Metal-organic frameworks derived low-crystalline NiCo2S4/Co3S4 nanocages with dual heterogeneous interfaces for high-performance supercapacitors

Nickel cobalt bimetallic heterogeneous sulfides are attractive battery-type materials for electrochemical energy storage. However, the precise synthesis of electrode materials that integrate highly efficient ions/electrons diffusion with abundant charge transfer channels has always been challenging. Herein, an effective and concise controllable hydrothermal approach is reported for tuning the crystalline and integrated structures of MOF-derived bimetallic sulfides to accelerate the charge transfer kinetics, and thus enabling rich Faradaic redox reaction. The as-obtained low-crystalline heterogeneous NiCo2S4/Co3S4 nanocages exhibit a high specific capacity (1023 C/g at 1 A/g), remarkable rate performance (560 C/g at 10 A/g), and outstanding cycling stability (89.6% retention after 5000 cycles). Furthermore, hybrid supercapacitors fabricated with NiCo2S4/Co3S4 and nitrogen-doped reduced graphene oxide display an outstanding energy density of 40.8 Wh/kg at a power density of 806.3 W/kg, with an excellent capacity retention of 88.3% after 10000 charge-discharge cycles.