Self-assembled MOF derived Co@C/rGO as positive electrode material for a supercapattery with high energy density

Co@C core-shell particles with a uniform size of approximately 100 nm anchored on rGO nano sheets is synthesized by a one-pot hydrothermal process. The Co@C particle formation is realized with a self-assembly procedure of metal-organic framework (MOF), and with GO as the precursor of rGO, Co@C/rGO is achieved. After calcination, the synthesized Co@C/rGO with high crystallization is obtained. Fabricated as an electrode by electrophoretic deposition, the calcined Co@C/rGO is evaluated with a high specific capacity of 810 C g −1 at a current density of 1 A g −1 . With the calcined Co@C/rGO served as positive electrode and with as-prepared 3D rGO aerogel as negative electrode, an assembled asymmetric supercapattery possesses a wide operating potential window of 1.2 V. The specific capacitance of the supercapattery can be as high as 120 F g −1 at 0.6 A g −1 , while the energy density reaches 29.5 W h kg −1 at a power density of 720 W kg −1 , and 11.2 W h kg −1 at 12,000 W kg −1 . After 10,000 cycles of charge-discharge process at 5 A g −1 , the asymmetric supercapattery device shows considerable cyclic stability with capacitance retention of 93.7%. • Co@C/rGO hybrid composite is synthesized with specific capacity of 810 C g −1 . • The fabricated supercapattery possesses energy density of 11.2 W h kg −1 at 12,000 W kg −1 . • The supercapattery has more activated property with a capacity retention of 93.7% after 10,000 cycles at 5 A g −1 .