LiCr0.2Ni0.4Mn1.4O4 spinels exhibiting huge rate capability at 25 and 55°C: Analysis of the effect of the particle size

The comparison of the rate capability of LiCr0.2Ni0.4Mn1.4O4 spinels synthesized by the sucrose aided combustion method at 900, 950 and 1000 degrees C is presented. XRD and TEM studies show that the spinel cubic structure remains unchanged on heating but the particle size is notably modified. Indeed, it increases from 695 nm at 900 degrees C to 1465 nm at 1000 degrees C. The electrochemical properties have been evaluated by galvanostatic cycling at 25 and 55 degrees C between 1 C and 60 C discharge rates. At both temperatures, all samples exhibit high working voltage (similar to 4.7 V), elevated capacity (similar to 140 mAh g(-1)) and high cyclability (capacity retention similar to 99% after 50 cycles even at 55 degrees C). The samples also have huge rate capability. They retain more than 70% of their maximum capacity at the very fast rate of 60C. The effect of the particle size on the rate capability at 25 and at 55 C has been investigated. It was demonstrated that LiCr0.2Ni0.4Mn1.4O4 annealed at 900 degrees C, with the lowest particle size, has the best electrochemical performances. In fact, among the LiNi0.5Mn1.5O4-based cathodes, SAC900 exhibits the highest rate capability ever published. This spinel, able to deliver 31,000 W kg(-1) at 25 degrees C and 27,500 W kg(-1) at 55 degrees C is a really promising cathode for high-power Li-ion battery. (C) 2011 Elsevier B.V. All rights reserved.