Electrochemical Properties of Porous Nickel-Based Alloy Foam as Anodes in Lithium Metal Batteries

Traditional graphite-anode-based lithium (Li)-ion batteries are challenged by the ever-increasing demand of today’s energy storage and power applications, especially for smart grid and electric vehicles because they have almost reached their theoretical specific energy limits. Among varieties of alternative anode materials, Li metal has been widely recognized as an ultimate anode material for high-energy rechargeable batteries due to its ultrahigh theoretical specific capacity (3860 mAh g^-1) and very low redox potential (- 3.04 V vs. standard hydrogen electrode). To date, considerable efforts have been made to developing ultra-high energy density Li metal-anode-based batteries, such as Li-S and Li-air batteries. However, uncontrollable dendritic growth and high reactivity of Li metal anodes result in poor cycle performance and severe safety concerns, hindering the practical application of Li metal anodes in rechargeable Li metal batteries. To solve these issues, various approaches have been developed to suppress Li dendrite formation, including artificial SEI layer construction, additives of electrolyte to improve the uniformity of Li-ion deposition, utilization of high-modulus polymer or ceramic solid-state electrolytes, separator modification, current collector modification, and so on. Particularly, current collectors play a critical role in facilitating uniform Li nucleation and deposition. Fabricating three-dimensional current collectors is emerging as an effective strategy for designing dendrite-free Li anodes. Recently, Y. Choi et al. have reported an oxidation method for achieving an ultra-lithiophilic NiO layer on the surface of a three-dimensional nickel (Ni)-foam, resulting in stable Li plating and stripping in an anode prepared using Li-infused oxidized Ni-foam. In this study, Ni-based alloy, NiCrAl, with porous three-dimensional or two-dimensional structures was used as an anode in Li metal batteries. NiCrAl showed higher mechanical properties than pure Ni in the molten Li, anticipating in facile electrode stacking and cell assembly of NiCrAl-foam anode compared to Ni-foam anode. Oxidized NiCrAl-foam was prepared by heat treatment at 600^oC for 10 min in ambient air. Li was introduced into the oxidized NiCrAl-foam by dipping into molten Li or electroplating. We present the electrochemical properties of oxidized NiCrAl-foam anodes with different foam thickness (0.2–1.0 mm) in the Li metal batteries.