Layered Lithium Metal Oxide Cathode with XRD-Tuned Cycle Stability
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Solution Overview
Problem
Lithium secondary batteries require improvements in cycle characteristics to meet the expanding demands of various applications.
Innovation Solution
A lithium metal composite oxide with a layered structure, containing specific elements like Co, Si, Ca, and Fe/Mg, and satisfying certain diffraction peak intensity and particle size ratios, is developed to enhance lithium ion diffusion and reduce strain, resulting in improved cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium metal composite oxides are used, then the battery can operate, but the cycle characteristics are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar ratio of M1 element relative to Co within 0.05-6, and controlling the diffraction peak intensity ratio I(006)/I(102) to be 0.44 or less. These parameter optimizations modify the crystal structure to reduce strain and improve lithium ion diffusion, thereby enhancing cycle characteristics and lifespan
Solution Approach 2:
The patent uses composite materials by incorporating multiple elements (Co, M1 from Si/Ca/Na group, and M2 from Fe/Mg group) in specific ratios within the lithium metal composite oxide. This multi-element composition creates a synergistic effect that improves both cycle characteristics and lifespan simultaneously
2Reliability
If the diffraction peak intensity ratio I(006)/I(102) is increased, then the crystal structure changes, but the cycle characteristics do not improve
Solution Approach 1:
The patent establishes a precise parameter range by setting the diffraction peak intensity ratio I(006)/I(102) to be 0.44 or less. This parameter control ensures the crystal structure has reduced strain and improved lithium ion diffusion pathways, directly achieving superior cycle characteristics
3Reliability
If the molar ratio of M1 element relative to Co is increased, then the composition changes, but the cycle characteristics may deteriorate
Solution Approach 1:
The patent defines an optimal parameter range by setting the molar ratio of M1 element to Co between 0.05 and 6. This compositional parameter control maintains structural stability while optimizing lithium ion diffusion and reducing crystal strain, achieving improved cycle characteristics without compromising compositional stability
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 lithium metal composite oxide provides lithium secondary batteries with superior cycle characteristics, ensuring longer lifespan and efficient lithium ion movement.
Implementation Method 1
enhance lithium ion diffusion
Implementation Method 2
In powder X-ray diffraction measurements using CuKα radiation
Implementation Method 3
two diffraction peaks exist within a range of 2θ = 38.0±0.5°
Data Source
Figure 1~2
AI summary
A lithium metal composite oxide having a layered structure, and satisfying (1) and (2) shown below. (1) The lithium metal composite oxide contains Co, an element M1 and an element M2, wherein the molar ratio of the element M1 relative to Co is at least 0.05 but not more than 6, the element M1 is one or more elements selected from the group consisting of Si, Ca and Na, and the element M2 is one or more elements selected from the group consisting of Fe and Mg. (2) In X-ray diffraction measurements using CuKα radiation, two diffraction peaks exist within a range of 2θ = 38.0±0.5°, and of those two peaks, if the diffraction peak on the lower angle side is deemed peak A and the diffraction peak on the higher angle side is deemed peak B, then the following formula is satisfied: 0.50 ≤ IA/IB ≤ 0.75 (wherein IA represents the peak area of the peak A, and IB represents the peak area of the peak B).