Aqueous Zn‐ion batteries (AZIBs) have been recognized as promising energy storage devices due to their high theoretical energy density and cost‐effectiveness. However, side reactions and Zn dendrite generation during cycling limit their practical application. Herein, ammonium acetate (CH₃COONH₄) is selected as a trifunctional electrolyte additive to enhance the electrochemical performance of AZIBs. Research findings show that NH₄⁺ (oxygen ligand) and CH₃COO^– (hydrogenligand) with preferential adsorption on the Zn electrode surface can not only hinder Zn anode directly contact with active H₂O, but also regulate the pH value of the electrolyte, thus suppressing the parasitic reactions. Additionally, the formed SEI is mainly consisted of Zn₅(CO₃)₂(OH)₆ with a high Zn²⁺ transference number, which could achieve a dendrite‐free Zn anode by homogenizing Zn deposition. Consequently, the Zn||Zn symmetric batteries with CH₃COONH₄‐based electrolyte can operate steadily at an ultrahigh current density of 40 mA cm^–2 with a cumulative capacity of 6880 mAh cm^–2, especially stable cycling at −10 °C. The assembled Zn||MnO₂ full cell and Zn||activated carbon capacitor also deliver prominent electrochemical reversibility. This work provides unique understanding of designing multi‐functional electrolyte additive and promotes a long lifespan at ultrahigh current density for AZIBs.

A ZnSe/MoSe ₂ @C composite was fabricated as a high performance anode material for LIBs/SIBs.

A facile route for fabrication of an Sn doped 1T–2H MoS₂ few-layer structure embedded in N/P co-doped bio-carbon is initially developed using natural chlorella as an adsorbent and a nanoreactor.