Porous Silicon-Coated Anode Material for Crack-Resistant Li-Ion Batteries
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Solution Overview
Problem
Lithium secondary batteries face issues with volume expansion of silicon-carbon composite anode active materials leading to cracks and exposure to electrolyte during charging and discharging, which affects capacity, output, and lifespan.
Innovation Solution
An anode active material with composite particles featuring a silicon-containing coating on carbon-based particles, controlled through heat treatment to achieve a specific C/SiC peak intensity ratio, and including pores and a carbon coating to stabilize silicon, suppressing the formation of SiC phase and reducing crystal grain size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-carbon composite is used as anode active material to increase capacity, then energy density is improved, but volume expansion during charging and discharging causes cracks and exposure to electrolyte
Solution Approach 1:
The patent applies nesting by placing silicon particles inside carbon-based particles with pores. The silicon is embedded within the carbon matrix, creating a nested structure where the inner silicon benefits from the outer carbon's mechanical stability while maintaining electrical contact. This resolves the contradiction by containing the expanding silicon within the resilient carbon framework.
Solution Approach 2:
The patent utilizes porous carbon-based particles where the pores can expand and contract to accommodate silicon's volume changes during lithiation and delithiation. The porous structure provides buffer space for expansion, preventing crack formation while maintaining structural integrity. This directly addresses the volume expansion issue while preserving the high capacity benefits of silicon.
2Use of energy by moving object
If silicon content is increased to improve capacity characteristics, then energy density is improved, but cracks occur due to volume expansion difference
Solution Approach 1:
The patent creates a composite material system combining silicon and carbon in a specific architecture. The silicon-containing coating is formed on carbon-based particles, creating a composite structure where each material contributes its strengths: silicon provides high capacity while carbon provides mechanical stability and crack resistance. This composite approach allows high silicon content while maintaining structural integrity.
Solution Approach 2:
The patent applies local quality by creating a silicon-containing coating specifically on the surface and within the carbon-based particle structure, rather than uniform mixing. The silicon is localized in regions where it can expand without compromising the overall particle structure, with the carbon matrix providing structural support in critical areas.
3Duration of action of stationary object
If heat treatment is performed to control C/SiC peak intensity ratio, then lifespan characteristics are improved, but manufacturing process complexity increases
Solution Approach 1:
The patent controls the C/SiC peak intensity ratio by adjusting heat treatment parameters (temperature, time, atmosphere). By optimizing these parameters, the patent achieves suppression of SiC phase formation and control of crystal grain size, which improves lifespan characteristics. The specific range of 900-1200°C for 6-9 hours represents an optimized parameter set that balances performance improvement with manufacturing feasibility.
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 capacity, output, and lifespan characteristics by preventing cracks and gas generation, enhancing mechanical and chemical stability under high-temperature conditions.
Implementation Method 1
performing heat treatment on the composite particles at 900°C to 1200°C for 6 hours to 9 hours
Implementation Method 2
suppressing the formation of SiC phase and reducing crystal grain size
Implementation Method 3
a silicon-containing coating formed on a surface of carbon-based particles comprising porous... suppressing the formation of SiC phase and reducing crystal grain size
Data Source
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AI summary
An anode active material for a lithium secondary battery according to embodiments of the present disclosure includes composite particles which comprise a silicon-containing coating formed on a surface of carbon-based particles comprising porous, wherein the composite particles have a C/SiC peak intensity ratio of 1.0 to 4.5, which is measured through X-ray diffraction analysis after performing heat treatment on the composite particles at 900°C to 1200 °C for 6 hours to 9 hours. A method of preparing an anode active material for a lithium secondary battery according to embodiments of the present disclosure comprise preparing preliminary carbon-based particles including pores; performing first calcination on the preliminary carbon-based particles with a hydrogen-containing gas to form carbon-based particles; and performing second calcination on the carbon-based particles with a silicon-containing gas to form composite particles which comprise a silicon-containing coating formed on a surface of the carbon-based particles, wherein the composite particles have a C/SiC peak intensity ratio of 1.0 to 4.5, which is measured through X-ray diffraction analysis after performing heat treatment on the composite particles at 900°C to 1200 °C for 6 hours to 9 hours.