobility of lithium ions, resulting in a more uniform electrode mixture layer and increased battery capacity.
Implementation Method 1
the binder resin... provides improved thixotropy
Implementation Method 2
improved adherence to the current collector
Implementation Method 3
maintaining electrochemical stability
Implementation Method 4
enhance lithium ion mobility
Data Source
AI summary
A binder resin for an electrode of a nonaqueous electrolyte secondary battery is provided, which is used as the binder resin in a slurry composition for an electrode of a nonaqueous electrolyte secondary battery, containing a binder resin, an active material and an organic solvent.