Dual-functional ionic liquids additive enables dendrite-free Zn anode with ultra-long cycle life over one year

Zn anodes suffer from the formation of uncontrolled dendrites aggravated by the uneven electric field and the insulating by-product accumulation in aqueous zinc-ion batteries (AZIBs). Here, an effective strategy implemented by 1-butyl-3-methylimidazolium hydrogen sulfate (BMIHSO₄) additive is proposed to synergistically tune the crystallographic orientation of zinc deposition and suppress the formation of zinc hydroxide sulfate for enhancing the reversibility on Zn anode surface. As a competing cation, BMI⁺ is proved to preferably adsorb on Zn-electrode compared with H₂O molecules, which shields the "tip effect" and inhibits the Zn-deposition agglomerations to inducing the horizontal growth along Zn (002) crystallographic texture. Simultaneously, the protonated BMIHSO₄ additives could remove the detrimental OH^- in real-time to fundamentally eliminate the accumulation of 6Zn(OH)₂·ZnSO₄·4H₂O and Zn₄SO₄(OH)₆·H₂O on Zn anode surface. Consequently, Zn anode exhibits an ultra-long cycling stability of one year (8762 h) at 0.2 mA cm^-2/0.2 mAh cm^-2, 3600 h at 2 mA cm^-2/2 mAh cm^-2 with a high plating cumulative capacity of 3.6 Ah cm^-2, and a high average Coulombic efficiency of 99.6 % throughout 1000 cycles. This work of regulating Zn deposition texture combined with eliminating notorious by-products could offer a desirable way for stabilizing the Zn-anode/electrolyte interface in AZIBs.