Porous Silicon Composite Cluster for Lithium Battery Anodes

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Solution Overview

Problem

Silicon electrodes in lithium-ion batteries face challenges due to large volume expansion, leading to electrically isolated active material and accelerated electrolyte decomposition, necessitating a structure that suppresses volume expansion and pulverization.

Innovation Solution

A porous silicon composite cluster structure is developed, comprising a porous silicon composite secondary particle with a carbonaceous layer and carbon flakes, which includes silicon suboxide and a carbon flake, providing a buffer against volume expansion and protecting the core from electrolyte permeation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon is used as negative electrode material to achieve high theoretical capacity, then battery capacity is improved, but volume expansion occurs during discharge leading to electrode pulverization

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrode structural integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The patent employs a nested structure where porous silicon particles are enclosed within carbonaceous material shells, forming a core-shell composite. This nested configuration allows the silicon to undergo volume expansion while being contained and supported by the outer carbonaceous layer, preventing electrode pulverization while maintaining high capacity.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent creates a composite material system combining silicon with carbonaceous materials (such as graphite, amorphous carbon, or carbon nanotubes). This composite structure leverages the high capacity of silicon while the carbonaceous component provides structural stability and accommodates volume changes, resolving the contradiction between capacity and structural integrity.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If specific surface area of silicon is increased to improve capacity, then battery capacity is improved, but electrolyte decomposition reaction is accelerated

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrolyte decomposition

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a carbonaceous material shell as an intermediary layer between the silicon particles and the electrolyte. This intermediate layer reduces direct contact between the high-surface-area silicon and the electrolyte, thereby suppressing electrolyte decomposition reactions while allowing lithium ion transport, thus maintaining high capacity without excessive side reactions.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If silicon undergoes volume expansion during discharge, then battery capacity is improved, but active material becomes electrically isolated

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrical conductivity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent employs a flexible carbonaceous material shell that can accommodate the volume expansion of silicon during discharge. This shell maintains continuous electrical contact with the conductive matrix, ensuring that the active silicon material remains electrically connected throughout the charge-discharge cycles, thus preserving both capacity and conductivity.

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

The porous silicon composite cluster structure enhances the lifespan and conductivity of lithium-ion batteries by reducing volume expansion and electrolyte interaction, improving capacity retention and rate capability.

Implementation Method 1

a porous silicon composite secondary particle... providing a buffer against volume expansion

Methodology Applied

Scientific EffectVolume expansion buffering: Porosity

Implementation Method 2

a carbonaceous layer on the porous silicon composite cluster, the carbonaceous layer comprising amorphous carbon... protecting the core from electrolyte permeation

Methodology Applied

Scientific EffectPhysical barrier protection: Permeation

Data Source

PatentUS11569500B2Porous silicon composite cluster structure, method of preparing the same, carbon composite using the same, and electrode, lithium battery, and device each including the same

Publication Date: 2023.01.31 SAMSUNG ELECTRONICS CO LTD

AI summary

A porous silicon composite including: a porous silicon composite cluster comprising a porous silicon composite secondary particle and a second carbon flake on at least one surface of the porous silicon composite secondary particle; and a carbonaceous layer on the porous silicon composite cluster, the carbonaceous layer comprising amorphous carbon, wherein the porous silicon composite secondary particle comprises an aggregate of two or more silicon primary particles, the two or more silicon primary particles comprise silicon, a silicon suboxide of the formula SiOx, wherein 0<x<2 on a surface of the silicon, and a first carbon flake on at least one surface of the silicon suboxide, the silicon suboxide is in a form of a film, a matrix, or a combination thereof, and the first carbon flake and the second carbon flake are each independently present in a form of a film, particles, a matrix, or a combination thereof. Also a method of preparing the porous silicon composite, a carbon composite, an electrode, and a device, each including the porous silicon composite, and a lithium battery including the electrode.