NiMn2O4 Nanosheet/Carbon Nanotube Composites for Aqueous Zinc-Ion Batteries

Abstract

Due to the continuous depletion of lithium resources and the security risks of organic electrolytes such as combustion and explosion, there is an imminent requirement to develop a type of energy accumulation system to adapt to the progression and progress of society. Zinc-ion batteries using aqueous electrolyte have the advantages of high safety, low cost, and environmental friendliness, which make them an ideal alternative to lithium-ion batteries as a next-generation energy storage system. Among the zinc-ion battery cathode materials, manganese-based materials and carbon materials occupy the main positions, respectively. Among them, nickel manganate (NiMn₂O₄) nanosheets and carbon nanotubes (CNTs) as active materials have received extensive attention. The CNTs could provide electronic conductive channels and NiMn₂O₄ nanosheets supply more active points for electrochemical reactions. The carbon shell with a porous structure also improves the electron transport and ionic conduction processes, so that the nickel manganate/carbon nanotube (NiMn₂O₄/CNTs) nanocomposites obtained a high specific capacitance of 333.6 mAh g^–1 at a current density of 0.2 A g^–1. After 500 cycles at a current density of 0.5 A g^–1 led to a high specific capacity of 73.6 mAh g^–1, it was shown that the material exhibits excellent comprehensive electrochemical properties. This synergistic strategy of combining structural design and electrochemical activation in NiMn₂O₄/CNTs nanocomposites can be a reference for other manganese-based cathode materials.