Rock-Salt Cathode Particle Shape for Uniform Battery Reactions

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Solution Overview

Problem

Existing lithium-metal composite oxides with a rock-salt structure have limited capacity improvement due to uneven particle shapes and high electronic conductivity, leading to uneven charge-discharge reactions and increased polarization.

Innovation Solution

Control the average aspect ratio of lithium-metal composite oxide particles to less than 2.10 and enhance the roundness to 0.55 or more, reducing tortuosity of electron conduction paths and promoting uniform charge-discharge reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the composition is controlled by adding Nb to achieve high capacity, then the capacity increases, but the effect of capacity increase is not sufficient

Engineering Contradiction:

ImprovecapacityVSAvoidcapacity increase effect

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The invention changes the particle shape parameters (aspect ratio and roundness) of the lithium-metal composite oxide instead of relying solely on compositional modifications. By controlling the aspect ratio to less than 2.10 and roundness to 0.55 or more, the invention achieves more effective capacity improvement that compositional control alone could not provide.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If particle shape is not controlled, then the manufacturing process is simpler, but the charge-discharge reactions become uneven and polarization increases

Engineering Contradiction:

Improveparticle shape controlVSAvoidcharge-discharge uniformity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention identifies particle shape parameters (aspect ratio and roundness) as critical control variables. By setting specific thresholds for these geometric parameters, the invention ensures uniform charge-discharge reactions and reduced polarization while maintaining manufacturability through clear, measurable control criteria.

Inventive Principle:

Principle #35Parameter changes

3Shape

If particle aspect ratio is high, then the particle shape is more irregular, but the electron conduction paths become more tortuous and capacity decreases

Engineering Contradiction:

Improveparticle shapeVSAvoiddischarge capacity

Core Design Contradiction:

ShapeVSQuantity of substance

Solution Approach 1:

The invention establishes asymmetric control criteria for particle geometry, specifically requiring the aspect ratio to be less than 2.10 and roundness to be 0.55 or more. This asymmetric control (different thresholds for different geometric parameters) optimizes the particle shape to reduce electron conduction path tortuosity while maintaining manufacturability.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentEP4661103A1Positive electrode active material for secondary batteries, and secondary battery

Publication Date: 2025.12.10 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

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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 space group Fm-3m. The lithium-metal composite oxide contains at least Li and Mn. The average aspect ratio of particles of the lithium-metal composite oxide is less than 2.10.