Rapid hydrothermal and post-calcination synthesis of well-shaped LiNi0.5Mn1.5O4 cathode materials for lithium ion batteries

Abstract

High voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode materials with well-developed polyhedral-shape structure have been successfully synthesized via a rapid hydrothermal process followed by high-temperature calcination with Li source. The as-synthesized samples were characterized by powder X-ray diffraction, Raman spectroscopy, Scanning electron microscopy and electrochemical test. All samples show polyhedral-shape morphologies as well as cubic spinel structure with Fd3m space group. Electrochemical analysis verifies that the spinel LNMO cathode prepared with sulfate at hydrothermal temperature of 200 °C exhibits the better electrochemical properties in terms of discharge capacity, cycling stability and rate performance. This sample delivers an initial discharge capacity of 131.1 mAh g−1 at 0.5 C rate at 25 °C, with the capacity retention of 85.2% after 100 charge-discharge cycles. Additionally, it still shows high rate performance with a discharge capacity of 110.9 mAh g−1 even at 20 C rate. The excellent electrochemical properties are mainly attributed to its high crystallinity, appropriate particle size and uniform particle size distribution. These results suggest that the rapid hydrothermal and post-calcination method is an effective way for preparing high voltage LNMO cathode materials which can be applied to lithium ion batteries.