Improved Na(+)/K(+) Storage Properties of ReSe(2)–Carbon Nanofibers Based on Graphene Modifications

Rhenium diselenide (ReSe(2)) has caused considerable concerns in the field of energy storage because the compound and its composites still suffer from low specific capacity and inferior cyclic stability. In this study, ReSe(2) nanoparticles encapsulated in carbon nanofibers were synthesized successfully with simple electrospinning and heat treatment. It was found that graphene modifications could affect considerably the microstructure and electrochemical properties of ReSe(2)–carbon nanofibers. Accordingly, the modified compound maintained a capacity of 227 mAh g(−1) after 500 cycles at 200 mA g(−1) for Na(+) storage, 230 mAh g(−1) after 200 cycles at 200 mA g(−1), 212 mAh g(−1) after 150 cycles at 500 mA g(−1) for K(+) storage, which corresponded to the capacity retention ratios of 89%, 97%, and 86%, respectively. Even in Na(+) full cells, its capacity was maintained to 82% after 200 cycles at 1C (117 mA g(−1)). The superior stability of ReSe(2)–carbon nanofibers benefitted from the extremely weak van der Waals interactions and large interlayer spacing of ReSe(2), in association with the role of graphene-modified carbon nanofibers, in terms of the shortening of electron/ion transport paths and the improvement of structural support. This study may provide a new route for a broadened range of applications of other rhenium-based compounds. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-019-0248-2) contains supplementary material, which is available to authorized users.