Tunable-Porosity Carbon-Silicon Anodes for Swelling Stability

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Solution Overview

Problem

Silicon anodes in lithium-ion batteries experience significant volume expansion during lithiation, leading to structural degradation, electrical isolation, and rapid capacity fading due to the 'breathing effect,' which compromises cycling stability and battery lifetime.

Innovation Solution

A composite material comprising mega pores and a three-dimensional carbon network, where mega pores are formed by carbonizing sacrificial particles, accommodates volume expansion of silicon particles, stabilizing the electrode structure and enhancing electrical connectivity and Li+ diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon particles are used as anode material to achieve high capacity, then the theoretical gravimetric capacity is improved, but the structural stability deteriorates due to volume expansion during lithiation

Engineering Contradiction:

Improvetheoretical gravimetric capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent employs a porous carbon matrix structure with controlled porosity to encapsulate silicon particles. The porous structure provides void space that accommodates the 400% volume expansion of silicon during lithiation, preventing structural degradation while maintaining electrical conductivity and mechanical integrity throughout charge-discharge cycles.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent creates a composite material system combining silicon particles with a carbon matrix. This composite structure leverages the high capacity of silicon while the carbon matrix provides structural stability, electrical conductivity, and mechanical support, resolving the contradiction between capacity and stability.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silicon particles undergo volume expansion during lithiation, then the capacity is improved, but the electrical conductivity deteriorates due to pulverization and loss of contact

Engineering Contradiction:

ImprovecapacityVSAvoidelectrical conductivity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent utilizes a flexible carbon matrix that can deform elastically to accommodate silicon volume changes. This carbon shell maintains continuous electrical contact with silicon particles throughout expansion and contraction cycles, preventing pulverization and ensuring stable electrical conductivity for reliable charge transfer.

Inventive Principle:

Principle #30Flexible shells and thin films

3Strength

If the carbon matrix is made denser to improve structural strength, then the mechanical strength is improved, but the Li+ diffusion deteriorates due to reduced porosity

Engineering Contradiction:

Improvestructural strengthVSAvoidLi+ diffusion rate

Core Design Contradiction:

StrengthVSSpeed

Solution Approach 1:

The patent implements local quality optimization by creating a carbon matrix with heterogeneous pore size distribution. The matrix contains both micropores for high surface area and electrical conductivity, and mesopores/macropores for efficient Li+ diffusion pathways. This local differentiation allows simultaneous achievement of mechanical strength and fast ion transport.

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 composite material delays fracturing of silicon particles, maintains structural integrity, and prevents rapid capacity fading, significantly improving the performance and longevity of lithium-ion batteries by buffering mechanical pressure and facilitating charge transfer.

Implementation Method 1

at least some of the mega pores are formed by carbonizing a plurality of sacrificial particles dispersed throughout a three-dimensional network

Methodology Applied

Scientific EffectPyrolysis: Pyrolysis

Implementation Method 2

Methodology Applied

Scientific EffectMechanical buffering:

Data Source

PatentUS20250002347A1Composite materials with tunable porosity and the preparation and uses thereof

Publication Date: 2025.01.02 ASPEN AEROGELS INC

AI summary

Provided herein are composite materials for use in an electrical energy storage system (e.g., a high-capacity battery) and methods for preparing the same. The composite materials provided herein are also useful as substrates for chemical vapor deposition of silicon. The composite materials of the present disclosure include a three-dimensional carbon network and optional silicon particles. The composite materials further include mega pores, at least some of which are formed by carbonizing sacrificial particles dispersed throughout a three-dimensional network. The mega pores advantageously provide a space to accommodate the strain and stress in the electrode structure due to volume changes of silicon (particles) during charge and discharge of the electrical energy storage system.