Polyaniline packed activated carbon as pseudocapacitive negative electrodes

•PANI evenly packing on nanopore surface of AC with suitable ion-diffusion structure.•AC@PANI combinates electrochemical double layer and pseudocapacitive capacitance as negative electrode.•AC@PANI exhibits high pseudocapacitive performance at high mass loadings.•AC@PANI-based HSCs present high energy and power density. Hybrid supercapacitors (HSCs) are attracting more attentions due to their potential high power and energy density. To exploring high capacity negative electrode materials, especially the capacitive materials, is more critical for further enhancing the energy density of HSC in comparing with more reported advanced battery-type positive materials. For perfect combination of electrochemical double layer and pseudocapacitive capacitance in negative electrode, the method of evenly filling polyaniline on nanopores of activated carbon is developed herein with keeping large surface area, the suitable ion-diffusion structure of activated carbon and further obtaining rich surface redox-active sites. The polyaniline packed activated carbons exhibit high specific capacitance (437.9 F g−1 at 0.5 A g−1) in negative voltage window (0 to −1.0 V), superior rate performance (378.0 F g−1 at 30 A g−1), and excellent capacitance retention even at a high mass loading and a high current density (326.5 F g−1 at 10 mg cm−2 and 20 A g−1). Additionally, an aqueous HSC based on the polyaniline packed activated carbon negative electrode and Ni-Co-LDH positive electrode presents higher energy density of 44.6 Wh kg−1 at a power density of 377.1 W kg−1. The present study presents novel method and materials for developing high performance capacitive negative electrode materials.