Integrating proton co-storage in iron-based anodes for high-performance nickel-iron batteries

The growing demand for sustainable energy solutions has intensified the need for efficient, cost-effective, and scalable energy storage technologies. Among candidate systems, nickel‑iron (Ni-Fe) batteries stand out due to their low cost, abundant materials, and inherent safety, offer significant potential for large-scale applications. However, their practical application is hindered by limited energy density and inefficient charge-storage mechanisms. This study presents a novel approach to address these challenges by integrating a proton co-storage mechanism into Ni-Fe batteries. The batteries are constructed using cobalt boride (Co-B) alloy cold-pressed onto Fe foam as anodes (Co-B/Fe) and in-situ grown hydroxyl hydroxide (NiOOH) on Ni foam as cathodes (NiOOH/Ni). The integration of proton co-storage enables additional redox reactions through reversible proton absorption and oxidation, leading to a record-high improvements in energy storage. The resulting battery delivers an exceptional areal capacity of ∼7.59 mAh cm^-2 and an energy density of ∼21.26 Wh cm^-2, while maintaining ∼91.1 % of its initial capacity after 3000 cycles, demonstrating acceptable cycling stability. This work paves the way for next-generation batteries, offering a new solution for cost-effective and environmentally friendly battery technologies.