Silicon Particle Surface Coatings for Stable Li-Ion Anodes

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Solution Overview

Problem

Lithium-ion battery electrodes face challenges with silicon anodes due to significant volume expansion during lithium insertion, leading to mechanical failure and loss of electrical contact, as well as inherent non-conductivity and high irreversible capacity losses.

Innovation Solution

A composite material film is developed with silicon particles coated with silicon carbide or a mixture of carbon and silicon carbide, integrated with a continuous carbon phase, which acts as an expansion buffer and maintains electrical contact, reducing mechanical failure and enhancing electrochemical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If silicon particles are used as anode material, then energy density is improved, but mechanical stability deteriorates due to volume expansion during lithium insertion

Engineering Contradiction:

Improveenergy densityVSAvoidmechanical stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

Silicon particles are encapsulated within a carbon matrix, creating a nested structure where the carbon shell contains the silicon core. This nesting approach allows the silicon to expand during lithiation while being constrained by the carbon matrix, preventing mechanical failure while maintaining high energy density.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention uses composite materials combining silicon and carbon in a matrix structure. The carbon matrix provides mechanical stability and structural integrity, while the silicon particles provide high capacity for lithium insertion. This composite approach resolves the contradiction between energy density and mechanical stability.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silicon particles are used as anode material, then capacity is improved, but electrical conductivity deteriorates due to inherent non-conductivity of silicon

Engineering Contradiction:

ImprovecapacityVSAvoidelectrical conductivity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

Silicon particles are merged with a conductive carbon matrix to form a composite electrode. The carbon matrix serves as both a structural support and an electrical conductive network, allowing electrons to flow throughout the electrode while silicon particles provide high capacity. This merging resolves the conductivity issue while maintaining high capacity.

Inventive Principle:

Principle #5Merging (Combining)

3Use of energy by moving object

If silicon particles are used as anode material, then energy density is improved, but irreversible capacity losses increase

Engineering Contradiction:

Improveenergy densityVSAvoidirreversible capacity losses

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

A carbon coating is applied to the silicon particles before electrode fabrication. This preliminary coating action creates a protective interface that reduces direct contact between silicon and electrolyte, minimizing side reactions and irreversible capacity losses during initial cycles while preserving the high energy density of silicon.

Inventive Principle:

Principle #10Preliminary action

4Quantity of substance

If silicon particles are used as anode material, then capacity is improved, but mechanical durability deteriorates due to expansion and contraction cycles

Engineering Contradiction:

ImprovecapacityVSAvoidcycle life

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

Silicon particles are enclosed in a flexible carbon matrix that can accommodate volume changes during lithiation and delithiation cycles. The carbon shell acts as a flexible container that maintains structural integrity through expansion and contraction, preventing particle pulverization and maintaining electrical contact over many cycles, thus improving durability while preserving high capacity.

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 composite material achieves high energy density, improved cycle life, and reduced irreversible capacity losses by constraining silicon expansion and maintaining electrical conductivity, resulting in enhanced performance and stability of lithium-ion battery electrodes.

Implementation Method 1

substantially all of the silicon particles have surface coatings comprising silicon carbide or a mixture of carbon and silicon carbide

Methodology Applied

Scientific EffectVolume expansion constraint:

Implementation Method 2

at least one of the one or more types of carbon phases is a substantially continuous phase

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20230387393A1Surface Modification of Silicon Particles for Electrochemical Storage

Publication Date: 2023.11.30 ENEVATE CORP

AI summary

Silicon particles for active materials and electro-chemical cells are provided. The active materials comprising silicon particles described herein can be utilized as an electrode material for a battery. In certain embodiments, the composite material includes greater than 0% and less than about 90% by weight silicon particles, the silicon particles having an average particle size between about 10 nm and about 40 μm, wherein the silicon particles have surface coatings comprising silicon carbide or a mixture of carbon and silicon carbide, and greater than 0% and less than about 90% by weight of one or more types of carbon phases, wherein at least one of the one or more types of carbon phases is a substantially continuous phase.