Fabrication of High Amount of ZnMnO2/Ag-CNts on Nickel Foam and its application in Zinc ion batteries

Nowadays, energy sources for portable devices, such as electronic devices, are under continual pressure to decrease both consumed power or weight (1). It makes the demand for safe, economic, and efficient rechargeable battery technologies increasing for portable electronics, electrified vehicles, and emerging renewable energy storage systems (2). There are a lot of experiments that researchers have done to fulfill people's demands of energy storage, and they found that electrochemical energy storage is the best choice for storing energy. Some energy storage uses electrochemical as their method, such as battery and supercapacitor, commonly used in daily life (3, 4). In the past several decades, The Lithium-ion battery has been chosen as one of the most promising breakthroughs in the energy storage field. Many researchers have led to LIB's significant development in electronic devices such as smartphones and personal computers (5). LIBs have dominated many aspects of the energy storage field because of their high energy density and long-cycle-life (6). However, its limited resources, high cost, and safety issue firmly limit its further large-scale development (7). In 1799, metallic zinc was chosen as an excellent negative cathode for Zinc based batteries because it has a high theoretical capacity, low redox potential, cheaper and more safety than other based batteries (8-9). Until 2014, the Kang Group invented the energetic zinc ion batteries that recently gained a lot of attention from scientists. They presented a safe and eco-friendly power-type battery that is composed of an α-MnO2 cathode, zinc anode, and ZnSO4 or Zn(NO3)2 as an aqueous electrolyte (10). As the newly discovered batteries, a comparison between lithium-ion batteries with organic electrolytes, which is unsafe and has a lot of toxicity than Zinc ion batteries with mild aqueous electrolytes, showed us Zinc ion batteries has a lot of strengths as a promising candidate for energy storage and wearable devices (11). But there is still the main challenge that should be solved: the dendrite formation of zinc during charge/discharge cycling. Similar to other metals such as Lithium, Nickel, and Copper, Zinc generally tends to deposit in the dendrite form, especially at high current densities, which results in low coulombic efficiency, rapid degradation of capacity, and poor stability (12-13). Finding a suitable cathode with high capacity is one of many solutions. There are many options, such as Manganese-based, such as manganese oxide (14), Vanadium-based, such as vanadium oxide (15), Organic compounds, such as polymers (16), Prussian Blue Analog based (17), etc. Among those cathode materials, manganese-based oxides are considered the most suitable cathode for aqueous ZIBS due to their natural abundance, low cost, low toxicity, and multiple valences state Manganese (18). But, Manganese oxide suffers from its poor conductivity that often occurs in the electrode’s high internal resistance, resulting in poor battery performance (19). Therefore, to improve its performance of the MnO2 cathode, it is necessary to increase the specific surface area of MnO2 and the ion diffusion rate (20, 21). Nickel Foam, a metallic foam, is essential to electrochemical energy-storing, which possesses lithium-based batteries’ large-scale applications due to its mechanical strength, inertness, low toxicity, and low cost, become the most promising metal product for the energy-storage system (22). Using Nickel foam as an electrode for an energy storage system is ideal because it has high porosity for growing the manganese on its surface using electrodeposition. Due to Saleh, Nickel foam presents better efficiency for supercapacitors (35 F/g). (25)