Carbon-Doped Silicon Monoxide Anode for Stable Li-Ion Cycling
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Solution Overview
Problem
Silicon-based anode materials for lithium ion batteries suffer from poor conductivity, unstable solid electrolyte interface (SEI) films, and significant volume expansion, leading to poor cycle performance and short cycle life.
Innovation Solution
An anode material comprising a matrix of carbon-doped silicon monoxide with specific carbon content, particle size, and surface area, optionally coated with carbon, oxide, or polymer, to stabilize the SEI and mitigate volume expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anode material is used, then capacity is improved, but conductivity deteriorates
Solution Approach 1:
The patent uses silicon oxycarbide composite material containing Si-O-C bonds, combining silicon's high capacity with carbon's conductivity and oxide's stability. This composite structure resolves the contradiction by integrating multiple material properties into a single functional anode material that simultaneously achieves high capacity and good conductivity.
Solution Approach 2:
The patent changes the chemical composition parameters by controlling the content of SiO2 (5-30 wt%) and carbon (70-40 wt%) in the silicon oxycarbide composite. By adjusting these compositional parameters, the material achieves optimal balance between capacity and conductivity, transforming the material properties to resolve the contradiction.
2Quantity of substance
If silicon-based anode material is used, then capacity is improved, but SEI film stability deteriorates
Solution Approach 1:
The silicon oxycarbide composite with Si-O-C bonds creates a more stable interface chemistry that forms stable SEI films. The presence of oxygen in the composite structure modifies the electrochemical behavior at the electrode-electrolyte interface, leading to stable SEI formation that maintains capacity over cycles.
Solution Approach 2:
The patent employs a carbon coating layer on the silicon oxycarbide particles that acts as a protective interface. This coating forms a stable SEI film that protects the underlying silicon from continuous degradation, effectively creating a stable interface that maintains performance over time.
3Quantity of substance
If silicon-based anode material is used, then capacity is improved, but volume expansion deteriorates
Solution Approach 1:
The silicon oxycarbide composite structure with Si-O-C bonds provides a more robust framework that accommodates volume changes during lithium insertion/extraction. The oxide and carbon components create a structural buffer that reduces the magnitude of volume expansion compared to pure silicon, maintaining structural integrity over cycles.
Solution Approach 2:
The carbon coating layer on silicon oxycarbide particles acts as a flexible protective shell that accommodates volume changes during charge-discharge cycles. This coating layer allows for controlled expansion and contraction while maintaining structural integrity, reducing particle fracture and preserving capacity.
4Reliability
If carbon content in matrix material is increased, then conductivity is improved, but SEI film stability deteriorates
Solution Approach 1:
The patent optimizes the carbon content parameter in the matrix material to a specific range (70-40 wt%) that balances conductivity and SEI stability. This parameter optimization ensures sufficient carbon for conductivity while maintaining enough SiO2 content for stable SEI formation, resolving the contradiction through precise compositional control.
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
Improves cycle performance at room temperature and high temperature by stabilizing the SEI and reducing expansion stress, enhancing the anode's conductivity and cycle life.
Implementation Method 1
the carbon is doped in the silicon monoxide
Implementation Method 2
the anode material further comprises a coating layer formed on at least a part of a surface of the matrix material
Implementation Method 3
the matrix material has an average particle size that ranges from 0.5 μm to 30 μm
Data Source
AI summary
An anode material, including a matrix material, and the matrix material comprises carbon-doped silicon monoxide, and a content of the carbon ranges from 0.5% to 10% based on a total mass of the carbon and silicon monoxide. The anode material can significantly improve the cycle performance of an electrochemical device at room temperature and high temperature.