Surface-Layered Silicon-Carbon Particles for Stable Li-Ion Anodes

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Solution Overview

Problem

Electrochemical apparatuses experience performance variability due to differences in negative electrode active materials, leading to deteriorated cycling performance, swelling, and rate performance, primarily attributed to significant volume changes in silicon-based materials during charge and discharge cycles.

Innovation Solution

The use of silicon-carbon particles with a surface layer and specific size and thickness ratios, combined with graphite particles, along with controlled porosity and orientation index, to stabilize volume changes and enhance ion migration, thereby improving cycling and rate performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If silicon-based materials are used as negative electrode active material, then energy density is improved, but volume change during charge and discharge cycles deteriorates cycling performance and causes swelling

Engineering Contradiction:

Improveenergy densityVSAvoidcycling performance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

Silicon particles are embedded within porous carbon particles, forming a nested structure where silicon is contained inside carbon. This nested configuration allows silicon to expand and contract within the porous carbon matrix during charge-discharge cycles, accommodating volume changes while maintaining structural integrity and improving cycling performance.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

A surface layer is formed on the silicon-carbon particles before electrochemical cycling begins. This preliminary surface layer formation prevents excessive electrolyte decomposition and stabilizes the electrode, improving rate performance and reducing swelling during subsequent cycles.

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If silicon-based materials are used as negative electrode active material, then energy density is improved, but swelling during charge and discharge cycles increases

Engineering Contradiction:

Improveenergy densityVSAvoidswelling

Core Design Contradiction:

Use of energy by moving objectVSVolume of moving object

Solution Approach 1:

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The porous carbon particles act as a flexible shell surrounding the silicon core. This carbon shell can accommodate the volume expansion of silicon during lithiation while maintaining overall particle integrity, thereby reducing swelling at the electrode level.

Inventive Principle:

Principle #30Flexible shells and thin films

3Speed

If surface layer is formed on silicon-carbon particles, then rate performance is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improverate performanceVSAvoidsurface layer thickness control

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The surface layer thickness is controlled within a specific parameter range (0.01-1.0 μm) to optimize rate performance. By defining this parameter range, the invention balances the need for sufficient surface area for rapid ion transport with the practical constraints of manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The surface layer is formed selectively on the silicon-carbon particles, providing enhanced properties where needed (at the particle surface for ion transport) while maintaining the bulk silicon-carbon structure. This localized modification improves rate performance without requiring precise control over the entire particle structure.

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 silicon-carbon particles with a surface layer and controlled parameters significantly improve cycling performance, swelling suppression, and rate performance by stabilizing the negative electrode active material, reducing electrolyte decomposition, and enhancing kinetic performance.

Implementation Method 1

providing a silicon-containing precursor on the porous carbon framework containing the metal salt, so that the silicon-containing precursor undergoes a chemical vapor reaction to form silicon-based particles, and the silicon-based particles deposit in the pores of the porous carbon framework

Methodology Applied

Scientific EffectChemical vapor reaction: Chemical Vapour Deposition

Data Source

PatentUS20250273652A1Silicon-carbon particle and preparation method thereof, electrochemical apparatus, and electronic apparatus

Publication Date: 2025.08.28 NINGDE AMPEREX TECHNOLOGY LTD

AI summary

An electrochemical apparatus includes a negative electrode plate and an electrolyte, where the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector and containing a negative electrode active material, the negative electrode active material including silicon-carbon particles and graphite particles. A surface of each silicon-carbon particle has a surface layer, a thickness of the surface layer is c μm, an average particle size of the silicon-carbon particles is d μm, and 0.42%<c/d<16.0%.