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Nanocrystalline LiMn 2 O 4 /graphene nanosheets nanocomposite has been successfully synthesized by a one-step hydrothermal method without post-heat treatment. In the nanocomposite, LiMn 2 O 4 nanoparticles of 10–30 nm in size are well crystallized and homogeneously anchored on the graphene nanosheets. The graphene nanosheets not only provide a highly conductive matrix for LiMn 2 O 4 nanoparticles but also effectively reduce the agglomeration of LiMn 2 O 4 nanoparticles. The nanocrystalline LiMn 2 O 4 /graphene nanosheets nanocomposite exhibited greatly improved electrochemical performance in terms of specific capacity, cycle performance, and rate capability compared with the bare LiMn 2 O 4 nanoparticles. The superior electrochemical performance of the nanocrystalline LiMn 2 O 4 /graphene nanosheets nanocomposite makes it promising as cathode material for high-performance lithium-ion batteries.

Nanocrystalline LiMn2O4/graphene nanosheet (GNS) composite is hydrothermally prepared by dispersing GNS in H2O followed by addition of KMnO4 and LiOH (autoclave, 180 °C, 5 h).

Waveguide superlattices, a special type of waveguide arrays, can be designed to achieve very low cross talk at submicrometer/subwavelength pitches. The theoretical framework and design rationales for such waveguide superlattices will be presented in depth. Waveguide sidewall roughness can help to deter the coherent coupling between identical waveguides in nearby supercells, but it also induces random fluctuation of transmission. Statistical behavior of the transmission due to roughness in a waveguide superlattice is systematically treated. Complex transmission characteristics due to spectral oscillation and random roughness will be presented, and their evolution with the superlattice length will be analyzed.