Paschen-Back effect modulation of SO₄^2- hydration in magnetized electrolyte toward dendrite-free Zn-ion batteries.

Abstract

Tuning anionic solvation structures and dynamic processes at solid-liquid interfaces is critical yet challenging for stabilizing Zn metal negative electrodes in Zn-ion batteries, particularly due to the issue of dendrite formation and hydrogen evolution reaction. Here, we show that highly hydrated SO₄^2- can be effectively modulated under a strong magnetic field via the Paschen-Back effect on O-H vibrations, which reorients individual water molecules to manipulate Zn²⁺ solvation and protonated water clusters (H₃O⁺). Molecular dynamics simulations and in situ Raman spectroscopy reveal that the hydrated SO₄^2--H₂O complexes promote Zn²⁺ nucleation and deposition on the (002) plane, with preferential oxygen adsorption inhibiting two-dimensional Zn²⁺ diffusion. Moreover, magnetizing the electrolyte disrupts the Grotthuss proton-transfer pathway, suppressing H₂ evolution and further reducing dendrite formation. By employing inexpensive permanent magnets without external power, this magnetization strategy offers a practical, energy-efficient route to enhance both the stability and performance of zinc-based rechargeable batteries.