Soft-Carbon-Coated Graphite Anode for Stable Electrode Rolling

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Solution Overview

Problem

Lithium secondary batteries face challenges in maintaining high-temperature storage performance due to changes in electrode structure and internal total pore volume during rolling, which affects their performance and lifespan, especially in rapid charging applications.

Innovation Solution

A negative electrode active material composed of artificial graphite coated with soft carbon, where the soft carbon content is between 3.5 wt% and 4.5 wt% based on the combined weight, and the total pore volume variation is minimized to 10 cm^3/g or less before and after rolling, achieving a target porosity of 25-32% and specific loading amounts to enhance high-temperature storage characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the internal total pore volume is high after electrode rolling, then the electrode structure has more space for lithium ion insertion, but the high-temperature performance of the negative electrode deteriorates

Engineering Contradiction:
Improveinternal total pore volumeVSAvoidhigh-temperature performance
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the soft carbon coating amount (3.5-4.5 wt%) and the artificial graphite particle size (D50: 15-25 μm) to optimize the electrode's total pore volume variation. This controlled parameter adjustment ensures that the pore volume change during rolling remains within 10 cm³/g, thereby maintaining high-temperature performance while preserving adequate space for lithium ion insertion.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If soft carbon is coated on artificial graphite to improve charging and discharging rates, then the high-temperature characteristics improve, but the crystal structure stability may be affected

Engineering Contradiction:
Improvecharging and discharging ratesVSAvoidcrystal structure stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent employs composite materials by combining artificial graphite (providing crystal structure stability) with a soft carbon coating layer (improving charging and discharging rates). The specific composition ratio (3.5-4.5 wt% soft carbon) creates a composite structure that maintains the stable graphite crystal lattice while the amorphous soft carbon layer facilitates rapid lithium ion transport, thus achieving both high productivity and structural stability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by coating soft carbon only on the surface of the artificial graphite particles rather than throughout the entire structure. This localized modification preserves the stable crystalline core while providing the high-conductivity surface layer needed for rapid charging and discharging, effectively separating the functional requirements of stability and reactivity to different regions of the material.

Inventive Principle:
Principle #3Local quality

3Quantity of substance

If the total pore volume variation during rolling is large, then the electrode can accommodate more lithium ions, but the high-temperature storage performance deteriorates

Engineering Contradiction:
Improvelithium ion capacityVSAvoidhigh-temperature storage performance
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the soft carbon coating amount (3.5-4.5 wt%) and the artificial graphite particle size (D50: 15-25 μm) to optimize the electrode's total pore volume variation. This controlled parameter adjustment ensures that the pore volume change during rolling remains within 10 cm³/g, thereby maintaining high-temperature performance while preserving adequate space for lithium ion insertion.

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 minimizes structural and pore volume changes during rolling, thereby improving the high-temperature storage performance and energy density of lithium secondary batteries, particularly suitable for rapid charging applications.

Implementation Method 1

a carbon-based negative electrode active material used for a negative electrode of a lithium secondary battery has a potential close to an electrode potential of lithium metal and has a small change in a crystal structure during intercalation and deintercalation of lithium ions

Methodology Applied
Scientific EffectIntercalation and deintercalation:

Implementation Method 2

so that a redox reaction may be continuously and repeatedly performed at the electrode, thereby providing a basis for the lithium secondary battery to exhibit high capacity and an excellent lifespan

Methodology Applied
Scientific EffectRedox reaction: Redox Reactions

Data Source

PatentEP3736887B1Anode active material for lithium secondary battery and anode for lithium secondary battery comprising same
Publication Date: 2023.09.13 LG ENERGY SOLUTION LTD

AI summary

The present invention relates to a negative electrode active material for a lithium secondary battery, a negative electrode including the same, and a lithium secondary battery including the negative electrode. Specifically, the present invention relates to a negative electrode active material capable of minimizing changes in a structure and internal total pore volume of an electrode during rolling of the electrode by controlling the type and amount of carbon coated on a surface of an artificial graphite active material, a negative electrode including the same, and a lithium secondary battery including the negative electrode.