Low-Cost Anode-Free Aqueous Batteries Using Permanent Magnets

Abstract

The rise in portable electronics has created an ever growing demand for more electrochemical energy storage (EES) systems. Lithium-ion batteries have achieved widespread commercial use because of their high energy density, but concerns about their safety and the sustainability of lithium have created a search for alternatives. Aqueous batteries present a much safer option, and they are cheaper both in materials and fabrication. The zinc-ion battery is among the most researched aqueous batteries, but problems remain with the formation of zinc dendrites during plating on the anode. A number of solutions to this problem have been proposed, including the use of a permanent magnet placed behind a zinc-foil anode, which creates uniform zinc deposition via the magnetohydrodynamic (MHD) effect. Herein, we expand this concept to zinc deposition on other substrates for the so-called anode-free configuration, in which an inactive current collector is used for the zinc to plate and strip off of during cycling. This anode-free configuration is a promising way to reduce the cost and increase the energy density of batteries by removing active material and allowing a cheaper, inactive material to serve as the substrate for metal plating and stripping, and the use of a permanent magnet precludes the need for a complicated material or over-engineered solution interface to prevent dendrite growth.