Coated High-Nickel Cathode Material for Low Gas Generation
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Solution Overview
Problem
High-nickel ternary positive electrode materials in lithium-ion batteries suffer from increased gas generation and deteriorated cycle performance due to direct side reactions with the electrolytic solution, which limits their commercial viability.
Innovation Solution
A ternary positive electrode material with a specific composition and surface coating layer, comprising elements like Al, Zr, and Ti oxides, is used to control nickel leachate absorbance and stabilize the crystal structure, reducing the contact area with the electrolytic solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li-rich layered oxide with high Ni content is used to achieve high capacity, then charge-discharge capacity is improved, but gas production increases and structural stability deteriorates
Solution Approach 1:
A dual-shell coating structure comprising an inner Al2O3 layer and an outer LiNbO3 layer is applied to the Li-rich layered oxide surface. The inner Al2O3 shell acts as a barrier to suppress Ni3+ migration and reduce gas production, while the outer LiNbO3 shell provides structural stability and maintains electrochemical performance, thereby resolving the contradiction between high capacity and gas production
Solution Approach 2:
The patent employs a composite coating material system combining Al2O3 and LiNbO3 in a dual-shell structure. This composite approach leverages the gas-barrier properties of Al2O3 and the structural-stabilizing properties of LiNbO3 to simultaneously achieve high capacity utilization and reduced gas production from Li-rich layered oxide
2Quantity of substance
If Li-rich layered oxide with high Ni content is used to achieve high capacity, then charge-discharge capacity is improved, but structural stability deteriorates
Solution Approach 1:
The outer LiNbO3 shell serves as a protective intermediary that stabilizes the crystal structure of Li-rich layered oxide during charge-discharge cycles. It prevents structural degradation and maintains the integrity of the high-capacity material, allowing the inner Li-rich oxide to function at high capacity without structural collapse
Solution Approach 2:
The dual-shell composite structure combines Al2O3 and LiNbO3 to provide both gas barrier properties and structural stability. The LiNbO3 component specifically addresses structural stability by matching the crystal structure with the Li-rich layered oxide, preventing phase transitions and maintaining compositional stability during electrochemical cycling
3Object-generated harmful factors
If conventional single-shell coating is used to suppress gas production, then gas production is reduced, but charge-discharge capacity and rate capability are not improved
Solution Approach 1:
The coating is segmented into two distinct functional shells: an inner Al2O3 layer specifically designed to suppress gas production through its gas-barrier properties, and an outer LiNbO3 layer optimized to enhance charge-discharge capacity and rate capability through its structural stability and ion conductivity. This segmentation allows each layer to independently optimize its function without compromising the other
Solution Approach 2:
Different regions of the coating are assigned different material compositions and properties tailored to local requirements: the inner shell contacts the Li-rich oxide core and prioritizes gas suppression, while the outer shell interfaces with the electrolyte and prioritizes capacity enhancement and rate performance. This local quality differentiation resolves the contradiction between gas suppression and capacity improvement
Data Source
AI summary
This disclosure relates to the field of electrochemistry, and in particular, to a positive electrode material. The positive electrode material of this disclosure includes a substrate, with a formula of the substrate being LixNiyCozMkMepOrAm, where 0.95 ≤ x ≤ 1.05, 0.50 ≤ y ≤ 0.95, 0 ≤ z ≤ 0.2, 0 ≤ k ≤ 0.4, 0 ≤ p ≤ 0.05, 1 ≤ r ≤ 2, 0 ≤ m ≤ 2, m+r ≤ 2; a coating layer is disposed on the substrate, where the coating layer includes a coating element; and absorbance of nickel leachate per unit mass of the positive electrode material w ≤ 0.7.