Targeted deflection of Zn2+ migration trajectory using the piezomagnetic effect to enable horizontal Zn deposition†

Abstract

The rampant growth of dendrites caused by the inhomogeneous Zn²⁺ ion flux and “tip effect” significantly hinders the development of aqueous Zn-ion batteries. The conventional artificial protective layers (APLs) improve Zn anode stability predominantly through promoting uniform Zn deposition across the entire surface, but still lack targeted control over the localized Zn²⁺ migration at the tips, resulting in insufficient suppression of protrusion growth. Herein, we have constructed a cobalt ferrite oxide magnetically functional layer on Zn foil (CFO–Zn), endowing the APLs with the ability to precisely control the migration and deposition behaviors of Zn²⁺via the piezomagnetic effect. The stress generated on the CFO layer during the deposition process could induce local magnetic field enhancement, deflecting Zn²⁺ away from the tips, stopping the protrusion growth and consequently rendering the Zn deposition along the horizontal direction. Meanwhile, the CFO magnetic nanoparticles can accelerate and disperse the Zn²⁺ flow on the anode surface, resulting in improved ion transport and reduced Zn²⁺ concentration gradient. Additionally, the Zn²⁺ motion trajectory under electric/magnetic field co-induction has been simulated, confirming the ability of the magnetic field to deflect Zn²⁺ migration. The CFO–Zn anodes achieve highly reversible Zn stripping/plating with a cumulative plated capacity of 4750 mA h cm⁻².