Composite Electrode Particle Design for Battery Rate Performance
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Solution Overview
Problem
Conventional composite particles for lithium-ion secondary battery electrodes with reduced particle size and carbon coating fail to enhance ion diffusion and electron conductivity effectively, leading to inadequate discharge capacities and rate characteristics, and pose challenges in handling large volumes of fine particles during production.
Innovation Solution
A composite particle design featuring a particulate core with a mother particle coated by an electron-conducting layer containing microparticles with a size of 300 nm or less, where both the mother and microparticles act as active materials, enhancing ion diffusion and electron conductivity, and a carbon content optimized to prevent excessive binder usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If particle size of active material is reduced to enhance ion diffusion capability and increase contact area with electrolytic solution, then ion diffusion capability is improved, but handling and processing of fine particles becomes difficult
Solution Approach 1:
The active material particles are segmented into fine particles (300 nm or less) and aggregated into larger composite particles (1 μm to 20 μm) containing multiple fine particles. This segmentation enables both high ion diffusion capability through fine particle size and ease of handling through larger composite structure. The composite particle acts as a cluster of fine particles that can be easily processed while maintaining the electrochemical advantages of fine particles.
Solution Approach 2:
Multiple fine particles are nested within a single composite particle structure. The fine particles (300 nm or less) are contained within the composite particle (1 μm to 20 μm), creating a nested structure where the inner fine particles provide high ion diffusion capability while the outer composite structure provides ease of handling and processing.
2Reliability
If fine particles of active material are mixed with carbon to compound the active material with carbon, then electron conductivity is improved, but contact between active material and conductive material becomes difficult leading to potential reduction in electroconductivity
Solution Approach 1:
The fine particles and carbon particles are merged into a single composite particle structure through coating or aggregation. This merging ensures intimate contact between the active material and conductive carbon, enabling efficient electron conductivity while maintaining the fine particle size for high ion diffusion capability.
Solution Approach 2:
The composite particle exhibits local quality differentiation where the surface or specific regions contain high concentrations of conductive carbon material to ensure electron conductivity, while the interior maintains fine active material particles for ion diffusion. This localized arrangement optimizes both electron and ion transport pathways.
Data Source
AI summary
A composite particle for electrode as an active material capable of forming an electrochemical device with excellent discharge capacities and rate characteristics is provided. A composite particle for electrode according to the present invention comprises a particulate core including at least one mother particle containing an electrode active material, and an electron-conducting layer which covers at least part of the surface of the particulate core, the electron-conducting layer including carbon and microparticles containing an electrode active material, and the microparticles having a particle size of 300 nm or less.