No abstract

High-energy nickel (Ni)–rich cathode will play a key role in advanced lithium (Li)–ion batteries, but it suffers from moisture sensitivity, side reactions, and gas generation. Single-crystalline Ni-rich cathode has a great potential to address the challenges present in its polycrystalline counterpart by reducing phase boundaries and materials surfaces. However, synthesis of high-performance single-crystalline Ni-rich cathode is very challenging, notwithstanding a fundamental linkage between overpotential, microstructure, and electrochemical behaviors in single-crystalline Ni-rich cathodes. We observe reversible planar gliding and microcracking along the (003) plane in a single-crystalline Ni-rich cathode. The reversible formation of microstructure defects is correlated with the localized stresses induced by a concentration gradient of Li atoms in the lattice, providing clues to mitigate particle fracture from synthesis modifications.

Liu and co-workers report a molecular engineering study of ferricyanide and ferrocyanide catholytes for pH neutral aqueous organic redox flow battery applications using a strategy of cation modulation. Compared with traditional potassium or sodium ferricyanide and ferrocyanide catholytes, the newly designed (NH 4 ) 3 [Fe(CN) 6 ] and (NH 4 ) 4 [Fe(CN) 6 ] catholytes manifest unprecedented electron storage capacities and robust battery performance, which promise sustainable and economical energy storage. Meanwhile, this work presents an efficient pathway to the development of high-performance redox active electrolytes for redox flow batteries.

Mg batteries are a promising energy storage system because of physicochemical merits of Mg metal as an anode material. However, the lack of electrochemically and chemically stable magnesium electrolytes impedes the development of Mg batteries. In this study, a newly designed chloride-free magnesium fluorinated pinacolatoborate, Mg[B((CF3)4C2O2)2]2 (abbreviated as Mg-FPB), was synthesized by convenient methods from commercially available reagents and fully characterized. The Mg-FPB electrolyte delivered outstanding electrochemical performance, specifically, 95% coulombic efficiency and 197 mV overpotential for reversible Mg deposition, and anodic stability up to 4.0 V vs Mg. The Mg-FPB electrolyte was applied to demonstrate a high voltage rechargeable Mg/MnO2 battery with a discharge capacity of 150 mAh/g.

Lithium carbonate is an unavoidable impurity at the cathode side.