Rock-Salt Cathode Material Particle Sizing for Li-Ion Cycle Stability
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Solution Overview
Problem
Existing positive electrode active materials for secondary batteries, particularly lithium-ion batteries, do not achieve sufficient capacity enhancement, and there is a need for improved cycle characteristics and high energy density.
Innovation Solution
A lithium-metal composite oxide with a rock salt type crystal structure (space group Fm-3m) is used, with controlled particle size distribution (D50 of 0.05 µm to 10 µm) and composition (Li1+xMn1-xO2) to enhance capacity and stability, incorporating elements like Ti and F to stabilize the structure and increase discharge potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If compositional control (addition of Nb) is used to increase capacity, then capacity is improved, but the capacity increasing effects are not sufficient
Solution Approach 1:
The patent changes the particle size parameter of the lithium-metal composite oxide to D50 of 0.05 µm to 10 µm, which fundamentally alters the electrochemical performance and achieves sufficient capacity increase that compositional control alone could not accomplish
2Productivity
If particle size is reduced to increase surface area, then reaction activity is improved, but cycle characteristics deteriorate
Solution Approach 1:
The patent optimizes the particle size parameter to a specific range (D50: 0.05 µm to 10 µm) that simultaneously provides sufficient surface area for high reaction activity and maintains structural integrity for good cycle characteristics, resolving the trade-off between productivity and reliability
Data Source
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AI summary
A positive electrode active material for secondary batteries contains a lithium-metal composite oxide having a rock salt type crystal structure assignable to the space group Fm-3m. The lithium-metal composite oxide contains at least Li and Mn and has a D50 of 0.05 µm or more and 10 µm or less in a volume-based cumulative particle size distribution of the lithium-metal composite oxide. A secondary battery includes the positive electrode active material in a positive electrode.