In Situ Constructing Robust Solid-Electrolyte Interphase for Advanced Zn Anode in Acidic Electrolyte.

Although dendrite formation and passivation of Zn anode can be inhibited using acidic electrolytes (pH< 4), acidic electrolytes are rarely employed in aqueous Zn-ion batteries (AZIBs) owing to the accelerated hydrogen evolution and corrosion at Zn anode|electrolyte interface. It is urgently required to construct the protective solid-electrolyte interphase (SEI) for acidic AZIBs. Herein, a robust organic/inorganic layered SEI is in situ constructed on Zn anode through the decomposition of tetraethylammonium tetrafluoroborate (TEATFB), involving BF4 --triggered hydrolysis chemistry. The inner inorganic layer containing ZnF2 accelerates Zn2+ migration, while the outer nitrogenous organic layer accommodates large volume changes. Meanwhile, preferentially adsorbed tetraethylammonium cation (TEA+) forms an electrostatic shielding layer and establishes a hydrophobic electric double layer (EDL), which induce uniform Zn deposition and exclude water molecules from the inner Helmholtz plane (IHP) layer. Benefiting from the formation of Zn2+-conducting SEI and water-proof EDL, the ultrahigh average Coulombic efficiency (ACE) of 99.9% for Zn||Cu asymmetric cell, along with long cycle life (3000 h) and high Zn utilization ratio (80%) for Zn||Zn symmetric cell, is achieved. Furthermore, the Zn||MnO2 full cell with low N/P (4:1) and high MnO2 loading mass (10.7 mg cm-2) delivers a high capacity retention of 82% after 500 cycles.