Metal-organic framework derived NiO/Ni@C composites as electrode materials with excellent electrochemical performance for supercapacitors

In this work, metal oxide/metal@carbon (NiO/Ni@C) composites as electrode materials have been successfully prepared using the pillared Ni-2(bdc)(2)(dabco) (bdc = 1,4-benzenedicarboxylic acid, dabco = 1,4diazabicyclo[2.2.2]-octane) as the precursor. Owing to the multiple active sites (NiO, Ni and Carbon), rich oxygen defects, and abundant Ni3+, the NiO/Ni@C composites show excellent electrochemical performance. A maximum specific capacitance of 805.3 F g(-1) at 0.5 A g(-1) and 576.2 F g(-1) at 10 A g(-1) is obtained for the NiO/Ni@C electrode material calcined at 500 degrees C, indicating a high rate capability. Meanwhile, the assembled asymmetric supercapacitor (ASC) NiO/Ni@C//PEDOT-AC (poly(3,4-ethylenedioxy-thiophene)activated carbon) has a wide working voltage of 0-1.7 V, high specific energy of 20.7 W h kg(-1), superior specific power of 12920 W kg(-1), and excellent cycle stability with capacitance retention of 69.7% after 10 000 cycles. Furthermore, a red light-emitting diode (LED) is lighted up by two NiO/Ni@C//PEDOT-AC ASCs in series connection.