Cathode Particle Coating With Ferroelectric Ceramics for Lower Resistance

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Solution Overview

Problem

Existing methods for reducing battery resistance in lithium ion secondary batteries require high temperature treatments, increasing costs, and result in coatings with lower lithium ion conductivity, limiting the reduction of battery resistance.

Innovation Solution

A method of producing a wet mixture containing coated lithium-containing positive electrode active material particles, where a lithium conductor forming solution is mixed with a mixed powder of lithium-containing positive electrode active material particles and ferroelectric ceramic particles, forming a coating of amorphous lithium conductor with dispersed ferroelectric ceramic particles, which reduces reaction resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high temperature treatment is applied to form a coating on positive electrode active material particles, then the coating structure is formed, but manufacturing costs increase and lithium ion conductivity decreases

Engineering Contradiction:

Improvecoating structure formationVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the temperature parameter from high temperature (700°C in prior art) to low temperature (drying at 100-200°C, sintering at 400-600°C) to form the coating. This parameter change resolves the contradiction by enabling coating formation at lower costs while maintaining or improving lithium ion conductivity through the amorphous structure formation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite coating material consisting of lithium ion conductor (such as Li2SiO3, Li2SiO2O, Li2SiO2S) and ferroelectric material (such as BaTiO3, Pb(Zr,Ti)O3). This composite approach allows the coating to form at lower temperatures while achieving both structural integrity and high lithium ion conductivity, resolving the contradiction between manufacturing cost and coating effectiveness.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If ferroelectric particles with size equal to or smaller than coating are used, then the coating can be formed, but the reduction of battery resistance is limited

Engineering Contradiction:

Improvecoating formationVSAvoidbattery resistance reduction

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention applies local quality by using ferroelectric particles with specific size ranges (0.1-10 μm, preferably 0.5-5 μm) that are optimized for both coating formation and battery resistance reduction. The particles are distributed throughout the coating matrix, creating local regions of high electric field that enhance lithium ion extraction. This resolves the contradiction by selecting particle sizes that satisfy both coating integrity and resistance reduction requirements.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention creates a composite material system where ferroelectric particles are dispersed in a lithium ion conductor matrix. The composite structure allows the coating to form continuously while incorporating ferroelectric particles that enhance lithium ion extraction through their piezoelectric and ferroelectric properties. This composite approach resolves the contradiction between coating formation and battery resistance reduction.

Inventive Principle:

Principle #40Composite materials

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 method achieves a significant reduction in reaction resistance of the positive electrode plate and consequently the lithium ion secondary battery, by facilitating smoother transfer of lithium ions during charging and discharging.

Implementation Method 1

forming a coating of amorphous lithium conductor with dispersed ferroelectric ceramic particles

Methodology Applied

Scientific EffectAmorphous coating formation:

Implementation Method 2

coating which is made of an amorphous lithium conductor and in which ferroelectric ceramic particles are dispersed on the surface

Methodology Applied

Scientific EffectFerroelectric effect:

Data Source

PatentUS12211987B2Wet mixture, coated lithium-containing positive electrode active material particles, and method of producing lithium ion secondary battery, and wet mixture, coated lithium-containing positive electrode active material particles, and lithium ion secondary battery

Publication Date: 2025.01.28 TOYOTA JIDOSHA KK

AI summary

A method of producing a wet mixture includes a stirring and mixing process in which lithium-containing positive electrode active material particles having surplus lithium compounds on the surface and crystalline ferroelectric ceramic particles are dried, stirred and mixed to obtain a mixed powder; and a solution mixing process in which a lithium conductor forming solution is mixed with the mixed powder to obtain a wet mixture containing coated lithium-containing positive electrode active material particles having a coating which is made of an amorphous lithium conductor and in which the ferroelectric ceramic particles are dispersed on the surface of the lithium-containing positive electrode active material particles.