Ultrathin Nanosheets NiCo2O4/C Hollow Microtube Composites with Superior Performances for Supercapacitors

Abstract

Herein, the NiCo2O4/C hollow microtube composites (NCHMCs) are synthesized taking advantage of the wipes as the sacrificial template and carbon resource. The specific capacitance of as‐prepared NCHMCs electrode is about 3070 F g−1 at 0.5 A g−1 current density, which reaches 86% of the theoretical specific capacitance of NiCo2O4. The specific capacitance still reaches 2607 F g−1 at 50 A g−1, and the corresponding rate capability is 85%. The capacitance retention rate still maintains 96% after 5000 cycles at 30 A g−1. Meanwhile, the highest specific capacitance of assembled LIR2032‐type coin cell with NiCo2O4/C as both of anode and cathode reaches to 173.50 F g−1. The superior performances of the NCHMCs are related to the unique microstructure, the NiCo2O4 ultrathin nanosheet arrays on hollow microtube with uniformly dispersed carbon. The ultrathin NiCo2O4 nanosheets reduce the diffusion length for the electrolyte ions, and most composites can take part in the electrochemical processes. The hollow interior within the tubular structure, which can accommodate the volumetric expansion during repeated multielectron Faradic reactions and efficiently alleviate pulverization of the electrode, is advantageous to ameliorate the structural integrity and enhance the cycling stability.