High-Nickel Cathode Material with Porous Buffer Layer Against Cracking
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Solution Overview
Problem
High-nickel layered positive electrode active materials experience severe volumetric deformation during charging and discharging, leading to internal cracking and reduced cycle performance due to stress accumulation and electrolyte penetration.
Innovation Solution
A multilayered structure comprising a core doped with element M', an intermediate porous layer, and a shell layer is introduced, where the core includes Li a1 Ni x1 M y1 M' z1 O m1 R n1, the intermediate layer is porous, and the shell layer includes Li a2 Ni x2 M y2 M' z2 O m2 R n2, with specific compositional and structural controls to enhance volume stability and mitigate cracking risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-nickel layered positive electrode active material is used, then specific capacity is improved, but volume stability deteriorates due to large volumetric deformation in charging and discharging
Solution Approach 1:
The positive electrode active material is divided into a core region and a shell layer, with the core containing high-nickel content material for high specific capacity and the shell layer providing structural stability. This segmentation allows each region to perform its specialized function, resolving the contradiction between high capacity and volume stability.
Solution Approach 2:
The patent creates a composite structure combining high-nickel layered material in the core with a stabilizing shell layer. The composite design integrates the high capacity advantage of high-nickel material with the structural stability of the shell, eliminating the volumetric deformation problem while maintaining high specific capacity.
2Use of energy by moving object
If high-nickel layered positive electrode active material is used, then specific capacity is improved, but cycle performance deteriorates due to internal cracking
Solution Approach 1:
By segmenting the material into core and shell regions, the patent isolates the high-nickel core that provides high capacity from the cracking-prone surface. The shell layer acts as a protective barrier that prevents crack initiation and propagation, thereby improving cycle performance while maintaining high specific capacity.
Solution Approach 2:
The shell layer serves as a pre-established protective barrier that cushions against the development of internal cracks during cycling. This beforehand cushioning prevents the harmful effects of cracking before they can occur, ensuring long-term cycle performance of the high-nickel material.
3Use of energy by moving object
If high-nickel layered positive electrode active material is used, then specific capacity is improved, but reliability deteriorates due to crack extension to particle surface and electrolyte penetration
Solution Approach 1:
The segmentation into core and shell creates a physical barrier that separates the high-capacity core from the electrolyte environment. The shell layer prevents electrolyte penetration to the core surface, eliminating the harmful effects of electrolyte contact while preserving the high specific capacity of the high-nickel material.
Solution Approach 2:
The shell layer acts as an intermediary barrier between the high-nickel core and the electrolyte. This intermediary structure allows the core to maintain high capacity while protecting it from harmful electrolyte penetration and crack extension, resolving the contradiction between capacity and reliability.
Data Source
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AI summary
A positive electrode active material and a preparation method therefor, a positive electrode plate, a battery, and a power consuming device. The positive electrode active material comprises: an inner core, which includes Lia1Nix1My1M'z1Om1Rn1, wherein 0.9 ≤ a1 ≤ 1.1, 0.6 ≤ x1 < 1, 0 ≤ y1 ≤ 0.4, 0 < z1 ≤ 0.01, 1.9 ≤ m1 ≤ 2.2, and 0 ≤ n1 ≤ 0.1; M comprises at least one of Co, Mn, Al, Ta, Mg, Mo, Ga, Sn, Ge, Te, La and Ce; M' comprises at least one of Y, La, Mo, Zr, W, Sb, Nb, Te, Sr, Ti, or Ga; R comprises at least one of F, Cl, or S; an intermediate layer, which is coated on at least a part of the outer surface of the inner core and has a porous structure; and an outer shell layer, which is coated on at least a part of the outer surface of the intermediate layer and includes Lia2Nix2My2M'z2Om2Rn2, wherein 0.9 ≤ a2 ≤ 1.1, 0.6 ≤ x2 <1, 0 ≤ y2 ≤ 0.4, 0 ≤ z2 ≤ 0.01, 1.9 ≤ m2 ≤ 2.2, and 0 ≤ n2 ≤0.1.