Amorphous Fe-Phytate Enables Fast Polysulfide Redox for High-Loading Lithium Sulfur Batteries.

Utilizing catalysts to accelerate polysulfides conversion are of paramount importance to eliminate the shuttling effect and improve the practical performance of lithium-sulfur (Li-S) batteries. The amorphism, attributes to the abundant unsaturated surface active sites, has recently been recognized as a contribution to increase the activity of catalysts. However, the investigation on amorphous catalysts has received limited interest in lithium-sulfur batteries due to lack of understanding of their composition structure activity. Herein, a amorphous Fe-Phytate structure is proposed to enhance polysulfide conversion and suppress polysulfide shuttling by modifying polypropylene separator (C-Fe-Phytate@PP). The polar Fe-Phytate with distorted VI coordination Fe active centers strongly intake polysulfide electron by forming FeS bond to accelerate the polysulfide conversion. The surface mediated polysulfides redox gives rise to a higher exchange current in comparison with carbon. Furthermore, Fe-Phytate owns robust adsorption to polysulfide and effectively reduce the shuttling effect. With the C-Fe-Phytate@PP separator, the Li-S batteries exhibit an outstanding rate capability of 690 mAh g-1 at 5 C and an ultrahigh areal capacity of 7.8 mAh cm-2 even at a high sulfur loading of 7.3 mg cm-2 . The work provides a novel separator for facilitating the actual applications of Li-S batteries.

Facile Synthesis of Nanoporous NiS Film with Inverse Opal Structure as Efficient Counter Electrode for DSSCs.

To satisfy the high requirement of catalytic activity for efficient dye-sensitized solar cells (DSSCs), a novel nanoporous NiS film with inverse opal structure and outstanding electrocatalytic properties was prepared by a facile template-assisted electrodeposition method. The inverse opal structure makes the film have a larger specific surface area and more catalytic sites, thereby result to a higher electrocatalytic activity. Compared with the flat NiS/FTO electrode, this kind of nanoporous NiS film with inverse opal structure has higher catalytic activity and can be used as a cheap and efficient Pt-free electrode to replace the traditional Pt/FTO electrode. It is of great significance to reduce the cost and promote the wide application of DSSCs. This study opens up a new experimental exploration for further improving the catalytic activity of NiS electrode and the according photovoltaic efficiency of DSSCs. The template-assisted electrodeposition method proposed in this work provides a facile method for morphology control and an easy to be realized way to optimize the catalytic performance of the metal sulfides counter electrode.

NiS submicron cubes with efficient electrocatalytic activity as the counter electrode of dye-sensitized solar cells.

In this work, nickel sulfide (NiS) submicron cubes, synthesized by an easy hydrothermal method, were investigated as an efficient electrocatalytic material of dye-sensitized solar cells (DSSCs), to our knowledge, for the first time. Part of the NiS submicron cubes were grown together in a hydrothermal procedure and formed the connected submicron cube cluster. The NiS submicron cubes (with a diameter of 300-800 nm) showed excellent electrocatalytic activity and presented superior photovoltaic performance when it was used as an electrocatalytic material for the counter electrode (CE) of DSSCs. The CE composed of the NiS submicron cubes could achieve a photovoltaic efficiency of 6.4%, showing their superior performance compared with the typical Pt electrode (which with the corresponding conversion efficiency was 5.3% at the same condition). The low-cost NiS submicron cube electrode could be a competitive candidate to replace the traditional Pt electrode in DSSCs. The simple composition procedure of NiS submicron cubes could enable the low-cost mass production of an efficient NiS submicron cube electrode to be easily accomplished.