Lithium–sulfur battery is recognized as one of the most promising energy storage devices, while the application and commercialization are severely hindered by both the practical gravimetric and ...volumetric energy densities due to the low sulfur content and tap density with lightweight and nonpolar porous carbon materials as sulfur host. Herein, for the first time, conductive CoOOH sheets are introduced as carbon‐free sulfur immobilizer to fabricate sulfur‐based composite as cathode for lithium–sulfur battery. CoOOH sheet is not only a good sulfur‐loading matrix with high electron conductivity, but also exhibits outstanding electrocatalytic activity for the conversion of soluble lithium polysulfide. With an ultrahigh sulfur content of 91.8 wt% and a tap density of 1.26 g cm−3, the sulfur/CoOOH composite delivers high gravimetric capacity and volumetric capacity of 1199.4 mAh g−1‐composite and 1511.3 mAh cm−3 at 0.1C rate, respectively. Meanwhile, the sulfur‐based composite presents satisfactory cycle stability with a slow capacity decay rate of 0.09% per cycle within 500 cycles at 1C rate, thanks to the strong interaction between CoOOH and soluble polysulfides. This work provides a new strategy to realize the combination of gravimetric energy density, volumetric energy density, and good electrochemical performance of lithium–sulfur battery.
Conductive cobalt oxyhydroxide (CoOOH) sheets are prepared as the carbon‐free immobilizer for Li–S batteries for the first time. The S/CoOOH composite exhibits outstanding electrochemical performance resulting from the remarkable conductive framework and electrocatalytic activity contributed by the CoOOH sheets. Moreover, such composite delivers high gravimetric and volumetric energy densities, owing to the high sulfur content and tap density.
Lithium–sulfur battery possesses a high energy density; however, its application is severely blocked by several bottlenecks, including the serious shuttling behavior and sluggish redox kinetics of ...sulfur cathode, especially under the condition of high sulfur loading and lean electrolyte. Herein, hollow molybdate (CoMoO4, NiMoO4, and MnMoO4) microspheres are introduced as catalytic hosts to address these issues. The molybdates present a high intrinsic electrocatalytic activity for the conversion of soluble lithium polysulfides, and the unique hollow spherical structure could provide abundant sites and spatial confinement for electrocatalysis and inhibiting shuttling, respectively. Meanwhile, it is demonstrated that the unique adsorption of molybdates toward polysulfides exhibits a “volcano‐type” feature with the catalytic performance following the Sabatier principle. The NiMoO4 hollow microspheres with moderate adsorption show the highest electrocatalytic activity, which is favorable for enhancing the electrochemical performance of sulfur cathode. Especially, the S/NiMoO4 composite could achieve a high areal capacity of 7.41 mAh cm−2 (906.2 mAh g−1) under high sulfur loading (8.18 mg cm−2) and low electrolyte/sulfur ratio (E/S, 4 µL mg−1). This work offers a new perspective on searching accurate rules for selecting and designing effective host materials in the lithium–sulfur battery.
Molybdate hollow spheres (CoMoO4, NiMoO4, MnMoO4) are employed as the host materials for Li–S battery, among which NiMoO4 with the moderate adsorption strength shows the highest catalytic efficiency toward sulfur conversion. The resulting S/NiMoO4 composite delivers high gravimetric capacity under high sulfur loading and lean electrolyte usage.
Lithium–sulfur (Li–S) batteries are regarded as the promising next‐generation energy storage device due to the high theoretical energy density and low cost. However, the practical application of Li–S ...batteries is still limited owing to the cycle stability of both the sulfur cathode and lithium anode. In particular, the instability in the bulk and at the surface of the lithium anode during cycling becomes a huge obstacle for the practical application of Li–S battery. Herein, a Li‐rich lithium–magnesium (Li–Mg) alloy is investigated as an anode for Li–S batteries, based on the consideration of improving the stability in the bulk and at the surface of the lithium anode. Our experimental results reveal that the robust passivation layer is formed on the surface of the Li–Mg alloy anode, which is helpful to reduce side reactions, and enable the smooth surface morphology of anode during cycling. Meanwhile, the mixed electron and Li‐ion conducting matrix of the Li‐poor Li–Mg alloy as a porous skeleton structure can also be formed after delithiation, which can guarantee the structural integrity of the anode in the bulk during Li stripping/plating process. Therefore, the Li‐rich Li–Mg alloy is demonstrated to be a very promising anode material for Li–S battery.
A Li‐rich Li–Mg alloy is investigated as an anode for Li–S batteries. The Li–Mg alloy demonstrates versatile functions, including active material, surface stabilizer, supporting, and conducting matrix, which are beneficial to realize good stability in the bulk and at the surface of the alloy anode for Li–S batteries.
Elemental sulfur possesses an ultra‐high theoretical specific capacity, while the practical application of sulfur in lithium–sulfur (Li–S) batteries is seriously hindered by the sluggish redox ...kinetics and serious shuttle effect. Enhancing the catalytic activity of the sulfur host by a rational structural design is the key to address these issues. Herein, for the first time, concave‐nanocubic (CNC) nickel–platinum (Ni–Pt) alloys bounded by high‐index facets (HIFs) are introduced as the core catalyst of sulfur for Li–S batteries. It is demonstrated that the CNC Ni–Pt alloy crystallites dispersed uniformly on graphene exhibit a high electrochemical activity to drive the conversion from intermediate lithium polysulfides to solid discharged products. Benefiting from the accelerated redox kinetics by HIFs, the cathode delivers a low capacity damping of 0.025% per cycle for 1000 cycles at 1 C rate. In particular, a high reversible capacity of 664.9 mAh g−1‐cathode with cathode as active material can be achieved with high sulfur loading (8.8 mg cm−2) and low electrolyte usage (5 µL mgs−1). This study focuses on improving the catalytic activity of sulfur hosts by modulating the exposed facets of core catalyst and provides a new path for the structure optimizing of host materials in Li–S batteries.
Well‐designed concave‐nanocubic nickel–platinum alloy crystallites with high‐index facets (HIFs), dispersed uniformly on graphene, are prepared as the catalytic host for lithium–sulfur batteries. The HIFs of the alloy nanocrystallites exhibit a high intrinsic electrocatalytic activity for the conversion of intermediate lithium polysulfides and discharged products. Therefore, the sulfur cathode delivers enhanced electrochemical performances.
Development of an efficient hydrogen evolution reaction (HER) catalyst composed of earth-abundant elements is scientifically and technologically important for the water splitting associated with the ...conversion and storage of renewable energy. Herein we report a new class of Co–C–N complex bonded carbon (only 0.22 at% Co) for HER with a self-supported and three-dimensional porous structure that shows an unexpected catalytic activity with low overpotential (212 mV at 100 mA cm–2) and long-term stability, better than that of most traditional-metal catalysts. Experimental observations in combination with density functional theory calculations reveal that C and N hybrid coordination optimizes the charge distribution and enhances the electron transfer, which synergistically promotes the proton adsorption and reduction kinetics.
Cardiac patch is considered a promising strategy for enhancing stem cell therapy of myocardial infarction (MI). However, the underlying mechanisms for cardiac patch repairing infarcted myocardium ...remain unclear. In this study, we investigated the mechanisms of PCL/gelatin patch loaded with MSCs on activating endogenous cardiac repair. PCL/gelatin patch was fabricated by electrospun. The patch enhanced the survival of the seeded MSCs and their HIF‐1α, Tβ4, VEGF and SDF‐1 expression and decreased CXCL14 expression in hypoxic and serum‐deprived conditions. In murine MI models, the survival and distribution of the engrafted MSCs and the activation of the epicardium were examined, respectively. At 4 weeks after transplantation of the cell patch, the cardiac functions were significantly improved. The engrafted MSCs migrated across the epicardium and into the myocardium. Tendency of HIF‐1α, Tβ4, VEGF, SDF‐1 and CXCL14 expression in the infarcted myocardium was similar with expression in vitro. The epicardium was activated and epicardial‐derived cells (EPDCs) migrated into deep tissue. The EPDCs differentiated into endothelial cells and smooth muscle cells, and some of EPDCs showed to have differentiated into cardiomyocytes. Density of blood and lymphatic capillaries increased significantly. More c‐kit+ cells were recruited into the infarcted myocardium after transplantation of the cell patch. The results suggest that epicardial transplantation of the cell patch promotes repair of the infarcted myocardium and improves cardiac functions by enhancing the survival of the transplanted cells, accelerating locality paracrine, and then activating the epicardium and recruiting endogenous c‐kit+ cells. Epicardial transplantation of the cell patch may be applied as a novel effective MI therapy.
This article deals with the set of minimal solutions for fuzzy relation inequalities with addition-min composition. We first show a necessary and sufficient condition for a solution of the fuzzy ...relation inequalities being a minimal one, then we propose an algorithm to find all minimal solutions of the fuzzy relation inequalities. Finally, we use all minimal solutions of the fuzzy relation inequalities to solve the related optimization problems, which will be illustrated by a series of numeral examples.
•Quantile-based dependence relationships in EUA futures market are discussed.•Dependence of EUA-energy and EUA-macro economy vary from one phase to another.•We found three significant structural ...breaks during the whole period.•Dependence changes of EUA-energy and macro economy across the breaks are analyzed.•Five influence paths from determinants to carbon future price are proposed.
This paper focuses on the quantile-based dependence and influence path between European Union allowance (EUA) and its drivers (energy prices and macroeconomic risk factors) during the three phases of the European Union Emissions Trading Scheme (EU ETS). Meanwhile, the quantile-based dependence changes sourced from exogenous shocks are explored as well. Our empirical evidences suggest that: (i) the reaction of fluctuation in carbon price in relation to its drivers across its conditional distribution in different phases is highly heterogeneous; (ii) production restrain effect→aggregated demand effect→substitution effect, the evolution pattern of influence paths from Phase I to Phase III exists in the prices of both coal and gas, whereas, the evolution pattern of oil price is substitution effect→production restrain effect→production restrain effect; (iii) for the macroeconomic risk factors, differing with the nearly stable energy price path in Phase I, the unstable industrial production paths are explored during Phase II and Phase III; (iv) the significant dependence changes caused by three structural breaks are confirmed during the whole period, and both effects from the occurrence of financial and energy shortage risks generate unstable dependence changes to commodity price index, coal and gas prices, but a stable dependence change to oil prices. However, the stable dependence changes to stock price index and T-bill rate are mainly affected from the occurrence of financial risk; (v) the market risk of carbon market measured by Value at Risk is mainly affected by energy prices, but commodity price index and the T-bill rate also have significant effects on it after the impact of financial risk.
Lithium‐metal (Li) electrode has been regarded as an excellent option to increase the energy density of next‐generation secondary batteries due to its low electrochemical potential and ultrahigh ...theoretical capacity. However, Li electrodes suffer from poor Coulombic efficiency (CE) and uneven lithium deposition issues during cycling that severely restrain its application. Herein, ammonium perfluoro(2‐methyl‐3‐oxahexanoate) (APFA), a pragmatic anionic surfactant, is introduced as an electrolyte additive to regulate the deposition behavior of lithium. Different from the conventional sacrificial additives that reinforce solid electrolyte interphase (SEI) layers on Li electrodes, the PFA− anions are mainly adsorbed on the Li surface, which improves the electron transfer step kinetics due to the ψ1 effect. The introduction of APFA in the electrolyte promises homogeneous and highly dense lithium deposition and the LiLi symmetric cell with APFA can operate over 4000 h with excellent stability and low polarization. This work provides a facile and promising strategy for fabricating stable Li anode for high‐energy‐density secondary batteries.
An organic surfactant of ammonium perfluoro(2‐methyl‐3‐oxahexanoate) as an electrolyte additive is employed for lithium electrodes. Because of the adsorption of the additive anions and the adapted electrical double layer on the surface, the electrode kinetics is greatly promoted, thus enabling a stable lithium electrode.
This article focuses on the α-migrativity of 2-uninorms with α∈0,1. It characterizes the α-migrativity for 2-uninorms with α∈0,1, which generalizes and unifies the characterizations for some existing ...α-migrativity of uni-nullnorms, null-uninorms, uninorms and nullnorms, respectively. It also proves that for every 2-uninorm U1 (resp. U2) and α∈0,1, there always exists a 2-uninorm U2≠U1 (resp., U1≠U2) such that U1 is α-migrative over U2.
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