Preparation of Co2Al layered double hydroxide nanosheet/Co2Mn bimetallic hydroxide nanoneedle nanocomposites on nickel foam for supercapacitors

摘要

Layered double hydroxides (LDH) can expose enough electroactive sites during the redox reaction to achieve high electrochemical performances. In this work, Co2Mn bimetallic hydroxide nanoneedles were directly synthesized on nickel foam by hydrothermal method, and then Co(2)AI LDH nanosheets were prepared on the Co2Mn nanoneedles by hydrothermal method to obtain the heterostructure nanocomposites (Co2Al/Co2Mn). The method for fabricating nickel foam loaded Co2Al/Co2Mn nanocomposites (Co2Al/Co2Mn/NF) avoids the addition of conductive agent and binder, reduces the electrode internal resistance, and enhances the charge transport capabilities. The performance of the nanocomposites used in Co2Al/Co2Mn/NF//AC/NF hybrid supercapacitors are improved significantly. At the current density of 1 A g(-1), the specific capacitance of the nanocomposites can reach 1125.9 C g(-1) (2502.0 F g(-1)). The specific capacitance of the material still maintains its initial specific capacitance of 82.53% at the current density of 20 A g(-1) after 6000 cycles. The specific capacitance of the constructed hybrid supercapacitor maintains its initial of 92.21% after 7000 cycles at the current density of 4 A g(-1). At the power density of 412.73 W kg(-1), the energy density of the hybrid supercapacitor can reach 64.58 Wh kg(-1). The constructed Co2Al/Co2Mn./NF//AC/NF hybrid supercapacitor with excellent cycle stability, huge power density, and easy assembling, showing that the material has certain prospects in practical applications. (C) 2020 Elsevier B.V. All rights reserved.