Separator pore size induced oriented Zn deposition

Abstract

Aqueous zinc batteries (AZBs) are promising alternatives to lead-acid batteries for large-scale energy storage. In this work, we developed a TiO2-grafted polyethylene (TiO2-PE) separator for AZBs with excellent hydrophilicity. The TiO2-PE separator demonstrates the thinnest thickness of 9 μm, significantly decreasing the inactive mass of the entire battery comparing with the commercial glass fiber separator (260 μm). We further prove that the separator pore size can modulate the Zn deposition morphology. The (002)-orientated Zn deposition is induced when the pore size is smaller than the crystal critical length. Therefore, the 0.2 μm pores in TiO2-PE induce a (002)-orientated Zn deposition, while the 2 μm pores in glass fiber lead to a randomly oriented growth of Zn metal. This work highlights the opportunities in the pore size-modulated deposition/dissolution process in Zn and other metal batteries.