Metal-organic framework-mediated synthesis of LiNi0.5Mn1.5O4: Tuning the Mn3+ content and electrochemical performance by organic ligands

Abstract Spinel LiNi 0.5 Mn 1.5 O 4 has drawn considerable attention due to its wide working voltage, high energy density, low cost, natural abundance, and environmental friendliness. However, as an electrode in lithium-ion batteries, its inferior ionic/electronic conductivity and high Mn 3+ concentration at the surface lead to low specific capacitance and poor rate/cycling performance, which have impeded its applications. In this work, a series of LiNi 0.5 Mn 1.5 O 4 is synthesized via a hydrothermally assisted method coupled with a high-temperature calcination process based on metal-organic frameworks. In addition, this study systematically explores the effect of the organic ligand species on the electrochemical properties of synthesized LiNi 0.5 Mn 1.5 O 4 . Furthermore, an optimal LiNi 0.5 Mn 1.5 O 4 electrode is demonstrated with a high discharge capacity of 145.3 mA h g −1 at a 1C rate. It provides a large capacity of 122.6 mA h g −1 even at a discharge rate as high as 20C. In particular, at an elevated temperature, 94.4% of the capacity is retained after 500 cycles at 1C and 40 °C. Thus, LiNi 0.5 Mn 1.5 O 4 will be a promising cathode for applications in next-generation lithium-ion batteries with high energy densities.