Enhancing Specific Capacitance and Structural Durability of VO2 Through Rationally Constructed Core-Shell Heterostructures

Abstract

The widespread applications of supercapacitors are greatly restricted by their inferior energy density. Developing advanced electrode materials with high capacitance and large voltage windows has been regarded as a promising way to conquer the above challenge. Considering this, VO2@NiO core-shell heterostructures were constructed by a facile and controllable hydrothermal reaction combined with the atomic layer deposition technique. The NiO coating layer can buffer the hydrolyzed reaction of VO2, improving the chemical/electrochemical stability of VO2. Moreover, heterogeneous interfaces between NiO and VO2 can effectively regulate the charge distribution around the phase boundaries, which can render additional active sites and enhance the intrinsic electronic conductivity of two building blocks. as a result, the as-prepared VO2@NiO heterostructure exhibits extremely high specific capacitance of 1265 F/g at 1 A/g and remains 80.6% of initial capacity after 5000 cycles at 10 A/g. The assembled asymmetric supercapacitors employing the VO2@NiO heterostructure materials as the negative electrode and the commercial nickel-cobalt-aluminum oxides as the positive electrode exhibit an attractive energy density (39.81 Wh/kg) and superior cycling lifespans. This work may guide the development of core-shell heterostructure as advanced electrodes for electrochemical energy storage.