Facile synthesis of shell-derived hard carbon as an anode material for lithium-ion batteries.

A comparatively facile and ecofriendly process has been developed to synthesize porous carbon materials from shells. Potassium carbonate solution (KCO) impregnation is introduced to modify the functional groups on the surface of 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 shells can also bring about the formation of pores. The shell-derived carbon has a large specific surface area of 1479 m g with a total pore volume of 0.832 cm g 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 after 100 cycles measured at 200 mA g 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.