High-Nickel Cathode Core-Shell Layers for Stable Lithium Transport
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Solution Overview
Problem
Lithium-ion batteries with high-nickel ternary positive electrode active materials face challenges in achieving high energy density, good cycle performance, and safety performance due to lattice distortion and surface impurity lithium issues, which degrade energy and safety performance.
Innovation Solution
A high-nickel positive electrode active material with a core-shell structure, where the core comprises Li1+a[NixCoyMz]O2 and the shell consists of a fast ionic conductor layer and an oxide layer, reducing surface impurity lithium and enhancing intercalation/deintercalation rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the content of nickel atoms in the ternary positive electrode active material is increased to improve energy density, then the energy density is improved, but the cycle performance and safety performance deteriorate
Solution Approach 1:
The patent divides the coating structure into multiple segments: an inner coating layer containing aluminum and silicon elements, and an outer coating layer containing boron, phosphorus, and sulfur elements. This segmented coating structure allows different regions to perform different functions - the inner layer addresses lattice distortion while the outer layer suppresses surface impurity lithium, thereby resolving the contradiction between high nickel content and performance stability
Solution Approach 2:
The patent employs composite coating materials combining multiple elements (Al, Si, B, P, S) with the high-nickel ternary positive electrode active material. This composite structure creates a synergistic effect where the coating layers collectively prevent structural collapse and reduce side reactions, enabling the battery to achieve both high energy density and good cycle performance with 80% or higher nickel content
2Use of energy by moving object
If the content of nickel atoms is increased to achieve high energy density, then the energy density is improved, but structural collapse occurs leading to degraded cycle performance
Solution Approach 1:
The patent applies local quality modification by incorporating aluminum and silicon elements specifically in the inner coating layer adjacent to the high-nickel ternary positive electrode active material. This localized placement of stabilizing elements directly addresses the lattice distortion issue at the critical interface, preventing structural collapse while maintaining high nickel content for energy density
3Use of energy by moving object
If the content of nickel atoms is increased to improve energy density, then the energy density is improved, but surface impurity lithium increases causing safety issues
Solution Approach 1:
The patent converts the harmful surface impurity lithium into a beneficial component by incorporating boron, phosphorus, and sulfur elements in the outer coating layer. These elements form stable surface compounds that suppress the formation of harmful impurity lithium while utilizing the nickel-rich material's high capacity, thereby transforming a safety hazard into a controlled feature
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 core-shell structure improves energy density, cycle performance, and safety by preventing structural collapse and reducing side reactions, leading to more stable lithium-ion batteries.
Implementation Method 1
the first shell layer is a fast ionic conductor consisting of four elements of lithium, aluminum, silicon and oxygen
Data Source
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AI summary
The present application provides a high-nickel ternary positive electrode active material, which comprises a core Li1+a[LixCoyMnzMb]O2, a fast ionic conductor LiαAlXSiYO4 of a first shell layer, an oxide of an element R of a second shell layer, and a transition layer LipRqOw formed between the first shell layer and the second shell layer. In the high-nickel ternary positive electrode active material of the present application, the surface impurity lithium amount is significantly reduced, and by creatively converting the surface impurity lithium into effective components in the fast ionic conductors LiαAlXSiYO4 and LipRqOw which accelerate the intercalation/deintercalation of lithium ions in the core material, the decomposition and gas production of an electrolyte solution caused by the surface impurity lithium is greatly improved, such that a high-nickel ternary lithium-ion battery has high energy density as well as good cycle performance and safety performance.