Multi-Element Cathode Structure for High-Pressure Electrode Rolling
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Solution Overview
Problem
Existing lithium-ion battery cathode materials are prone to fracture under high rolling pressure, leading to high defect rates and compromised safety, high-temperature stability, and cycle performance, particularly in electric vehicle batteries.
Innovation Solution
A multi-element cathode material with secondary particles composed of primary particles arranged in an irregular, non-radial, and disordered manner, featuring a high ratio of grain boundaries and low porosity, enhancing processability and resistance to fracture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If rolling pressure is increased to improve energy density, then energy density is improved, but the cathode material plate fractures
Solution Approach 1:
The patent applies local quality by creating a radial distribution of crystal grain orientations within the cathode material particles. The crystal grains are oriented such that their c-axes are predominantly aligned in the radial direction from the particle center to the surface. This localized orientation arrangement allows different regions of the particle to respond differently to applied pressure, with the radial orientation providing enhanced mechanical strength and crack resistance in the direction of rolling pressure, thereby enabling higher energy density without plate fracture.
2Duration of action of stationary object
If radial distribution is designed to improve cycle performance, then cycle performance is improved, but the plate becomes prone to fracture under rolling pressure
Solution Approach 1:
The patent applies parameter changes by modifying the crystal grain orientation parameters within the cathode material particles. Specifically, it controls the orientation distribution of crystal grains so that their c-axes are radially aligned, and adjusts parameters such as grain size, grain boundary characteristics, and phase composition. These parameter changes enable the material to simultaneously achieve improved cycle performance through stable lithium ion diffusion paths and enhanced resistance to rolling pressure through the radial orientation structure.
Data Source
AI summary
The present disclosure relates to the technical field of lithium-ion batteries, and particularly, to a multi-element cathode material, a preparation method thereof, a positive electrode plate, and a lithium-ion battery. The multi-electrode material is composed of secondary particles agglomerated by primary particles. A ratio of a total cross-sectional area of the primary particles with more than 5 grain boundaries to a cross-sectional area of the secondary particles is greater than or equal to 3:4. A porosity on a cross-section of the secondary particles is less than or equal to 2%. A grain boundary is a contour line of an interface between the primary particles with the same structure but different orientations on the cross-section of the secondary particles and a length of the grain boundary is greater than or equal to 0.1 μm.