Highly Zn2+-conductive and robust modified montmorillonite protective layer of electrodes toward high-performance rechargeable zinc-ion batteries

Abstract

• A protective layer of electrodes with expanded and robust interlayer. • Protective layer is prepared from organic montmorillonite and ZnSO 4 /MnSO 4 solution. • Protective layer with low-cost, high ionic conductivity and Zn 2+ transfer number. • Alleviate Zn corrosion, MnO 2 dissolution, side-reaction and Zn dendrite generation. • Improved rate capability and cyclability of the battery with the protective layer. The corrosion, parasitic side-reaction and dendrite of Zn anode as well as the dissolution of MnO 2 cathode limit the commercial application of zinc-ion batteries (ZIBs). Herein, a novel coating layer on Zn anode and MnO 2 cathode of rechargeable ZIBs is rationally designed by mixing hexadecyl trimethyl ammonium bromide(CTAB)-pillared organic montmorillonite with ZnSO 4 /MnSO 4 solution (ZnOMMT). ZnOMMT can serve as the protective layer to alleviate Zn corrosion and MnO 2 dissolution while the unique interlayer structure of ZnOMMT can also offer a selective pathway for fast Zn 2+ transfer and uniform Zn 2+ diffusion to inhibit the side-reaction and Zn dendrite generation. Notably, by the powerful pillaring of CTAB cations, the expanded and robust nanoscale interlayer tunnels of ZnOMMT for Zn 2+ diffusion are constructed to guarantee outstanding ionic conductivity (6.52 mS cm −1 ), high Zn 2+ transference number ( t + =0.66) and outstanding cyclic stability during deep cycles. Therefore, ZIBs with ZnOMMT coating layer deliver a steady long-term reversible capacity (267 mAh g −1 until 300 cycles at 0.5 A g −1 , 205 mAh g −1 until 700 cycles at 1.0 A g −1 ). The rational design of CTAB-pillared montmorillonite protective layer brings a brand-new opportunity to the realization of high-performance rechargeable ZIBs. A novel protective layer of electrodes with outstanding ionic conductivity, high Zn 2+ transference number, low-cost, expanded and robust nanoscale interlayer is fabricated from CTAB-pillared organic montmorillonite and ZnSO 4 /MnSO 4 solution, and utilized to alleviate Zn corrosion, MnO 2 dissolution, side-reaction and Zn dendrite generation and thus improve cyclability and rate capability.