Metallic antimony (Sb) is an attractive anode material for lithium-/sodium-ion batteries (LIBs/SIBs) because of its high theoretical capacity (660 mA h g), but it suffers from poor cycling performance caused by the huge volume expansion and the unstable solid electrolyte interphase (SEI). Here, we report a high-performing microsized Sb anode for both LIBs and SIBs by coupling it with fluoroethylene carbonate (FEC) containing electrolytes. The optimum amount of FEC (10 vol %) renders a stable LiF/NaF-rich SEI on Sb electrodes that can suppress the continuous electrolyte decomposition and accommodate the volume variation. The microsized Sb electrode gradually evolves into a porous integrity assembled by nanoparticles in FEC-containing electrolytes during cycling, which is totally different from that in the FEC-free counterpart. As a result, the microsized Sb electrodes exhibit a reversible capacity of 540 mA h g with 85.3% capacity retention after 150 cycles at 1000 mA g for LIBs and 605 mA h g with 95.4% capacity retention after 150 cycles at 200 mA g for SIBs. More impressively, the prototype full Li-based (i.e., Sb/LiNiCoMnO cell) and Na-based (i.e., Sb/NaV(PO)OF cell) batteries also achieve good cycling durability. This facile strategy of electrolyte formulation to boost the cycling performance of microsized Sb anodes will provide a new avenue for developing stable alloying-type materials for both LIBs and SIBs.