Radial High-Nickel Cathode Structure for Crack-Resistant Cycling
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Solution Overview
Problem
High-nickel ternary positive electrode materials for lithium-ion batteries face issues with internal crack growth during cyclic processes due to volumetric changes, leading to reduced cycle performance and particle instability.
Innovation Solution
A positive electrode material with primary crystal particles distributed in a diverging shape and a length/diameter ratio of 3 or more, combined with a method involving specific salt solutions, complexing agents, and roasting treatments to enhance radial distribution and intercalation/deintercalation of lithium ions, along with a doped surface layer for improved stress conduction and adhesive effects.
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 divided into primary particles (1-5 μm) that aggregate into secondary particles (5-20 μm). The primary particles maintain a length/diameter ratio of 2-5 and are arranged radially, creating a segmented structure that accommodates volumetric changes during phase transitions while maintaining overall particle integrity and preventing pulverization.
Solution Approach 2:
The patent creates a composite structure where primary particles with specific morphology (length/diameter ratio 2-5) are aggregated into secondary particles. This composite architecture combines the high capacity of nickel-rich materials with a structured arrangement that mitigates phase transition damage, achieving both high specific capacity and particle stability.
2Ease of manufacture
If conventional sintering methods are used to prepare high-nickel positive electrode material, then the material can be synthesized, but pre-sintering is required in advance which increases processing difficulty and does not effectively suppress crack growth
Solution Approach 1:
The patent performs preliminary formation of primary particles with specific morphology (length/diameter ratio 2-5) and radial arrangement before final sintering. This preliminary structuring creates a robust framework that prevents crack propagation during subsequent processing and cycling, eliminating the need for additional pre-sintering steps and simplifying the overall manufacturing process.
Solution Approach 2:
The patent controls specific parameters during synthesis including particle size (1-5 μm for primary particles), length/diameter ratio (2-5), and radial distribution proportion (≥60%). By optimizing these parameters, the material achieves both ease of manufacture through direct synthesis and superior crack suppression without requiring complex multi-step sintering procedures.
3Object-affected harmful factors
If secondary coating is performed at low temperature to form protective effect on particle surface, then surface protection is achieved, but it lacks mutually supportive effect among primary particles and fails to suppress internal crack growth
Solution Approach 1:
The patent establishes the radial arrangement of primary particles with appropriate length/diameter ratios before coating. This preliminary structural configuration creates mutual support among primary particles that prevents internal crack propagation. The subsequent low-temperature coating then provides surface protection without compromising the internal structural integrity already established.
Solution Approach 2:
The patent creates a composite structure combining the radially arranged primary particles (providing internal structural support) with a protective coating layer (providing surface protection). This multi-layer composite architecture simultaneously achieves both surface protection and internal crack suppression, overcoming the limitations of coating alone.
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 solution significantly enhances the cycle performance and particle strength of the lithium-ion battery, allowing it to withstand higher stresses and maintain capacity retention over multiple cycles.
Implementation Method 1
adding a complexing agent and a precipitant into a reaction kettle to obtain a first mixed solution; adding the mixed metal salt solution into the reaction kettle at a flow rate of 1-2.5 L/h to perform a first reaction, wherein the first reaction is performed at 50-80° C. for 6-10 h; filtering the first mixed slurry to obtain a precursor crystal nucleus
Implementation Method 2
adding a lithium source and an additive M into a roasting kettle to perform a first roasting treatment, wherein the first roasting treatment is performed at 700-900° C. for 8-18 h; adding an additive N into the roasting kettle to perform a second roasting treatment, wherein the second roasting treatment is performed at 600-800° C. for 10-20 h
Implementation Method 3
subjecting a mixture comprising a lithium source and a metal hydroxide to a first heat treatment in an oxidizing gas atmosphere, to obtain nickel-based active material secondary particles
Data Source
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.