Positive Electrode Active Material for Lithium-Ion Battery
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Solution Overview
Problem
Existing positive electrode active materials for non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, do not adequately address the need for increased capacity, particularly when used in vehicles, despite efforts to improve crystal structure and composition.
Innovation Solution
A positive electrode active material with a specific crystal structure belonging to the space group R-3m, represented by the compositional formula Li α Na β Ni 1-b-c Mn b X c O d, where the integrated intensity ratio I 101 /I 012 of X-ray diffraction peaks is controlled to less than 2.2, stabilizing the layered rock-salt structure and enhancing charge-discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional lithium-transition metal composite oxide is used as positive electrode active material, then basic battery function is achieved, but charge-discharge capacity is insufficient for vehicle applications
Solution Approach 1:
The patent applies parameter changes by precisely controlling the integrated intensity ratio I(101)/I(012) of X-ray diffraction peaks to be 1.2 or more, and controlling the ratio of Ni 3d3/2 to Ni 3d5/2 peak intensities. These parameter controls optimize the crystal structure to achieve higher charge-discharge capacity while maintaining stability, resolving the contradiction between capacity and reliability.
Solution Approach 2:
The patent uses composite materials by incorporating multiple elements (Ni, Mn, and other transition metals) in specific ratios within the lithium-transition metal composite oxide structure. This composite approach enables optimization of both capacity and stability, achieving vehicle-grade battery performance requirements.
2Quantity of substance
If crystal structure is optimized to increase capacity, then charge-discharge capacity improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces direct mechanical/crystallographic control methods with X-ray diffraction characterization-based control. By using I(101)/I(012) ratio and peak intensity ratios as control parameters, the patent simplifies manufacturing precision requirements while achieving the desired crystal structure optimization for high capacity.
3Quantity of substance
If element composition is adjusted to improve battery performance, then capacity increases, but material complexity increases
Solution Approach 1:
The patent manages material complexity by establishing specific parameter ranges for element ratios (Ni 3d3/2 to Ni 3d5/2 intensity ratio, I(101)/I(012) ratio) rather than controlling individual element compositions separately. This parameter-based approach simplifies the complexity of multi-element composition optimization while achieving high capacity performance.
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 proposed active material significantly increases the charge-discharge capacity of non-aqueous electrolyte secondary batteries by maintaining a stable crystal structure, thereby improving battery performance.
Implementation Method 1
an integrated intensity ratio I 101 /I 012 of diffraction peaks of a (101) plane and a (012) plane of an X-ray diffraction pattern
Implementation Method 2
integrated intensity ratio I 101 /I 012 of diffraction peaks of a (101) plane and a (012) plane of an X-ray diffraction pattern
Data Source
Figure 1
Figure 2
AI summary
A positive electrode active material according to the present invention has a crystalline structure belonging to the space group R-3m, and is represented by the compositional formula LiαNaβNi1-b-cMnbXcOd, wherein X is at least one element selected from the group consisting of representative elements and transition metal elements other than Li, Na, Ni, and Mn, 0.80 < α ≤ 1.20, 0 < β ≤ 0.20, 0.80 < α+β ≤ 1.20, 0< 1-b-c ≤1, 0 ≤ b < 1, 0 ≤ c <1, and d is a value that satisfies electrical neutrality. The ratio I101/I012 of the integrated intensity I101 of a diffraction peak in the (101) plane to the integrated intensity I012 of a diffraction peak in the (012) plane of an X-ray diffraction pattern obtained through powder X-ray diffraction of the positive electrode active material is less than 2.2.