A High‐Performance Na–Al Battery Based on Reversible NaAlCl₄ Catholyte

Abstract

mainly hampered by issues arising from the use of aqueous electrolytes, such as the formation of a passive oxidation layer, anode corrosion, and hydrogen evolution reactions. [3] The last five years have witnessed more extensive research into nonaqueous aluminum batteries, particularly those based on ionic liquid (IL) electrolytes that enable reversible stripping and deposition of aluminum. [4] However, various roadblocks still remain to develop an efficient nonaqueous aluminum battery with high capacity and long cycle life, and the major challenge lies in the lack of suitable cathode materials. Scheme 1 summarizes the electrochemical behaviors of some representative cathode materials recently assessed for aluminum-based batteries. In 2015, Lin et al. [5] reported a rechargeable Al battery comprising a chloroaluminate IL electrolyte, a pyrolytic graphite foil cathode, and an aluminum anode. Operated through the intercalation/de-intercalation of chloroaluminate anions (AlCl 4 −) in the graphite, the battery exhibited a specific capacity of ≈70 mAh g −1 at a discharge voltage plateau near 2.0 V versus Al 3+ /Al. Following this work, various carbon-based intercalation cathodes (e.g., graphitic foams, graphene aerogel, and natural graphite) [6] were studied to further improve the capacity and power density. Unfortunately, limited by the storage mechanism based on monovalent AlCl 4 − , most carbon-based materials have shown capacities of less than 100 mAh g −1 , which needs to be improved for practical applications. In parallel, transition-metal oxides and chalcogenides (e.g.

Aqueous Aluminum Cells: Mechanisms of Aluminum Anode Reactions and Role of the Artificial Solid Electrolyte Interphase

“…The destructive effect of the high concentration of halide ions on the Al 2 O 3 layer on the surface of the aluminum foil was also discussed by the Li group at PNNL. 30 During these measurements, once the fresh (in view of pitting corrosion 29 ) Al surface came in contact with the aqueous electrolyte, the voltage difference between the Al//Al and T-Al//T-Al symmetric cells decreased. Therefore, the electrochemical process on the Al electrode was dominated by the corrosion reaction (passivation/activation) and not (as has previously been suggested 19,22 ) by the redox reaction (Al 3+ /Al).…”

“…The reactant layer of T-Al contained a sufficient amount of chloride ions, , which were released into the electrolyte during electrochemical measurements and activated the Al electrode by destroying the dense Al oxide layer. The destructive effect of the high concentration of halide ions on the Al 2 O 3 layer on the surface of the aluminum foil was also discussed by the Li group at PNNL . During these measurements, once the fresh (in view of pitting corrosion) Al surface came in contact with the aqueous electrolyte, the voltage difference between the Al//Al and T-Al//T-Al symmetric cells decreased.…”

Evaluating ZEBRA Battery Module under the Peak-Shaving Duty Cycles

“…Among various sodium (Na)-based rechargeable batteries, sodium-metal halide (Na-MH or ZEBRA) batteries use low cost and abundant Na, nickel (Ni), and iron (Fe) as the main battery constituents and also offer superior battery safety and durability, thereby providing great potential for various grid applications [ 5 , 6 , 7 ]. The ZEBRA battery using Ni/Fe cathodes is the most popular redox chemistry among the vast majority of Na-MH batteries including Na-NiCl 2 , Na-FeCl 2 , Na-ZnCl 2 , and Na-Al batteries reported in the past [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ], and the overall cell reaction of ZEBRA battery can be described as follows [ 19 , 20 ]: 2Na + MCl 2 (Charge) ←→ 2NaCl + M (Discharge), where M is Ni, Fe with E 0 = 2.58 V for Ni, and 2.35 V for Fe, respectively. The tubular or clover shape β″-Al 2 O 3 solid electrolyte (BASE) tube has been used for ZEBRA batteries as a key component to facilitate Na + ion transportation but stop material cross-over between the cathode and anode sides [ 20 ].…”

Effect of Cathode Microstructure on Electrochemical Properties of Sodium Nickel-Iron Chloride Batteries

“…However, commercial Na/NiCl 2 cells have poor price competitiveness because of the large amount of Ni they contain and their high operation temperature. Because of these weaknesses, many experimental strategies for improving Na/NiCl 2 batteries have been attempted, such as replacing the Ni in the cathode with other metals [ 5 , 6 , 7 , 8 , 9 , 10 ], decreasing the operating temperature [ 11 , 12 , 13 , 14 ] and enhancing Ni-based cathodes [ 15 , 16 , 17 , 18 ]. However, the cathode microstructure, which is essential for in-depth cathode studies on topics such as the NaCl size effect or granule density, has not been researched in detail.…”

“…However, this result was related to the effects of cell degradation. Additionally, although the effect of NaCl size on Na/AlCl 3 batteries was briefly studied [ 6 ], its effect on Na/NiCl 2 and Na/(Ni,Fe)Cl 2 batteries remains unidentified. Moreover, the effects of the granule manufacturing process have been studied [ 19 ], but this study mainly analyzed the granule production conditions, whereas the microstructure was not examined in detail.…”