Flexible and Safe Additives-Based Zinc-Binder-Free-Hierarchical MnO₂-Solid Alkaline Polymer Battery for Potential Wearable Applications

Abstract

The next-generation flexible wearable electronics are among the most rapidly growing industries due to their extended use in everyday applications resulting in an increased demand for cheaper, safer, and flexible energy storage devices. This study aims to investigate and enhance the overall performance of a Zn-MnO² alkaline battery and make it suitable for safe and flexible wearable applications. To achieve high cyclability and performance of the cathode, issues of low active-material availability for redox reactions and inactive-phase formations are overcome by fabricating a binder-free hierarchical (increased surface area) additives (enabled reversible compound formation) based MnO² cathode. Furthermore, zinc/stainless steel composite anode (to reduce anode shape changes) and calcium hydroxide coated polymer electrolyte (to stop zincate ion transfer) are used to improve cyclability. By assembling the above mentioned layers, excellent rate capabilities, high-capacity utilization (487 mAh g⁻¹), long cycling stabilities (1000 cycles with 70% retention), and high energy density (400 Wh kg⁻¹) are achieved. Moreover, bending, hammering, puncturing, and lighting up an light emitting diode are conducted (under flat, bent, and cut) to demonstrate the cells’ safety, flexibility, and robustness. The successful findings in this study can chart new pathways to the development of safe, flexible, and cost-effective next-generation energy storage sources for wearables.