Ultrathin MnO 2 /graphene oxide/carbon nanotube (G/M@CNT) interlayers are developed as efficient polysulfide-trapping shields for high-performance Li-S batteries. A simple layer-by-layer procedure is used to construct a sandwiched vein-membrane interlayer of thickness 2 µm and areal density 0.104 mg cm −2 by loading MnO 2 nanoparticles and graphene oxide (GO) sheets on superaligned carbon nanotube films. The G/M@CNT interlayer provides a physical shield against both polysulfide shuttling and chemical adsorption of polysulfides by MnO 2 nanoparticles and GO sheets. The synergetic effect of the G/M@CNT interlayer enables the production of Li-S cells with high sulfur loadings (60-80 wt%), a low capacity decay rate (−0.029% per cycle over 2500 cycles at 1 C), high rate performance (747 mA h g −1 at a charge rate of 10 C), and a low self-discharge rate with high capacity retention (93.0% after 20 d rest). Electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy observations of the Li anodes after cycling confirm the polysulfide-trapping ability of the G/M@CNT interlayer and show its potential in developing high-performance Li-S batteries.

We describe a distributed implementation of optimal power flow on a network of workstations. High performance is achieved on large real-world systems, including a 2587 line representation of the ERCOT system. The approach illustrates a general framework for parallelizing power system optimization problems.

Sulfur-porous carbon nanotube (S-PCNT) composites are proposed as cathode materials for advanced lithium-sulfur (Li-S) batteries. Abundant mesopores are introduced to superaligned carbon nanotubes (SACNTs) through controlled oxidation in air to obtain porous carbon nanotubes (PCNTs). Compared to original SACNTs, improved dispersive behavior, enhanced conductivity, and higher mechanical strength are demonstrated in PCNTs. Meanwhile, high flexibility and sufficient intertube interaction are preserved in PCNTs to support binder-free and flexible electrodes. Additionally, several attractive features, including high surface area and abundant adsorption points on tubes, are introduced, which allow high sulfur loading, provide dual protection to sulfur cathode materials, and consequently alleviate the capacity fade especially during slow charge/discharge processes. When used as cathodes for Li-S batteries, a high sulfur loading of 60 wt % is achieved, with excellent reversible capacities of 866 and 526 mAh g(-1) based on the weights of sulfur and electrode, respectively, after 100 cycles at a slow charge/discharge rate of 0.1C, revealing efficient suppression of polysulfide dissolution. Even with a high sulfur loading of 70 wt %, the S-PCNT composite maintains capacities of 760 and 528 mAh g(-1) based on the weights of sulfur and electrode, respectively, after 100 cycles at 0.1C, outperforming the current state-of-the-art sulfur cathodes. Improved high-rate capability is also delivered by the S-PCNT composites, revealing their potentials as high-performance carbon-sulfur composite cathodes for Li-S batteries.