Sarish Rehman

Rational Design of Si/SiO2@Hierarchical Porous Carbon Spheres as Efficient Polysulfide Reservoirs for High‐Performance Li–S Battery

Integrated design of Si/SiO2 @hierar-chical porous carbon spheres is made and used as efficient polysulfide reservoir for enhancing lithium-sulfur battery (LSB) in terms of capacity, rate ability, and cycling stability via combined chemical and physical effects.

Nanostructured cathode materials for lithium–sulfur batteries: progress, challenges and perspectives

Lithium–sulfur batteries (LSBs) possess many fold higher energy densities than conventional batteries; however, their establishment as a dominant niche in modern electronics and grid level storage energy techniques is critically impeded by their short cycling life, limited sulfur loading and severe polysulfide shuttling effect. Tremendous achievement has been made during the last decade in eliminating the aforementioned obstacles by employing various strategies to enhance their performance and make them promising alternative candidates for the present energy storage technology that shows great potential for next-generation high-energy systems. To promote breakthroughs in this exciting field, here this article will highlight the recent progress in the innovation of sulfur cathodes with an emphasis on the design of a new class of materials, and engineering of advanced nanostructures and novel cell configurations to enhance the electrochemical stability of LSBs. We also discuss future research directions and the remaining challenging issues in the concluding remarks that pave the way for further significant progress in this field.

Integrated Design of MnO2@Carbon Hollow Nanoboxes to Synergistically Encapsulate Polysulfides for Empowering Lithium Sulfur Batteries

Lithium sulfur batteries (LSBs) with high theoretical energy density are being pursued as highly promising next-generation large-scale energy storage devices. However, its launch into practical application is still shackled by various challenges. A rational nanostructure of hollow carbon nanoboxes filled with birnessite-type manganese oxide nanosheets (MnO2 @HCB) as a new class of molecularly-designed physical and chemical trap for lithium polysulfides (Li2 Sx (x = 4-8)) is reported. The bifunctional, integrated, hybrid nanoboxes overcome the obstacles of low sulfur loading, poor conductivity, and redox shuttle of LSBs via effective physical confinement and chemical interaction. Benefiting from the synergistic encapsulation, the developed MnO2 @HCB/S hybrid nanoboxes with 67.9 wt% sulfur content deliver high specific capacity of 1042 mAh g-1 at the current density of 1 A g-1 with excellent Coulombic efficiency ≈100%, and retain improved reversible capacity during long term cycling at higher current densities. The developed strategy paves a new path for employing other metal oxides with unique architectures to boost the performance of LSBs.

Multifunctional Nitrogen-Doped Loofah Sponge Carbon Blocking Layer for High-Performance Rechargeable Lithium Batteries

Low-cost, long-life, and high-performance lithium batteries not only provide an economically viable power source to electric vehicles and smart electricity grids but also address the issues of the energy shortage and environmental sustainability. Herein, low-cost, hierarchically porous, and nitrogen-doped loofah sponge carbon (N-LSC) derived from the loofah sponge has been synthesized via a simple calcining process and then applied as a multifunctional blocking layer for Li-S, Li-Se, and Li-I2 batteries. As a result of the ultrahigh specific area (2551.06 m(2) g(-1)), high porosity (1.75 cm(3) g(-1)), high conductivity (1170 S m(-1)), and heteroatoms doping of N-LSC, the resultant Li-S, Li-Se, and Li-I2 batteries with the N-LSC-900 membrane deliver outstanding electrochemical performance stability in all cases, i.e., high reversible capacities of 623.6 mA h g(-1) at 1675 mA g(-1) after 500 cycles, 350 mA h g(-1) at 1356 mA g(-1) after 1000 cycles, and 150 mA h g(-1) at 10550 mA g(-1) after 5000 cycles, respectively. The successful application to Li-S, Li-Se, and Li-I2 batteries suggests that loofa sponge carbon could play a vital role in modern rechargeable battery industries as a universal, cost-effective, environmentally friendly, and high-performance blocking layer.

Facile synthesis of anisotropic single crystalline α-Fe2O3 nanoplates and their facet-dependent catalytic performance

In this work, a one step solvothermal method was used to synthesize uniform anisotropic hexagonal and cylindrical hematite nanoplates in the presence of methanol and ethylene di-amine. The phase and morphology of the samples were confirmed by X-ray diffraction (XRD) and electron microscopy. Photocatalytic degradation of methylene blue (MB) was carried out using two different hematite nanoplates to compare their catalytic performance. A systematic study of different parameters affecting the photodegradation of MB was performed. Hexagonal nanoplates exposing (110), (102) and (104) facets exhibit enhanced photocatalytic activity compared to the cylindrical nanoplates that expose only (110) and (102) facets, confirming that the high catalytic activity of the hexagonal nanoplates is attributed to the exposure of more catalytically active facets.

Porous Carbon Spheres: Rational Design of Si/SiO2@Hierarchical Porous Carbon Spheres as Efficient Polysulfide Reservoirs for High-Performance Li–S Battery (Adv. Mater. 16/2016)

S. Guo, Y. Hou, and S. Rehman develop a new class of silicon crosslinked with hierarchical porous carbon spheres usable as an efficient polysulfide reservoir for enhancing the performance of lithium-sulfur batteries. As described on page 3167, the developed hybrid material adsorbs negatively charged polysulfides via both chemical and physical adsorption. Remarkably, the hybrid spheres show a high specific capacity, an excellent rate capability and long cyclability.