Critical Role of Ultrathin Graphene Films with Tunable Thickness in Enabling Highly Stable Sodium Metal Anodes

Sodium (Na) metal has shown great promise as an anode material for the next-generation energy storage systems because of its high theoretical capacity, low cost, and high earth abundance. However, the extremely high reactivity of Na metal with organic electrolyte leads to the formation of unstable solid electrolyte interphase (SEI) and growth of Na dendrites upon repeated electrochemical stripping/plating, causing poor cycling performance, and serious safety issues. Herein, we present highly stable and dendrite-free Na metal anodes over a wide current range and long-term cycling via directly applying free-standing graphene films with tunable thickness on Na metal surface. We systematically investigate the dependence of Na anode stability on the thickness of the graphene film at different current densities and capacities. Our findings reveal that only a few nanometer (∼2–3 nm) differences in the graphene thickness can have decisive influence on the stability and rate capability of Na anodes. To achieve the optimal performance, the thickness of the graphene film covered on Na surface needs to be meticulously selected based on the applied current density. We demonstrate that with a multilayer graphene film (∼5 nm in thickness) as a protective layer, stable Na cycling behavior was first achieved in carbonate electrolyte without any additives over 100 cycles at a current density as high as 2 mA/cm² with a high capacity of 3 mAh/cm². We believe our work could be a viable route toward high-energy Na battery systems, and can provide valuable insights into the lithium batteries as well

Synthesis and Electrochemical Performance of SnO<i>_x</i> Quantum Dots@ UiO-66 Hybrid for Lithium Ion Battery Applications

A novel method that combines the dehydration of inorganic clusters in metal–organic frameworks (MOFs) with nonaqueous sol–gel chemistry and pyrolysis processes is developed to synthesize SnO<i>_x</i> quantum dots@Zr-MOFs (UIO-66) composites. The size of as-prepared SnO<i>_x</i> nanoparticles is approximately 4 nm. Moreover, SnO<i>_x</i> nanoparticles are uniformly anchored on the surface of the Zr-MOFs, which serves as a matrix to alleviate the agglomeration of SnO<i>_x</i> grains. This structure provides an accessible surrounding space to accommodate the volume change of SnO<i>_x</i> during the charge/discharge process. Cyclic voltammetry and galvanostatic charge/discharge were employed to examine the electrochemical properties of the ultrafine SnO<i>_x</i>@Zr-MOF (UIO-66) material. Benefiting from the advantages of the smaller size of SnO<i>_x</i> nanoparticles and the synergistic effect between SnO<i>_x</i> nanoparticles and the Zr-MOFs, the SnO<i>_x</i>@Zr-MOF composite exhibits enhanced electrochemical performance when compared to that of its SnO<i>_x</i> bulk counterpart. Specifically, the discharge-specific capacity of the SnO<i>_x</i>@Zr-MOF electrode can still remain at 994 mA h g^–1 at 50 mA g^–1 after 100 cycles. The columbic efficiencies can reach 99%

Understanding the Role of Different Conductive Polymers in Improving the Nanostructured Sulfur Cathode Performance

Lithium sulfur batteries have brought significant advancement to the current state-of-art battery technologies because of their high theoretical specific energy, but their wide-scale implementation has been impeded by a series of challenges, especially the dissolution of intermediate polysulfides species into the electrolyte. Conductive polymers in combination with nanostructured sulfur have attracted great interest as promising matrices for the confinement of lithium polysulfides. However, the roles of different conductive polymers on the electrochemical performances of sulfur electrode remain elusive and poorly understood due to the vastly different structural configurations of conductive polymer–sulfur composites employed in previous studies. In this work, we systematically investigate the influence of different conductive polymers on the sulfur cathode based on conductive polymer-coated hollow sulfur nanospheres with high uniformity. Three of the most well-known conductive polymers, polyaniline (PANI), polypyrrole (PPY), and poly­(3,4-ethylenedioxythiophene) (PEDOT), were coated, respectively, onto monodisperse hollow sulfur nanopsheres through a facile, versatile, and scalable polymerization process. The sulfur cathodes made from these well-defined sulfur nanoparticles act as ideal platforms to study and compare how coating thickness, chemical bonding, and the conductivity of the polymers affected the sulfur cathode performances from both experimental observations and theoretical simulations. We found that the capability of these three polymers in improving long-term cycling stability and high-rate performance of the sulfur cathode decreased in the order of PEDOT > PPY > PANI. High specific capacities and excellent cycle life were demonstrated for sulfur cathodes made from these conductive polymer-coated hollow sulfur nanospheres

Nonfilling Carbon Coating of Porous Silicon Micrometer-Sized Particles for High-Performance Lithium Battery Anodes

Silicon is widely recognized as one of the most promising anode materials for lithium-ion batteries due to its 10 times higher specific capacity than graphite. Unfortunately, the large volume change of Si materials during their lithiation/delithiation process results in severe pulverization, loss of electrical contact, unstable solid–electrolyte interphase (SEI), and eventual capacity fading. Although there has been tremendous progress to overcome these issues through nanoscale materials design, improved volumetric capacity and reduced cost are still needed for practical application. To address these issues, we design a nonfilling carbon-coated porous silicon microparticle (nC-pSiMP). In this structure, porous silicon microparticles (pSiMPs) consist of many interconnected primary silicon nanoparticles; only the outer surface of the pSiMPs was coated with carbon, leaving the interior pore structures unfilled. Nonfilling carbon coating hinders electrolyte penetration into the nC-pSiMPs, minimizes the electrode–electrolyte contact area, and retains the internal pore space for Si expansion. SEI formation is mostly limited to the outside of the microparticles. As a result, the composite structure demonstrates excellent cycling stability with high reversible specific capacity (∼1500 mAh g^–1, 1000 cycles) at the rate of C/4. The nC-pSiMPs contain accurate void space to accommodate Si expansion while not losing packing density, which allows for a high volumetric capacity (∼1000 mAh cm^–3). The areal capacity can reach over 3 mAh cm^–2 with the mass loading 2.01 mg cm^–2. Moreover, the production of nC-pSiMP is simple and scalable using a low-cost silicon monoxide microparticle starting material

Core–Shell Nanoparticle Coating as an Interfacial Layer for Dendrite-Free Lithium Metal Anodes

Lithium metal based batteries represent a major challenge and opportunity in enabling a variety of devices requiring high-energy-density storage. However, dendritic lithium growth has limited the practical application of lithium metal anodes. Here we report a nanoporous, flexible and electrochemically stable coating of silica@poly­(methyl methacrylate) (SiO₂@PMMA) core–shell nanospheres as an interfacial layer on lithium metal anode. This interfacial layer is capable of inhibiting Li dendrite growth while sustaining ionic flux through it, which is attributed to the nanoscaled pores formed among the nanospheres. Enhanced Coulombic efficiencies during lithium charge/discharge cycles have been achieved at various current densities and areal capacities

Magnetic Field-Controlled Lithium Polysulfide Semiliquid Battery with Ferrofluidic Properties

Large-scale energy storage systems are of critical importance for electric grids, especially with the rapid increasing deployment of intermittent renewable energy sources such as wind and solar. New cost-effective systems that can deliver high energy density and efficiency for such storage often involve the flow of redox molecules and particles. Enhancing the mass and electron transport is critical for efficient battery operation in these systems. Herein, we report the design and characterization of a novel proof-of-concept magnetic field-controlled flow battery using lithium metal-polysulfide semiliquid battery as an example. A biphasic magnetic solution containing lithium polysulfide and magnetic nanoparticles is used as catholyte, and lithium metal is used as anode. The catholyte is composed of two phases of polysulfide with different concentrations, in which most of the polysulfide molecules and the superparamagnetic iron oxide nanoparticles can be extracted together to form a high-concentration polysulfide phase, in close contact with the current collector under the influence of applied magnetic field. This unique feature can help to maximize the utilization of the polysulfide and minimize the polysulfide shuttle effect, contributing to enhanced energy density and Coulombic efficiency. Additionally, owing to the effect of the superparamagnetic nanoparticles, the concentrated polysulfide phase shows the behavior of a ferrofluid that is flowable with the control of magnetic field, which can be used for a hybrid flow battery without the employment of any pumps. Our innovative design provides new insight for a broad range of flow battery chemistries and systems

Table3_DNA5mC Regulator-Mediated Molecular Clusters and Tumor Microenvironment Signatures in Glioblastoma.XLSX

Growing evidence links DNA methylation to tumor immunity. The impact of DNA methylation (5 mC) on the microenvironment surrounding tumors and immunotherapy remains to be clarified. Through clustering gene expression of 20 DNA methylation regulators, this study aimed at systematically analyzing DNA methylation regulator patterns and tumor microenvironment characteristics of TCGA-GBM patients. Various subtypes of glioblastoma exhibit different tumor microenvironments and DNA methylation patterns. Each DNA methylation modification was then assigned a DNA methylation score (DMS). High DMS was associated with a good prognosis. In contrast, the low DMS group had a relatively low survival rate. A correlation was also found between high DMS and enhanced immunotherapy efficacy in two immune checkpoint blocking treatment cohorts. To conclude, identifying DNA methylation regulation patterns may prove critical to understanding glioblastoma progression and differentiation, as well as future therapeutic targets.</p

Table1_DNA5mC Regulator-Mediated Molecular Clusters and Tumor Microenvironment Signatures in Glioblastoma.XLSX

Growing evidence links DNA methylation to tumor immunity. The impact of DNA methylation (5 mC) on the microenvironment surrounding tumors and immunotherapy remains to be clarified. Through clustering gene expression of 20 DNA methylation regulators, this study aimed at systematically analyzing DNA methylation regulator patterns and tumor microenvironment characteristics of TCGA-GBM patients. Various subtypes of glioblastoma exhibit different tumor microenvironments and DNA methylation patterns. Each DNA methylation modification was then assigned a DNA methylation score (DMS). High DMS was associated with a good prognosis. In contrast, the low DMS group had a relatively low survival rate. A correlation was also found between high DMS and enhanced immunotherapy efficacy in two immune checkpoint blocking treatment cohorts. To conclude, identifying DNA methylation regulation patterns may prove critical to understanding glioblastoma progression and differentiation, as well as future therapeutic targets.</p

Table2_DNA5mC Regulator-Mediated Molecular Clusters and Tumor Microenvironment Signatures in Glioblastoma.XLSX

Growing evidence links DNA methylation to tumor immunity. The impact of DNA methylation (5 mC) on the microenvironment surrounding tumors and immunotherapy remains to be clarified. Through clustering gene expression of 20 DNA methylation regulators, this study aimed at systematically analyzing DNA methylation regulator patterns and tumor microenvironment characteristics of TCGA-GBM patients. Various subtypes of glioblastoma exhibit different tumor microenvironments and DNA methylation patterns. Each DNA methylation modification was then assigned a DNA methylation score (DMS). High DMS was associated with a good prognosis. In contrast, the low DMS group had a relatively low survival rate. A correlation was also found between high DMS and enhanced immunotherapy efficacy in two immune checkpoint blocking treatment cohorts. To conclude, identifying DNA methylation regulation patterns may prove critical to understanding glioblastoma progression and differentiation, as well as future therapeutic targets.</p

Image1_DNA5mC Regulator-Mediated Molecular Clusters and Tumor Microenvironment Signatures in Glioblastoma.TIF

Growing evidence links DNA methylation to tumor immunity. The impact of DNA methylation (5 mC) on the microenvironment surrounding tumors and immunotherapy remains to be clarified. Through clustering gene expression of 20 DNA methylation regulators, this study aimed at systematically analyzing DNA methylation regulator patterns and tumor microenvironment characteristics of TCGA-GBM patients. Various subtypes of glioblastoma exhibit different tumor microenvironments and DNA methylation patterns. Each DNA methylation modification was then assigned a DNA methylation score (DMS). High DMS was associated with a good prognosis. In contrast, the low DMS group had a relatively low survival rate. A correlation was also found between high DMS and enhanced immunotherapy efficacy in two immune checkpoint blocking treatment cohorts. To conclude, identifying DNA methylation regulation patterns may prove critical to understanding glioblastoma progression and differentiation, as well as future therapeutic targets.</p