Si-C Composite Anode Duplex Structure for Cycling Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium-ion batteries face challenges with silicon anode materials due to large volume changes during charge cycles, leading to poor cycling performance and capacity fade, despite efforts to improve silicon-based electrodes through particle size reduction, carbon matrix composites, and copper frameworks, which either fail to maintain long-term stability or reduce energy density.

Innovation Solution

The development of a silicon-based anode electrode with a duplex structure of alternating graphite and silicon stripes, achieved through co-extrusion printing, which controls volume changes and maintains high electronic conductivity, combined with a new binder system and surface modifications to enhance mechanical and electrochemical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon particles are used as anode material to increase capacity, then specific capacity is improved, but volume changes during charge cycles cause poor cycling performance

Engineering Contradiction:

Improvespecific capacityVSAvoidcycling performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

Silicon particles are embedded within a graphite matrix structure, where the graphite acts as a stable host that accommodates silicon's volume expansion. The silicon particles are nested inside the graphite framework, allowing high capacity from silicon while maintaining structural integrity through graphite's stability.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent creates a composite anode material combining silicon and graphite in a duplex structure. The composite leverages silicon's high theoretical capacity (4200 mAh/g) while graphite provides structural stability and accommodates volume changes, achieving both high capacity and good cycling performance.

Inventive Principle:

Principle #40Composite materials

2Reliability

If silicon particle size is reduced to improve cycling performance, then volume change stress is reduced, but manufacturing complexity increases

Engineering Contradiction:

Improvecycling performanceVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent optimizes the particle size parameters of both silicon and graphite components, creating a size-matched duplex structure. By carefully controlling the size parameters and distribution of silicon particles within the graphite matrix, the invention achieves reduced volume stress without requiring excessive manufacturing complexity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If carbon coating layer is applied on silicon particles to improve stability, then cycling performance is improved, but energy density decreases

Engineering Contradiction:

Improvecycling performanceVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

Instead of coating silicon particles with carbon, the patent uses a graphite matrix composite structure where graphite serves as both the stable matrix and the conductive framework. This approach provides stability benefits without the energy density penalty of thick carbon coatings, as graphite is part of the active capacity-bearing structure.

Inventive Principle:

Principle #40Composite materials

4Reliability

If three-dimensional copper framework is used to restrict volume changes, then cycling performance is improved, but volumetric energy density is reduced

Engineering Contradiction:

Improvecycling performanceVSAvoidvolumetric energy density

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent replaces the copper framework with a graphite-based duplex composite structure. The graphite matrix itself provides the structural framework that accommodates silicon's volume changes, eliminating the need for separate copper support structures and thereby maintaining high volumetric energy density while achieving stable cycling performance.

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

This approach results in a silicon-based anode with improved specific capacity, longer cycling performance, and higher volumetric energy density, effectively addressing the issue of volume changes while maintaining high energy density and stability.

Implementation Method 1

achieved through co-extrusion printing, which controls volume changes and maintains high electronic conductivity

Methodology Applied

Scientific EffectCo-extrusion printing: Extrusion

Implementation Method 2

large volume changes (～300%) upon the intercalation of Li-ion during charge step

Methodology Applied

Scientific EffectVolume expansion: Thermal Expansion

Implementation Method 3

upon the intercalation of Li-ion during charge step

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Data Source

PatentUS10115964B2Advanced Si-C composite anode electrode for high energy density and longer cycle life

Publication Date: 2018.10.30 XEROX CORP

AI summary

An electrode has a first set of stripes of a graphite-containing material, and a second set of stripes of silicon-containing material interdigitated with the first set of stripes. A method of manufacturing an electrode includes extruding first and second materials simultaneously onto a substrate in interdigitated stripes, wherein the first material comprises a graphite-containing material and the second material comprises a silicon-containing material.