Silicon Oxide Negative Electrode Current Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-aqueous electrolyte secondary batteries using silicon oxide as a negative electrode material face challenges in achieving a balance between high initial capacity and good cycling performance due to irreversible capacity loss and degradation caused by lithium pre-doping, which concentrates electric current and promotes deterioration.
Innovation Solution
A two-component system of undoped silicon oxide particles and lithium-doped silicon oxide particles with specific particle size ratios is used, where the ratio of the average particle sizes is between 1.5 and 11.2, to distribute electric current evenly and mitigate reactivity differences, thereby enhancing cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium pre-doping is applied to silicon oxide, then irreversible capacity loss is decreased and initial capacity is improved, but cycling performance is degraded due to alkaline component formation and concentrated electric current
Solution Approach 1:
The negative electrode active material is segmented into two distinct types of silicon oxide particles: undoped SiOx particles and Li-doped SiOx particles. This segmentation allows each particle type to fulfill different functional roles - undoped particles provide structural stability while Li-doped particles contribute to capacity, thereby resolving the contradiction between initial capacity and cycling performance.
Solution Approach 2:
Different regions of the negative electrode are assigned different local qualities through the use of undoped and Li-doped SiOx particles. The Li-doped particles are specifically positioned to provide high capacity contribution, while undoped particles are distributed to maintain structural integrity and reduce alkaline component formation, creating a spatially differentiated quality distribution that balances capacity and stability.
2Quantity of substance
If a two-component system of undoped SiOx and Li-doped SiOx is adopted, then irreversible capacity loss is decreased and initial capacity is improved, but electric current concentrates to Li-doped SiOx causing cycling performance degradation
Solution Approach 1:
The particle size parameter is changed and optimized to resolve current concentration issues. By controlling the average particle size of undoped SiOx to be 0.5 μm to 5 μm and Li-doped SiOx to be 1 μm to 10 μm, the electrical resistance and current distribution are adjusted. This parameter optimization ensures that electric current is evenly distributed between both particle types, preventing harmful current concentration while maintaining high initial capacity.
Data Source
AI summary
A negative electrode for a non-aqueous electrolyte secondary battery is provided. The negative electrode includes at least a negative electrode active material. The negative electrode active material includes a first type of silicon oxide particles and a second type of silicon oxide particles. The first type of silicon oxide particles has not been pre-doped with lithium. The second type of silicon oxide particles has been pre-doped with lithium. The first type of silicon oxide particles has a first average particle size. The second type of silicon oxide particles has a second average particle size. The ratio of the second average particle size to the first average particle size is not lower than 1.5 and not higher than 11.2.