Composite Negative Electrode Material for Si Volume Expansion

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Solution Overview

Problem

Existing negative electrode active materials face challenges in maintaining high electrode capacity while achieving good cycle characteristics due to the volume change caused by lithium ion occlusion and release, leading to electrode collapse.

Innovation Solution

Incorporating Si particles with first and second particles having specific volume expansion rates (0-80% and 100-300%, respectively) into the negative electrode active material, with controlled particle diameters and content ratios, to alleviate stress and prevent electrode collapse.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If Si particles are used as negative electrode active material to increase capacity, then electrode capacity is improved, but volume change causes electrode collapse and cycle characteristics deteriorate

Engineering Contradiction:
Improveelectrode capacityVSAvoidcycle characteristics
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The invention uses a composite material system consisting of Si particles combined with particles having small volume expansion rates (0-80%) and particles having large volume expansion rates (100-300%). This composite structure allows the Si particles to provide high capacity while the other particles compensate for volume changes, preventing electrode collapse and improving cycle characteristics.

Inventive Principle:
Principle #40Composite materials

2Reliability

If material with small volume expansion rate is mixed to prevent electrode collapse, then cycle characteristics are improved, but electrode capacity decreases

Engineering Contradiction:
Improvecycle characteristicsVSAvoidelectrode capacity
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The invention applies local quality by assigning different functional roles to different particle components: Si particles (20-80 mass%) provide high capacity, particles with small volume expansion rate (10-70 mass%) provide structural stability, and particles with large volume expansion rate (1-60 mass%) provide volume compensation. This functional differentiation allows simultaneous achievement of high capacity and good cycle characteristics.

Inventive Principle:
Principle #3Local quality

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 proposed solution maintains high electrode capacity and improves cycle characteristics, enabling the development of miniaturized lithium ion batteries with high energy density.

Implementation Method 1

Si and Sn have a large volume change such as expansion and contraction along with occlusion and release of the lithium ions

Methodology Applied
Scientific EffectVolume expansion due to Li occlusion:

Implementation Method 2

Li ions are occluded in a negative electrode active material during charging

Methodology Applied
Scientific EffectLithium ion occlusion: Absorption (physical)

Data Source

PatentUS20260045485A1Negative electrode active material
Publication Date: 2026.02.12 DAIDO STEEL CO LTD

AI summary

The present invention relates to a negative electrode active material including: Si particles; first particles; and second particles, in which the first particles have a volume expansion rate due to Li occlusion of 0% to 80%, and the second particles have a volume expansion rate due to Li occlusion of 100% to 300%.