Artificial Graphite Anode Layer for Press Crack and Orientation Control

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Solution Overview

Problem

Lithium secondary batteries face issues with anode material cracking during the press process, leading to insufficient electrode density and power degradation due to particle orientation properties.

Innovation Solution

An anode for lithium secondary batteries is developed using a combination of assembly-type and single-type artificial graphite particles, where the single-type particles are added to improve mechanical stability and fill gaps between assembly-type particles, enhancing electrode density and preventing particle cracks, while maintaining an XRD orientation index within a specific range to improve power and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If granulated artificial graphite particles are used to improve capacity, then capacity is improved, but particle cracks occur during press process leading to power degradation

Engineering Contradiction:

ImprovecapacityVSAvoidpower stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent uses a composite particle system combining assembly-type graphite particles (providing high capacity) with single-type graphite particles (providing mechanical stability). This composite approach allows the benefits of both particle types to coexist, preventing cracks while maintaining high capacity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Single-type graphite particles are added beforehand to act as a cushioning matrix that prevents crack propagation in assembly-type particles during the press process. This prior protective measure ensures power stability is maintained throughout battery operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Volume of stationary object

If assembly-type artificial graphite particles are used to increase electrode density, then electrode density is improved, but particle orientation properties cause power degradation

Engineering Contradiction:

Improveelectrode densityVSAvoidpower performance

Core Design Contradiction:

Volume of stationary objectVSReliability

Solution Approach 1:

The patent creates local quality differentiation by distributing single-type particles throughout the assembly-type particle matrix. This local distribution ensures that orientation-induced stress is locally managed, preventing power degradation while maintaining high electrode density.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Single-type graphite particles serve as an intermediary material that mediates between the assembly-type particles and the press process. This intermediary layer absorbs orientation stresses and prevents direct transmission of damaging forces to the capacity-providing assembly particles.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If single-type artificial graphite particles are added to improve mechanical stability, then mechanical stability is improved, but electrode density decreases due to gaps between particles

Engineering Contradiction:

Improvemechanical stabilityVSAvoidelectrode density

Core Design Contradiction:

StrengthVSVolume of stationary object

Solution Approach 1:

The patent implements a nested structure where single-type particles are distributed within and between assembly-type particles. This nesting arrangement allows single-type particles to provide mechanical stability without creating excessive gaps, as they fill interstitial spaces efficiently.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent optimizes the weight ratio parameter of single-type to assembly-type particles (specifically 10-40 wt%) to achieve the best balance between mechanical stability and electrode density. This parameter optimization ensures neither property is excessively compromised.

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 anode material exhibits improved mechanical stability, capacity retention, and power performance by preventing particle cracks and optimizing electrode density, thus enhancing the overall performance and lifespan of the battery.

Implementation Method 1

the single-type particles are added to improve mechanical stability and fill gaps between assembly-type particles, enhancing electrode density and preventing particle cracks

Methodology Applied

Scientific EffectParticle packing:

Implementation Method 2

An X-ray diffraction (XRD) orientation index defined as a ratio of x-ray diffraction peak intensities of a (004) plane and a (110) plane and represented as I(004)/I(110) by an XRD analysis measured from the anode active material layer

Methodology Applied

Scientific EffectX-ray diffraction: X-Ray

Data Source

PatentUS20240047677A1Anode for secondary battery and secondary battery including the same

Publication Date: 2024.02.08 SK ON CO LTD

AI summary

An anode for a lithium secondary battery includes an anode current collector, and an anode active material layer on the anode current collector. The anode active material layer includes an anode active material that includes assembly-type artificial graphite particles and single-type artificial graphite particles. An XRD orientation index defined as a ratio of peak intensities of a (004) plane and a (110) plane and represented as I(004)/I(110) by an XRD analysis measured from the anode active material layer is in a range from 6 to 13.