One‐Step Synthesis of Ultrathin NiMn Layered Double Hydroxide Nanosheets for Supercapacitors.

With the help of ethylenediamine (EN), we built through hydrothermal synthesis a multiple‐level NiMn layered double hydroxide nanostructure consisting of ultrathin nanosheets (UNML) with plenty buffer spaces. Such porous structure provides more active sites, shortens the diffusion path of electrolyte ions, and creates massive "live volume" to ensure structural integrity during long‐term cycling. The UNML possesses high specific capacitance (1513 F g−1 at 1 A g−1). Moreover, the hybrid supercapacitor employing UNML and AC as positive and negative electrode delivers enhanced energy density up to 59 Wh kg−1 at a power density of 808 W kg−1 and robust cycling stability with capacitance degradation of 8.7 % after 5000 cycles. This simple strategy is expected to cope with the prevalent issues facing battery‐type electrode materials, ensuring improvement of the overall electrochemical performance. [ABSTRACT FROM AUTHOR]