Effect of pyrolysis temperature on carbon obtained from green tea biomass for superior lithium ion battery anodes

Carbonaceous materials pyrolyzed from green tea leaves are fabricated and characterized for their potential application as high-performance anodes in lithium ion batteries (LIBs). Three different pyrolysis temperatures (700, 800, and 900 degrees C) are employed, and the most efficient pyrolysis temperature is determined through a variety of physical and electrochemical measurements. The carbon pyrolyzed at a relatively low temperature of 700 degrees C contains numerous functional groups, defects that are different from those in graphitic carbon, and large pores. Consequently, the sample exhibited a relatively large capacity of 471 mAh g(-1) at the 50th cycle, even though high initial irreversibility was observed. Furthermore, when compared to the extremely low capacity of graphite (12.7 mAh g(-1)), the carbon specimen pyrolyzed at 700 degrees C displays an excellent high-rate capability of 131 mAh g(-1) at 10 C. Such a result is attributed to the relatively isotropic structures and large-size pores in the sample, which facilitates the rapid diffusion of lithium ions. (C) 2014 Elsevier B.V. All rights reserved.