Synthesis of nanoarchitectured LiNi0.5Mn0.5O2 spheres for high-performance rechargeable lithium-ion batteries via an in situ conversion route

LiNi0.5Mn0.5O2 nanoarchitectured spheres (NA-LiNi0.5Mn0.5O2) have been synthesized via an in situ conversion route derived from the use of [gamma]-MnO2 hollow nanostructured spheres. The complete conversion of the [gamma]-MnO2 precursor to layered [small alpha]-NaFeO2-type NA-LiNi0.5Mn0.5O2 has been confirmed by XRD, FE-SEM, TEM, and HR-TEM. This NA-LiNi0.5Mn0.5O2 cathode exhibits a remarkable enhancement of rate performance compared with that of LiNi0.5Mn0.5O2 particles prepared by a conventional solid-state reaction method (SS-LiNi0.5Mn0.5O2). The batteries based on NA-LiNi0.5Mn0.5O2 retain a discharge capacity of 153.5 mA h g-1 (93% of the first discharge capacity) after 75 cycles. A specific discharge capacity of 121.9 mA h g-1 was retained at a rate of 3.2 C, which is about 70% of the capacity at a rate of 0.2 C.