Facile synthesis of <i>Camellia oleifera</i> shell-derived hard carbon as an anode material for lithium-ion batteries

Abstract

A comparatively facile and ecofriendly process has been developed to synthesize porous carbon materials from <i>Camellia oleifera</i> shells. Potassium carbonate solution (K₂CO₃) impregnation is introduced to modify the functional groups on the surface of <i>Camellia oleifera</i> shells, which may play a role in promoting the development of pore structure during carbonization treatment. Moreover, a small amount of naturally embedded nitrogen and sulfur in the <i>Camellia oleifera</i> shells can also bring about the formation of pores. The <i>Camellia oleifera</i> shell-derived carbon has a large specific surface area of 1479 m² g^-1 with a total pore volume of 0.832 cm³ g^-1 after being carbonized at 900 °C for 1 h. Furthermore, when used as an anode for lithium-ion batteries, the sample shows superior electrochemical performance with a specific capacity of 483 mA h g^-1 after 100 cycles measured at 200 mA g^-1 current density. Surprisingly, the specific capacity is even gradually increased with cycling. In addition, this sample exhibits almost 100% retention capacity after 250 cycles at a current density of 200 mA g^-1.