Cross-Linked Silicon Anode Composite for Structural Stability

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Solution Overview

Problem

Existing negative electrode materials for lithium secondary batteries, such as graphite and silicon, suffer from structural degradation due to volume expansion, leading to reduced lifespan and stability issues, while lithium metal electrodes pose fire risks due to reactivity with moisture and oxygen.

Innovation Solution

A composite particle for negative electrodes is developed, comprising a cross-linked polymer and rubber with epoxy groups, combined with silicon or silicon oxide, and optionally graphite, to control volume expansion and enhance stability, featuring a conductive material and specific weight ratios for improved performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If silicon is used as negative electrode material to increase energy density, then energy density is improved, but volume expansion causes structural degradation and reduced lifespan

Engineering Contradiction:

Improveenergy densityVSAvoidstructural stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies composite materials by combining silicon particles with a polymer matrix containing functional groups (carboxyl, hydroxyl, amine, amide, or imide groups). This composite structure allows the silicon to provide high energy density while the polymer matrix constrains volume expansion and prevents structural degradation, resolving the contradiction between energy density improvement and structural stability maintenance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the physical and chemical parameters of the binder material by using polymers with specific functional groups that can form cross-linked structures. These parameter changes enable the binder to adapt to silicon's volume expansion during lithiation, maintaining structural integrity while allowing the high energy density characteristics of silicon to be utilized

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If lithium metal is used to increase energy capacity, then energy capacity is improved, but reactivity with moisture and oxygen causes fire risks

Engineering Contradiction:

Improveenergy capacityVSAvoidreactivity with moisture and oxygen

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a polymer matrix as an intermediary material that surrounds and protects the lithium metal or silicon particles. This intermediary layer prevents direct contact between the reactive metal and moisture/oxygen in the environment, eliminating fire risks while preserving the high energy capacity benefits of lithium metal

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If graphite structure is used to maintain stability, then structural stability is improved, but energy density is limited compared to silicon

Engineering Contradiction:

Improvestructural stabilityVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent creates a composite material system where silicon particles (providing high energy density) are embedded in a polymer matrix (providing structural stability). This composite approach allows the system to achieve both high energy density from silicon and structural stability from the polymer, overcoming the energy density limitation of pure graphite while maintaining stability through the functional group-containing polymer binder

Inventive Principle:

Principle #40Composite materials

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 composite particle enhances the energy density, discharge capacity, and charge/discharge efficiency of lithium secondary batteries, with improved lifespan and reduced risk of structural damage, while maintaining flexibility and stability.

Implementation Method 1

the polymer and the rubber are cross-linked

Methodology Applied

Scientific EffectCross-linking: Chemical Bonding

Data Source

PatentUS20250286067A1Composite particles for negative electrodes, methods of preparation thereof, and lithium-ion batteries comprising the same

Publication Date: 2025.09.11 HYUNDAI MOTOR CO LTD

AI summary

This disclosure relates to a composite particle for a negative electrode in lithium secondary batteries. The composite includes a polymer with functional groups such as hydroxy, carboxyl, acrylate, amine, amide, or imide, and a rubber containing an epoxy group. These components are cross-linked and combined with an active material like silicon or silicon oxide. The composite may also incorporate conductive materials like carbon nanotubes or graphite. The preparation method involves pretreating rubber, forming a slurry with the polymer, active material, and conductive material, and then spray drying. This composite is used to enhance the performance of negative electrodes in lithium batteries.