Nanostructured Nickel Hydroxide Cathodes for Energy Dense, Safe, Aqueous Rechargeable Nickel–Zinc Batteries

Abstract

Batteries that offer high gravimetric and volumetric densities coupled to improved safety and lower cost are needed for applications ranging from electric vehicles, portable electronic devices, and grid-level energy storage. Lithium-ion is presently the go-to high-energy battery technology of choice due to its high energy content, but suffers from inherent safety issues that can result in fires and explosions causing property damage to injury or death. The alkaline nickel–zinc (Ni–Zn) battery is an attractive alternative to Li-ion because it uses nonflammable aqueous electrolyte and benign electrode materials. Recent work at the U.S. Naval Research Laboratory has demonstrated that monolithic three-dimensional zinc “sponge” architectures solve long-standing performance limitations for zinc anodes and pave the way for next generation Ni–Zn batteries that approach the specific energy of Li-ion systems.1 To match these advancements at the zinc anode, Ni(OH)2 cathode structures with device-relevant capacity loading and rate capability are required. We use precipitation and microwave-assisted synthesis to explore the effects of varying Ni(OH)2 composition and nanostructure as a means to increase specific capacity beyond the performance of benchmark β-Ni(OH)2 cathodes. Our preliminary results show that isomorphic metallic substitution within Ni(OH)2 stabilizes typically unstable α-Ni(OH)2 under alkaline conditions and provides improved charge-storage capability at high rate compared with β-Ni(OH)2. Promising α-Ni(OH)2 nanomaterials are fabricated into high areal–capacity cathodes, paired with zinc sponge anodes, and evaluated in coin cells under challenging charge–discharge conditions. References Parker, J.; Chervin, C.N.; Pala, I.R.; Machler, M.; Burz, M.F.; Long, J.W.; Rolison, D.R., Rechargeable Nickel–3D Zinc Batteries: An Energy-Dense, Safer Alternative to Lithium-Ion. Science 2017, 356, 414–417.