LiNi0.5Mn1.5O4 single crystals are synthesized using a two-step method consisting of emulsion/in situ co-precipitation and sintering reaction. In this process, Oil-in-water (Span80-Tween80-kerosene-H2O) emulsion is used as the in situ co-precipitation site. The co-precipitation is occurred within each emulsion droplet to produce the precursor when the aqueous precipitant is dropped into the emulsion. For the starting concentration of the nickel and manganese solution determines the composition of each emulsion droplet, micrometer-sized single crystals of LiNi0.5Mn1.5O4 are finally produced based on the size and concentration of the emulsion droplet. Bigger crystals are helpful on the cyclic performance, whereas smaller crystals are effective on the specific capacity but negative on the cyclic performance. LNM-0.5 pm sized crystals deliver specific capacity of 136 mA g(-1), at the 1st cycle and retain 129 mAh g(-1) after 200 cycles, maintaining 95% of its initial capacity. However, LNM-0.25 nanoparticles deliver capacity of 119 mAh g(-1) after 200 cycles and only maintain 89% of its initial capacity. At 20C rate, LNM-0.5 sample retains specific capacity of 111 mAh g(-1), after 200 cycles, which is higher than that of LNM-0.25 sample with retention of only 90 mAh g(-1). Based on the characterization and electrochemical measurement, it is observed that the LNM-0.5 sample with preferential crystal size presents excellent cyclic performance and rate performance. (C) 2018 Published by Elsevier B.V.