Bimodal Battery Electrode Composition for High-Rate Capacity
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Solution Overview
Problem
Current non-aqueous electrolyte secondary batteries face challenges in maintaining large capacity when discharging at high currents, necessitating improvements in output characteristics.
Innovation Solution
The development of an electrode composition for non-aqueous electrolyte secondary batteries, featuring a molded body with a bimodal volume-based particle size distribution of electrode active material, combined with a conductive assistant and solid electrolyte, optimized to enhance ionic and electronic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the particle size of the positive electrode active material is reduced to improve output characteristics, then the output characteristics are improved, but the energy density decreases
Solution Approach 1:
The electrode active material particles are segmented into two distinct size groups: small particles (0.1-1.0 μm) that provide high surface area and good ionic contact for high output characteristics, and large particles (1.0-10.0 μm) that provide high volumetric energy density. This segmentation allows both size benefits to coexist in the same electrode structure.
Solution Approach 2:
Different regions of the electrode composition are assigned different particle size qualities. The small particles are distributed throughout to ensure good ionic conductivity and contact with the solid electrolyte, while large particles are also present to maintain high energy density. This local differentiation of particle quality optimizes both output characteristics and energy density simultaneously.
2Reliability
If a non-aqueous electrolyte solution containing organic solvent is used to achieve good electrochemical performance, then the electrochemical performance is improved, but the safety deteriorates due to flammability
Solution Approach 1:
The electrolyte phase is changed from liquid non-aqueous electrolyte solution to solid electrolyte. This parameter change in the physical state eliminates the flammability issue inherent in organic solvents while maintaining good ionic conductivity and electrochemical performance through the solid electrolyte material.
Data Source
AI summary
The electrode for a non-aqueous electrolyte secondary battery of the present invention has a molded body of an electrode composition containing at least particles of an electrode active material, a solid electrolyte, and particles of a conductive assistant. The volume-based particle size distribution of the particles of the electrode active material has two distributions: that is, a distribution of small particles with a diameter D1 at the maximum frequency, and another distribution of large particles with a diameter D2 at the maximum frequency. The volume fraction of the large particles is larger than the volume fraction of the small particles. The mode diameters D3 of the particles of the conductive assistant obtained from the cross section and D2 are D3≤D2. The average distance of the gravity centers between adjacent particles of the conductive assistant has a relationship of L≤D2.