Microwave-assisted hydrothermal synthesis of a high-voltage microcube LiMn1.5Ni0.5O4−δ spinel cathode material

Abstract

• High-quality LiMn 1.5 Ni 0.5 O 4−δ was synthesized by microwave-assisted hydrothermal method. • Microwave-treated LiMn 1.5 Ni 0.5 O 4−δ offers higher battery performance than LiMn 2 O 4. • Microwave irradiation modulates content of Mn 3+ and O vacancy improving performance. • Material with longer irradiation shows higher discharge capacity but less stability. • Improving intrinsic stability is required before practical use in Li-ion batteries. Electric vehicles (EVs) require high operating voltages as well as high-capacity batteries. One candidate material that has received a great deal of attention is the nickel-substituted “high-voltage” spinel LiMn 1.5 Ni 0.5 O 4 , which offers the advantages of both higher capacity and higher operating voltage than spinel LiMn 2 O 4 . These features, along with the relatively benign constituent elements, have made this material a top choice for the next generation of high-power batteries. In this study, LiMn 1.5 Ni 0.5 O 4−δ materials were synthesized by a microwave-assisted hydrothermal method. Analyses show that microwave irradiation enables the tuning of the Mn 3+ concentration, which is related to the degree of disorder and enhances the electrochemical performance. However, with increasing synthesis time, the material limit of the elastic strain was exceeded, and the structure became morphologically unstable, which deteriorated the electrochemical performance. Thus, further efforts are necessary to improve its intrinsic stability. The LiMn 1.5 Ni 0.5 O 4−δ cathode active material may be suitable for the rapid charging of electric vehicle batteries.