Silicon-Carbon Negative Electrode Composite for Side-Reaction Suppression
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Solution Overview
Problem
Si-containing materials used as negative electrode active materials in non-aqueous electrolyte secondary batteries face issues with side reactions and increased reaction resistance, deteriorating the cycle characteristic of the battery.
Innovation Solution
A Si-containing composite material is developed, comprising an amorphous carbon phase with silicon and a metal oxide dispersed within, where the metal oxide content is between 0.001% and 2% by mass, and silicon content is less than 60% by mass, to suppress side reactions and maintain low reaction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Si-containing material is used as negative electrode active material, then battery capacity is improved, but side reactions with electrolyte increase and cycle characteristic deteriorates
Solution Approach 1:
The patent uses a composite material consisting of silicon particles dispersed in a carbon matrix with metal oxide additives. This composite structure allows the silicon to provide high capacity while the carbon matrix suppresses side reactions with the electrolyte. The metal oxide component further enhances the suppression of side reactions, resolving the contradiction between achieving high capacity and maintaining good cycle characteristic.
Solution Approach 2:
The carbon matrix acts as an intermediary between silicon and the electrolyte, preventing direct contact and side reactions. Additionally, metal oxide serves as a mediator that further suppresses harmful interactions. This intermediary approach allows silicon to function at high capacity while protecting the system from degradation, thus improving cycle characteristic.
2Quantity of substance
If Si-containing material is used as negative electrode active material, then battery capacity is improved, but reaction resistance increases
Solution Approach 1:
The composite structure of silicon dispersed in carbon with metal oxide additives creates a material that maintains low reaction resistance. The carbon matrix provides a stable interface with the electrolyte, while metal oxide further reduces resistance by suppressing side reactions. This allows the high-capacity silicon to function effectively without suffering from increased reaction resistance.
Solution Approach 2:
The patent optimizes the composition parameters by controlling the amount of metal oxide (0.01-5 mass%) and silicon content, along with the particle size distribution. By adjusting these parameters, the material achieves both high capacity and low reaction resistance, resolving the contradiction between these two properties.
Data Source
AI summary
A composite material (30) as one example of the embodiment of the present invention includes an Si-containing composite material (30) that contains an amorphous carbon phase (31), and silicon (32) and a metal oxide (35) which are dispersed in the carbon phase (31). The content of the metal oxide (35) is 0.001-2% by mass relative to the mass of the Si-containing composite material (30). The content of the silicon (32) is 60% by mass or less relative to the mass of the Si-containing composite material (30).