High-Nickel Cathode Grain Orientation for Crack-Resistant Cycling
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Solution Overview
Problem
Existing high-nickel ternary positive electrode materials for lithium ion batteries suffer from internal crack growth during the charging and discharging process due to volumetric changes, leading to reduced cycle performance and particle pulverization.
Innovation Solution
A positive electrode material is developed with primary crystal particles distributed in a diverging shape along the diameter direction, having a length/diameter ratio of 3 or greater and a radial distribution proportion of 60% or more, combined with an oxide distribution and a cladding layer to enhance structural integrity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel ternary positive electrode material is used to achieve high mass specific capacity and volumetric specific capacity, then the capacity is improved, but the crystal structure undergoes many phase transitions during charging and discharging, causing volumetric change and particle pulverization
Solution Approach 1:
The positive electrode material is segmented into primary particles (5-20 μm) that aggregate to form secondary particles (10-30 μm). This segmentation allows the primary particles to maintain structural integrity during phase transitions while the aggregate structure accommodates volumetric changes, preventing particle pulverization and improving cycle performance.
Solution Approach 2:
The positive electrode material uses a composite structure combining multiple elements (Ni, Co, Mn, Al) in the ternary compound LiNi1-x-yCoxM yO2. This composite material approach leverages the high capacity of nickel while cobalt, manganese, and aluminum provide structural stability, reducing phase transitions and volumetric changes during cycling.
2Shape
If pre-sintering is performed in advance during the preparation process to obtain directionally arranged primary particles, then the particle arrangement is improved, but the processing difficulty increases
Solution Approach 1:
The precursor particles are pre-formed with controlled morphology (5-20 μm primary particles) before the final sintering process. This preliminary action of shaping particles in the precursor stage eliminates the need for complex post-sintering processing to achieve directional arrangement, simplifying the overall manufacturing process while maintaining good particle morphology.
3Object-affected harmful factors
If secondary coating is performed at low temperature to form protective effect on particle surface, then the surface protection is improved, but the protection only covers the particle surface and lacks mutually supportive effect among primary particles, failing to suppress internal crack growth
Solution Approach 1:
The coating is applied at the primary particle level rather than only on the secondary aggregate surface. This segmentation ensures that each primary particle (5-20 μm) receives protective coating and maintains structural integrity, creating a mutually supportive network that suppresses internal crack growth throughout the material.
Solution Approach 2:
The low-temperature secondary coating process applies protective material specifically to the surface of primary particles, creating local quality enhancement at the critical interface where cracks would initiate. This localized protection combined with the segmented structure effectively suppresses internal crack growth while maintaining surface protection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The material improves cycle performance by facilitating lithium ion intercalation/deintercalation and stress conduction, resulting in enhanced particle strength and prolonged battery life.
Implementation Method 1
sintering the mixture to obtain the high-nickel positive electrode material with primary particles being directionally arranged
Implementation Method 2
the cladding layer prevents element loss and suppresses secondary phase formation on the particle surface
Implementation Method 3
facilitating lithium ion intercalation/deintercalation
Data Source
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AI summary
A positive electrode material for a lithium ion battery and a preparation method therefor, and a lithium ion battery, relating to the technical field of secondary batteries. The positive electrode material comprises a high-nickel multi-element positive electrode material, the high-nickel multi-element positive electrode material is formed by agglomerating multiple primary grains, and the primary grains are distributed in a divergent shape along the diameter direction of the high-nickel multi-element positive electrode material, the aspect ratio L/R of the primary grains in the positive electrode material is greater than or equal to 3, and the radial distribution ratio of the primary grains in the positive electrode material is greater than or equal to 60%. The lithium ion battery containing the positive electrode material has high capacity and greatly improved particle strength.