Controllable preparation of nickel cobalt manganese ternary metal-organic frameworks for high-performance supercapacitor

In this study, Ni, Co and Mn metal-organic frameworks (MOFs, Ni2Co1-XMnX-MOFs-S, X = 0, 0.25, 0.5) nanorods are successfully obtained by a one-step hydrothermal method under the aid of C12H25SO4Na (SDS). The morphology and the size of the nanorods can be controlled by changing the doping method and content of Mn, resulting in the different electrochemical performances. The study proves that SDS has a great influence on the capacitance of the ternary metal NiCoMn-MOFs. Research results show that the optimized Ni2Co0.75Mn0.25- MOFs-S displays a capacitance of 1428 F center dot g-1 at current density of 1 A center dot g-1. Meanwhile, controlling partial substitution of Mn is beneficial to improve the stability of MOFs, such as the charge-discharge cycle stability of Ni2Co0.75Mn0.25-MOFs-S is high to 83.5 % after 3000 cycles. The energy density of the asymmetric super capacitor (Ni2Co0.75Mn0.25-MOFs-S//AC) is 38.10 Wh center dot kg- 1 at a power density of 884.38 W center dot kg-1. In addition, the act of Mn on improving material stability is studied.

Automated summary

In this study, Ni, Co and Mn metal-organic frameworks (MOFs, Ni2Co1-XMnX-MOFs-S, X = 0, 0.25, 0.5) nanorods were successfully synthesized through a one-step hydrothermal method with the assistance of C12H25SO4Na (SDS). The morphology and size of the nanorods could be controlled by changing the doping method and Mn content, resulting in different electrochemical performances. The study demonstrated that SDS had significant influence on the capacitance of the ternary metal NiCoMn-MOFs. The optimized Ni2Co0.75Mn0.25-MOFs-S exhibited a capacitance of 1428 F·g-1 at a current density of 1 A·g-1. Moreover, partial substitution of Mn improved the stability of MOFs, as evidenced by the high charge-discharge cycle stability (83.5% after 3000 cycles) of Ni2Co0.75Mn0.25-MOFs-S. The asymmetric supercapacitor (Ni2Co0.75Mn0.25-MOFs-S//AC) achieved an energy density of 38.10 Wh·kg-1 at a power density of 884.38 W·kg- 1. The role of Mn in enhancing the stability of the material was also investigated.