Magnetic field regulation of zinc dendrite growth in aqueous zinc metal batteries: An in-situ observation

Aqueous zinc metal batteries exhibit remarkable theoretical capacity and safety advantages, but their practical application is severely constrained by zinc dendrite growth, which induces internal short circuits and degrades cyclic durability. Conventional dendrite-inhibition strategies, including anode architecture engineering, interface modification and electrolyte optimization, inevitably introduce extraneous components that elevate inactive mass and impair energy density. Herein, we innovatively combine in-situ optical microscopy and nonlinear phase-field simulations to systematically elucidate dendrite growth mechanisms at varied current densities, and propose a magnetic field regulation strategy based on the magnetohydrodynamic effect. The Lorentz force derived from coupled electromagnetic fields drives helical migration of Zn²⁺, resulting in dense and uniform zinc deposition. At 10 mA·cm⁻², dendrite height is reduced from 601 μm to 50 μm. The α-MnO₂//Zn full cell delivers 337.4 mAh·g⁻¹ after 100 cycles at 1 C, far exceeding the 298 mAh·g⁻¹ of the control group. This work demonstrates magnetic field modulation as a feasible approach to high-performance aqueous zinc batteries and supports their potential for practical applications.