Carbon-Coated Natural Graphite Anode for Volume Expansion Control

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Solution Overview

Problem

Current secondary batteries face challenges in controlling volume expansion and electrolyte side reactions of natural graphite during charging and discharging, which affects rapid charging performance and lifespan.

Innovation Solution

A negative electrode with natural graphite particles coated with a carbon layer, having a specific particle size distribution and surface area, is used to mitigate internal stress and control volume expansion, improving charging performance and battery lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a carbon coating layer is disposed on natural graphite to control volume expansion, then the volume expansion is partially controlled, but the stress inside the natural graphite is not sufficiently reduced and electrolyte side reactions are not sufficiently controlled

Engineering Contradiction:

Improvevolume expansion controlVSAvoidstress control and electrolyte side reaction control

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent uses a composite structure consisting of natural graphite particles coated with a carbon layer. This composite material approach combines the high capacity of natural graphite with the protective properties of the carbon coating, effectively controlling volume expansion while reducing internal stress and preventing electrolyte side reactions.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes specific parameters including particle size distribution (D50 between 6-9.2 μm) and half-width (5.0-5.5 μm) of the natural graphite particles. By controlling these physical parameters, the invention achieves effective stress management and volume expansion control while maintaining good electrochemical performance.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If natural graphite is used as negative electrode active material, then high capacity is achieved, but volume expansion occurs during charging and discharging

Engineering Contradiction:

Improvelithium ion capacityVSAvoidvolume expansion

Core Design Contradiction:

Quantity of substanceVSVolume of stationary object

Solution Approach 1:

The carbon coating layer is applied beforehand to the natural graphite particles to create a protective buffer. This pre-applied coating cushions the internal stress and volume changes during lithium ion insertion and extraction, preventing excessive expansion while maintaining high capacity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The composite structure of natural graphite core with carbon coating shell combines the advantages of both materials - the high lithium ion capacity of natural graphite with the volume stability and stress resistance of the carbon coating, effectively resolving the capacity-expansion contradiction.

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 solution effectively reduces volume expansion and internal stress, enhancing rapid charging performance and extending battery lifespan by using particles with a tailored size distribution and surface area.

Implementation Method 1

the stress inside the natural graphite may be mitigated

Methodology Applied

Scientific EffectStress mitigation:

Implementation Method 2

the degree of volume expansion of natural graphite in the negative electrode active material particles may be reduced

Methodology Applied

Scientific EffectVolume expansion control:

Implementation Method 3

a current may be evenly transmitted into a negative electrode

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 4

the specific surface area of the negative electrode active material particles is 0.6 m2/g to 2.2 m2/g

Methodology Applied

Scientific EffectSurface area control:

Data Source

PatentUS12080873B2Negative electrode and secondary battery including the negative electrode

Publication Date: 2024.09.03 LG ENERGY SOLUTION LTD

AI summary

A negative electrode and a secondary battery including the negative electrode. The negative electrode including a current collector and a negative electrode active material layer, wherein the negative electrode active material layer includes negative electrode active material particles, the negative electrode active material particles include natural graphite particles and a carbon coating layer disposed on the natural graphite particles. The negative electrode active material particles have a D50 of 6 μm to 9.2 μm and a half-width of 5.0 μm to 5.5 μm based on a particle size distribution, and the specific surface area of the negative electrode active material particles is from 0.6 m2/g to 2.2 m2/g.