Uniform deposition of Zn induced by Triethylmethylammonium tetrafluoroborate additives in aqueous electrolytes

Aqueous zinc ion batteries (AZIBs) present considerable potential for the development of large-scale aqueous battery systems. However, the zinc anode encounters various issues, including pronounced dendrite formation and side reactions that adversely affect its operational lifespan. To address these issues, triethylmethylammonium tetrafluoroborate (TEMA.BF4) is incorporated as an additive in the ZnSO4 electrolyte to attain a highly reversible zinc anode. Firstly, TEMA+ preferentially adsorbs onto the zinc anode, creating an electrostatic shielding layer. This suppresses uncontrolled growth at the tip, effectively preventing the development of zinc dendrites. Secondly, TEMA.BF4 participates in establishing a stable solid electrolyte interphase (SEI) layer through electrochemical reduction. This SEI layer increases the nucleation overpotential, resulting in denser zinc deposition, thereby preventing interfacial side reactions like hydrogen generation. As a result, TEMA.BF4 enables the Zn||Zn symmetric cell to be operated stably for more than 2500 h at 0.5 mA cm−2 and 0.5 mAh cm−2. Furthermore, the Zn||Cu cell incorporating TEMA.BF4 demonstrates a reversible plating/stripping process for over 760 cycles, achieving an average CE of 98 %. Notably, the assembled full cells using V2O5 cathodes could endure 4000 cycles, sustaining a capacity of 120 mAh g−1 at a rate of 10 A g−1. These findings suggest that the application of ionic liquid additives remains highly viable for enhancing the energy storage performance of AZIBs. TEMA.BF4 is adsorbed on the zinc metal surface via electrostatic interactions and participates in the formation of SEI film, preventing dendrite formation and side reactions, thus enhancing the stability of the zinc anode/electrolyte interface. [Display omitted] •TEMA+ preferentially adsorbs onto the zinc anode, creating an electrostatic shielding layer.•TEMA.BF4 participates in establishing a stable solid electrolyte interphase (SEI) layer through electrochemical reduction.•TEMA.BF4 enables the Zn||Zn symmetric cell to be operated stably for more than 2500 h at 0.5 mA cm−2 and 0.5 mAh cm−2.•The assembled full cells using V2O5 could endure 4000 cycles, sustaining a capacity of 120 mAh g−1 at a rate of 10 A g−1.