Honeycomb-like nitrogen-doped porous carbon decorated with Co3O4 nanoparticles for superior electrochemical performance pseudo-capacitive lithium storage and supercapacitors

The three-dimensional honeycomb-like N-doped porous carbon networks decorated with tricobalt tetraoxide nanoparticles (N-CN/Co3O4) were synthesized via energy- and cost-efficient NaCl-assisted strategy. Benefiting from the unique designed configuration, the intrinsic low electron conductivity and relatively huge volumetric expansion during the charge/discharge processes were effective relieved. Furthermore, the nitrogen elements are introduced to regulate the element composition, optimizing the surface activity and improving the electrochemical performance. Under the synergistic effect of the optimization measures, the prepared electrodes demonstrated excellent electrochemical performance. Particularly, the N-CN/Co3O4 electrodes showed capacitive-dominated lithium storage behavior with a high reversible discharge capacity of 1323.2 mAh g−1 after 100 lifespans at 0.05 A g−1, which was far beyond its theoretical specific capacity, and 766.7 mAh g−1 after 700 cycles at 1.0 A g−1. The capacitive-dominated lithium storage behavior was proved by the quantitative kinetic analysis and the supercapacitor (SCs) behavior, where a 60.66% fraction of the total charge resulting from capacitive contribution was achieved for lithium storage, the specific capacitance of 1115.4 F g−1 was obtained at 1.0 A g−1, and 98.6% of the initial specific capacitance was still maintained after 5000 cycles at 12.0 A g−1 as electrodes for supercapacitors. This work offers a simple and efficient route to prepare high-performance electrodes for lithium storage and SCs, lighting the approaches to improve the electrochemical properties of transition metal oxide electrodes.