Hierarchical Porous Carbon Anode Materials Derived from Rice Husks with High Capacity and Long Cycling Stability for Sodium-Ion Batteries

Compared with the cathode materials, the research on the anode materials of the sodium-ion batteries has lagged behind. Therefore, development of the anode materials with high capacity, long life, and excellent rate properties is the key to unlocking the practical application for sodium-ion batteries. This study presents the preparation of hierarchical porous hard carbon as an active anode material from rice husks. The as-synthesized materials are characterized by X-ray diffraction, N-2 adsorption, Raman spectra, scanning electron microscopy and transmission electron microscopy. These porous hard carbon materials exhibit a high specific surface area and are promising for reversible sodium storage. Galvanostatic studies show that the specific initial capacities of all samples were in the range of 130-300 mA h g(-1) at a current density of 100 mA g(-1) between 0.01 V and 2.3 V. Compared to the other samples, the hard carbon materials prepared at 800 degrees C from rice husk (RHPC-800) can deliver a high reversible capacity of 274 mA h g(-1) at a current density of 25 mA g(-1), maintain a capacity of approximately 260 mA h g(-1), and retain 92.7 % of its capacity after 500 cycles. This excellent electrochemical performance of the as-prepared RHPC-800 material is attributed to the high specific surface area and low charge transfer resistance.