NiCo layered double hydroxide/biomass-derived porous carbon aerogel composite for high-performance hybrid supercapacitors

Supercapacitors are widely concerned due to their advantages of fast charge and discharge speed, remarkable cycle stability, better safety and friendly environment, and the selection of electrode materials plays a crucial role in affecting the performance of supercapacitors. In this work, chitosan was used to prepare porous carbon aerogel (PCA). Subsequently, nickel-cobalt layered double hydroxide (NiCo-LDH) microspheres with pseudocapacitive properties were loaded on the prepared PCA in the form of nanowires. In general, highly conductive PCA skeletons with large specific surface area provided more active sites for rapid charge and ion transport and might regulate the growth of nanowires. Due to the synergistic effect of NiCo-LDH and PCA, the optimal NiCo-LDH/PCA-30 material exhibited a high specific capacitance of 1362 F g(-1) (189 mAh g(-1)) at 1 A g(-1) and good cycle stability (capacitance retention of 75 % after 4000 cycles) in a three-electrode system using 3 M KOH as the electrolyte, which were higher than that of pure NiCo-LDH. Moreover, the assembled hybrid supercapacitor (HSC) based on NiCo-LDH/PCA-30//PCA provided an excellent energy density of 33.1 Wh kg(-1) at the power density of 807.3 W kg(-1)), a maximum power density of 7998 W kg(-1) and an outstanding cycle retention rate (81.1 % after 5000 cycles). Our investigation has proved that the introducing of porous carbon aerogel could improve the electrochemical performance of NiCo-LDH.