Alkaline-based aqueous sodium-ion batteries (ASIBs) offer a promising solution for large-scale energy storage due to their safety, low environmental impact, and cost-effectiveness. However, their performance is limited by water decomposition, which leads to hydrogen evolution and oxygen evolution reactions, reducing energy density and lifespan. This study presents an alkaline ASIB with a Mn-based Prussian blue analogue (NMF) cathode and a NaTi₂(PO₄)₃ (NTP) anode, using a fluorine-free alkaline electrolyte of sodium perchlorate (NaClO₄). The battery exhibits a lifespan of 13,000 cycles at 10 C and an energy density of 88.9 Wh kg⁻¹ at 0.5 C. The key innovation is the use of a nickel/carbon (Ni/C) coating on the NMF cathode, which creates a H₃O⁺-rich local environment near the cathode surface, suppressing oxygen evolution and electrode dissolution. Additionally, Ni atoms are in-situ embedded into the cathode to enhance its durability in alkaline conditions. The battery also demonstrates excellent cycling stability, with a capacity retention of 91.3% after 200 cycles at 0.5 C under -30°C. The alkaline electrolyte also allows the battery to function at low temperatures, with a lower freezing point than highly concentrated electrolytes. The study also shows that the Ni/C coating can be used to substitute Ni for Mn vacancies in the NMF cathode, further stabilizing the structure. The battery's performance is compared with other aqueous batteries, showing significant advantages in terms of energy density, safety, and environmental impact. The study highlights the potential of alkaline-based ASIBs for large-scale energy storage applications.Alkaline-based aqueous sodium-ion batteries (ASIBs) offer a promising solution for large-scale energy storage due to their safety, low environmental impact, and cost-effectiveness. However, their performance is limited by water decomposition, which leads to hydrogen evolution and oxygen evolution reactions, reducing energy density and lifespan. This study presents an alkaline ASIB with a Mn-based Prussian blue analogue (NMF) cathode and a NaTi₂(PO₄)₃ (NTP) anode, using a fluorine-free alkaline electrolyte of sodium perchlorate (NaClO₄). The battery exhibits a lifespan of 13,000 cycles at 10 C and an energy density of 88.9 Wh kg⁻¹ at 0.5 C. The key innovation is the use of a nickel/carbon (Ni/C) coating on the NMF cathode, which creates a H₃O⁺-rich local environment near the cathode surface, suppressing oxygen evolution and electrode dissolution. Additionally, Ni atoms are in-situ embedded into the cathode to enhance its durability in alkaline conditions. The battery also demonstrates excellent cycling stability, with a capacity retention of 91.3% after 200 cycles at 0.5 C under -30°C. The alkaline electrolyte also allows the battery to function at low temperatures, with a lower freezing point than highly concentrated electrolytes. The study also shows that the Ni/C coating can be used to substitute Ni for Mn vacancies in the NMF cathode, further stabilizing the structure. The battery's performance is compared with other aqueous batteries, showing significant advantages in terms of energy density, safety, and environmental impact. The study highlights the potential of alkaline-based ASIBs for large-scale energy storage applications.