Two LiNi0.5Mn1.5O4 spinels with different mean particle sizes (30 nm and 3 mu m) were tested over a wide range of discharge rates (from C/4 to 10C) in lithium cells. Capacity retention in the nanometric sample on cycling was quite good at high rates, but significantly decreased at low discharge rates. The micrometric spinel exhibited the opposite behavior (its capacity dropped at high rates). One simple and effective way of avoiding this drawback is by homogeneously mixing both spinels in a 1:1 weight ratio. The composite electrodes thus obtained exhibited improved integrity upon cycling and an acceptable performance at both low and high discharge rates. (c) 2005 The Electrochemical Society.