Changing y in the LiCryMn2-yO4 materials enables the monitoring of the average discharge voltage between 4 and 4.5 V. The Cr substitution is beneficial to the specific energy (and to the specific capacity) that increase,, by 16% compared to LiMn2O4, for 0.25 less than or equal to y less than or equal to 0.62. The cycling behavior is all the more poor as y is high in the composition range 0.62 less than or equal to y less than or equal to 1. The best cyclability is observed for y = 0.25. Its loss of the relative capacity after 280 cycles is about twice as small as that observed for LiMn2O4. The irreversible capacity, due to electrolyte oxidation, decreases rapidly with the cycle number and reaches a limit of about 2 to 6% of the cyclable capacity, depending on the experimental conditions. This limit is lowered when the end-of-charge voltage is decreased and/or when the charge rate is increased. The capacity decrease is negligible for discharge rates slower than D/2 in the 5.4-3.4 V range, and remains smaller than 50% for discharge rates slower than 8D. The power behavior of materials with y = 0.06, 0.25, and 0.5 has proved to be excellent, with very high powers of similar to 6000 mW g(-1) for energies of 100 mWh g(-1).