Carbon-Silicon Composite Particles With Gradient Mesopore Support
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Solution Overview
Problem
Conventional porous carbon supports have deep pores that are not adequately filled during chemical vapor deposition, leading to reduced charge/discharge capacity and cycle characteristics of silicon-based negative electrode materials due to volume expansion.
Innovation Solution
Carbon-silicon composite particles with a porous carbon support containing mesopores of 2 to 50 nm, a surface layer mesopore ratio of 0.5 to 0.76, and a tap density of 0.7 g/mL or less, allowing silicon deposition into deep pores, enhancing charge/discharge capacity and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional porous carbon supports with micropores are used, then the carbon support structure is simple and easy to manufacture, but the chemical vapor deposition cannot reach the deep pores well, resulting in insufficient silicon deposition
Solution Approach 1:
The patent applies porous materials by designing a carbon support with specifically controlled mesopore structure (2-50 nm diameter) and optimized pore size distribution. The surface layer is engineered to have higher porosity than the core, creating a gradient pore structure that facilitates vapor penetration while maintaining mechanical integrity. This resolves the contradiction by using tailored porous architecture to enable complete silicon deposition without oversimplifying the structure.
Solution Approach 2:
The patent implements local quality by creating a non-uniform pore distribution where the surface layer has different porosity characteristics than the core. The surface layer contains more mesopores to facilitate vapor entry and distribution, while the core has a different pore configuration. This local differentiation allows the deposition process to reach deep pores effectively while maintaining overall structural stability.
2Quantity of substance
If silicon-based active materials are used to increase battery capacity, then the theoretical capacity is improved, but the large volume expansion rate reduces battery lifespan
Solution Approach 1:
The patent applies flexible shells and thin films by using a porous carbon support structure that acts as a flexible container for silicon. The carbon matrix accommodates silicon's volume expansion during lithiation/delithiation cycles while maintaining structural integrity. The porous architecture allows the silicon to expand and contract without causing catastrophic failure, thus preserving battery lifespan while utilizing high-capacity silicon materials.
Solution Approach 2:
The patent implements composite materials by creating a carbon-silicon composite structure where silicon particles are deposited within the porous carbon support matrix. This composite architecture combines the high capacity of silicon with the structural stability and conductivity of carbon. The carbon support serves multiple functions: providing mechanical framework, enabling ion transport pathways, and accommodating volume changes, thus resolving the capacity-lifespan trade-off.
3Quantity of substance
If the pore size is reduced to increase surface area for silicon deposition, then the silicon capacity is improved, but the deposition process cannot penetrate into deep pores
Solution Approach 1:
The patent applies parameter changes by optimizing the pore diameter to the specific range of 2-50 nm (mesopores) and controlling the pore size distribution gradient from surface to core. This parameter optimization allows the pore size to be small enough to provide high surface area for silicon deposition while remaining large enough to permit vapor phase silicon precursors to penetrate effectively. The controlled pore size parameters resolve the contradiction between surface area and penetration speed.
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 solution enables high charge/discharge capacity and improved cycle characteristics of the negative electrode material by ensuring sufficient silicon deposition within the porous carbon support, minimizing volume expansion-related damage.
Implementation Method 1
conventional porous carbon supports mainly include micropores, and when chemical vapor deposition (CVD) is performed in a subsequent process, there is a problem in that the deposition does not reach the deep pores well
Data Source
Figure 1A~1B
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Figure 3
AI summary
According to an embodiment of the present invention, the present invention can provide carbon-silicon composite particles, each comprising: a porous carbon support comprising a surface layer part and a core part; and silicon (Si), wherein the porous carbon support comprises mesopores having a diameter of 2-50 nm, and the ratio of the volume of the mesopores of the surface layer part to the volume of the total mesopores of the porous carbon support is 0.5-0.76.