Li4Ti5O12/activated-carbon hybrid anodes prepared by in situ copolymerization and post-CO2 activation for high power Li-ion capacitors

Hybrid anodes with Li4Ti5O12 nanoparticles uniformly embedding in a mesoporous activated carbon matrix are prepared by CO2 activation of copolymerized resorcinol and hexamethylenetetramine loaded by lithium acetate and tetrabutyl titanate. The Li4Ti5O12/activated-carbon hybrid anodes show increased capacity retention as the activated carbon content in the composite increases, although their overall specific capacity decreases gradually. The hybrid anode with an activated-carbon content of 54 wt% exhibits the highest capacity retention of 67% at 4 A g−1 referencing to that at 0.1 A g−1. When coupling it with commercial AC cathode, the Li-ion capacitor displays an outstanding high energy density of 38 Wh kg−1 even at a high power density of 7964 W kg−1. Moreover, an energy density retention of 90.8% after 2000 cycles at 1 A g−1 is preserved, demonstrating its very stable cycle performance. The results reported in this work indicate that the Li4Ti5O12/activated-carbon hybrids prepared by the proposed copolymerization and post-activation process may be very promising anode materials of Li-ion capacitors designed for high power applications.