energy storage (EES) systems can store and deliver on-demand renewable power, smoothing the intermittency associated with wind and solar energy when installed in large renewable-energy plants [3,4] Electricity generation systems based on renewable resources present an environmentally and socioeconomically more sustainable alternative to those based on fossil fuels. [5] Ensuring a steady energy supply can accelerate the transition to a lower carbon economy, approaching toward the emission reductions of 30% by 2030 to meet the goals of Paris Agreement.Thanks to their high energy density and long cycling stability, [6] lithium ion batteries (LIBs) are dominant in the portable electronics and electric vehicle (EV) markets. However, the implementation of LIBs as stationary grid storage has been constrained so far due to the fact that LIBs present several sustainability issues. The use of large quantities of scarce and toxic cathode materials (lithium, cobalt, or nickel) inevitably increases their environmental burdens. [7] Environmentally speaking, sodium ion batteries (NIBs) are emerging as a potential alternative to LIBs given the natural availability of sodium. [8] NIBs are cost-effective, offer acceptable energy densities and enable the use of bio-derived electrodes, [9][10][11] so they have a prominent position to next-generation batteries replacing LIBs. As for LIBs, a completely inert, oxygen Aqueous zinc ion batteries (AZIBs) are gaining widespread scientific and industrial attention thanks to their safety and potential environmental sustainability in comparison with other battery chemistries relying on organic electrolytes. AZIBs are good candidates for sustainable stationary storage, covering household energy needs or smoothing the intermittency associated with wind and solar energy. In spite of their potential as a sustainable energy storage technology, the study of their environmental repercussions remains unexplored. The environmental impacts associated with the fabrication of AZIBs are quantified using a cradle-to-gate life cycle assessment (LCA) methodology. Six laboratory-scale battery designs offering high delivered capacity, energy density and operating lifespan are selected. The contribution of different battery components to eighteen environmental impact indicators is shown. An average value of 45.1 kg CO 2 equiv per 1 kWh is obtained considering the metallic Zn anode, the cathode, the separator, the aqueous electrolyte and the electricity required for cell assembly. AZIBs are environmentally competitive with lithium-ion, lithium-oxygen, lithium-sulfur, and sodium-ion battery technologies and are attractive from a Circular Economy viewpoint given the potential of renewable materials as separators and the high recycling rates of electrodes. The obtained results prove the suitability of zinc ion batteries as a sustainable stationary energy storage solution.