Composite cathodes are prepared by blending the olivine LiFe0.3Mn0.7PO4 (LFMP) and spinel LiMn1.9Al0.1O4 (LMO) in order to combine the high capacity of LFMP with the rate capability of the spinel. While tap density, capacity and energy density show a linear dependency on the blend ratio, a remarkable synergetic effect between LFMP and LMO improving the electrochemical performance at higher C-rates is demonstrated. Potential curves of blend electrodes at rates of 3C reveal a less pronounced polarization for the Mn2+/3+ plateau than expected from theoretical calculations. This buffer effect is also observed for high current pulses (5C) where blend electrodes resemble the behavior of pure spinel electrodes. In terms of power density at high states of charge (SoC), the performance of the Blend(50LFMP/50LMO cap%) exceeds even that of pure spinel. In addition, the spinel-related manganese dissolution can be drastically reduced by blending spinel with LFMP. This study shows the expected and synergetic effects of LFMP/spinel blends and compares the results with theoretical calculations.