Functionalized Silicon Nanoparticles for Stable High-Loading Anodes

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Solution Overview

Problem

Conventional lithium-ion batteries face limitations due to the limited capacity of graphite electrodes, which undergo significant volume changes during lithiation and de-lithiation, leading to pulverization, electrical isolation, and rapid capacity degradation, hindering the commercialization of silicon-based electrodes.

Innovation Solution

The development of covalently functionalized silicon particles with attached functional groups such as —OH, —COOH, —C—O—C—, —NH2, —NHR, dispersed within a polymer network, specifically a porous polymer network, to enhance dispersion and reduce stress during charging and discharging processes, thereby improving the stability and performance of silicon-based electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon particles are used as anode material to increase capacity, then lithium storage capacity is improved, but volume expansion during lithiation causes pulverization and electrical isolation

Engineering Contradiction:

Improvelithium storage capacityVSAvoidelectrode structural stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A carbon coating layer is applied on the surface of silicon particles to form a flexible protective shell. This carbon shell accommodates volume expansion during lithiation while maintaining structural integrity and electrical conductivity, preventing pulverization and electrical isolation of silicon particles.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

Silicon particles are combined with carbon material to form a composite structure (silicon core with carbon shell). This composite material leverages the high capacity of silicon and the structural stability and conductivity of carbon, resolving the contradiction between capacity and stability.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silicon particles undergo volume expansion during lithiation, then lithium capacity is increased, but stress and strain cause cracks and breakage

Engineering Contradiction:

Improvelithium capacityVSAvoidparticle structural strength

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The carbon coating layer acts as a flexible shell that can stretch and deform during volume expansion, absorbing stress and strain without causing cracks or breakage of the silicon core particles.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The carbon coating is applied beforehand to cushion and distribute the stress generated during volume expansion, preventing crack formation before they can propagate through the silicon particles.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Quantity of substance

If silicon fragments lose electrical contact during cycling, then capacity is increased, but electrical isolation causes capacity degradation

Engineering Contradiction:

Improvesilicon contentVSAvoidelectrical conductivity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The carbon-coated silicon composite maintains electrical conductivity through the conductive carbon shell, which provides continuous electrical pathways even when silicon particles undergo volume changes, preventing electrical isolation.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The flexible carbon shell maintains intimate contact with the silicon core during volume expansion and contraction, ensuring continuous electrical contact between the active silicon material and the current collector.

Inventive Principle:

Principle #30Flexible shells and thin films

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 increases silicon mass loading, improves dispersion within the battery matrix, reduces stress on the matrix, and enhances the electrical connection between silicon particles and the matrix, leading to improved cycling stability and capacity retention in lithium-ion batteries.

Implementation Method 1

dispersed within a polymer network, specifically a porous polymer network, to enhance dispersion and reduce stress during charging and discharging processes

Methodology Applied

Scientific EffectStress absorption: Absorption (physical)

Implementation Method 2

covalently functionalized silicon particles with attached functional groups such as —OH, —COOH, —C—O—C—, —NH2, —NHR, dispersed within a polymer network

Methodology Applied

Scientific EffectElectrostatic interaction: Electrostatics

Data Source

PatentUS20250006933A1Functionalized silicon nanoparticles, composite materials including them, and preparation and uses thereof

Publication Date: 2025.01.02 ASPEN AEROGELS INC

AI summary

Provided herein are composite materials for use in electrical energy storage systems (e.g., high-capacity batteries) and methods for preparing the same. The composite materials of the present disclosure include a plurality of covalently functionalized silicon particles and a polymer network. Individual silicon particles within the plurality of silicon particles are dispersed throughout the polymer network. Covalently attached functional groups to a surface of the plurality of the silicon particles enable dispersion of the silicon particles throughout the polymer network.