Multiphase Lithium Composite Oxide for High-Capacity Battery
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Solution Overview
Problem
Existing lithium-ion battery positive-electrode active materials lack high capacity and stability due to limited lithium diffusion paths and structural instability during charging and discharging.
Innovation Solution
A lithium composite oxide with a multiphase mixture structure, comprising a first phase with a crystal structure belonging to space group Fm-3m and a second phase with a structure belonging to space groups Fd-3m, R-3m, or C2/m, optimizing the integrated intensity ratio of X-ray diffraction peaks to achieve enhanced lithium diffusion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single-phase lithium composite oxide is used, then the crystal structure is simple, but the lithium diffusion path is limited and capacity is low
Solution Approach 1:
The lithium composite oxide is divided into multiple phases with different crystal structures (Fm-3m, Fd-3m, R-3m, or C2/m space groups). Each phase provides different lithium diffusion paths and capacities, and the combination of phases creates synergistic effects that overcome the limitations of single-phase materials.
Solution Approach 2:
The patent creates a composite material system by combining lithium composite oxides with different crystal structures in a multiphase mixture. This composite approach allows the material to exhibit properties that are superior to individual phases, including enhanced lithium diffusion capacity and improved structural stability during charging and discharging cycles.
2Quantity of substance
If the crystal structure is optimized for high capacity, then lithium intercalation capacity increases, but structural stability during charging and discharging deteriorates
Solution Approach 1:
The material is segmented into multiple phases where each phase can undergo structural changes independently. The Fm-3m phase provides high lithium capacity while the Fd-3m, R-3m, or C2/m phases maintain structural stability, allowing the composite to achieve both high capacity and stability simultaneously.
Solution Approach 2:
The patent optimizes the ratio of phases by controlling the integrated intensity ratio I(18°-20°)/I(43°-46°) in the XRD pattern, ensuring it falls within 0.05≤I(18°-20°)/I(43°-46°)≤0.90. This parameter control allows tuning of the balance between capacity and stability by adjusting the relative amounts of different crystal phases in the composite.
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 multiphase structure increases lithium intercalation and deintercalation capacity, providing a high-capacity and long-life battery with improved diffusibility and structural stability.
Implementation Method 1
The multiphase structure increases lithium intercalation and deintercalation capacity, providing a high-capacity and long-life battery with improved diffusibility
Implementation Method 2
in an X-ray diffraction (XRD) pattern of the lithium composite oxide, the integrated intensity ratio I(18°-20°)/I(43°-46°) of a first maximum peak I(18°-20°) within a first range of 18 degrees to 20 degrees at a diffraction angle 2θ to a second maximum peak I(43°-46°) within a second range of 43 degrees to 46 degrees at the diffraction angle 2θ satisfies 0.05≤I(18°-20°)/I(43°-46°)≤0.90
Data Source
AI summary
A positive-electrode active material contains a lithium composite oxide, wherein the lithium composite oxide is a multiphase mixture including a first phase, of which a crystal structure belongs to a space group Fm-3m, and a second phase, of which a crystal structure belongs to a space group Fd-3m; and in an XRD pattern of the lithium composite oxide, the integrated intensity ratio I(18°-20°)/I(43°-46°) of a first maximum peak I(18°-20°) within a first range of 18 degrees to 20 degrees at a diffraction angle 2θ to a second maximum peak I(43°-46°) within a second range of 43 degrees to 46 degrees at the diffraction angle 2θ satisfies 0.05≤I(18°-20°)/I(43°-46°)≤0.90.