Spherical Graphite Anode Coating for Stable Gaps and Cycle Life

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Solution Overview

Problem

Existing methods for preparing spherical graphite particles for anode active materials in lithium secondary batteries face limitations in charge/discharge characteristics and cycle life-span due to insufficient gap formation between flaky graphite fragments, leading to unstable structures and irreversible reactions with the electrolyte.

Innovation Solution

A mechanochemical reaction is employed to coat graphite byproduct particles with composite materials like silicon, tin, or their oxides, followed by spheroidization and amorphous carbon coating to form gaps and improve stability, utilizing a dry process to enhance the properties of spherical graphite particles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If spherical graphite particles are granulated without gaps between flaky graphite fragments, then particle density is improved, but charge/discharge characteristics are reduced

Engineering Contradiction:

Improveparticle densityVSAvoidcharge/discharge characteristics

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The flaky graphite particles are segmented into smaller fragments during the spheroidization process, creating gaps between the fragments on the particle surface. This segmentation allows electrolyte penetration while maintaining overall particle density, resolving the contradiction between dense packing and charge/discharge performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spherical graphite particles are designed with a porous structure featuring gaps and voids between flaky fragments on the surface. This porous architecture enables electrolyte access to internal graphite structures, improving lithium ion insertion/extraction kinetics without sacrificing particle density.

Inventive Principle:

Principle #31Porous materials

2Shape

If conventional granulation process is used, then spherical shape is achieved, but bonding force of flaky graphite fragments is reduced

Engineering Contradiction:

Improvespherical shapeVSAvoidbonding force of fragments

Core Design Contradiction:

ShapeVSStrength

Solution Approach 1:

The spherical graphite particles are constructed as composite structures combining multiple flaky graphite fragments bonded together. The controlled gaps between fragments create a composite architecture that maintains structural integrity through interfragment bonding while preserving spherical external shape.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The spheroidization process incorporates preliminary cushioning measures by controlling the degree of fragmentation and gap formation before final particle formation. This prevents excessive mechanical stress that would weaken fragment bonding while still achieving the desired spherical shape and internal porosity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Duration of action of moving object

If repeated charging and discharging occurs, then battery cycling is enabled, but structure stability deteriorates

Engineering Contradiction:

Improvecycle life-spanVSAvoidstructure stability

Core Design Contradiction:

Duration of action of moving objectVSStability of the object's composition

Solution Approach 1:

The spherical graphite particles are coated with thin film layers that act as protective shells. These films accommodate volume changes during lithium insertion/extraction cycles, preventing structural degradation and maintaining particle stability over extended cycling while enabling long-term battery operation.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The surface chemistry and physical parameters of the graphite particles are modified through controlled oxidation and coating processes. These parameter changes enhance structural stability by reducing surface reactivity and preventing electrolyte-induced degradation during repeated charging/discharging cycles.

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 method improves high-rate charge/discharge characteristics and cycle life-span of secondary batteries by forming stable gaps and enhancing the bonding force of graphite particles, resulting in improved electrical conductivity and capacity retention.

Implementation Method 1

preparing coated particles by mixing the graphite byproduct particles with composite particles and performing a mechanochemical reaction thereon to coat the surface of the graphite byproduct particles with the composite particles

Methodology Applied

Scientific EffectMechanochemical reaction:

Implementation Method 2

spheroidizing the coated particles and coating the surface thereof with amorphous carbon to prepare spherical graphite

Methodology Applied

Scientific EffectSpheroidization:

Data Source

PatentUS12555788B2Manufacturing method of anode active material and secondary battery comprising the same

Publication Date: 2026.02.17 FIC ADVANCED MATERIALS INC

AI summary

The present invention relates to a method for preparing an anode active material and a secondary battery including the anode active material. The anode active material may be prepared by a method including the steps of: obtaining byproduct particles that have not been spheroidized in a step of pulverizing and spheroidizing flaky graphite particles; preparing coated particles by mixing the graphite byproduct particles with composite particles and performing a mechanochemical reaction thereon to coat the surface of the graphite byproduct particles with the composite particles; and spheroidizing the coated particles and coating the surface thereof with amorphous carbon to prepare spherical graphite.