Multieffect Preoxidation Strategy to Convert Bituminous Coal into Hard Carbon for Enhancing Sodium Storage...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Preoxidation of coal is crucial for inhibiting graphitization during carbonization.
• Traditional preoxidation methods offer limited surface-active sites, hindering sodium storage capacity.
• Developing advanced hard carbon anodes from coal is essential for efficient sodium-ion batteries.

Purpose of the Study:

• To propose a multieffect preoxidation strategy for coal-based hard carbon.
• To suppress structural rearrangement and create abundant surface-active sites.
• To enhance the sodium storage performance of coal-based hard carbon anodes.

Main Methods:

• Utilized Mg(NO3)2·6H2O for preoxidation of bituminous coal at 450 °C.
• Employed Mg(NO3)2·6H2O as a cross-linking agent to inhibit carbon layer rearrangement.
• Leveraged the MgO residue to create surface-active sites through reaction with carbon.

Main Results:

• The optimized coal-based hard carbon exhibited enhanced pseudographitic domains and sodium storage active sites.
• Achieved an excellent capacity of 287.1 mAh g⁻¹ at 20 mA g⁻¹.
• Demonstrated remarkable cycling stability with 96.1% capacity retention after 200 cycles and 88.9% after 1000 cycles.

Conclusions:

• The multieffect preoxidation strategy effectively suppresses structural rearrangement and creates active sites.
• The developed coal-based hard carbon anodes show superior performance for sodium-ion batteries.
• This work presents a practical approach for converting low-cost coal into high-performance anode materials.