Rational design of three-dimensional metal-organic framework-derived active material/graphene aerogel composite electrodes for alkaline battery-supercapacitor hybrid device

The inherent electrochemical performance of the electrode material is mainly decided by its morphology and architecture. Therefore, to address the issues of metal-organic frameworks (MOFs) derived materials with low electrical conductivity and easy aggregation. Herein, we successfully in-situ grow Zn-Co MOF and zeolitic imidazolate framework-8 (ZIF-8) on the three-dimensional (3D) network structure of graphene aerogel (GA) to prepare 3D ZnCo2O4/GA cathode and 3D ZIF-8-derived N-doped active carbon/GA (N-AC/GA) anode for an alkaline battery-supercapacitor hybrid device, respectively. As a result, the 3D ZnCo2O4/GA delivers a high specific capacity of 241.1 mAh g(-1) at 0.5 A g(-1) and even retains 156 mAh g(-1) under 20 A g(-1), indicating an outstanding rate capability and capacity retention (-65%). Furthermore, the 3D N-AC/GA shows a high capacitance of 408.5 F g(-1) (corresponding to a specific capacity of 112.9 mAh g(-1)) at 0.5 A g(-1) and exhibits an excellent rate capability with -56% capacitance retention (-228 F g(-1)) even at 20 A g(-1). Then, the 3D ZnCo2O4/GA//3D N-AC/GA device achieves a maximum energy density of 30.5 Wh kg(-1), a maximum power density of 6.5 kW kg(-1), and good cycle stability with -76.9% capacity retaining capability over 10,000 cycles under 10 A g(-1). Besides, our samples can be easily coated on conductive polypyrrole-modified commercial printing paper to construct flexible electrodes.

Automated summary

The electrode materials, including 3D ZnCo2O4/GA cathode and 3D N-AC/GA anode, synthesized in this study by growing Zn-Co MOF and ZIF-8 on the 3D graphene aerogel showed excellent rate capability and capacity retention. The 3D ZnCo2O4/GA//3D N-AC/GA device achieved high energy density, high power density, and good cycle stability.