Improving Capacity Retention of Anode-Free Zinc Batteries with Simple Geometry and Lorentz Forces

While aqueous zinc-ion batteries (AZIBs) are promising candidates for a safe, environmentally friendly, and low-cost alternative to lithium-ion batteries, they remain held back by poor energy density. One proposed method to improve their energy density is the anode-free configuration, in which the zinc anode is removed to improve zinc utilization; however, this configuration greatly reduces the system's long-term cyclability. Herein, we present a series of strategies that improve the capacity retention of the anode-free system without the need for expensive or complex modifications to the current collector that would increase production difficulty or inhibit recyclability. We demonstrate that a >99% reduction in the surface area of the current collector (further reducing material costs and energy density compared to the standard configuration) can improve capacity retention by more than 400% over the control, and the inclusion of a 100 mT magnetic field via an internal permanent magnet coupled with a 1 h hold at the end of discharge can further improve this retention increase by another 350%. These strategies demonstrate significant improvement with negligible penalty to cost, environmental friendliness, safety, and recyclability, the primary advantages of AZIBs.