Cathode Active Material with Controlled Fine Powder Distribution
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Solution Overview
Problem
Conventional cathode active materials in lithium secondary batteries, primarily in the form of secondary particles, suffer from non-uniform particle size distribution and excessive fine powder generation during the firing process, leading to reduced battery lifespan and increased resistance due to side reactions and internal impedance.
Innovation Solution
A cathode active material comprising one-body primary particles of lithium transition metal complex oxide, with a cumulative relative particle amount of 25% or less having a particle size of 1.5 μm or less, achieved through a post-treatment process applying forces like pressure or shear, to control fine powder generation and enhance particle uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If one-body primary particles are used to reduce aggregation and improve battery characteristics, then side reactions with electrolyte are reduced and particle destruction is minimized, but particle size distribution becomes non-uniform and fine powder generation increases during firing
Solution Approach 1:
The patent applies parameter changes by precisely controlling the cumulative relative particle amount of particles with size 1.5 μm or less to be 25% or less in the particle size distribution. This parameter control resolves the contradiction by maintaining optimal particle distribution that prevents fine powder generation while preserving the benefits of one-body structure for battery performance.
2Manufacturing precision
If post-treatment grinding is applied to achieve uniform particle distribution, then particle size uniformity is improved, but fine powder generation increases and battery characteristics deteriorate
Solution Approach 1:
The patent applies partial action by implementing controlled post-treatment that achieves sufficient particle distribution uniformity without excessive grinding. By limiting the cumulative relative particle amount of fine particles to 25% or less, the treatment provides just enough uniformity improvement while avoiding the harmful effects of excessive fine powder generation.
3Area of stationary object
If secondary particles are used to increase specific surface area, then contact area with electrolyte increases, but internal impedance increases and initial discharge capacity decreases
Solution Approach 1:
The patent applies segmentation by using one-body primary particles instead of aggregated secondary particles. This segmentation approach provides adequate surface area for electrolyte contact while eliminating the internal impedance and capacity loss associated with aggregated structures, as each primary particle acts as an independent functional unit.
Data Source
AI summary
Disclosed is a cathode active material for a lithium secondary battery comprising one-body primary particles of lithium transition metal complex oxide and having a cumulative relative particle amount (%) of particles having a particle size of 1.5 μm or less, which is 25% or less of a total amount of particles in a particle size distribution (PSD) graph (X-axis: particle size (μm), Y-axis: relative particle amount (%)).