Internal Magnetic Fields Enhance Capacity Retention in Aqueous Zinc‐Organic Batteries With Quinone Cathodes

The development of alternatives to lithium‐ion batteries (LIBs) is critical to address concerns related to resource availability, cost, and sustainability. Aqueous zinc‐ion batteries (AZIBs) are promising alternatives to LIBs due to their low cost and ease of fabrication, inherent safety, material abundance, recyclability, and high theoretical specific capacity. However, their practical implementation is hindered by dendrite formation, interfacial instability, and capacity fading. Here, we investigate the use of internal magnetic fields as a passive, zero‐energy input strategy to enhance the electrochemical performance of AZIBs employing poly(2‐chloro‐3,5,6‐trisulfide‐1,4‐benzoquinone) (PCTB) organic cathodes. Through the incorporation of internal magnetic fields into Swagelok‐type AZIBs, several electrochemical performance metrics are improved. Interestingly, cells operated under a 50 mT internal magnetic field exhibit reduced charge‐transfer resistance (~80% decrease relative to 0 mT), improved specific discharge capacity (16.4% increase after 250 cycles at 1C), and enhanced capacity retention. Electrochemical impedance spectroscopy, galvanostatic cycling, and post‐cycling structural analyses suggest that magnetic‐field‐induced magnetohydrodynamic effects contribute to more uniform zinc deposition and improved interfacial stability. These results demonstrate that internal magnetic fields can serve as an efficient and scalable strategy to improve the performance of AZIBs with organic cathodes, without additional materials or energy input.