Sieving-type Electric Double Layer with Hydrogen Bond Interlocking to Stable Zinc Metal Anode

The stability of aqueous zinc metal batteries is significantly affected by side reactions and dendrite growth on the anode interface, which primarily originate from water and anions. Herein, we introduce a multi H-bond site additive, 2, 2'-Sulfonyldiethanol (SDE), into an aqueous electrolyte to construct a sieving-type electric double layer (EDL) by hydrogen bond interlock in order to address these issues. On the one hand, SDE replaces H₂O and SO₄ ^2- anions that are adsorbed on the zinc anode surface, expelling H₂O/SO₄ ^2- from the EDL and thereby reducing the content of H₂O/SO₄ ^2- at the interface. On the other hand, when Zn²⁺ are de-solvated at the interface during the plating, the strong hydrogen bond interaction between SDE and H₂O/SO₄ ^2- can trap H₂O/SO₄ ^2- from the EDL, further decreasing their content at the interface. This effectively sieves them out of the zinc anode interface and inhibits the side reactions. Moreover, the unique characteristics of trapped SO₄ ^2- anions can restrict their diffusion, thereby enhancing the transference number of Zn²⁺ and promoting dendrite-free deposition and growth of Zn. Consequently, utilizing an SDE/ZnSO₄ electrolyte enables excellent cycling stability in Zn//Zn symmetrical cells and Zn//MnO₂ full cells with lifespans exceeding 3500 h and 2500 cycles respectively.