Negative Electrode Slurry Two-Step Kneading for Si Expansion Control

The patent uses a composite binder system comprising both polyacrylic acid and carboxnymethylcellulose in specific weight ratios (0.1-10:0.1-10 by weight) to achieve synergistic effects. This composite approach allows the slurry to simultaneously reduce electrode expansion during charge-discharge cycles while maintaining excellent cycling performance, resolving the contradiction between partial improvement and insufficient expansion control.

The patent optimizes the weight ratio parameters of the binder components (polyacrylic acid and carboxnymethylcellulose) within specific ranges (0.1-10:0.1-10 by weight) to achieve the desired balance between cycling performance and expansion control. By adjusting these compositional parameters, the slurry formulation achieves sufficient expansion reduction while maintaining reliable cycling performance.

The carboxnymethylcellulose binder acts as an intermediary material that mediates between the carbon-based and Si-based active materials. It provides a stable matrix that accommodates the expansion and shrinkage of Si-based materials during charge-discharge cycles, allowing the high-capacity composite active material system to function without excessive electrode expansion.

The patent controls the weight ratio parameters of the binder components within specific ranges to optimize the balance between maintaining battery capacity (from carbon and Si-based materials) and controlling electrode expansion. The optimized binder composition enables the electrode to accommodate high-capacity active materials while minimizing expansion.