Silicon Anode Coating for Battery Volume Expansion
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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 conductivity.
Engineering Contradictions & Design Principles
Engineering 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
Solution Approach 1:
The patent applies nested doll by placing silicon particles inside a carbon matrix structure, where the carbon phase acts as a container that accommodates silicon's volume expansion. The silicon is embedded within the carbon framework, allowing the outer carbon structure to absorb dimensional changes while maintaining overall structural integrity and preventing mechanical failure.
Solution Approach 2:
The patent creates a composite material system combining silicon particles with carbon phases (graphite, amorphous carbon, or carbon nanotubes). This composite structure leverages silicon's high energy density while using carbon's mechanical stability and flexibility to constrain volume expansion, achieving both high capacity and structural reliability during lithium insertion cycles.
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
Solution Approach 1:
The patent merges silicon particles with conductive carbon phases to create a composite where the carbon network provides continuous electrical pathways. The carbon matrix surrounds and connects the silicon particles, ensuring that electrons can transport efficiently from the silicon active material to the current collector, thereby maintaining high electrical conductivity while preserving silicon's high capacity.
3Use of energy by moving object
If silicon particles are used as anode material, then energy density is improved, but cycle life deteriorates due to mechanical failure and loss of electrical contact
Solution Approach 1:
The patent employs a flexible carbon matrix structure that can deform and accommodate silicon's volume changes during lithium insertion and extraction cycles. The carbon framework acts as a flexible container that maintains structural integrity over repeated cycles, preventing particle fragmentation and maintaining electrical contact, thereby significantly extending battery cycle life while preserving high energy density.
4Quantity of substance
If silicon particles are used as anode material, then capacity is improved, but irreversible capacity losses increase
Solution Approach 1:
The patent introduces carbon phases as an intermediary material between silicon and the electrolyte. This carbon layer serves as a protective interface that reduces direct contact between silicon and electrolyte, minimizing unwanted side reactions and formation of thick SEI layers. The intermediary carbon structure allows reversible lithium insertion while reducing irreversible capacity losses, thereby improving overall battery efficiency.
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, enabling stable and efficient lithium-ion battery performance.
Implementation Method 1
silicon anodes due to significant volume expansion during lithium insertion
Implementation Method 2
substantially all of the silicon particles have surface coatings comprising silicon carbide or a mixture of carbon and silicon carbide
Implementation Method 3
at least one of the one or more types of carbon phases is a substantially continuous phase
Implementation Method 4
pyrolyzing the precursor to convert the precursor into one or more types of carbon phases, and forming silicon carbide on at least a portion of silicon particles
Implementation Method 5
forming silicon carbide on at least a portion of silicon particles
Data Source
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.