During the 2025 (10th) New Energy Industry Expo, organized by Shanghai Nonferrous Network Information Technology Co., Ltd. (SMM), Lin Shaoxiong, Vice President of the Central Research Institute of Carbon One Group, discussed the topic of silicon-based anode materials and the challenges they face.
<h2>Challenges and Future Directions for Silicon-Based Anodes</h2>
As the demand for battery anodes evolves, the future requirements include <b>high energy density</b>, <b>high safety</b>, <b>low expansion</b>, <b>long lifespan</b>, and the ability to support <b>fast charging</b> (4-8C). Silicon-based anodes are positioned as a promising trend, with applications in <b>consumer batteries</b>, <b>power batteries</b>, and in fields such as <b>drones</b> and <b>eVTOL</b> aircraft. However, several challenges must be addressed, including <b>process safety</b>, <b>batch stability</b>, initial efficiency, expansion, storage, fast charging capabilities, and cost.
<h2>Silicon-Carbon Process Scaling Challenges</h2>
The limitations of rotary kilns include:
<ul>
<li><b>Silane (SiH4)</b> deposition is inconsistent due to uncontrolled particle movement, leading to uneven silicon deposition and incomplete carbon coating, resulting in poor batch consistency.</li>
</ul>
In terms of fluidized bed production:
<ul>
<li>While fluidized beds can achieve uniform deposition, they require high levels of equipment sealing and precise pressure control, making it difficult to scale up to ton-level capacity. This results in low utilization rates of silane (only 30%-50%), which increases costs.</li>
</ul>
Moreover, precise control of temperature and pressure is essential:
<ul>
<li>The <b>CVD (Chemical Vapor Deposition)</b> process requires accurate temperature regulation in various zones of the furnace and control of silane partial pressure; otherwise, it may lead to the formation of <b>amorphous silicon</b> or silicon particle agglomeration, which negatively impacts performance.</li>
</ul>
<h2>Future Approaches for Silicon-Based Anodes</h2>
The new direction for silicon-carbon anodes involves the <b>vapor deposition process</b>. This method offers:
<ul>
<li><b>Abundant sources of porous carbon</b>: Biomass materials such as coconut shells, rice husks, and wood waste are renewable; resin materials like phenolic resin are chemical products.</li>
<li><b>High energy density</b>: Silicon-carbon anodes exhibit high specific capacity, enabling greater energy density and thus extending battery range.</li>
<li><b>Long cycle life</b>: These anodes demonstrate good stability, withstanding hundreds or even thousands of charge-discharge cycles, thereby prolonging battery life.</li>
<li><b>Environmental friendliness</b>: The CVD vapor separation technology is an eco-friendly preparation method that does not produce harmful waste and aligns with green energy requirements.</li>
</ul>
<h2>Directions for Porous Carbon Substrates</h2>
To mitigate silicon-carbon expansion, strategies include:
<ul>
<li>Incorporating mesopores to provide a buffer space for expansion, combined with interface coating technology.</li>
<li>Enhancing fast charging performance and improving the initial efficiency of silicon-carbon anodes.</li>
</ul>
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