Mg(OH) 2 nanocrystallines with rod-, tube-, needle-, or lamella-like morphologies have been synthesized by a hydrothermal reaction using different magnesium precursors and solvents as the reactants. The products appeared to have narrow size distributions with a monodisperse nature. Subsequent thermal decomposition at 450 °C gave nanosized MgO, which preserved well the morphological features of the Mg(OH) 2 samples. The specific surface areas of the MgO samples were determined by the BET technique, which gave a feature of high surface area generally larger than 100 m 2 /g. The channels formed in the thermal dehydroxylation process may account for this feature of the MgO nanocrystallines. CM000607E

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Rechargeable lithium-sulfur (Li-S) batteries have been expected for new-generation electrical energy storages, which are attributed to their high theoretical energy density, cost effectiveness, and eco-friendliness. But Li-S batteries still have some problems for practical application, such as low sulfur utilization and dissatisfactory capacity retention. Herein, we designed and fabricated a foldable and compositionally heterogeneous three-dimensional sulfur cathode with integrated sandwich structure. The electrical conductivity of the cathode is facilitated by three different dimension carbons, in which short-distance and long-distance pathways for electrons are provided by zero-dimensional ketjen black (KB), one-dimensional activated carbon fiber (ACF) and two-dimensional graphene (G). The resultant three-dimensional sulfur cathode (T-AKG/KB@S) with an areal sulfur loading of 2 mg cm exhibits a high initial specific capacity, superior rate performance and a reversible discharge capacity of up to 726 mAh g at 3.6 mA cm with an inappreciable capacity fading rate of 0.0044% per cycle after 500 cycles. Moreover, the cathode with a high areal sulfur loading of 8 mg cm also delivers a reversible discharge capacity of 938 mAh g at 0.71 mA cm with a capacity fading rate of 0.15% per cycle and a Coulombic efficiency of almost 100% after 50 cycles.

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