Silicon-Carbon Anode Production: The Key Role of Rotary Kilns

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Silicon-Carbon Anode Production: The Key Role of Rotary Kilns

Driven by lithium batteries' high energy density demand, silicon-carbon anodes (Si-C composites) are a core direction due to silicon's theoretical capacity of 4200 mAh/g (far exceeding graphite's 372 mAh/g). However, silicon's 300%-400% volume expansion during lithium intercalation requires high-temperature carbonization and coating processes. Rotary kilns, with advantages of "continuous operation, precise temperature control, and uniform heating", have become core equipment for large-scale silicon-carbon anode production.

1. Core Applications of Rotary Kilns in Silicon-Carbon Anode Production

In silicon-carbon anode preparation, rotary kilns mainly serve high-temperature heat treatment to solve key process pain points:

Silicon Powder Carbon Coating: Mix silicon powder with carbon sources (e.g., pitch), heat at 800-1200℃ under inert atmosphere. Cylinder rotation ensures uniform coating layer (thickness deviation ≤±0.5μm) after carbon source pyrolysis, buffering silicon expansion and improving conductivity.
Si-C Composite Carbonization: For silicon-resin precursors, carbonize at 900-1500℃ (heating rate 5-10℃/min) under nitrogen protection. Precise temperature control (±3℃) avoids silicon oxidation, while rotation prevents agglomeration to form porous carbon framework.
Doping Modification: Mix silicon-carbon materials with dopants (e.g., urea) at 600-900℃, rotation enables uniform diffusion of N/P/S elements to enhance cycle stability.

2. Core Advantages of Rotary Kilns

Compared with traditional box furnaces and pusher kilns, rotary kilns have significant adaptability:

More Uniform Heating & Mixing: Rotation + flight design eliminates "edge-center temperature difference", avoiding electrode failure caused by local silicon enrichment;
Stable Atmosphere Control: Closed structure + inert gas circulation, oxygen content ≤10ppm to prevent silicon oxidation;
Continuous Mass Production: Daily output per unit up to ton-level, far exceeding box furnaces' tens of kg per batch;
Flexible Parameter Adjustment: Cylinder speed (0.5-5r/min) and temperature (600-1500℃) adjustable for formulas with 5%-30% silicon content.

3. Key Process Control Points

Temperature Curve: Slow heating (2-3℃/min) at 200-500℃ to prevent carbon source volatilization, fast heating at 800-1500℃ to promote carbon graphitization;
Atmosphere & Pressure: Inert gas flow 1-3m³/h to exhaust waste gas, micro-positive pressure (50-100Pa) to prevent air infiltration;
Material Control: Feed particle size 1-50μm, filling rate 30%-50% matching rotation speed.

4. Our Rotary Kilns' Competitiveness & Outlook

As a professional lithium battery equipment manufacturer, our rotary kilns address industry pain points:
Ultra-Precise Temperature Control: Zoned heating + imported modules, temperature difference ±2℃ (better than industry ±5℃);
Low Oxygen Environment: Dual-cycle inert gas system + patented sealing, oxygen content ≤5ppm;
Intelligence & Customization: IoT platform for remote monitoring, customized design for capacity (lab scale to 10k-ton level) with on-site commissioning and lifelong after-sales service.

Currently, our equipment serves dozens of leading lithium battery enterprises, helping customers increase silicon-carbon anode's initial discharge capacity by 15%-20% and maintain ≥85% capacity after 500 cycles. We will continue optimizing energy efficiency and intelligent operation to support high-energy-density lithium battery production.