Negative Electrode Binder Distribution for Silicon-Carbon Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current secondary batteries face challenges in achieving high energy density and stable battery characteristics, particularly in electronic devices where size, weight, and performance are critical, due to limitations in negative electrode materials and binder distribution.
Innovation Solution
A negative electrode configuration for secondary batteries is developed, comprising carbon and silicon-based active material particles with a polyvinylidene fluoride binder, where the binder abundance ratio around silicon particles is higher than around carbon particles, enhancing the stability and capacity of the electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon material is used as negative electrode active material to increase capacity, then energy density is improved, but expansion and shrinkage during charging/discharging occurs causing poor cycle characteristics
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of polyvinylidene fluoride binder around silicon particles, with higher binder abundance (M2/M1 ratio > 1) specifically at silicon particle surfaces where expansion/shrinkage occurs. This localized binder concentration provides targeted mechanical support and stress distribution exactly where needed, preventing electrode degradation while maintaining high silicon content for high energy density.
Solution Approach 2:
The patent uses composite materials by combining silicon particles with carbon materials and polyvinylidene fluoride binder to create a negative electrode active material layer. The silicon-carbon composite structure with optimized binder distribution provides both high capacity (from silicon) and structural stability (from carbon and binder), resolving the contradiction between high energy density and cycle characteristics.
2Reliability
If binder abundance around silicon particles is increased to prevent expansion/shrinkage, then cycle characteristics are improved, but electrode structure complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the binder abundance ratio (M2/M1) as a key parameter, where M2 is binder abundance around silicon particles and M1 is binder abundance around carbon particles. By setting M2/M1 > 1, the patent achieves improved cycle characteristics through controlled binder distribution without requiring complex electrode architecture, simply adjusting material composition parameters.
Data Source
AI summary
A secondary battery includes a negative electrode including a plurality of first negative electrode active material particles, second negative electrode active material particles, and a negative electrode binder. The first negative electrode active material particles include a carbon material, and the second negative electrode active material particles include a silicon material. The negative electrode binder includes polyvinylidene fluoride and at least a part of the negative electrode binder is provided on a part of the surface of each of the second negative electrode active material particles. A ratio M2/M1 of an abundance M2 of the negative electrode binder on the surface and in proximity to each of the second negative electrode active material particles to an abundance M1 of the negative electrode binder on the surface and in proximity to each of the first negative electrode active material particles is larger than 1.