Converting commercial MnO2 into Co-doped LiNi0.5Mn1.5O4 with adjustable disordered/ordered phase ratio by a quaternary molten salt

The electrochemical performances of LiNi0.5Mn1.5O4 (LNMO) materials are strongly correlated with the ratio of disordered to ordered phases. Nevertheless, there are few reports on the adjustment of ordered and disordered phase ratio. In this paper, the ratio of ordered to disordered phases in LNMO is successfully adjusted by using a quaternary molten salt, which is proven by XRD refinement, FT-IR, and XPS. Reductive quaternary molten salt and Co doping are favorable for Ni/Mn cation disorder, leading to the increased disordered phase. LNMO with an appropriate ratio of ordered to disordered phases can exhibit enhanced electronic/ionic transfer rate and structural stability, revealed by electrochemical tests and ex situ characterizations. Therefore, the optimized material delivers a reversible capacity of 121 mA h g-1 at 20 mA g-1 and a long cyclic life with 61 mA h g- 1 at 1000 mA g-1 over 1200 cycles. The present work offers a new idea for achieving a regulated ratio of ordered to disordered phases in LNMO.