High-performance Li-Ion capacitor constructed from biomass-derived porous carbon and high-rate Li_4Ti_5O_(12)

摘要

In this study we prepared a biomass-derived porous carbon and a high-rate Li4Ti5O12 (LTO) as cathode and anode materials, respectively, for Li-ion capacitors (LICs). We synthesized the bio-derived carbon through pyrolysis of rubberwood as the carbon source. The as-synthesized carbon featured a hierarchical micro/mesoporous architecture with a surface area of 1365 m(2) g(-1) and excellent electrochemical properties. A symmetric supercapacitor (SC) based on the bio-derived carbon material exhibited excellent capacitance characteristics and remarkable cycling stability. Furthermore, the rate performance of the spray-dried LTO modified through ionic doping and surface coating was much better than that of the unmodified LTO, due to enhanced conductivity and ionic diffusivity. Because of the outstanding rate capability of the modified LTO, the kinetic mismatch between the cathode and anode-a general problem for LICs-was overcome. After coupling the bio-derived porous carbon with the high-rate LTO, the as-fabricated LIC displayed a high energy/power density of 142 Wh kg(-1)/253 W kg(-1), and even provided a value of 52.9 Wh kg(-1) at 4556 W kg(-1). In addition, this LIC retained 85.7% of its original capacity after 10,000 cycles.