Ammonium enables reversible aqueous Zn battery chemistries by tailoring the interphase

L Ma and TP Pollard and Y Zhang and MA Schroeder and XM Ren and KS Han and MS Ding and AV Cresce and TB Atwater and J Mars and LS Cao and HG Steinru and KT Mueller and MF Toney and M Hourwitz and JT Fourkas and EJ Maginn and CS Wang and O Borodin and K Xu, ONE EARTH, 5, 413-421 (2022).

DOI: 10.1016/j.oneear.2022.03.012

Aqueous rechargeable Zn metal batteries (RZMBs) are promising candidates for coupling with intermittent renewable energy sources to realize a carbon-neutral energy transition. However, irreversible issues of Zn metal anodes and a poor understanding of the interphasial chemistry severely limit the viability of RZMBs. Here, we demonstrate that the addition of an asymmetric alkylammonium cation, trimethylethyl ammonium- bis(trifluoromethylsulfonyl)imide (Me3EtN-TFSI), as a supporting salt into a traditional aqueous electrolyte results in improved Zn anode reversibility. Performance improvements are attributed to the formation of interphasial chemistries including ZnF2, ZnCO3, and fluoro-polymeric species, especially when combined with CO2. By tailoring the Zn interphase, this electrolyte exhibited excellent stability in Na2V6O16 $ 1.63H(2)O (HNVO)/Zn full cells, with a high specific capacity sustained (> 100 mAh g(-1)) over 1,000 cycles at 300 mA g(-1). A combination of experiments and modeling showed the importance of tuning interphases to further improve Zn reversibility and RZMBs.

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