Silicon-Carbon Composite Anode With Metal Layer for Cycle Stability
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Solution Overview
Problem
Silicon-based anode materials face issues such as low first-cycle coulombic efficiency, insufficient long-cycling stability, and poor rate performance due to repeated volume changes and defective side reactions during lithium deintercalation/intercalation, limiting their practical application.
Innovation Solution
A method involving the preparation of a silicon/carbon composite anode material through heating a hypercrosslinked polymer to form a porous carbide, mixing with a silicon-containing solution, and adding a complexing agent, metal salt, and reducing agent to form a silicon/carbon composite anode material with a metal layer for improved electrical conductivity and stress resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anode materials are used to achieve high theoretical lithium storage capacity, then the lithium storage capacity is improved, but the material deactivates due to repeated volume changes and electrical contact loss
Solution Approach 1:
A carbon coating layer is formed on the silicon-based anode material surface through chemical vapor deposition, creating a flexible protective shell that accommodates volume changes during lithium intercalation/deintercalation while maintaining electrical contact and preventing material degradation
Solution Approach 2:
The invention creates a composite structure combining silicon-based material with carbon coating and metal layer, where each component addresses specific issues: silicon provides high capacity, carbon coating maintains structural integrity during volume changes, and metal layer enhances electrical conductivity
2Quantity of substance
If silicon-based anode materials with larger specific surface area are used to increase reaction sites, then the lithium storage capacity is improved, but defective side reactions increase causing low first-cycle coulombic efficiency
Solution Approach 1:
The carbon coating is applied selectively on the silicon-based anode material surface, creating regions with different properties: the core silicon provides high capacity while the coated surface regions prevent unwanted side reactions, achieving local optimization of reactivity
3Quantity of substance
If silicon-based anode materials are used to achieve high theoretical lithium storage capacity, then the lithium storage capacity is improved, but long-cycling stability becomes insufficient due to repeated expansion and contraction
Solution Approach 1:
The carbon coating layer acts as a flexible shell that can expand and contract with the silicon core during cycling, maintaining structural integrity and preventing material pulverization, thereby ensuring long-term cycling stability
Solution Approach 2:
The carbon coating is applied beforehand to create a protective cushion that absorbs the mechanical stress of repeated expansion and contraction, preventing direct damage to the silicon-based material and maintaining structural integrity over many cycles
4Speed
If the electrical conductivity of silicon-based anode materials is to be improved, then the rate performance can be enhanced, but the material structure becomes more complex requiring additional metal layers
Solution Approach 1:
The invention merges multiple functions into a single integrated structure: the carbon coating layer simultaneously provides electrical conductivity enhancement, structural protection during volume changes, and prevention of side reactions, while the metal layer adds further conductivity improvement without requiring separate complex systems
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 silicon/carbon composite anode material exhibits enhanced cycling performance and electrical conductivity, effectively bearing stress from volume changes and improving lithium ion diffusion, thus enhancing the anode's stability and efficiency.
Implementation Method 1
heating a hypercrosslinked polymer in an inert atmosphere for carbonization to obtain a porous carbide
Implementation Method 2
adding a complexing agent, a metal salt, and a reducing agent to the silicon-containing porous carbide suspension to allow a reaction
Data Source
AI summary
The present disclosure discloses a preparation method for a silicon/carbon composite anode material and use of thereof. The preparation method includes the following steps: heating a hypercrosslinked polymer in an inert atmosphere for carbonization to obtain a porous carbide; mixing the porous carbide with a silicon-containing solution to obtain a silicon-containing porous carbide suspension; and adding a complexing agent, a metal salt, and a reducing agent to the silicon-containing porous carbide suspension to allow a reaction, and after the reaction is completed, conducting solid-liquid separation to obtain a solid, and heating the solid in an inert atmosphere to obtain the silicon/carbon composite anode material. In the present disclosure, the metal salt is reduced with the reducing agent under an action of the complexing agent through a metal-embedded-into-silicon treatment, such that a metal layer is formed on a silicon layer adsorbed on the porous carbide.