Carbon used as an electrode material for lithium ion batteries (LIBs) is being continually developed to improve its electrochemical performance and lower its cost. Recently, many attempts to achieve high capacity and high-rate cycling stability in carbon materials have been made. However, carbon materials still face major problems, such as limited raw material resources, a high temperature process, and a complex synthesis method. Herein, to solve these problems, we report an approach to synthesizing tunable ternary (boron, phosphorus, and nitrogen)-doped carbon derived from tofu using a simple doping process. Tunable ternary-doped carbon materials, which show a synergistic effect when used with protein-based tofu, including N and the introduced heteroatoms (B and P), are successfully synthesized. The tunable ternary doped carbon materials showed improved specific capacity (381 mAh g^-1 after 100 cycles at 100 mA g^-1) and excellent high-rate cycling stability (190 mAh g^-1 after 400 cycles at 2000 mA g^-1). These results were attributed to the synergetic effect of enhanced carbon conductivity from B-doping, increased functional groups from P-doping, and an increase in the number of active sites from N-doping. Therefore, tunable ternary-doped carbon materials derived from tofu may be used as a potential electrode for high-performance LIBs.

Keywords: Lithium ion batteries, Carbon, Heteroatom doping, Synergistic effect, High-rate performance