Three-Dimensional CNT/Graphene–Li₂S Aerogel as Freestanding Cathode for High-Performance Li–S Batteries

Three-dimensional (3D) CNT/graphene-Li₂S (3DCG–Li₂S) cathodes with 81.4 wt % record Li₂S loading have been realized through solvothermal reaction and a subsequent liquid-infiltration-evaporation coating method. The highly flexible, conductive 3D mesoporous interconnected network based on two-dimensional (2D) graphene nanosheets and one-dimensional (1D) carbon nanotubes (CNTs) provides highly efficient channels for electron transfer and ionic diffusion, and leads to a low solubility of polysulfides in electrolytes in charges/discharges. Without polymeric binders or conductive additives, the freestanding 3DCG–Li₂S cathode exhibits record electrochemical performances including reversible discharge capacities of 1123.6 mAh g^–1 and 914.6 mAh g^–1, 0.02% long-term capacity decay per cycle and a high-rate capacity of 514 mAh g^–1 at 4 C. The reported 3DCG–Li₂S aerogel with ultrahigh Li₂S content presents promising application potentials in high-performance Li–S batteries

Tellurium-Impregnated Porous Cobalt-Doped Carbon Polyhedra as Superior Cathodes for Lithium–Tellurium Batteries

Lithium–tellurium (Li–Te) batteries are attractive for energy storage owing to their high theoretical volumetric capacity of 2621 mAh cm^–3. In this work, highly nanoporous cobalt and nitrogen codoped carbon polyhedra (C–Co–N) derived from a metal–organic framework (MOF) is synthesized and employed as tellurium host for Li–Te batteries. The Te@C–Co–N cathode with a high Te loading of 77.2 wt % exhibits record-breaking electrochemical performances including an ultrahigh initial capacity of 2615.2 mAh cm^–3 approaching the theoretical capacity of Te (2621 mAh cm^–3), a superior cycling stability with a high capacity retention of 93.6%, a ∼99% Columbic efficiency after 800 cycles as well as rate capacities of 2160, 1327.6, and 894.8 mAh cm^–3 at 4, 10, and 20 C, respectively. The redox chemistry of tellurium is revealed by <i>in operando</i> Raman spectroscopic analysis and density functional theory simulations. The results illustrate that the performances are attributed to the highly conductive C–Co–N matrix with an advantageous structure of abundant micropores, which provides highly efficient channels for electron transfer and ionic diffusion as well as sufficient surface area to efficiently host tellurium while mitigating polytelluride dissolution and suppressing volume expansion

From Metal–Organic Framework to Li₂S@C–Co–N Nanoporous Architecture: A High-Capacity Cathode for Lithium–Sulfur Batteries

Owing to the high theoretical specific capacity (1166 mAh g^–1), lithium sulfide (Li₂S) has been considered as a promising cathode material for Li–S batteries. However, the polysulfide dissolution and low electronic conductivity of Li₂S limit its further application in next-generation Li–S batteries. In this report, a nanoporous Li₂S@C–Co–N cathode is synthesized by liquid infiltration–evaporation of ultrafine Li₂S nanoparticles into graphitic carbon co-doped with cobalt and nitrogen (C–Co–N) derived from metal–organic frameworks. The obtained Li₂S@C–Co–N architecture remarkably immobilizes Li₂S within the cathode structure through physical and chemical molecular interactions. Owing to the synergistic interactions between C–Co–N and Li₂S nanoparticles, the Li₂S@C–Co–N composite delivers a reversible capacity of 1155.3 (99.1% of theoretical value) at the initial cycle and 929.6 mAh g^–1 after 300 cycles, with nearly 100% Coulombic efficiency and a capacity fading of 0.06% per cycle. It exhibits excellent rate capacities of 950.6, 898.8, and 604.1 mAh g^–1 at 1C, 2C, and 4C, respectively. Such a cathode structure is promising for practical applications in high-performance Li–S batteries

Three-Dimensional Hierarchical Reduced Graphene Oxide/Tellurium Nanowires: A High-Performance Freestanding Cathode for Li–Te Batteries

Three-dimensional aerogel with ultrathin tellurium nanowires (TeNWs) wrapped homogeneously by reduced graphene oxide (rGO) is realized <i>via</i> a facile hydrothermal method. Featured with high conductivity and large flexibility, the rGO constructs a conductive three-dimensional (3D) backbone with rich porosity and leads to a free-standing, binder-free cathode for lithium–tellurium (Li–Te) batteries with excellent electrochemical performances. The cathode shows a high initial capacity of 2611 mAh cm^–3 at 0.2 C, a high retention of 88% after 200 cycles, and a high-rate capacity of 1083 mAh cm^–3 at 10 C. In particular, the 3D aerogel cathode delivers a capacity of 1685 mAh cm^–3 at 1 C after 500 cycles, showing pronounced long-cycle performance at high current density. The performances are attributed to the well-defined flexible 3D architecture with high porosity and conductivity network, which offers highly efficient channels for electron transfer and ionic diffusion while compromising volume expansion of Te in charge/discharge. Owing to such advantageous properties, the reported 3D rGO/tellurium nanowire (3DGT) aerogel presents promising application potentials as a high-performance cathode for Li–Te batteries

Microfluidic co-culture device design.

<p>(A) Image of the microfluidic device mainly composed of a double-layer chip and an injection pump. (B) Schema chart of the double-layer chip: (a)-(b) the layout of each layer. (C) Photograph of medium flow direction in the chip. (a) Injection of red and blue indicators from inlet A and B representing two types of cells, respectively, to demonstrate indirect contact co-culture. (b) Injection of black indicator from medium inlet to demonstrate medium injection. A simple external small clip was served as micro-valves to facilitate the medium flowing downstream. (D) The diffusion of FITC-Dextran in 3D matrix. (a) After 5 min. (b) After 60 min. Magnification: ×100.</p

A microfluidic chip designed for the study of cancer cells invasion in 3D matrix.

<p>(A) Schematic representation of the microfluidic platform. Layout of the integrated microfluidic device is composed of three units sharing a common outlet, each of which contains an inlet, three parallel main channels, three cell culture chambers and an outlet. (B) A magnified illustration of one cell culture chamber. (C) Photograph of the microfluidic system.</p

Analysis of GRP78 expression and effect of EGCG on VP-16 induced apoptosis in myofibroblasts.

<p>(A) GRP78 protein assay by immunofluorescence imaging on (a) myofibroblasts and (b) fibroblasts. Magnification: ×600. (B) The average expression of GRP78 in per cell was reflected by normalized fluorescent intensity. Data were shown as mean±SD of triplicate determinations. (C) Fluorescent analysis of percentage of apoptotic cells for myofibroblasts by EGCG pretreated and non-EGCG pretreated groups after treatment with VP-16 (30 µM). Magnification: ×100. (D) The statistic analysis of percentage of apoptotic cells for myofibroblasts in EGCG pretreated and non-EGCG pretreated groups after treatment with different concentrations of VP-16 (0–60 µM). *p<0.05 compared with the control group. All the experiments were repeated at least three times.</p

Actual invadopodia formation of A549 cells in control group (A), EGF group (B), and GM6001/EGF group (C) in 3D extracellular matrix in the microfluidic device with confocal system.

<p>Invadopodia could be obviously induced by EGF in (B), <b>while</b> this induction could be inhibited by GM6001 in (C). White arrowheads represented invadopodia. Magnification: ×1200.</p

Illustration of medium flow direction in the microfluidic device.

<p>The blue, red and green indicators represented control group, EGF group, GM6001/EGF group respectively. These three indicators were perfused into microchannels from inlet A, B, C simultaneously and separately, while these indicators could spread out to cell chambers of both sides via oval microchannels uniformly and in parallel without crossing.</p

Analysis of α-SMA expression and measurement of apoptosis in fibroblasts induced and non-induced by lung cancer cells.

<p>(A) α-SMA protein assay by immunofluorescence imaging on fibroblasts induced and non-induced by lung cancer cells. (a) Induced. (b) Non-induced. Magnification: ×600. (B) The average expression of α-SMA in per cell was reflected by normalized fluorescent intensity. Data were shown as mean±SD of triplicate determinations. (C) Fluorescent analysis of apoptosis in fibroblasts induced and non-induced by lung cancer cells with PI and Hoechst after treatment with VP-16 (30 µM). Magnification: ×100. (D) The statistic analysis of percentage of apoptotic cells induced and non-induced by the lung cancer cells after treatment with different concentrations of VP-16 (0–60 µM). *p<0.05 compared with the control group. All the experiments were repeated at least three times.</p