A novel nitrogen/oxygen co-doped carbon sponge (NOCS) is directly applied as a monolithic binder-free electrode for supercapacitors. It exhibits a high specific capacitance and excellent electrochemical cyclability.

A kind of Se/C nanocomposite is fabricated by dispersing selenium in interconnected porous hollow carbon bubbles (PHCBs) via a melt-diffusion method. Such PHCBs are composed of porous hollow carbon spheres with a size of ∼70 nm and shells of ∼12 nm thickness interconnected to each other. Instrumental analysis shows that the porous shell of the PHCBs could effectively disperse and sequester most of the selenium, while the inner cavity remains hollow. When evaluated as cathode materials in a carbonate-based electrolyte for Li-Se batteries, the Se/PHCBs composites exhibit significantly excellent cycling performance and a high rate capability. Especially, the Se/PHCBs composite with an optimal content of ∼50 wt% selenium (Se50/PHCBs) displays a reversible discharge capacity of 606.3 mA h g(-1) after 120 cycles at 0.1 C charge-discharge rate. As the current density increased from 0.1 to 1 C (678 mA g(-1)), the reversible capacity of the Se50/PHCBs composite can still reach 64% of the theoretical capacity (431.9 mA h g(-1)). These outstanding electrochemical features should be attributed to effective sequestration of Se in the PHCBs, as well as to the ability to accommodate volume variation and enhance the electronic transport by making Se have close contact with the carbon framework.

A Co 2 SnO 4 hollow cube/graphene composite (Co 2 SnO 4 HC@rGO) was synthesized by pyrolysis-induced transformation from the hydrothermally synthesized hollow cubic precursor and subsequent combination with graphene sheets via the analogous mechanism of electrostatic interactions. The Co 2 SnO 4 HCs with a size of 240 nm and the shell of 50-70 nm thickness were uniformly encapsulated in the graphene sheets. As an anode material for lithium-ion batteries, the Co 2 SnO 4 HC@rGO exhibited significantly enhanced cyclability and superior rate capability compared to the pure Co 2 SnO 4 counterpart. Even after 100 cycles, it still delivered a capacity over 1000 mA h g À1 at 100 mA g À1 .

A multifunctional separator composed of different dimensional ZnO and graphene is fabricated via a vacuum filtration method, which can provide sufficient active sites to adsorb polysulfides, thus enhancing the cycling stability and rate performance of lithium–sulfur batteries.