Nowadays, extensive researches to overcome the world energy crisis has emphasized the urgent necessity of developing sustainable energy storage systems. The rechargeable lithium-ion battery (LIB) dominates today's battery market for portable device applications. Nonetheless, the crucial issues concerning its safety, eco-friendliness, and cost-effectiveness, as well as the controversies associated with the availability of lithium resources, have led to the continuous exploration of new battery chemistries. Sodium-ion, potassium-ion, and aluminum-ion batteries are promising alternative since these devices are based on relatively abundant and cheap sodium, potassium, and aluminum elements, respectively. However, these battery systems also suffer from complicated issues of safety, processing costs, and environmental concerns. Earlier efforts for developing a rechargeable aqueous zinc-ion battery (ZIB), which facilitates energy storage application via zinc-ion insertion/extraction, has opened the way for the realization of safe, environmentally benign and cost-effective next generation energy storage system. ZIB is still in the stage of early phase of development, therefore, fundamental studies concentrating on the zinc-ion insertion mechanism is an attractive goal to pursue. In this work, we used nanorod alpha-type manganese dioxide cathode for ZIB application. Alpha-type manganese deioxide was prepared by a simple hydrothermal synthesis. SEM and TEM studies showed rod-type sample with approximately 20 and 200 nm of width and length, respectively. The nanorod cathode exhibited an initial discharge capacity of 176.8 mAh g^-1 at a current density of 83 mA g^-1 and demonstrated nearly 100% Coulombic efficiencies under prolonged cycling when tested for zinc storage properties. Rate performance measurements revealed that specific capacities of 43.33 and 31.48 mAh g^-1 were registered at current densities as high as 1333 and 1666 mA g^-1. A combination of ex-situ synchrotron XRD and XAS studies confirmed the reversibility of electrochemical zinc-ion insertion into [2x2] tunnels of the alpha-type manganese dioxide host structure. The host exhibits structural stability by accommodating an unit cell volume expansion of approximately 3.12% during Zn-insertion. The present study hence paves the way for further development of rechargeable aqueous ZIB as an alternative ideal energy storage system due to its excellent safety and reliability.