LinG3D: visualizing the spatio-temporal dynamics of clonal evolution.

BACKGROUND: Cancers are spatially heterogenous, thus their clonal evolution, especially following anti-cancer treatments, depends on where the mutated cells are located within the tumor tissue. For example, cells exposed to different concentrations of drugs, such as cells located near the vessels in contrast to those residing far from the vasculature, can undergo a different evolutionary path. However, classical representations of cell lineage trees do not account for this spatial component of emerging cancer clones. Here, we propose routines to trace spatial and temporal clonal evolution in computer simulations of the tumor evolution models. RESULTS: The LinG3D (Lineage Graphs in 3D) is an open-source collection of routines (in MATLAB, Python, and R) that enables spatio-temporal visualization of clonal evolution in a two-dimensional tumor slice from computer simulations of the tumor evolution models. These routines draw traces of tumor clones in both time and space, and may include a projection of a selected microenvironmental factor, such as the drug or oxygen distribution within the tumor, if such a microenvironmental factor is used in the tumor evolution model. The utility of LinG3D has been demonstrated through examples of simulated tumors with different number of clones and, additionally, in experimental colony growth assay. CONCLUSIONS: This routine package extends the classical lineage trees, that show cellular clone relationships in time, by adding the space component to show the locations of cellular clones within the 2D tumor tissue patch from computer simulations of tumor evolution models.

Ruthenium single-atom doping-driven modulation of Co3O4 spinel tetrahedral site 3d-orbital occupancy in lithium-oxygen batteries.

Metal single-atom catalysts have attracted widespread attention in the field of lithium-oxygen batteries due to their unique active sites, high catalytic selectivity, and near total atomic utilization efficiency. Isolated metal atoms not only serve as the active sites themselves, but also function as modulators, reversely regulating the surface electronic structure of the support to enhance its inherent electrocatalytic activities. Despite the potential of isolated metal atom-driven active sites, understanding the structure-activity relationship remains a challenge. In this study, we present a ruthenium single-atom doping-driven cost-effective and durable tricobalt tetroxide electrocatalyst with excellent oxygen electrode electrocatalytic activity. The lithium-oxygen battery with this catalyst as the oxygen electrode demonstrates high performance, achieving a capacity of up to 25 000 mA h g-1 and maintaining good stability over 400 cycles at a current density of 100 mA g-1. This improvement is attributed to the exquisite control of the morphology and structure of the discharge product, lithium peroxide. The aresults of physical characterization and theoretical calculations reveal that isolated ruthenium atoms bond with the tetrahedral cobalt site, resulting in spin polarization enhancement and rearrangement of d orbital energy levels in cobalt. This rearrangement reduces the dz2 orbital occupancy and promotes their transfer to the octahedral cobalt site, thereby enhancing its adsorption capacity for the oxygen-containing intermediates, and ultimately increasing the electrocatalytic activity of the oxygen evolution reaction. This work presents an innovative strategy to regulate the catalytic activity of metal oxides by introducing another metal single atom.

Visualizing the Spatio-Temporal Dynamics of Clonal Evolution with LinG3D software.

Cancer clonal evolution, especially following anti-cancer treatments, depends on the locations of the mutated cells within the tumor tissue. Cells near the vessels, exposed to higher concentrations of drugs, will undergo a different evolutionary path than cells residing far from the vasculature in the areas of lower drug levels. However, classical representations of cell lineage trees do not account for this spatial component of emerging cancer clones. Here, we propose the LinG3D (Lineage Graphs in 3D) algorithms to trace clonal evolution in space and time. These are an open-source collection of routines (in MATLAB, Python, and R) that enables spatio-temporal visualization of clonal evolution in a two-dimensional tumor slice from computer simulations of the tumor evolution models. These routines draw traces of tumor clones in both time and space, with an option to include a projection of a selected microenvironmental factor, such as the drug or oxygen distribution within the tumor. The utility of LinG3D has been demonstrated through examples of simulated tumors with different number of clones and, additionally, in experimental colony growth assay. This routine package extends the classical lineage trees, that show cellular clone relationships in time, by adding the space component to show the locations of cellular clones within the 2D tumor tissue patch from computer simulations of tumor evolution models.

Ultralong Cycling and Safe Lithium-Sulfur Pouch Cells for Sustainable Energy Storage.

While layered metal oxides remain the dominant cathode materials for the state-of-the-art lithium-ion batteries, conversion-type cathodes such as sulfur present unique opportunities in developing cheaper, safer, and more energy-dense next-generation battery technologies. There has been remarkable progress in advancing the laboratory scale lithium-sulfur (Li-S) coin cells to a high level of performance. However, the relevant strategies cannot be readily translated to practical cell formats such as pouch cells and even battery pack. Here these key technical challenges are addressed by molecular engineering of the Li metal for hydrophobicization, fluorination and thus favorable anode chemistry. The introduced tris(2,4-di-tert-butylphenyl) phosphite (TBP) and tetrabutylammonium fluoride (TBA+F-) as well as cellulose membrane by rolling enables the formation of a functional thin layer that eliminates the vulnerability of Li metal towards the already demanding environment required (1.55% relative humidity) for cell production and gives rise to LiF-rich solid electrolyte interphase (SEI) to suppress dendrite growth. As a result, Li-S pouch cells assembled at a pilot production line survive 400 full charge/discharge cycles with an average Coulombic efficiency of 99.55% and impressive rate performance of 1.5 C. A cell-level energy density of 417 Wh kg-1 and power density of 2766 W kg-1 are also delivered via multilayer Li-S pouch cell. The Li-S battery pack can even power an unmanned aerial vehicle of 3 kg for a fairly long flight time. This work represents a big step forward acceleration in Li-S battery marketization for future energy storage featuring improved safety, sustainability, higher energy density as well as reduced cost.

Engineering dual-crystal configurations in perovskite oxides boosts electrocatalysis of lithium-oxygen batteries.

Sculpting crystal configurations can vastly affect the charge and orbital states of electrocatalysts, fundamentally determining the catalytic activity of lithium-oxygen (Li-O2) batteries. However, the crucial role of crystal configurations in determining the electronic states has usually been neglected and needs to be further examined. Herein, we introduce orthorhombic and trigonal system into 0.5La0.6Sr0.4MnO3-0.5LaMn0.6Co0.4O3 (LSMCO) by selectively incorporating Sr and Co cations into the LaMnO3 framework during the sol-gel process, which is used to explore the relationship among crystal structure, electronic states and catalytic performance. Based on both experimental and theoretical calculations, the dual-crystal configurations induce strong lattice distortion, which promotes MnO6 octahedra vibration and shortened MnO bonds. Furthermore, the suppressed Jahn-Teller distortion weakens the orbital arrangement and accelerates the charge delocalization, leading to the conversion of Mn3+ to Mn4+ and optimized electronic states. Ultimately, this resulted in optimized Mn 3d and O 2p orbital hybridization and activated lattice oxygen function, leading to a significant improvement in electrocatalytic activity. The LSMCO catalyzed Li-O2 battery achieves enhanced discharge capacity of 14498.7 mAh/g and cycling stability of 258 cycles. This work highlights the significance of inner structure and presents a feasible strategy for engineering crystal configurations to boost electrocatalysis of Li-O2 batteries.

Directionally-Resolved Phononic Properties of Monolayer 2D Molybdenum Ditelluride (MoTe2) under Uniaxial Elastic Strain.

Understanding the phonon characteristics of two-dimensional (2D) molybdenum ditelluride (MoTe2) under strain is critical to manipulating its multiphysical properties. Although there have been numerous computational efforts to elucidate the strain-coupled phonon properties of monolayer MoTe2, empirical validation is still lacking. In this work, monolayer 1H-MoTe2 under uniaxial strain is studied via in situ micro-Raman spectroscopy. Directionally dependent monotonic softening of the doubly degenerate in-plane E2g1 phonon mode is observed with increasing uniaxial strain, where the E2g1 peak red-shifts -1.66 ± 0.04 cm-1/% along the armchair direction and -0.80 ± 0.07 cm-1/% along the zigzag direction. The corresponding Grüneisen parameters are calculated to be 1.09 and 0.52 along the armchair and zigzag directions, respectively. This work provides the first empirical quantification and validation of the orientation-dependent strain-coupled phonon response in monolayer 1H-MoTe2 and serves as a benchmark for other prototypical 2D transition-metal tellurides.

Nonflammable Polyfluorides-Anchored Quasi-Solid Electrolytes for Ultra-Safe Anode-Free Lithium Pouch Cells without Thermal Runaway.

The safe operation of rechargeable batteries is crucial because of numerous instances of fire and explosion mishaps. However, battery chemistry involving metallic lithium (Li) as the anode is prone to thermal runaway in flammable organic electrolytes under abusive conditions. Herein, an in situ encapsulation strategy is proposed to construct nonflammable quasi-solid electrolytes through the radical polymerization of a hexafluorobutyl acrylate (HFBA) monomer and a pentaerythritol tetraacrylate (PETEA) crosslinker. The quasi-solid system eliminates the inherent flammability of ether electrolytes with zero self-extinguishing time owing to the gas-phase radical capturing ability of HFBA. Additionally, the graphitized carbon layer generated during the decomposition of PETEA at high temperatures obstructs the heat and oxygen required for combustion. When coupled with Au-modified reduced graphene oxide anodic current collectors and lithium sulfide cathodes, the assembled anode-free Li-metal cell based on the quasi-solid electrolyte exhibits no signs of cell expansion or gas generation during cycling, and thermal runaway is eliminated under multiple mechanical, electrical, and thermal abuse scenarios and even rigorous strikes. This nonflammable quasi-solid configuration with gas- and condensed-phase flame-retardant mechanisms can drive a technological leap in anode-free Li-metal pouch cells and secure the practical applications necessary to power this society in a safe manner.

Scalable fabrication of ultra-fine lithiophilic nanoparticles encapsulated in soft buffered hosts for long-life anode-free Li2S-based cells.

Minimizing the amount of metallic lithium (Li) to zero excess to achieve an anode-free configuration can help achieve safer, higher energy density, and more economical Li metal batteries. Nevertheless, removal of excess Li creates challenges for long-term cycling performance in Li metal batteries due to the lithiophobic copper foils as anodic current collectors. Here, we improve the long-term cycling performance of anode-free Li metal batteries by modifying the anode-free configuration. Specifically, a lithiophilic Au nanoparticle-anchored reduced graphene oxide (Au/rGO) film is used as an anodic modifier to reduce the Li nucleation overpotential and inhibit dendrite growth by forming a lithiophilic LixAu alloy and solid solution, which is convincingly evidenced by density functional theory calculations and experimentally. Meanwhile, the flexible rGO film can also act as a buffer layer to endure the volume expansion during repeated Li plating/stripping processes. In addition, the Au/rGO film promotes a homogeneous distribution of the electric field over the entire anodic surface, thus ensuring a uniform deposition of Li during the electrodeposition process, which is convincingly evidenced by finite element simulations. As expected, the Li||Au/rGO-Li half-cell shows a highly stable long-term cycling performance for at least 500 cycles at 0.5 mA cm-2 and 0.5 mA h cm-2. A Li2S-based anode-free full cell allows achieving a stable operation life of up to 200 cycles with a capacity retention of 63.3%. This work provides a simple and scalable fabrication method to achieve anode-free Li2S-based cells with high anodic interface stability and a long lifetime.

Artificial bi-functional layers promoting Zn2+ desolvation and homogeneous deposition for reversible zinc metal anodes.

Rechargeable aqueous zinc-ion hybrid supercapacitors (ZHSs) are drawing extensive attention because of their cost-effectiveness and diminished safety hazards. Nevertheless, large-scale application of ZHSs has been hindered by the severe side reactions and rampant dendrites growth on the surface of Zn metal anodes. Herein, we propose a three-dimensional organic-inorganic composite frame material as an artificial bi-functional layer coated on the zinc foil, featuring nitrogenous functional groups with zincophilicity (abbreviated as NCFM@Zn). The nitrogen (N) site's strong adsorption capacity and synergistic effect of the sub-nanopore size promote rapid desolvation of zinc ions and reduce side reactions, while also prolonging galvanized nucleation's Sand's time and allowing for even nucleation. Moreover, the uniform distribution of N on the layer results in homogeneous zinc ions flux and supports consistent zinc plating while inhibiting dendrites generation. As a result of this unique artificial bi-functional layer, symmetric Zn cells can survive 2500 h at 2.5 mA cm-2. High-areal-capacity zinc||activated carbon hybrid supercapacitors also demonstrate 20,000 cycles at high Coulombic efficiency, thus highlighting the utter convenience and potential of this strategy for modifying rechargeable metal hybrid supercapacitor surfaces.

Manipulating hydrogen and coordination bond chemistry for reversible zinc metal anodes.

Aqueous zinc ion hybrid capacitors (ZHCs) are promising as electrochemical energy storage devices due to their safety and cost-effectiveness. However, the practical application of aqueous ZHCs is impeded by zinc dendrite growth and side reactions induced by H2O during long-term cycling. Herein, an organic small molecule, dimethyl sulfoxide (DMSO), is elaborately introduced into 2 M ZnSO4 electrolyte to simultaneously overcome these challenges. As convincingly evidenced by experimental and theoretical results, the DMSO reconstructs the Zn[(H2O)6]2+ structure and original hydrogen bond networks at the molecular level. By forming coordination bonds with Zn2+ and hydrogen bonds with H2O due to the stronger electron donating ability of oxygen in molecule, DMSO establishes a Zn2+ solvation shell structure that inhibits H2O decomposition and dendrite growth. As a proof of concept, the implementation of this hybrid electrolyte in a Zn||Cu asymmetrical cell results in a high Coulombic efficiency (CE) of over 99.8% for 568 cycles at a current density of 2 mA cm-2. Furthermore, the full cells using this hybrid electrolyte coupled with activated carbon (AC) cathode can operate for over 30,000 cycles. These results suggest that reconstructing the solvation structure and hydrogen bond networks guide the design of electrolytes for the development of high-performance aqueous ZHCs.

N, F-enriched inorganic/organic composite interphases to stabilize lithium metal anodes for long-life anode-free cells.

The practical application of lithium metal batteries is considered to be one of the most promising successors for lithium-ion batteries due to their ability to meet the high-energy storage demands of modern society. However, their application is still hindered by the unstable solid electrolyte interphase (SEI) and uncontrollable dendrite growth. In this study, we propose a robust composite SEI (C-SEI) that consists of a fluorine doped boron nitride (F-BN) inner layer and an organic polyvinyl alcohol (PVA) outer layer. Both theoretical calculations and experimental results demonstrate that the F-BN inner layer induces the formation of favourable components (LiF and Li3N) at the interface, promoting rapid ionic transport and inhibiting electrolyte decomposition. The PVA outer layer acts as a flexible buffer in the C-SEI, ensuring the structural integrity of the inorganic inner layer during lithium plating and stripping. The C-SEI modified lithium anode shows a dendrite-free performance and stable cycle over 1200 h, with an ultralow overpotential (15 mV) at 1 mA cm-2 in this study. This novel approach also enhances the stability of capacity retention rate by 62.3% after 100 cycles even in anode-free full cells (C-SEI@Cu||LFP). Our findings suggest a feasible strategy for addressing the instability inherent in SEI, showing great prospects for the practical application of lithium metal batteries.

Identifying the Role of Lewis-base Sites for the Chemistry in Lithium-Oxygen Batteries.

Lewis-base sites have been widely applied to regulate the properties of Lewis-acid sites in electrocatalysts for achieving a drastic technological leap of lithium-oxygen batteries (LOBs). Whereas, the direct role and underlying mechanism of Lewis-base in the chemistry for LOBs are still rarely elucidated. Herein, we comprehensively shed light on the pivotal mechanism of Lewis-base sites in promoting the electrocatalytic reaction processes of LOBs by constructing the metal-organic framework containing Lewis-base sites (named as UIO-66-NH2 ). The density functional theory (DFT) calculations demonstrate the Lewis-base sites can act as electron donors that boost the activation of O2 /Li2 O2 during the discharged-charged process, resulting in the accelerated reaction kinetics of LOBs. More importantly, the in situ Fourier transform infrared spectra and DFT calculations firstly demonstrate the Lewis-base sites can convert Li2 O2 growth mechanism from surface-adsorption growth to solvation-mediated growth due to the capture of Li+ by Lewis-base sites upon discharged process, which weakens the adsorption energy of UIO-66-NH2 towards LiO2 . As a proof of concept, LOB based on UIO-66-NH2 can achieve a high discharge specific capacity (12 661 mAh g-1 ), low discharged-charged overpotential (0.87 V) and long cycling life (169 cycles). This work reveals the direct role of Lewis-base sites, which can guide the design of electrocatalysts featuring Lewis-acid/base dual centers for LOBs.

Achieving Stable Lithium Metal Anode at 50 mA cm-2 Current Density by LiCl Enriched SEI.

Lithium metal batteries are intensively studied due to the potential to bring up breakthroughs in high energy density devices. However, the inevitable growth of dendrites will cause the rapid failure of battery especially under high current density. Herein, the utilization of tetrachloroethylene (C2 Cl4 ) is reported as the electrolyte additive to induce the formation of the LiCl-rich solid electrolyte interphase (SEI). Because of the lower Li ion diffusion barrier of LiCl, such SEI layer can supply sufficient pathway for rapid Li ion transport, alleviate the concentration polarization at the interface and inhibit the growth of Li dendrites. Meanwhile, the C2 Cl4 can be continuously replenished during the cycle to ensure the stability of the SEI layer. With the aid of C2 Cl4 -based electrolyte, the Li metal electrodes can maintain stable for >300 h under high current density of 50 mA cm-2 with areal capacity of 5 mAh cm-2 , broadening the compatibility of lithium metal anode toward practical application scenarios.

Chromium-doped inverse spinel electrocatalysts with optimal orbital occupancy for facilitating reaction kinetics of lithium-oxygen batteries.

Tailored electrocatalysts that can modulate their electronic structure are highly desirable to facilitate the reaction kinetics of oxygen evolution reaction (OER) and oxidation reduction reaction (ORR) in lithium-oxygen batteries (LOB). Although octahedron predominant inverse spinels (e.g., CoFe2O4) have been proposed as promising candidates for catalytic reactions, their performance has remained unsatisfactory. Herein, the chromium (Cr) doped CoFe2O4 nanoflowers (Cr-CoFe2O4) are elaborately constructed on nickel foam as a bifunctional electrocatalyst that drastically improves the performance of LOB. The results show that the partially oxidized Cr6+ stabilizes the cobalt (Co) sites at high-valence and regulates the electronic structure of Co sites, facilitating the oxygen redox kinetics of LOB due to their strong electron-withdrawing capability. Moreover, DFT calculations and ultraviolet photoelectron spectrometer (UPS) results consistently demonstrate that Cr doping optimizes the eg electron filling state of the active octahedral Co sites, significantly improves the covalency of Co-O bonds, and enhances the degree of Co 3d-O 2p hybrids. As a result, Cr-CoFe2O4 catalyzed LOB can achieve low overpotential (0.48 V), high discharge capacity (22030 mA h g-1) and long-term cycling durability (over 500 cycles at 300 mA g-1). This work promotes the oxygen redox reaction and accelerates the electron transfer between Co ions and oxygen-containing intermediates, highlighting the potential of Cr-CoFe2O4 nanoflowers as bifunctional electrocatalysts for LOB.

Air-Stable Protective Layers for Lithium Anode Achieving Safe Lithium Metal Batteries.

With markedly expansive demand in energy storage devices, rechargeable batteries will concentrate on achieving the high energy density and adequate security, especially under harsh operating conditions. Considering the high capacity (3860 mA h g-1 ) and low electrochemical potential (-3.04 V vs the standard hydrogen electrode), lithium metal is identified as one of the most promising anode materials, which has sparked a research boom. However, the intrinsically high reactivity triggers a repeating fracture/reconstruction process of the solid electrolyte interphase, side reactions with electrolyte and lithium dendrites, detrimental to the electrochemical performance of lithium metal batteries (LMBs). Even worse, when exposed to air, lithium metal will suffer severe atmospheric corrosion, especially the reaction with moisture, leading to grievous safety hazards. To settle these troubles, constructing air-stable protective layers (ASPLs) is an effective solution. In this review, besides the necessity of ASPLs is highlighted, the modified design criteria, focusing on enhancing chemical/mechanical stability and controlling ion flux, are proposed. Correspondingly, current research progress is comprehensively summarized and discussed. Finally, the perspectives of developing applicable lithium metal anodes (LMAs) are put forward. This review guides the direction for the practical use of LMAs, further pushing the evolution of safe and stable LMBs.

Band engineering in heterostructure catalysts to achieve High-Performance Lithium-Oxygen batteries.

The electronic structure of cathode catalysts dominates the electrochemistry reaction kinetics in lithium-oxygen batteries. However, conventional catalysts perform inferior intrinsic activity due to the low d-band level of the active sites makes it difficult to bond with the reaction intermediates, which results in poor electrochemical performance of lithium-oxygen batteries. Herein, NiFe2O4/MoS2 heterostructures are elaborately constructed to reach an electronic state balance for the active sites, which realizes the upper shift of the d-band level and enhanced adsorption of intermediates. Density functional theory calculation suggests that the d-band center of Fe active sites on the heterostructure moves toward the Fermi level, demonstrating the heterointerface engineering endows Fe active sites with high d-band level by the transfer and balance of electron. As a proof of concept, lithium-oxygen battery catalyzed by NiFe2O4/MoS2 exhibits a large specific capacity of 21526 mA h g-1 and an extended cycle performance for 268 cycles. Moreover, NiFe2O4/MoS2 with strong adsorption to intermediates promotes the uniform growth of discharge products, which is favor of the reversible decomposition during cycling. This work presents the energy band regulation of the active sites in heterostructure catalysts has great feasibility for enhancing catalytic activities.

Single Nickel Atom Catalysts Enable Fast Polysulfide Redox for Safe and Long-Cycle Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have attracted great interest due to their low cost, high theoretical energy density, and environmental friendliness. However, the sluggish conversion of lithium polysulfides (LiPS) to S and Li2 S during the charge/discharge process leads to unsatisfactory rate performance of lower to 0.1 C (1 C = 1675 mA g-1 ) especially for Li-S pouch batteries, thus hindering their practical applications in high power batteries. Here, well-defined and monodispersed Ni single-atom catalysts (SACs) embedded in highly porous nitrogen-doped graphitic carbons (NiSA-N-PGC) are designed and synthesized to form Ni-N4 catalytic sites at the atomic level. When serving as a bifunctional electrocatalyst, the Ni-N4 catalytic sites cannot only promote the interfacial conversion redox of LiPS by accelerating the transformation kinetics, but also suppress the undesirable shuttle effect by immobilizing LiPS. These findings are verified by both experimental results and DFT theoretical calculations. Furthermore, Li ions show low diffusion barrier on the surface of Ni-N4 sites, resulting in enhanced areal capacity of batteries. As a result, the Li-S battery delivers stable cycling life of more than 600 cycles with 0.069% capacity decay per cycle at a rate of 0.5 C. More importantly, the Li-S pouch cells with NiSA-N-PGC show an initial capacity of 1299 mAh g-1 at a rate of 0.2 C even with high sulfur loading of 6 mg cm-2 . This work opens up an avenue for developing single-atom catalysts to accelerate the kinetic conversion of LiPS for highly stable Li-S batteries.

Mapping Techniques for the Design of Lithium-Sulfur Batteries.

Mapping technique has been the powerful tool for the design of next-generation energy storage devices. Unlike the traditional ion-insertion based lithium batteries, the Li-S battery is based on the complex conversion reactions, which require more cooperation from mapping techniques to elucidate the underlying mechanism. Therefore, in this review, the representative works of mapping techniques for Li-S batteries are summarized, and categorized into the studies of lithium metal anode and sulfur cathode, with sub-sections based on shared characterization mechanisms. Due to specific features of mapping techniques, various aspects such as compositional distribution, in-plain/cross section characterization, coin cell/pouch cell configuration, and structural/mechanical analysis are emphasized in each study, aiming for the guidance for developing strategies to improve the battery performances. Benefited from the achieved progresses, suggestions for future studies based on mapping techniques are proposed to accelerate the development and commercialization of the Li-S battery.

Synergy of cobalt vacancies and iron doping in cobalt selenide to promote oxygen electrode reactions in lithium-oxygen batteries.

Electronic structural engineering plays a key role in the design of high-efficiency catalysts. Here, to achieve optimal electronic states, introduction of exotic Fe dopant and Co vacancy into CoSe2 nanosheet (denoted as Fe-CoSe2-VCo) is presented. The obtained Fe-CoSe2-VCo demonstrates excellent catalytic activity as compared to CoSe2. Experimental results and density functional theory (DFT) calculations confirm that Fe dopant and Co defects cause significant electron delocalization, which reduces the adsorption energy of LiO2 intermediate on the catalyst surface, thereby obviously improving the electrocatalytic activity of Fe-CoSe2-VCo towards oxygen redox reactions. Moreover, the synergistic effect between Co vacancy and Fe dopant is able to optimize the microscopic electronic structure of Co ion, further reducing the energy barrier of oxygen electrode reactions on Fe-CoSe2-VCo. And the lithium-oxygen batteries (LOBs) based on Fe-CoSe2-VCo electrodes demonstrate a high Coulombic efficiency (CE) of about 72.66%, a large discharge capacity of about 13723 mA h g-1, and an excellent cycling life of about 1338 h. In general, the electronic structure modulation strategy with the reasonable introduction of vacancy and dopant is expected to inspire the design of highly efficient catalysts for various electrochemical systems.

Ion-Inserted Metal-Organic Frameworks Accelerate the Mass Transfer Kinetics in Lithium-Sulfur Batteries.

Lithium-sulfur battery promises great potential to promote the reform of energy storage field. Modified functional interlayer on separator has been recognized as efficient method to promote battery performances, mainly focusing on the entrapment and catalytic effect toward lithium polysulfide, while the mass transfer property across the interlayers has not been carefully considered. Herein, a dense layer composed of ion-inserted metal-organic frameworks is used to facilitate mass transfer across the layer and ensure high polysulfides entrapment efficiency. In situ Raman study reveals that the dense functional layer blocks the transfer of Li ions, while the ion-inserted layer can accelerate the ion-transfer kinetics and avoid the ion depletion caused polarization. As a result, a specific capacity of 742 mAh g-1 is obtained at 2 C, with the decay rate of 0.089% per cycle at 1 C over 600 cycles, demonstrating great potential for the application in advanced Li-S batteries.