Potassium-Based α-Manganese Dioxide Nanofiber Binder-Free Self-Supporting Electrodes: A Design Strategy for High Energy Density Batteries

This work minimizes the passive components of electrodes and moves toward bridging the gap between actual and theoretical battery gravimetric energy density. Binder-free self-supporting (BFSS) cathodes were prepared from redox-active, high aspect ratio, potassium α-MnO₂ nanofibers (K-OMS-2) by eliminating the binder and current collector. The electroactive and structural element, K-OMS-2, was prepared by using a scalable, moderate temperature, aqueous synthesis. The BFFS electrode approach allows fabrication of thick, high energy density electrodes with low impedance, with up to 10-fold improvement in delivered specific energy relative to conventional cathodes. This could enable the design of high-capacity large form factor cells, as required for applications demanding high energy content. In principle, this approach suggests a widely applicable paradigm for the construction of other BFFS electrodes through the targeted synthesis of other transition-metal oxides with high aspect, fibrous morphologies.