Core-Shell Silicon Anode Particles with SiC Coating for Expansion Control
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Solution Overview
Problem
Lithium-ion batteries face limitations due to the high volume expansion and instability of monatomic silicon anode materials, leading to pulverization, electrode separation, and reduced cycle performance, while SiOx anodes offer improved stability but still suffer from expansion issues and unsatisfactory cycle life compared to traditional graphite anodes.
Innovation Solution
A silicon-based particle with a core-shell structure is developed, comprising an oxygen-containing silicon-based compound matrix, nano-silicon grains, a silicon carbide layer, and a carbon layer, which reduces expansion rates, enhances mechanical strength, and improves cycle stability by inhibiting SEI film damage and facilitating electron and lithium ion transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If monatomic silicon anode material is used, then capacity is improved, but volume expansion rate increases
Solution Approach 1:
The patent embeds monatomic silicon nanoparticles (0.1-20 nm) within an oxygen-containing silicon-based compound matrix, creating a nested core-shell structure. The silicon particles are dispersed and confined within the matrix, allowing high capacity utilization while the matrix constrains volume expansion during lithiation-delithiation cycles.
Solution Approach 2:
The patent creates a composite anode material consisting of monatomic silicon particles embedded in an oxygen-containing silicon-based compound matrix (SiOx, lithium silicate, or silicon oxide), coated with silicon carbide and carbon layers. This composite structure combines the high capacity of monatomic silicon with the expansion resistance of the oxygen-containing matrix and protective coatings.
2Quantity of substance
If monatomic silicon anode material is used, then capacity is improved, but cycle stability deteriorates
Solution Approach 1:
The patent applies multiple protective coatings before battery operation: an oxygen-containing silicon-based compound matrix that buffers expansion stress, a silicon carbide layer that prevents particle aggregation and maintains structural integrity, and a carbon layer that provides additional mechanical protection. These pre-applied protective measures prevent pulverization and electrode separation during cycling.
Solution Approach 2:
The composite structure combines monatomic silicon particles with an oxygen-containing silicon-based compound matrix and dual-layer coatings (silicon carbide and carbon), creating a hierarchical composite material that maintains high capacity while achieving excellent cycle stability through the synergistic protection of multiple materials.
3Reliability
If SiOx anode material is used, then cycle stability is improved, but capacity is reduced
Solution Approach 1:
The patent applies local quality by dispersing monatomic silicon particles (0.1-20 nm) within the oxygen-containing silicon-based compound matrix rather than using bulk SiOx. This localized high-silicon content in specific regions maintains high capacity while the overall oxygen-containing matrix structure provides expansion resistance and cycle stability.
Solution Approach 2:
The patent creates a composite material that combines monatomic silicon particles with an oxygen-containing silicon-based compound matrix, achieving a balance between capacity and cycle stability. The composite structure allows the silicon particles to contribute high capacity while the oxygen-containing matrix provides structural stability and resistance to expansion.
4Quantity of substance
If silicon anode material is used, then capacity is improved, but electrode separation occurs
Solution Approach 1:
The patent creates a composite anode material where monatomic silicon particles are embedded in an oxygen-containing silicon-based compound matrix and coated with silicon carbide and carbon layers. This composite structure maintains strong bonding between the active silicon particles and the conductive matrix, preventing electrode separation even during repeated expansion and contraction cycles.
Solution Approach 2:
The patent applies thin film coatings (silicon carbide layer: 1-200 nm; carbon layer: 1-2000 nm) on the silicon-based particles. These flexible thin films accommodate volume changes during lithiation-delithiation while maintaining electrical conductivity and mechanical connection to the current collector, preventing electrode separation.
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 core-shell structure increases connection strength, reduces peeling of the carbon layer, and enhances the electrochemical participation of silicon-based particles, resulting in improved cycle performance, reduced expansion rates, and increased energy density and capacity retention.
Implementation Method 1
The oxygen-containing silicon-based compound matrix can effectively buffer the expansion and contraction of silicon-based particles during the process of charging and discharging, so as to avoid particle pulverization
Implementation Method 2
the silicon carbide layer and the carbon layer can effectively maintain the structural strength of the silicon-based particles in the process of charging and discharging
Implementation Method 3
facilitating electron and lithium ion transmission
Implementation Method 4
facilitating electron and lithium ion transmission
Implementation Method 5
enhances mechanical strength, and improves cycle stability by inhibiting SEI film damage
Data Source
AI summary
A silicon-based particle with a core-shell structure, a method for preparing the same, an anode material, an electrode and a battery. The silicon-based particle includes: a core comprising an oxygen-containing silicon-based compound matrix and nano-silicon grains, a molar ratio of oxygen to silicon in the core being 0.5-1.5; a silicon carbide layer covering the core; and a carbon layer covering the silicon carbide layer. The silicon-based particle is used in batteries, and has the characteristics of low expansion rate, long cycle life, high capacity and high coulombic efficiency.