Positive Electrode Active Material With Core-Shell Lattice Control
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Solution Overview
Problem
Lithium-ion batteries face challenges in maintaining cycle performance and kinetic performance under high temperatures and high voltages due to phase transition failures and interfacial charge transfer resistance.
Innovation Solution
A positive active material with a core and shell layer is developed, where the interplanar spacing of the (003) plane of the first material is controlled to be less than that of the core, and the shell layer has a higher molar percent of Al, enhancing structural stability and lithium-ion conductivity, thereby reducing interfacial charge transfer resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the interplanar spacing of the (003) plane is reduced to improve lithium-ion conductivity, then kinetic performance is improved, but structural stability may deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the surface region (shell) has different crystallographic properties than the core. Specifically, the (003) plane orientation is controlled at the surface to achieve reduced interplanar spacing for improved lithium-ion conductivity, while the core maintains the original structure for structural stability. This local differentiation allows simultaneous optimization of both kinetic performance and structural stability.
Solution Approach 2:
The patent changes the crystallographic parameter (interplanar spacing of (003) plane) at the surface region through controlled orientation and phase structure. By adjusting the surface crystal structure to have reduced d-spacing while maintaining core integrity, the patent achieves improved lithium-ion transport kinetics without compromising the overall structural stability of the material.
2Reliability
If the surface structure is modified to reduce phase transition failure, then cycle performance is improved, but interfacial charge transfer resistance may increase
Solution Approach 1:
The patent applies local quality by differentiating the surface shell from the core in terms of crystal phase and orientation. The surface shell is specifically engineered with controlled (003) plane orientation to prevent phase transition during cycling, thereby improving cycle performance. Meanwhile, the core retains the original high-capacity structure, and the interface between core and shell is designed to maintain good electrical contact, minimizing charge transfer resistance.
Solution Approach 2:
The patent uses a composite core-shell structure where the surface shell acts as a protective layer that prevents phase transition, while the core provides high capacity. The interface between core and shell is designed to ensure good electrical connectivity, thus achieving both improved cycle performance and maintained charge transfer kinetics through the composite architecture.
3Reliability
If a shell layer with high Al content is added to improve structural stability, then cycle performance is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by concentrating the stabilizing element (Al) specifically in the surface shell layer rather than distributing it throughout the entire material. This localized enrichment of Al in the shell provides structural stability and improves cycle performance, while the core maintains its high-capacity composition. This selective local modification reduces the overall complexity compared to uniform doping throughout the material.
Solution Approach 2:
The patent segments the material into core and shell regions with different compositions and functions. The shell layer, containing high Al content, provides structural stability, while the core maintains high capacity. This segmentation allows each region to be optimized independently, improving cycle performance without requiring complex multi-element compositions throughout the entire material.
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
This solution improves both cycle and kinetic performance of lithium-ion batteries by reducing phase transition risks and enhancing lithium-ion conductivity, leading to better energy density and longevity under high stress conditions.
Implementation Method 1
reduces a risk of phase transition failure of an active crystal plane that provides a lithium ion channel
Implementation Method 2
the first material poses a relatively low resistance to the lithium ions transported in the first material, and provides a relatively high lithium-ion conductivity
Implementation Method 3
the shell layer has a higher molar percent of Al, enhancing structural stability and lithium-ion conductivity
Data Source
AI summary
A positive active material, including a matrix and a first material existing on a surface of the matrix. The matrix includes a core and a shell layer. An interplanar spacing d1 of a (003) plane of the first material is less than an interplanar spacing d2 of a (003) plane of the core. By controlling the interplanar spacing d1 of the (003) plane of the first material to be less than the interplanar spacing d2 of the (003) plane of the core, the structural stability of the surface of the positive active material can be improved, and an interfacial charge transfer resistance of the positive active material can be reduced, thereby helping to improve both cycle performance and kinetic performance of the electrochemical device.