Lithium-Metal Oxide Cathode Morphology for High-Rate Batteries
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Solution Overview
Problem
Existing lithium secondary batteries face limitations in rate performance due to inadequate control of particle shape and crystal structure in lithium-metal composite oxides used as positive electrode active materials.
Innovation Solution
A lithium-metal composite oxide with specific ratios of half-widths of diffraction peaks and controlled convexity, aspect ratio, and circularity of particles, formulated as Li[Li x (Ni (1-a-b) M1 a M2 b ) 1-x ]O 2, where M1 includes Co, Mn, and Al, and M2 includes Cu, Ti, Mg, W, Mo, Nb, Zn, Sn, Zr, Ga, B, Si, or P, to enhance lithium ion conduction and diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If particle shape and crystal structure of lithium-metal composite oxide are controlled, then rate performance of lithium secondary battery is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the A/B ratio (half-width ratio of diffraction peaks) within 1.35-2.25 and particle convexity within 0.971-1.000. These parameter specifications transform the manufacturing process from qualitative to quantitative control, enabling systematic production of particles with optimized crystal structure and morphology for high rate performance
Solution Approach 2:
The patent employs preliminary action by pre-defining the target particle characteristics (convexity range and A/B ratio range) before the actual battery assembly process. This allows the positive electrode active material to be prepared in advance with optimized properties, ensuring high rate performance is achieved through pre-optimized particle morphology rather than post-processing adjustments
2Reliability
If diffraction peak half-width ratio (A/B) is controlled within 1.35-2.25, then lithium ion conduction is enhanced, but measurement precision requirements increase
Solution Approach 1:
The patent transforms the crystal structure characterization into a quantitative parameter control problem by specifying the A/B ratio range (1.35-2.25). This parameter change approach allows standard XRD measurement procedures to be used while achieving reliable lithium ion conduction through precise control of the half-width ratio, making the measurement process routine rather than exceptional
3Quantity of substance
If particle convexity is controlled within 0.971-1.000, then discharge capacity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by defining a specific convexity range (0.971-1.000) that balances particle sphericity with manufacturing feasibility. This quantitative specification transforms the abstract concept of 'particle shape control' into a measurable and controllable manufacturing parameter, enabling consistent production of particles with optimized discharge capacity
Solution Approach 2:
The patent employs preliminary action by pre-establishing the convexity specification range before production. This allows manufacturing processes to be designed and optimized around this target parameter, ensuring that particles are produced with the necessary geometric properties for high discharge capacity from the outset rather than requiring post-production sorting or rejection
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 controlled particle shape and crystal structure improve the rate performance of lithium secondary batteries by increasing lithium ion conduction paths and filling density, resulting in enhanced discharge capacity and cycle retention.
Implementation Method 1
in a powder X-ray diffraction measurement of the lithium-metal composite oxide using a CuKα ray
Implementation Method 2
in a powder X-ray diffraction measurement of the lithium-metal composite oxide using a CuKα ray
Data Source
Figure 1~2
AI summary
A lithium-metal composite oxide contains at least Ni, in which the lithium-metal composite oxide contains a plurality of particles, in a powder X-ray diffraction measurement of the lithium-metal composite oxide using a CuKα ray, in a case where a diffraction peak on a low-angle side in a range of 2θ = 38.0 ± 0.5° is defined as a peak A and a diffraction peak on a high-angle side is defined as a peak B, a ratio A/B of a half-width of the peak A to a half-width of the peak B is 1.35 or more and 2.25 or less, and an average convexity of the lithium-metal composite oxide is 0.971 or more and 1.000 or less.