Improved cycling performance of oxygen-stoichiometric spinel Li1+xAl yMn2-x-yO4+δ at elevated temperature

Li1+xAl yMn2-x-yO4±δ spinel cathode materials for lithium-ion batteries have been prepared by two methods, a specific two-step and the conventional one-step solid-state calcination methods. Compared with the conventional method, the new two-step method can guarantee the oxygen stoichiometry in spinel samples as well as reduced surface area. These characters lead to the improvement in cycling performance of spinel cathode even at elevated temperature. Moreover, the increase in doping amount of Al into Mn-spinel contributes to smearing the oxygen deficiency at high calcination temperature (1000 oC). The oxygen stoichiometric spinel samples exhibited greatly improved cycling performance. Further, Mn dissolution from spinel cathodes into the electrolyte was sufficiently suppressed even at elevated temperature of 60 oC. This beneficial influence would be reflected more remarkably in the cycles of lithium-ion full cells (spinel/C)