Preparation and sodium-storing property of rice husk-based porous hard carbon

The hard carbon anode materials (RHPC-1-2 and RHPC-1-1) of sodium ion batteries were prepared by hydrothermal method using rice husk as the raw material and different concentrations of potassium hydroxide solution as the activator. The structure, morphology and electrochemical properties of the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area test system (BET) and battery performance test system. The results showed that the porous carbon material (RHPC-1-2) prepared by taking 2 mol/L potassium hydroxide as the activator had a high specific area of 37.6336 m²/g and formed a large number of micropores and mesopores. The RHPC-1-2 material had a high reversible specific capacity of 285 mAh/g and an initial coulombic efficiency of 72%. The RHPC-1-2 material exhibited excellent cycle performance: its discharge specific capacity was 204 mAh/g in the first cycle, and the capacity was still 200 mAh/g after 100 cycles at a current density of 100 mA/g, with almost no attenuation. It also displayed excellent rate performance. Its discharge specific capacities were 265, 247, 213, 170 and 112 mAh/g at different current densities of 25, 50, 100, 200 and 500 mA/g, respectively. When the current density was 25 mA/g, there was nearly no decrease found in the discharge specific capacity of RHPC-1-2 material.