Doped Silicon-Carbon Anode Coating for Volume Expansion Control
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Solution Overview
Problem
Silicon-based negative electrode materials in batteries face challenges due to violent volume expansion, leading to structural collapse, reduced cycle stability, and difficulty in forming a stable solid-state electrolyte interface, which affects battery capacity and longevity.
Innovation Solution
An element-doped silicon-carbon composite negative electrode material is developed, featuring a silicon nanoparticle core with a first carbon coating layer to suppress volume expansion and a second carbon coating layer for enhanced conductivity, along with a method that includes nano-sizing, doping with specific elements, and self-assembly processes to prevent oxide formation and improve electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon material is used as negative electrode to achieve high specific capacity, then battery capacity is improved, but volume expansion causes structural collapse and reduces cycle stability
Solution Approach 1:
The patent employs a nested structure where silicon nanoparticles are embedded within carbon layers. The silicon core maintains high capacity while the surrounding carbon shell constrains volume expansion. This nested configuration allows the inner silicon to expand/contract within the protective outer carbon structure, resolving the contradiction between high capacity and cycle stability.
Solution Approach 2:
The patent creates a composite material system combining silicon and carbon in a core-shell structure. The silicon provides high specific capacity while the carbon matrix provides structural stability and conductivity. This composite approach allows both materials to contribute their strengths, achieving high capacity retention over many cycles.
2Reliability
If silicon oxide shell is formed to suppress volume expansion, then structural stability is improved, but conductivity decreases and lithium ion consumption increases
Solution Approach 1:
The patent changes the material parameter from silicon oxide to carbon for the coating layer. Carbon maintains electrical conductivity and allows reversible lithium insertion/extraction, unlike silicon oxide which consumes lithium ions irreversibly. This parameter change preserves both structural stability and electrochemical activity.
Solution Approach 2:
The patent applies different properties to different parts of the structure: the silicon core provides high capacity while the carbon shell provides structural constraint and conductivity. This local differentiation allows the shell to suppress expansion without the detrimental effects of oxidation, maintaining both stability and low lithium consumption.
3Reliability
If element doping is applied to suppress volume expansion, then cycle performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent modifies the silicon material by doping with elements such as phosphorus or boron, changing its physical and chemical properties. This doping suppresses volume expansion and improves cycle performance. While doping adds a process step, it integrates well with existing semiconductor manufacturing techniques, keeping complexity manageable.
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 element-doped silicon-carbon composite negative electrode material significantly improves cycle performance, maintains high capacity retention, and enhances conductivity, reducing lithium ion consumption and oxidative corrosion, resulting in more efficient and stable battery operation.
Implementation Method 1
The element-doped silicon nanoparticle includes a silicon matrix and dopant elements located inside the silicon matrix
Implementation Method 2
a first carbon coating layer to suppress volume expansion
Data Source
AI summary
An element-doped silicon-carbon composite negative electrode material is provided. The negative electrode material comprises a plurality of element-doped silicon-carbon composite negative electrode material particles, and each them comprises an element-doped silicon nanoparticle, a first carbon coating layer and a second carbon coating layer. The element-doped silicon nanoparticle is a core, and the first carbon coating layer is coated on the element-doped silicon nanoparticle, the second carbon coating layer covers the first carbon coating layer. The dopant element comprises at least one of a group IIIA element, a group VA element and a transition metal element. A method of preparing the element-doped silicon-carbon composite negative electrode material is further provided.