• Three zwitterions with identical quaternary ammonium cations but distinct anionic groups (carboxylate, sulfonate, phosphate) show distinct impact in aqueous zinc ion batteries.
• The zwitterion with phosphate group (MPC) uniquely promotes oriented Zn (002) plane deposition and provides pH buffering capability, effectively suppressing dendrite formation and side reactions.
• The Zn//NaVO full cell with MPC additive delivers an ultralong cycling life of 4000 cycles with an exceptionally low capacity decay of 0.014% per cycle.
• The Zn//Zn cell with MPC additive in ZnSO4 electrolyte exhibits an ultralong lifespan over 5000 hours, demonstrating the synergistic effect of quaternary ammonium and phosphate groups.