Carbon-Coated Graphite Anodes With Controlled Edge Planes
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Solution Overview
Problem
Lithium secondary batteries face deterioration and reduced capacity during high-temperature storage due to side reactions between the negative electrode and electrolyte solution, leading to loss of lithium participating in reversible reactions.
Innovation Solution
A negative electrode active material is developed using artificial graphite with a carbon coating layer, where the edge plane has a specific surface area of 1.0 m2/g to 1.9 m2/g, minimizing side reactions and enhancing lithium retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If artificial graphite with smaller diameter is used to suppress side reactions, then reliability improves, but productivity deteriorates due to reduced energy density
Solution Approach 1:
The invention changes the particle size parameter of artificial graphite to a specific range (5 μm to 20 μm) to optimize the balance between suppressing side reactions and maintaining energy density. This parameter optimization resolves the contradiction by finding the optimal size that provides sufficient surface area reduction for reliability while maintaining adequate capacity for productivity.
Solution Approach 2:
The invention uses composite artificial graphite particles formed by aggregating multiple primary particles, creating a hierarchical structure that combines the benefits of smaller particles (reduced side reactions) with the advantages of larger particles (higher energy density). This composite structure resolves the contradiction between reliability and productivity.
2Reliability
If artificial graphite with smaller diameter is used to reduce side reaction sites, then reliability improves, but loss of substance worsens due to reduced capacity
Solution Approach 1:
The invention optimizes the particle size parameter within a specific range (5 μm to 20 μm) to balance the reduction of side reaction sites with the maintenance of lithium capacity. This parameter control ensures that while side reactions are suppressed, the graphite retains sufficient capacity to participate in reversible lithium reactions.
Solution Approach 2:
The invention uses uniformly sized artificial graphite particles with controlled morphology that replicate optimal structural characteristics, ensuring consistent performance in suppressing side reactions while maintaining reversible lithium capacity across the electrode material.
Data Source
AI summary
A negative electrode active material which includes a core including artificial graphite, and a carbon coating layer disposed on the surface of the core, wherein an edge plane of the negative electrode active material has a specific surface area of 1.0 m2/g to 1.9 m2/g, a negative electrode including the same, and a secondary battery including the negative electrode.