Sodium phosphosilicate glasses exhibit unique properties with mixed network formers, and have various potential applications. However, proper understanding on the network structures and property-oriented methodology based on compositional changes are lacking. In this study, we have developed an extended topological constraint theory and applied it successfully to analyze the composition dependence of glass transition temperature (Tg) and hardness of sodium phosphosilicate glasses. It was found that the hardness and Tg of glasses do not always increase with the content of SiO2, and there exist maximum hardness and Tg at a certain content of SiO2. In particular, a unique glass (20Na2O-17SiO2-63P2O5) exhibits a low glass transition temperature (589 K) but still has relatively high hardness (4.42 GPa) mainly due to the high fraction of highly coordinated network former Si((6)). Because of its convenient forming and manufacturing, such kind of phosphosilicate glasses has a lot of valuable applications in optical fibers, optical amplifiers, biomaterials, and fuel cells. Also, such methodology can be applied to other types of phosphosilicate glasses with similar structures.

A hybrid Li−air battery uses a protected lithium anode and a porous air cathode in an aqueous electrolyte, based on a 4-e oxygen reduction reaction/oxygen evolution reaction (ORR/OER). It avoids the insoluble and insulating Li 2 O 2 product in a typical nonaqueous Li−air battery, and it owns unique advantages. A bifunctional cathode catalyst is crucial to battery performance. Here, we synthesize an ultrathin N-doped grapheneencapsulated nanosphere Co−Ni alloy (Co−Ni@NG). It has hierarchical architecture consisting of a uniform Co−Ni nanoalloy coated with a thin layer of N-doped graphene, showing high activity, high stability, and lower overpotential between the ORR and OER (0.55 V between onset potentials). It exhibited a discharge/charge voltage gap of 0.55 V at a current density of 1.4 mA cm −2 , which is much smaller than the commercial Pt/C catalyst. It delivered an energy density of 3158 Wh kg −1 and a power density as high as 134.2 W m −2 at a current density of 7 mA cm −2 . The graphene shells protect the alloy catalyst and improve the durability of the catalyst. One hundred cycles were demonstrated without significant deterioration. It was testified as a promising energy storage system with high energy density, efficiency, reliability, and durability.

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