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, TiO2 nanotubes supported ultrafine MnCo2O4 nanoparticles with the size of 5-10 nm is solvothermally synthesized. It is found that the introduction of TiO2 nanotubes can weaken the aggregation of MnCo2O4 nanoparticles, therefore causing the enhancement in the electrode/electrolyte interfacial contact and the reduction in Li thorn diffusion path. Benefiting from the synergy effect of MnCo2O4 and TiO2 which can alleviate the volume change of MnCo2O4, the MnCo2O4/TiO2 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 MnCo2O4/TiO2//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). (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

A TiO2 nanotubes supported ultrafine MnCo2O4 nanoparticles composite was synthesized via solvothermal method, demonstrating excellent electrochemical performance in lithium-ion batteries. The introduction of TiO2 weakened the aggregation of MnCo2O4, contributing to improved electrode/electrolyte contact and reduced Li diffusion path. The MnCo2O4/TiO2 composite showed high reversible capacity and impressive rate performance in LIBs.