Molecular engineering of separator enables zwitterion migration channels for corrosion-resistant, HER-inhibiting and dendrite-free zinc metal anode

An AmPAM based electrospun separator is first proposed for an ultra-stable Zn metal anode through molecular engineering. • Numerous zwitterion migration channels are formed through electrostatic attraction for highly efficient ion transport. • The Zn|Zn cells using the AmPAM separators achieve unprecedented ultra-low polarization voltage and exceptional lifespans. Rechargeable aqueous zinc-based batteries hold great potential for next-generation energy storage devices, but face three interdependent challenges of dendrite, HER, and corrosion in the Zn metal anode toward practical application. To simultaneously address all three challenges, an amphoteric polyacrylamide (AmPAM) based electrospun separator is first proposed for an ultra-stable Zn metal anode through molecular engineering. The well-designed AmPAM chains with side-chain sulfonate and quaternary ammonium groups in appropriate density form numerous zwitterion migration channels through electrostatic attraction for highly efficient ion transport, thereby leading to negligible Zn 2+ concentration gradient and thus homogenized Zn 2+ flux. The Zn 2+ ion also undergoes rapid desolvation due to a synergistic effect between the hydrogen-bond interaction of amide groups and the electrostatic interaction of sulfonate groups, resulting in inhibited water reactivity and suppressed H 2 O-induced side reactions. Significantly, the Zn|Zn cells using the AmPAM separators achieve unprecedented ultra-low polarization voltage of ∼5.0 mV, exceptional lifespans up to 3000 h at 1 mA cm −2 /1 mAh cm −2 and even over 500 h at 10 mA cm −2 /10 mAh cm −2 , accompanied by reduced corrosion current density (0.15 mA cm −2 ), negligibly small HER current density (−0.0002 mA cm −2 ) and dendrite-free Zn deposition, which are superior to those of the conventional GF separator. Furthermore, the Zn|MnO 2 full battery delivers satisfactory rate performance and long-term cycling stability with capacity retention of 91% after 1000 cycles. This work offers a fresh insight into corrosion-resistant, HER-inhibiting and dendrite-free zinc metal anode from separator molecular engineering. An amphoteric polyacrylamide based electrospun separator with zwitterion migration channels is first proposed to simultaneously address all three challenges of dendrite, HER, and corrosion for an ultra-stable Zn anode through molecular engineering. Download: Download high-res image (253KB) Download: Download full-size image