Negative Electrode Composite Particles with Silicate Film

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Solution Overview

Problem

The existing negative electrode composite material layers in batteries experience nonuniform electrolyte solution distribution and increased resistance during high-rate charge and discharge cycles due to volume changes of active material particles, leading to electrolyte solution release and increased resistance.

Innovation Solution

A negative electrode composite material layer is formed with composite particles that include a negative electrode active material coated with a layered silicate mineral film and bound by nanofibers, which becomes loosely packed during discharge and densely packed during charge, mitigating electrolyte solution flow and resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If hard small particles (filler) are disposed within space between negative electrode active material particles, then the electrolyte solution distribution is improved, but the release of electrolyte solution during charge-discharge is not sufficiently mitigated

Engineering Contradiction:

Improveelectrolyte solution distribution uniformityVSAvoidelectrolyte solution retention

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent uses a composite structure consisting of negative electrode active material particles (graphite) coated with a layered silicate mineral film (such as montmorillonite). This composite particle structure combines the high capacity of graphite with the electrolyte-retaining properties of the layered silicate mineral, creating a synergistic effect that both improves electrolyte distribution and prevents electrolyte release during charge-discharge cycles

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The layered silicate mineral forms a thin film coating on the surface of the negative electrode active material particles. This thin film acts as a flexible barrier that allows electrolyte penetration while preventing excessive electrolyte release during volume changes, effectively retaining electrolyte within the composite material layer

Inventive Principle:

Principle #30Flexible shells and thin films

2Productivity

If charge and discharge are carried out at high rate, then power output is improved, but volume change of active material particles increases causing electrolyte release

Engineering Contradiction:

Improvecharge-discharge rateVSAvoidelectrolyte solution release

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The layered silicate mineral film is pre-applied to the surface of negative electrode active material particles before assembly into the battery. This film acts as a protective cushion that anticipates and prevents electrolyte release during high-rate charge-discharge cycles, accommodating volume changes of the active material without losing electrolyte

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Power

If Joule heat is generated during high-rate charge-discharge, then power delivery is improved, but electrolyte solution temperature increases causing swelling and resistance rise

Engineering Contradiction:

Improvepower delivery capabilityVSAvoidelectrolyte solution temperature

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The layered silicate mineral film changes its physical parameters (such as interlayer spacing and flexibility) in response to temperature changes during high-rate operation. This parameter adaptation allows the film to maintain its electrolyte-retaining function even when electrolyte temperature increases due to Joule heating, preventing excessive swelling and resistance rise

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

This configuration reduces the rise in resistance during high-rate cycles and decreases initial resistance by ensuring uniform electrolyte distribution and preventing excessive electrolyte release, while maintaining suitable hardness.

Implementation Method 1

The film contains a layered silicate mineral. The layered silicate mineral may have an adsorption action on the electrolyte solution, and, thereby, release of the electrolyte solution from the negative electrode composite material layer may be mitigated.

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

The binder includes nanofibers. The nanofibers may link the negative electrode active material particle (or film) to one another

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 3

The negative electrode active material particles swell during charge and shrink during discharge. Accordingly, the negative electrode composite material layer swells during charge and shrinks during discharge.

Methodology Applied

Scientific EffectSwelling:

Data Source

PatentUS11539048B2Negative electrode, battery, and method of producing negative electrode

Publication Date: 2022.12.27 TOYOTA JIDOSHA KK

AI summary

A negative electrode includes at least a negative electrode composite material layer. The negative electrode composite material layer contains at least composite particles and a binder. Each composite particle includes a negative electrode active material particle and a film. The film covers at least part of a surface of the negative electrode active material particle. The film contains a layered silicate mineral. The binder includes nanofibers.