Tartaric acid has been used as chelating agent in the sol-gel method for preparation of pure LiNi0.5Mn1.5O4 with desired Fd m structural units. The prepared LiNi0.5Mn1.5O4 demonstrates better cycle stability at 1C by retaining 90% of its capacity after 200 cycles compared to the procured LiNi0.5Mn1.5O4, which only retained 75% of the initial capacity. This excellent cycle stability is the result of shorter diffusion paths of the Li ions and the better contact area of electrode and electrolyte due to the smaller particle size. Tartaric acid-based sol-gel method should be a convenient and efficient approach for the synthesis of LiNi0.5Mn1.5O4.