Pie-like electrode design for high-energy density lithium–sulfur batteries

Owing to the overwhelming advantage in energy density, lithium–sulfur (Li–S) battery is a promising next-generation electrochemical energy storage system. Despite many efforts in pursuing long cycle life, relatively little emphasis has been placed on increasing the areal energy density. Herein, we have designed and developed a ‘pie’ structured electrode, which provides an excellent balance between gravimetric and areal energy densities. Combining lotus root-like multichannel carbon nanofibers ‘filling’ and amino-functionalized graphene ‘crust’, the free-standing paper electrode (S mass loading: 3.6 mg cm[superscript −2]) delivers high specific capacity of 1,314 mAh g[superscript −1] (4.7 mAh cm[superscript −2]) at 0.1 C (0.6 mA cm[superscript −2]) accompanied with good cycling stability. Moreover, the areal capacity can be further boosted to more than 8 mAh cm[superscript −2] by stacking three layers of paper electrodes with S mass loading of 10.8 mg cm[superscript −2].National Science Foundation (U.S.) (DMR-1120901)Wuxi Weifu High-technology Group Co., Ltd

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

General solution growth of mesoporous NiCo2O4 nanosheets on various conductive substrates as high-performance electrodes for supercapacitors

Mesoporous NiCo2O4 nanosheets can be directly grown on various conductive substrates, such as Ni foam, Ti foil, stainless-steel foil and flexible graphite paper, through a general template-free solution method combined with a simple post annealing treatment. As a highly integrated binder- and conductive-agent-free electrode for supercapacitors, the mesoporous NiCo2O4 nanosheets supported on Ni foam deliver ultrahigh capacitance and excellent high-rate cycling stability

General synthesis of multi-shelled mixed metal oxide hollow spheres with superior lithium storage properties

Complex hollow structures of transition metal oxides, especially mixed metal oxides, could be promising for different applications such as lithium ion batteries. However, it remains a great challenge to fabricate well-defined hollow spheres with multiple shells for mixed transition metal oxides. Herein, we have developed a new “penetration–solidification–annealing” strategy which can realize the synthesis of various mixed metal oxide multi-shelled hollow spheres. Importantly, it is found that multi-shelled hollow spheres possess impressive lithium storage properties with both high specific capacity and excellent cycling stability. Specifically, the carbon-coated CoMn2O4 triple-shelled hollow spheres exhibit a specific capacity of 726.7 mA h g−1 and a nearly 100 % capacity retention after 200 cycles. The present general strategy could represent a milestone in design and synthesis of mixed metal oxide complex hollow spheres and their promising uses in different areas

Controlled growth of NiCo2O4 nanorods and ultrathin nanosheets on carbon nanofibers for high-performance supercapacitors

Two one-dimensional hierarchical hybrid nanostructures composed of NiCo2O4 nanorods and ultrathin nanosheets on carbon nanofibers (CNFs) are controllably synthesized through facile solution methods combined with a simple thermal treatment. The structure of NiCo2O4 can be easily controlled to be nanorods or nanosheets by using different additives in the synthesis. These two different nanostructures are evaluated as electrodes for high performance supercapacitors, in view of their apparent advantages, such as high electroactive surface area, ultrathin and porous features, robust mechanical strength, shorter ion and electron transport path. Their electrochemical performance is systematically studied, and both of these two hierarchical hybrid nanostructures exhibit high capacitance and excellent cycling stability. The remarkable electrochemical performance will undoubtedly make these hybrid structures attractive for high-performance supercapacitors with high power and energy densities.Published versio

Hierarchical MoS2 shells supported on carbon spheres for highly reversible lithium storage

Hierarchical MoS2 shells supported on carbon spheres (denoted as C@MoS2) have been synthesized through a one-step hydrothermal method. The obtained hierarchical C@MoS2 microspheres simultaneously integrate the structural and compositional design rationales for high-energy electrode materials based on two-dimensional (2D) nanosheets. When evaluated as an anode material for lithium-ion batteries (LIBs), the hierarchical C@MoS2 microspheres manifest high specific capacity, enhanced cycling stability and good rate capability

Mixed metal sulfides for electrochemical energy storage and conversion

Mixed metal sulfides (MMSs) have attracted increased attention as promising electrode materials for electrochemical energy storage and conversion systems including lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), hybrid supercapacitors (HSCs), metal–air batteries (MABs), and water splitting. Compared with monometal sulfides, MMSs exhibit greatly enhanced electrochemical performance, which is largely originated from their higher electronic conductivity and richer redox reactions. In this review, recent progresses in the rational design and synthesis of diverse MMS-based micro/nanostructures with controlled morphologies, sizes, and compositions for LIBs, SIBs, HSCs, MABs, and water splitting are summarized. In particular, nanostructuring, synthesis of nanocomposites with carbonaceous materials and fabrication of 3D MMS-based electrodes are demonstrated to be three effective approaches for improving the electrochemical performance of MMS-based electrode materials. Furthermore, some potential challenges as well as prospects are discussed to further advance the development of MMS-based electrode materials for next-generation electrochemical energy storage and conversion systems

Complex cobalt sulfide nanobubble cages with enhanced electrochemical properties

Metal-organic frameworks (MOFs) have been widely employed as precursors to prepare various nanostructured functional materials. Here we report a “nanoparticles-in-MOF” dual-template approach for generating complex cobalt sulphide (CoS) nanobubble cages. A novel nanoparticles-in-MOF hybrid structure consisting of a Co-based MOF polyhedron host and many encapsulated mesostructured TiO2 nanospheres is first prepared, followed by a sulfidation process to obtain a complex cage structure consisting of CoS nanobubbles in the shell. Importantly, this strategy can be extended to prepare many other functional nanoparticles-in-MOF hybrid structures. When evaluated as an electrode material for hybrid supercapacitors, the as-derived CoS nanobubble cages manifest remarkable electrochemical performance with long cycle life and good rate capability.NRF (Natl Research Foundation, S’pore)Accepted versio