A Li-Mn-O defective spinel phase material has been synthesized through repeated grinding and heating (T < 400 degrees C) steps from a mixture of LiOH and MnO2. The sample has been characterized by X-ray diffraction, thermogravimetric analysis and elemental and oxidation state analyses. At a C/12 charge/discharge rate, the material showed a first-cycle capacity of almost 200 mAh/g that decreased upon cycling to a stable value of 120 mA h/g after the 20th cycle. At a higher rate (C/3.7), the material showed a long cycle life upon Lithium insertion/deinsertion with more than 50% of the initial capacity delivered at the 750th cycle. The work was developed within the ALPE (Advanced Lithium polymer Electrolyte) battery project, an Italian project devoted to the realization of lithium polymer batteries for electric vehicle applications.