Crumpled graphene-encapsulated sulfur for lithium-sulfur batteries.

Lithium-sulfur batteries are promising technology in electrical vehicles and large-scale energy storage systems. However, their market penetration is seriously impeded by great challenges such as the low electrical conduction of sulfur and lithium sulfides, and lithium polysulfides' shuttling effect. This work shows that such challenges can be partly resolved by encapsulating sulfur in crumpled reduced graphene oxide (S@crGO), which was synthesized by a facile and scalable one-step in situ method. The strong interaction between sulfur and the graphene host, micro- and meso-pore structures, and rich surface functional groups contribute to the high performance of the S@crGO cathode for lithium-sulfur batteries.

Processable and Moldable Sodium-Metal Anodes.

Sodium-ion batteries are similar in concept and function to lithium-ion batteries, but their development and commercialization lag far behind. One obstacle is the lack of a standard reference electrode. Unlike Li foil reference electrodes, sodium is not easily processable or moldable and it deforms easily. Herein we fabricate a processable and moldable composite Na metal anode made from Na and reduced graphene oxide (r-GO). With only 4.5 % percent r-GO, the composite anodes had improved hardness, strength, and stability to corrosion compared to Na metal, and can be engineered to various shapes and sizes. The plating/stripping cycling of the composite anode was significantly extended in both ether and carbonate electrolytes giving less dendrite formation. We used the composite anode in both Na-O2 and Na-Na3 V2 (PO4 )3 full cells.