TiO2 nanotubes supported ultrafine MnCo2O4 nanoparticles as a superior-performance anode for lithium-ion capacitors

Lithium-ion capacitors (LICs) are considered as a promising energy storage device possessing large specific energy along with high specific power due to the integration of the merits of electric double-layer capacitors (ELDCs) and lithium-ion batteries (LIBs). In the present work, TiO 2 nanotubes supported ultrafine MnCo 2 O 4 nanoparticles with the size of 5–10 nm is solvothermally synthesized. It is found that the introduction of TiO 2 nanotubes can weaken the aggregation of MnCo 2 O 4 nanoparticles, therefore causing the enhancement in the electrode/electrolyte interfacial contact and the reduction in Li + diffusion path. Benefiting from the synergy effect of MnCo 2 O 4 and TiO 2 which can alleviate the volume change of MnCo 2 O 4 , the MnCo 2 O 4 /TiO 2 composite used in LIBs displays a large reversible capacity of 743 mAh g −1 at 0.2 A g −1 after 100 cycles and impressive rate performance. This composite as anode is assembled with an activated carbon (AC) electrode as cathode into MnCo 2 O 4 /TiO 2 //AC LIC working in a wide voltage range of 0.5–4 V. This LIC can deliver high specific energies of 89.8 and 44.1 Wh kg −1 at specific power of 0.25 and 3.41 kW kg −1 , respectively, and presents outstanding cyclic stability (76.4% of initial capacity at the end of 5000 cycles). A high-performance MnCo 2 O 4 /TiO 2 composite was synthesized and used as an anode of Li-ion capacitors. • TiO 2 nanotubes are employed to support ultrafine MnCo 2 O 4 nanoparticles. • MnCo 2 O 4 /TiO 2 composite can deliver high reversible capacity. • A Li-ion capacitor is assembled by using MnCo 2 O 4 /TiO 2 composite as anode. • The Li-ion capacitor shows high specific energy and specific power.