Embedding Co3O4 nanoparticles in three-dimensionally ordered macro-/mesoporous TiO2 for Li-ion hybrid capacitor.

Co 3 O 4 nanoparticles embedded in 3D ordered macro-/mesoporous TiO 2 have been synthesized through a in situ method form dual templates and the anode shows good electrochemical performance in Li-ion capacitor. [Display omitted] • Co 3 O 4 nanoparticles embedded in 3D ordered macro-/mesoporous TiO 2 are prepared. • The Co 3 O 4 @TiO 2 shows enhanced rate capability and cycling performance in LIBs. • The Co 3 O 4 @TiO 2 composite exhibits great electrochemical performance for LICs. Lithium-ion hybrid capacitors (LICs) have gained increasing focus owing to their high energy/power densities. The development of anodes with superior rate capability is an effective way to surmount the kinetic mismatch between anodes and cathodes, and thus, enhancing the energy/power densities. Herein, Co 3 O 4 nanoparticles embedded in three-dimensionally (3D) ordered macro-/mesoporous TiO 2 (Co 3 O 4 @TiO 2) are synthesized through an in situ method from dual templates. Differing from the composite prepared by loading active nanoparticles on support, Co 3 O 4 nanoparticles are embedded in TiO 2 framework, which can improve the stability of the electrode. Furthermore, the hierarchically porous structure of TiO 2 is in favor of the rapid diffusion of ions and electrolyte. As a result, The Co 3 O 4 @TiO 2 -2 composite with an optimized Co 3 O 4 content (~25 wt%) delivers a high capacity of 944.1 mAh g−1 after 100 cycles at 0.1 A g−1 and high-rate capability (405.7 mAh g−1 after 1000 cycles at 5 A g−1). The LIC assembled with Co 3 O 4 @TiO 2 -2 anode and activated carbon (AC) cathode delivers high energy/power densities (maximum, 87.9 Wh kg−1/10208.9 W kg−1) and great cycle stability (88.1%, 6000 cycles, 0.5 A g−1). [ABSTRACT FROM AUTHOR]