A porous polycaprolactone coating with abundant ester groups for stable Zn metal anodes

Owing to the merits of inexpensive, superior safety, and considerable volumetric capacity, aqueous Zn metal batteries (AZMBs) are regarded as powerful competitors for large-scale energy storage. Nevertheless, unsatisfactory interface stability and cycling lifespan resulting from parasitic reactions and dendrite issues significantly impede the further development of AZMBs. Herein, a porous polycaprolactone (pPCL) coating strategy is implemented to achieve durable Zn anodes. On the one hand, the pPCL membrane can inhibit the surface/ interface parasitic reactions. On the other hand, abundant ester groups and microchannels in the pPCL membrane can improve the uniformity of Zn2+ transport and induce horizontal Zn deposition. Accordingly, the pPCLcoated Zn anode could steady cycling over 2400 h at 5 mA cm-2, about 10 times longer than that of bare Zn (229 h). Meanwhile, the Zn nucleation overpotential decreases from 63 to 29 mV, and the average Coulombic efficiency of the Zn plating/stripping process is up to 99.76%. Moreover, the full cell also exhibits superior cyclability over 1000 cycles at 1 A g-1. This facile and cost-effective porous polymer coating strategy sheds light on the future orientation of Zn anode protection.