Silicon-Carbon Anode with SiC Interface for Battery Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Silicon-carbon negative electrode materials in lithium-ion batteries face issues with volume expansion and structural pulverization during charge and discharge, leading to loss of electrical contact and electrolyte consumption, which affects cycle performance.

Innovation Solution

A silicon-carbon negative electrode material is developed with silicon carbide connecting silicon and carbon, and a heat treatment process under oxygen-isolated conditions forms silicon carbide on the surface of silicon particles, enhancing mechanical strength and reducing volume expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon is used as negative electrode material to increase specific capacity, then battery energy density is improved, but volume expansion and structural pulverization occur during charge and discharge

Engineering Contradiction:

Improvespecific capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

Silicon particles are embedded within carbon matrix, forming a nested structure where silicon is contained inside carbon. This nested configuration allows silicon to expand and contract during lithium insertion/extraction while being constrained by the carbon shell, preventing structural pulverization and maintaining electrical contact.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention creates a composite material system combining silicon and carbon, where silicon provides high specific capacity and carbon provides structural stability. The composite structure leverages the advantages of both materials: silicon's high lithium capacity and carbon's mechanical strength and dimensional stability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If silicon particles are dispersed in carbon matrix, then electrical contact is maintained, but volume expansion still causes separation of silicon-carbon interface

Engineering Contradiction:

Improveelectrical contactVSAvoidvolume expansion

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

A carbon shell or film surrounds the silicon particles, forming a flexible protective layer that can accommodate volume changes during lithium insertion/extraction. This carbon shell maintains the integrity of the silicon-carbon interface and ensures continuous electrical contact even during expansion and contraction cycles.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The carbon matrix acts as a cushioning structure that anticipates and accommodates the volume expansion of silicon before damage occurs. The carbon framework provides a buffer zone that absorbs expansion stress, preventing direct contact between expanded silicon particles and preventing interface separation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If heat treatment is performed to form silicon carbide, then structural stability and mechanical strength are improved, but processing complexity increases

Engineering Contradiction:

Improvemechanical strengthVSAvoidprocessing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The invention utilizes parameter changes during heat treatment, specifically controlling temperature and atmosphere conditions to promote the formation of silicon carbide at the silicon-carbon interface. By optimizing heat treatment parameters (temperature range, heating rate, atmosphere composition), the process achieves desired structural stability without excessive complexity.

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 solution improves structural stability, reduces ion diffusion impedance, and enhances lithium ion migration, resulting in improved cycle capacity retention and reduced expansion, with a balanced preparation process that is efficient and cost-effective.

Implementation Method 1

the silicon is at least partially connected to the carbon through the silicon carbide

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 2

performing heat treatment on a silicon-carbon raw material under an oxygen-isolated condition to obtain the silicon-carbon negative electrode material

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentEP4661112A1Silicon-carbon negative electrode material and preparation method therefor, negative electrode sheet, and electrochemical device

Publication Date: 2025.12.10 BYD CO LTD

Figure 1

AI summary

Silicon-carbon negative electrode material and preparation method therefor, negative electrode sheet, and electrochemical device This application relates to the technical field of battery negative electrode materials, and specifically to a silicon-carbon negative electrode material and a preparation method therefor, a negative electrode plate, and an electrochemical apparatus. The silicon-carbon negative electrode material includes carbon and modified particles dispersed in the carbon, the modified particles include silicon carbide and silicon; and the silicon is at least partially connected to the carbon through the silicon carbide, and a mass ratio of the silicon carbide to the silicon is 1:1-50.