Mn-Doped Ni/Co LDH Nanosheets Grown on the Natural N-Dispersed PANI-Derived Porous Carbon Template for a Flexible Asymmetric Supercapacitor

The Mn doping effect (Mn²⁺ ⇋ Mn³⁺ ⇋ Mn⁴⁺) has been proven to be an efficient method to improve the specific capacitance and rate properties of the supercapacitor. Hence, in this article, we deposited Mn ions into Ni-Co-layered double hydroxide (MLDH) nanosheet-coated polyaniline (PANI)-derived carbon (PAC), which shows a 4-fold increase in specific capacity (from 310.02 to 1282.06 C/g). Furthermore, in order to widen the voltage window and increase the energy density, a flexible all-solid-state asymmetric supercapacitor is also fabricated by employing MLDH@PAC as a positive electrode and, respectively, nitrogen/oxygen self-doped PAC as a negative electrode. Noticeably, the assembled asymmetric devices with a wide voltage window of 1.6 V exhibit a high energy density of 78.9 Wh kg^-1 at a power density of 1.55 kW kg^-1, the long-term cyclic stability with 82.66% capacitance retention after 10 000 cycles, and reliable flexibility. Such excellent results will offer a feasible and effective Mn doping approach to prepare a hybrid electrode nanomaterial for energy storage devices.