Enhanced Pseudocapacitive Lithium-Ion Storage in a Coherent rGO/VO2‑R Heterojunction

Exploring novel anode materials plays a crucial role in further improving the overall electrochemical performance of rechargeable Li-ion batteries (LIBs) for emerging applications in large-scale energy storage. Vanadium dioxide (VO2) has a high theoretical capacity and low cost, possessing great potential as an alternative anode material for rechargeable LIBs. Compared to monoclinic VO2-M and metastable VO2-B, the electrochemical Li-ion storage capability of tetragonal rutile-type VO2-R (particularly in the nanoscale form) has been less refined, limiting its potential application in LIBs. Herein, a heterostructure nanocomposite, constructed by few-layered reduced graphene oxide (rGO) sheets covered by VO2-R nanoparticles (rGO/VO2-R), has been successfully synthesized by a controlled wet-chemical route. The resultant rGO/VO2-R composite exhibits good electrochemical properties with high capacity and superior rate and cycling performances owing to the effective combination of the high electrical conduction of the flexible rGO substrate and VO2-R nanoparticles with enhanced redox kinetics. First-principles simulations reveal that the formation of a graphene/VO2 heterostructure is energetically feasible. Further, such a heterostructure can benefit the electron/Li+ transfer and afford abundant sites for Li+ storage at the interface. The presented research can provide some new insights into the reasonable design and fabrication of carbon-related (nano)­composites with distinct phase and composition control for promising applications in rechargeable Li-ion batteries and supercapacitors.