Multicomponent mixed metallic hierarchical ZnNi@Ni@PEDOT arrayed structures as advanced electrode for high-performance hybrid electrochemical cells

Engineering multicomponent nanomaterials as an electrode with rationalized ordered structures is a promising strategy for fulfilling the high-energy storage needs of supercapacitors (SCs). Even now, the fundamental barrier to utilizing hydroxides/hydroxyl carbonates is their poor electrochemical performance, resulting from the significantly poor electrical conductivity and sluggish charge storage kinetics. Hence, a multilayered structural approach is primarily and successfully used to construct electrodes as one of the efficient approaches. This method has made it possible to develop well-ordered nanostructured electrodes with good performance by taking advantage of tunable approach parameters. Herein, we report the design of multilayered heterostructure porous zinc-nickel nanosheets@nickel flakes hydroxyl carbonates and/or hydroxides integrated with conductive PEDOT fibrous network (i.e., ZnNi@Ni@PEDOT) via facile synthesis methods. The combined hybrid electrode acquires the features of high electrical conductivity from one part and various valance states from another one to develop a well-organized nanosheet/flake/fibrous-like heterostructure with decent mechanical strength, creating robust synergistic results. Thus, the designed binder-free ZnNi@Ni@PEDOT electrode delivers a high areal capacity value of 1050.1 µA h cm−2 at 3 mA cm−2 with good cycling durability, significantly outperforming other individual electrodes. Moreover, its feasibility is also tested by constructing a hybrid electrochemical cell (HEC). The assembled HEC exhibits a high areal capacity value of 783.8 µA h cm−2 at 5 mA cm−2, and even at a high current density of 100 mA cm−2 (484.6 µA h cm−2), the device still retains a rate capability of 61.82%. Also, the HEC shows maximum energy and power densities of 0.595 mW h cm−2 and 77.23 mW cm−2, respectively, along with good cycling stability. The obtained energy storage capabilities effectively power various electronic components. These results provide a viable and practical way to construct a positive electrode with innovative heterostructures for high-performance energy storage devices and profoundly influence the development of electrochemical SCs.