Title: Quasispheroidal LiNi0.5Mn1.5O4 coated with Y2O3 and distributed over graphene nanosheets enabling high-voltage and high-energy as cathode in lithium-ion batteries

Abstract

LiNi0.5Mn1.5O4 is a promising cathode material for lithium-ion batteries with a high-voltage spinel structure. A microwave-assisted chemical co-precipitation method was used to synthesize Y2O3 coated quasi-spheres of LiNi0.5Mn1.5O4. The coating of Y2O3 and subsequent wrapping of quasi-spheres in graphene nanosheets does not alter the volume or promote the formation of unwanted phases. TGA analysis shows high thermal stability in the material. The material has an initial capacity of 133 mAh g−1 at C/10 with a retention of 98% after 100 cycles. In addition, cathode samples show a good capacity of 132 g−1 after 20 cycles at higher temperatures (55°C). Oxide coatings protect the particles from ionic leaching but limit the electrical conductivity of the materials. However, graphene enhances the conductivity of the synthesized material and wraps active particles in a conductive channel. Due to the synergistic design of the material and the robust manufacturing technique, parasitic reactions are suppressed without affecting the electrical conductivity. To increase their cyclic performance, the suggested material synthesis approach may successfully be applied to various electrode materials.