1. Introduction
With fast advancements in wearable and portable electronics, the urgent need for a comprehensive array of energy storage solutions with high surface energy and power densities, quick charging-discharging, and stable cycle performance has been raised and is being widely explored.1-5
The primary obstacle hampering the practical utilization of zinc ion hybrid supercapacitors (ZISCs) is the scarcity of cathode materials with high reversible capacitance, reliable cycling stability, and suitable operating voltage. Transition metal oxides exhibit excellent electrochemical properties in aqueous solution, including fast discharge kinetics and high multiplicity performance.6-10MnO2 has become a particularly attractive option for ZISCs cathode materials due to its reasonable price, ease of processing, and eco-friendliness.11 Due to the tunneling and layered structure, MnO2 can offer ample pathways and active sites for the transport and embedding of various ions, such as Li, Na, K, and Zn ions.12 Xu et al. assembled the ZISCs with the MnO2 nanorods anode, AC cathode, and ZnSO4 (2M) electrolyte, and different mass ratios of electrodes were investigated.13 At the most suitable mass ratio of 2.5:1, the ZISCs could operate with an operating range of 0-2.0 V. The structure and conductivity of MnO2-based ZISCs need to be improved to gain a commercial market position. Chen et al. studied the pre-intercalation of Zn2+ on the carbon cloth with a substantial loading quantity of 12 mg cm-2 to grow highly stabilized ZnxMnO2 nanowires with tunneling structures, obtaining excellent electrochemical properties.14 However, the lack of MnO2 conductivity still affects the cycling stability of ZISCs.15,16
In the present work, a new type of ZISCs is assembled using Mn-based cathode and carbon-based anode materials. ZnxMnO2 (ZMO) nanowires were fabricated by the ordinary hydrothermal method, and investigated the microscopic morphology structure and electrochemical performance of ZMO/PPy (ZMOP). The addition of Zn(NO3)2 provides a Zn2+ ion, which makes the structure of MnO2 more stable than before. The unique structure of PPy can greatly improve the electrical conductivity and cycle efficiency of Mn-based electrodes. When ZMOP was used as the cathode material of ZISCs, the PPy-derived porous carbon nanotubes (PCNTs) were selected as the anode material to assemble ZMOP//PCNT ZISCs. The insertion-extraction on the positive electrode of ZMOP nanowires and the adsorption-desorption on the PCNTs negative electrode shows excellent electrochemical properties. The assembled ZISCs delivered an outstanding energy density of 37 wh kg-1 with a power density of 64 w kg-1, it could maintain a capacity of 86.4% for 5000 cycles at 0.2 Ag-1.