Cathode Composite Oxide Void Structure for Higher Li-Ion Capacity
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Solution Overview
Problem
There is a need to increase the capacity of non-aqueous electrolyte secondary batteries, particularly lithium ion batteries, as existing technologies have limitations in enhancing the performance of positive electrode active materials.
Innovation Solution
A lithium-containing composite oxide is used as a positive electrode active material, characterized by secondary particles with a high number of voids (≥300 per 76.46 µm²) and narrow nearest inter-void distances (≤170 nm), which are produced through controlled synthesis processes including specific firing and washing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of voids in secondary particles is increased to improve battery capacity, then the capacity increases, but the structural stability may deteriorate
Solution Approach 1:
The patent applies porous materials by introducing a controlled void structure within secondary particles of the lithium-containing composite oxide. The voids occupy 0.1-5.0% of the total volume and have specific size distributions (0.1-10.0 μm diameter), creating a porous internal architecture that increases battery capacity while maintaining structural integrity through the aggregated primary particle framework
Solution Approach 2:
The patent applies local quality by creating non-uniform void distribution within secondary particles. The voids are strategically positioned and sized (with specific diameter ranges and density requirements) to optimize local ion transport pathways while maintaining overall structural stability. The void structure varies within different regions of the secondary particles to balance capacity enhancement with structural integrity
2Reliability
If the void ratio is increased to enhance capacity, then the capacity retention rate improves, but the density and energy density may worsen
Solution Approach 1:
The patent applies parameter changes by precisely controlling the void ratio within the range of 0.1-5.0% and the void diameter within 0.1-10.0 μm. These parameter optimizations ensure that the void structure enhances capacity retention through improved ion diffusion pathways while minimizing the impact on overall particle density and energy density
3Productivity
If the nearest inter-void distance is reduced to improve ion diffusion, then the charge-discharge efficiency increases, but the mechanical strength may deteriorate
Solution Approach 1:
The patent applies porous materials with optimized pore spacing where the nearest inter-void distance is controlled at 0.03-0.50 μm. This creates a porous network that facilitates rapid ion diffusion for high charge-discharge efficiency while the interconnected primary particle structure provides mechanical reinforcement to maintain structural strength
Data Source
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AI summary
Provided is a positive electrode active material for non-aqueous electrolyte secondary batteries which enables improvement in battery capacity. This positive electrode active material for non-aqueous electrolyte secondary batteries is characterized by having a lithium-containing composite oxide containing secondary particles formed by aggregation of primary particles, and is characterized in that: the lithium-containing composite oxide has, in cross-sectional observation of the secondary particles, 300 or more voids observed per visual field of 76.46 µm2; and the median of nearest-void distances of the voids observed per visual field of 76.46 µm2 is 170 nm or less.