An efficient binder-free electrode with multiple carbonized channels wrapped by NiCo2O4 nanosheets for high-performance capacitive energy storage

Abstract

Despite possessing 3D network structure, the electrochemical behaviors of binder-free electrodes using carbonized melamine foam (CMF) as scaffold are still limited in supercapacitors (SCs), which is mainly due to the CMF scaffold with some damaged carbonized skeleton after high temperature carbonization. Herein, an efficient binder-free electrode (NiCo2O4/MCMF) with multiple carbonized channels wrapped by NiCo2O4 nanosheets has been successfully fabricated, which is realized by using carbon nanofibers-modified CMF (MCMF) as scaffold through chemical vapor deposition (CVD). Remarkably, numerous branched carbon nanofibers interconnect with each other around the carbonized skeleton in MCMF, not only providing multiple conductive channels for rapid charge transport and ionic diffusion, but also allowing the high mass-loading of pseudocapacitive NiCo2O4 nanosheets. The resultant NiCo2O4/MCMF binder-free electrode delivers a high specific capacitance (1541 F g−1 at 1 A g−1) with excellent durability (85.8% capacitance retention after 10000 cycles at 10 A g−1). Furthermore, a kind of high performance asymmetric SCs (ASC) are assembled using NiCo2O4/MCMF as positive electrode and MCMF as negative electrode. The ASCs exhibit low internal resistance, maximum energy density (53.1 Wh kg−1) and power density (18000 W kg−1), which can act as efficient energy storage devices to supply power without obvious degradation after repeating.