Silicon-Based Anode Composite with Controlled Oxide Shell
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Solution Overview
Problem
Silicon-based anode materials for secondary batteries face challenges due to volume variation during charging and discharging, leading to irreversible reactions and reduced lifespan, and existing fabrication methods are not economically scalable for high-capacity applications.
Innovation Solution
A silicon-based active material composite is developed, comprising silicon and silicon oxide with a controlled oxygen content of 9 wt % to 20 wt %, where silicon is either coated with a silicon oxide shell or dispersed within a matrix, and optionally accompanied by a conductive layer to enhance electrical connectivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as anode material to achieve high capacity, then capacity is improved, but volume variation during charging and discharging causes electric connection breakage and active material isolation
Solution Approach 1:
The patent embeds silicon particles within a porous carbon matrix structure, creating a nested configuration where silicon is contained within the carbon framework. This nesting approach allows the carbon matrix to accommodate silicon's volume expansion while maintaining structural integrity and electrical connectivity throughout charge/discharge cycles.
Solution Approach 2:
The patent creates a composite material system combining silicon and carbon in a specific architecture where silicon particles are dispersed within a porous carbon matrix. This composite structure leverages the high capacity of silicon while the carbon matrix provides structural stability, conductivity, and tolerance to volume changes, resolving the contradiction between capacity and reliability.
2Quantity of substance
If silicon is used as anode material to achieve high capacity, then capacity is improved, but irreversible reactions and active material erosion occur reducing lifespan
Solution Approach 1:
The patent pre-establishes a protective porous carbon matrix framework before silicon undergoes volume expansion and contraction during cycling. This pre-formed carbon structure acts as a cushioning framework that absorbs mechanical stress and prevents direct contact between silicon and electrolyte, thereby preventing erosion and irreversible reactions that would otherwise reduce lifespan.
Solution Approach 2:
The porous carbon matrix serves as an intermediary between silicon and the electrolyte environment. It mediates the interaction by providing a stable interface that prevents direct harmful reactions between silicon and electrolyte, while still allowing lithium ion transport. This intermediary layer protects silicon from erosion and irreversible reactions, extending battery lifespan.
3Productivity
If conventional fabrication methods are used for silicon anode, then production is achieved, but economic scalability for high-capacity applications is limited
Solution Approach 1:
The patent employs a preliminary action approach by first forming the porous carbon matrix structure, then impregnating it with silicon particles in a sequential manufacturing process. This preliminary formation of the carbon framework enables subsequent easy infiltration of silicon, simplifying the overall fabrication process and making it more economically scalable compared to simultaneous synthesis methods.
Solution Approach 2:
The patent utilizes liquid-phase infiltration where silicon particles are introduced in liquid form or suspension that penetrates the porous carbon matrix through capillary action and fluid flow. This hydraulic/pneumatic infiltration method enables simple, scalable processing that can be easily implemented in large-scale production, improving economic feasibility compared to solid-state mixing or high-energy processing methods.
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 maintains 80% or greater capacity retention over 50 charge/discharge cycles, improving lifespan and energy density while allowing for massive, cost-effective production, by controlling volume expansion and irreversibility through the strategic incorporation of silicon oxide.
Implementation Method 1
silicon and silicon oxide obtained by oxidizing at least a part of the silicon
Data Source
AI summary
Provided is an anode active material for a secondary battery and a method of fabricating the anode active material. A silicon-based active material composite according to an embodiment of the inventive concept includes silicon and silicon oxide obtained by oxidizing at least a part of the silicon, and an amount of oxygen with respect to a total weight of the silicon and the silicon oxide is restricted to 9 wt % to 20 wt %.