A porous membrane electrolyte enabled by poly(biphenyl piperidinium triphenylmethane) for dendrite-free zinc anode with enhanced cycling life

Aqueous zinc-ion batteries show great advantages as the sustainable energy storage devices, but suffer from inferior cycling life and low energy density due to the notorious zinc dendrites and possible side reactions in aqueous electrolytes. Herein, we propose a zinc-ions (Zn2+) soaked porous membrane electrolyte (GF/PBPT) by incorporating poly(biphenyl piperidinium triphenylmethane) (PBPT) into glass fiber (GF) via non-solvent-induced phase separation. The PBPT was synthesized via a super-acid catalyzed polymerization reaction. The fabricated membrane electrolyte containing PBPT of 42 wt% (GF/PBPT-42%) exhibits suitable pores and reasonable mechanical robustness of 4.24 MPa. Moreover, the abundant tertiary amines on PBPT backbones have specific affinity to Zn2+, which benefits the uniform Zn2+ flux through the membrane electrolyte. As a result, the electrolyte of GF/PBPT-42% greatly facilitates dendrite-free Zn anode and enables the Zn/Zn cell to deliver a superior cycling life over 1540 h at 0.5 mA cm−2 at room temperature (RT). In addition to be used in the Zn/Zn cells, the GF/PBPT-42% membrane has been demonstrated its application as the electrolyte in the Zn/MnO2 cell with enhanced cycling stability at both RT and −10 °C.