Disordered Rock Salt Cathode Material for Stable Li-Ion Cycling

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Solution Overview

Problem

Positive electrode active materials with a rock salt structure experience significant volume changes during charging and discharging, deteriorating the cycle characteristics of lithium-ion batteries.

Innovation Solution

A positive electrode active material with a disordered rock salt structure belonging to space group Fm-3m and a composition of Li1+xTiyVzO2 (0<x≤0.20, 0<y≤0.40, 0.40≤z≤0.85) is produced by dry mechanical milling of an intermediate substance with a layered rock salt structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a layered rock salt structure positive electrode active material is used, then the charge-discharge capacity can be maintained, but the volume changes significantly during charging and discharging, deteriorating the cycle characteristics

Engineering Contradiction:

Improvecharge-discharge capacityVSAvoidcycle characteristics

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The invention changes the crystal structure parameter from layered rock salt (space group R-3m) to disordered rock salt (space group Fm-3m). This parameter change in the crystal structure fundamentally alters the volume stability during lithium ion insertion/extraction, reducing volume changes while maintaining charge-discharge capacity. The disordered structure allows more isotropic volume changes compared to the anisotropic changes in layered structure.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a rock salt structure positive electrode active material is used, then the material can be applied to lithium-ion battery, but the volume changes during charging and discharging deteriorate the cycle characteristics

Engineering Contradiction:

Improveapplicability to lithium-ion batteryVSAvoidcycle characteristics

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention modifies the crystal structure parameter from ordered rock salt to disordered rock salt structure. This parameter change maintains the rock salt structure's high capacity characteristics while improving volume stability during cycling, thereby enhancing reliability and cycle characteristics without sacrificing adaptability to lithium-ion battery applications.

Inventive Principle:

Principle #35Parameter changes

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 material exhibits small volume changes during charging and discharging, improving the cycle characteristics of lithium-ion batteries and maintaining high charge-discharge capacity.

Implementation Method 1

subjecting the intermediate substance to dry mechanical milling to obtain a positive electrode active material having a disordered rock salt structure

Methodology Applied

Scientific EffectMechanical milling:

Data Source

PatentUS12537194B2Positive electrode active material for lithium-ion battery, production method therefor, and lithium-ion battery

Publication Date: 2026.01.27 TOYOTA JIDOSHA KK

AI summary

Disclosed is a positive electrode active material for a lithium-ion battery, wherein the positive electrode active material has small volume changes during charging and discharging, and when applied to a battery, can improve the cycle characteristics of the battery. The positive electrode active material of the present disclosure has a disordered rock salt structure belonging to space group Fm-3m, and has a composition represented by Li1+xTiyVzO2 (where 0<x≤0.20, 0<y≤0.40, and 0.40≤z≤0.85).