Phosphidated Ni-Mn layered double hydroxide–based electrode material with superior electrochemical performance for supercapacitors

Abstract

Layered double hydroxides (LDHs) exhibit excellent electrochemical performance in alkali solutions. However, their low conductivity and poor cycle stability limit their application. In this work, Ni-Mn LDH was grown on activated carbon nanofibers (ACNFs) and then phosphidated to obtain an electrode material with a three-dimensional core–shell structure (ACNFs@Ni-Mn-P). This composite combines the electrochemical activity of the two-dimensional phosphidated nanosheets with the structural stability of the one-dimensional nanofibers. The resulting ACNFs@Ni-Mn-P electrode exhibits a high specific capacitance of 1077 F g−1 at 1 A g−1, which is 4.9 times higher than that of a non-phosphidated ACNFs@Ni-Mn LDH electrode, and retains stability of 88.53% at a high current density of 10 A g−1 even after 5000 cycles. Moreover, an asymmetrical supercapacitor featuring an ACNFs@Ni-Mn-P positive electrode achieves comparatively prominent specific energy of 56.25 Wh kg−1 at 806.13 W kg−1, respectively. Therefore, ACNFs@Ni-Mn-P as electrode material has great potential for application in supercapacitors.