Li[Mn-2]O-4 spinel cathode material was prepared via a sol-gel method. Unlike typical Li[Mn-2]O-4 spinels that have been reported so far, our Li[Mn-2]O-4 spinel material showed no capacity fading in the 3 V range and delivered a reversible capacity of 137 similar to 139 mAh/g in the voltage range of 2.4-3.4 V at a current density of 0.2 mA/cm(2), which corresponds to 93 similar to 94% of the theoretical capacity of Li[Mn-2]O-4. Even better performance was observed at 54 degrees C. In the 4 V range, on the other hand, the material exhibited the charge/discharge characteristics typical of undoped, stoichiometric Li[Mn-2]O-4 spinel and the discharge capacity decreased by ca. 10% of the initial capacity (103 similar to 108 mAh/g) after 40 cycles. However, when cycled over the entire voltage range, including both the 3 and 4 V plateaus, the capacity loss in the 4 V range was smaller than when cycled only in the 4 V range. The electrochemical characteristics of the Li[Mn-2]O-4 spinel material and the origin of the capacity fading are discussed.