Li-rich Mn-based Li1+x(Mn0.533Ni0.233Co0.233)(1-x)O-2 (x =0, 0.045, 0.09, 0.135, 0.18, 0.225) materials have been prepared by a conventional solid-state reaction. XRD, SEM and half-cell tests are investigated on the influence of Li content. Pure phase can be obtained when Li-excessive value x keeps between 0.045 and 0.18. The initial efficiency (Q(1d)/Q(1c)) almost keeps the same level of 70% for different Li-excessive samples. Li1.045Mn0.509Ni0.223Co0.223O2 sample shows highest discharge capacity of 259.8 mA h g(-1). Li1.09Mn0.486Ni0.212Co0.212O2 sample exhibits the best rate capability, and almost no reduction is observed after 24-time cycles in different discharge current density. (C) 2012 Elsevier B.V. All rights reserved.