Application of Hierarchical ZnCo2O4 Hollow Nanofibers for Anode Materials in Lithium-ion Batteries

Hierarchical ZnCo2O4 hollow nanofibers were prepared by electrospinning and subsequent heat-treatment process. The spinning solution containing polystyrene (PS) nanobeads was electrospun to nanofibers. During heat-treatment process, PS nanobeads in the composite were decomposed and therefore generated numerous pores uniformly in the structure, which facilitated the heat transfer and gas penetration into the structure. The resulting hierarchical ZnCo2O4 hollow nanofibers were applied as an anode material for lithium-ion batteries. The discharge capacity of the nanofibers was 815 mA h g(-1) (646 mA h cm(-3)) after the 300th cycle at a high current density of 1.0 A g(-1). However, ZnCo2O4 nanopowders showed the discharge capacity of 487 mA h g(-1) (450 mA h cm(-3)) after 300th cycle. The excellent lithium ion storage property of the hierarchical ZnCo2O4 hollow nanofibers was attributed to the synergetic effects of the hollow nanofiber structure and the ZnCo2O4 nanocrystals composing the shell. The hierarchical hollow nanofiber structure introduced in this study can be extended to various metal oxides for various applications, including energy storage.