LiNi0.5Mn1.5O4 was prepared by an improved solid-state reaction at high heating and cooling rates, the mixed precursors were initially heated up to 900°C, then directly cooled down to 600°C and heated for 24h in air. X-ray diffraction (XRD) pattern shows that LiNi0.5Mn1.5O4 has cubic spinel structure; scanning electron microscopic (SEM) image shows that the particle size is about 0.2μm together with homogenous distribution. Electrochemical measurements show that LiNi0.5Mn1.5O4 powders delivered up to 143mAhg−1 with superior cycling performance at the rate of 5/7C.