High-Nickel Cathode Precursor Structure for Crack-Resistant Compaction
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Solution Overview
Problem
High nickel ternary materials exhibit poorer energy density and lower cycling performance due to volume changes and anisotropic stress during charge/discharge processes, leading to structural collapse and performance degradation.
Innovation Solution
A positive electrode material precursor with a composite structure comprising a radially arranged inner layer and a layer-stacked outer layer, where primary particles of the inner layer grow radially and those of the outer layer are stacked perpendicularly, enhancing mechanical strength and reducing stress anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel ternary material is used to increase capacity and reduce cost, then cost and capacity advantages are achieved, but cycling performance deteriorates and structural stability worsens
Solution Approach 1:
The positive electrode material precursor is segmented into multiple primary particles (5-20 micrometers) that aggregate to form secondary particles (8-15 micrometers). This hierarchical segmentation allows the material to accommodate volume changes during charge-discharge cycles, reducing structural degradation and improving cycling performance while maintaining high nickel content for high capacity.
Solution Approach 2:
The invention uses a composite structure where primary particles with specific crystal orientations aggregate to form secondary particles. The composite morphology, combined with surface modification techniques, creates a multi-scale hierarchical structure that enhances both capacity and cycling stability of high nickel ternary materials.
2Quantity of substance
If radial agglomerated secondary spherical particle structure is used for high nickel ternary precursor, then initial capacity is increased, but compression resistance deteriorates and compaction density decreases
Solution Approach 1:
The invention optimizes the spherical morphology of secondary particles by controlling the radial aggregation of primary particles. The spherical shape with controlled surface characteristics improves packing density and compression resistance while maintaining high initial capacity, addressing the weaknesses of conventional radial agglomerated structures.
3Ease of manufacture
If conventional ternary precursor structure is used, then production is simplified, but particle size consistency and elemental ratio uniformity deteriorate
Solution Approach 1:
The invention employs preliminary classification and surface modification steps in the precursor preparation process. By pre-controlling particle size distribution and surface characteristics before sintering, the method achieves consistent particle size and uniform elemental ratios in the final product while maintaining production efficiency.
Data Source
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AI summary
The present application provides a positive electrode material precursor, a preparation method therefor, a positive electrode material, and a lithium ion battery, and relates to the technical field of new energy. The positive electrode material precursor includes secondary particles each composed of primary particles and is a composite structure comprising an inner layer arranged in a radial shape along the center of the positive electrode material precursor and an outer layer wrapped around the inner layer and formed by laying in layer and stacking lamellar primary particles and arranged in a lamellar shape, wherein the lamellae of the outer layer are perpendicular to the direction of pressure in the compaction process, so that the mechanical strength of the secondary particles of the present application is higher than that of secondary particles in a common radial structure or block structure. After inheriting this structure, the positive electrode material can obtain a higher compaction density than that of a common secondary particle product, and the energy density of the material is significantly improved. In the present application, the inner layer and the outer layer of the secondary particles have different lamellar orientations, and a sintered positive electrode material inherits this characteristic structure. In the charging/discharging cycle, the expansion and contraction directions of the material are different, preventing or reducing the occurrence of cracks causing collapse of the particle structure, and thereby improving the cycle performance.