batterydata/paper-abstracts huggingface dataset:
We evaluated the charge–discharge behavior of four types of graphite electrode, including raw synthetic graphite (SG), shaped natural graphite (NG), soft carbon-coated natural graphite (SCNG), and hard carbon-coated natural graphite (HCNG), in a 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMImFSI) ionic liquid. Based on the charge–discharge curves for the first cycle in LiTFSI/EMImFSI, capacity loss arising from an irreversible reaction on the graphite anodes was clearly observed for the cells consisting of SG and SCNG, whereas the capacity loss for the cells containing NG and HCNG was relatively low. The coulombic efficiency during cell cycling also confirmed that the charge–discharge behavior of graphite in LiTFSI/EMImFSI is strongly affected by the surface structure of the graphite and that basal-plane-oriented graphite, such as NG and HCNG, can reduce the primary charge capacity loss. The advantages of the stable charge–discharge behavior provided by FSI-based ionic liquids for lithium ion batteries are also discussed based on the application of voltammetric and electrochemical impedance techniques to model carbon electrodes in ionic liquids. Based on these analyses, a mechanism involving a double-layer-based interface (not a solid electrolyte interface (SEI)) is proposed to stabilize the surface of graphite negative electrodes.
Olivine-type LiFePO4 (LFP) is one of the most widely utilized cathode materials for high power Li-ion batteries (LIBs). In spite of rapidly growing popularity of LIBs, the rate performance of the highest power LFP cells is still insufficiently high for some high-power applications. In this work we demonstrate that vacuum-infiltration of LFP precursors into pores of low-cost expanded graphite (EG), an in-situ sol-gel process, followed by calcination, allows formation of LFP/EG nanocomposites that demonstrate remarkable performance in higher power Li-ion capacitor (LIC) applications. Such composites comprise spherical LFP particles embedded into EG pores and additionally wrapped by EG films, forming a highly efficient and stable conducting network. Such a morphology greatly accelerates Li-ion diffusion and improves Li-ion exchange between LFP and electrolyte. As a result, compared to commercial LFP particles of comparable size, the optimized LFP/EG nanocomposite shows significantly higher rate performance, dramatically better stability and higher specific capacitance of up to about 1200Fg−1. The use of environmentally friendly, safe and low-cost aqueous electrolyte is particularly advantageous for LIC applications that are cost-sensitive and require enhanced safety. Our results demonstrate a great promise of our approach, which is additionally applicable for a broad range of other intercalation chemistries.
A technology that combines phase change materials (PCMs) with a natural cold source is proposed to reduce the space cooling energy of telecommunications base stations (TBSs). First, a mathematical model was developed to assess this technology. Then, a full-scale prototype, named latent heat storage unit (LHSU), was designed, built, and tested in an enthalpy difference laboratory. The energy efficiency ratio (EER) and the adjusted energy efficiency ratio (AEER) were used as the criteria to evaluate the performance of this unit and to compare it with conventional air conditioners. LHSU performance simulations were carried out based on the unit’s operation in TBSs located in five Chinese cities with different climates. The simulated average annual AEER was 14.04W/W, which is considerably higher than the limiting value of 3.2W/W for air conditioners with a cooling capacity of less than 4500W. The estimated average energy savings potential of the LHSU was 50%. Based on these results, it was concluded that LHSUs could be used in TBSs to reduce a significant amount of their energy consumed in space cooling.
A heat-flow calorimeter was designed and built. Its measurements are 26cm×26cm×26cm (17.6dm3). 18,796 thermocouples are used to measure the heat-flow from the vessel walls to the outer walls, for which temperature is controlled within 0.01°C from 0 to 100°C by a refrigerating/heating circulator. Homogeneity of temperature in the measuring vessel is improved by a fan with constant power. The calibration was performed with an electric heater, with input power up to 50W. The device constant is 5.8954±0.0025WV−1; the time constant is 501.7±3.2s; the uncertainty is 0.6% at 2W to 0.06% at 50W. Nonlinearity of this calorimeter is analyzed. The calorimeter can be utilized for studies of kinetics and thermodynamics of physical, chemical and biological systems of decimeter-size. A Sony 26650 Li-ion rechargeable battery was tested with this device during charging and discharging, and an electrolytic cell with Pd-D2O was also tested with this device.
A conventional lithium-ion battery makes use of both an anode and a cathode. Now, a new design of batteries with no anodes in their initial state is shown to be promising for practical applications.
In most of the maximum power point tracking (MPPT) methods described currently in the literature, the optimal operation point of the photovoltaic (PV) systems is estimated by linear approximations. However these approximations can lead to less than optimal operating conditions and hence reduce considerably the performances of the PV system. This paper proposes a new approach to determine the maximum power point (MPP) based on measurements of the open-circuit voltage of the PV modules, and a nonlinear expression for the optimal operating voltage is developed based on this open-circuit voltage. The approach is thus a combination of the nonlinear and perturbation and observation (P&O) methods. The experimental results show that the approach improves clearly the tracking efficiency of the maximum power available at the output of the PV modules. The new method reduces the oscillations around the MPP, and increases the average efficiency of the MPPT obtained. The new MPPT method will deliver more power to any generic load or energy storage media.
Mixtures of RhO x +Co3O4 have been electrochemically studied by cyclic voltammetry in acid solution as a function of composition. The electrodes were prepared by thermal decomposition at 400°C of mixtures of nitrate precursors. Their electrochemical behavior shows substantial dependence on the electrode’s composition. The Co site controls the electrochemical behavior of the system in the 5–10mol.% Rh composition range. A significant increase in the electrodes’ active area is observed for compositions corresponding to more than 10mol.% RhO x in admixture with Co3O4. Above 10mol.% Rh, the voltammetric curves become more similar to that for RhO x and then RhO x becomes able to stabilize the Co3O4 in the mixture. Electrodes of this kind have been found to perform as good materials in electrochemical capacitor applications, exhibiting specific capacitances of 500–800Fg−1 over to 20–60mol.% RhO x composition range. The large specific capacitance exhibited by this system arises from a combination of the double-layer capacitance and the pseudocapacitance associated with Rh surface redox-type reactions.
We report a facile method to prepare the MoS2–graphene composites by liquid phase co-exfoliation of commercial MoS2 with graphene nanoplatelet (GnP) and chemically converted graphene (CCG) in N-methyl pyrrolidone with the aid of ultrasonication. The combination of SEM, XRD and BET results reveal that the MoS2–graphene composites are mesoporous materials consisting of very thin MoS2 flakes and graphene sheets. The prepared MoS2–graphene composites display good performance as anode materials for lithium ion batteries. Exfoliation of the MoS2 is the key factor for high electrochemical lithiation/delithiation performance. The MoS2/CCG composite exhibits the best reversible capacity (up to 750 mA h g−1 after 50 cycles), excellent cycling stability and high rate capability. The reversible capacity at a rate of 2000 mA g−1 is over 350 mA h g−1 and recovers to as high as 720 mA h g−1 at a rate of 100 mA g−1.
Although sleep bruxism (SB) is one of the most important clinical problems in dental practice, there is no definitive method for controlling it. This pilot study evaluated the effects of contingent vibratory feedback stimuli using an occlusal splint for inhibition of sleep bruxism.
The adaptive energy management strategies proposed in this paper are based on a 2-dimensional (2D) optimization function designed for fuel economy of the fuel cell hybrid power system operating under the variable power profiles of renewable energy sources and loads, which will define the dynamic power profile on the DC bus. The power-following control is designed to mitigate the variability of the DC power based on the DC power flow balance, so the energy management unit generates the power-following reference and two other references for searching the optimum, which are used to control the inputs for the boost power converter and for the air and fuel regulators. All three energy management 2D strategies obtained by selecting the mentioned references to the controlled inputs of the fuel cell system are analyzed and compared with the types 1D and other reference strategies reported in literature using the fuel economy as a performance indicator. For example, the fuel economy for a 6 kW load cycle is of 42 and 18 L for the strategies 2D-RTO1 and 2D-RTO2 compared to the benchmark strategy based on static feed-forward control.
Fatigue, pain, and emotional distress are common symptoms among patients with cancer. We sought to learn about patient perceptions of these symptoms and their treatment.
Although lithium-sulfur batteries show great promise for next-generation energy storage due to their high energy density, the practical implementation of lithium-sulfur batteries has been largely impeded by the shuttle effect of lithium polysulfides and low areal capacity (< 2 mAh cm−2). Here we rationally design a new self-standing host enabled by a 3D hierarchically-porous titanium monoxide-graphene composite film to overcome the two issues at once. The hierarchically porous graphene scaffold not only can facilitate rapid lithium ion and electron transport, but also provide sufficient spaces to accommodate sulfur and buffer the volume expansion during the lithiation process. In addition, the ultrafine and polar titanium monoxide nanoparticles embedded in the three-dimensional graphene networks show strong chemical anchoring for polysulfides as evidenced by ex-situ X-ray photoelectron spectroscopy analysis, and their inherent metallic conductivity accelerates the redox reaction kinetics. Benefiting from this attractive architecture, the freestanding titanium monoxide-graphene/sulfur cathode delivered a high initial capacity of 1350 mAh g−1 at 0.1 C, a Coulombic efficiency approaching 100%, and a high-rate capacity of 832 mAh g−1 at 2 C. Moreover, when the areal sulfur loading was increased to 5.2 mg cm−2, the titanium monoxide-graphene/sulfur electrode delivered a high areal capacity of 3.2 mAh cm−2 after 300 cycles at 0.2 C, demonstrating excellent cycling performance compared with other recently reported sulfur cathodes with high areal sulfur loadings.
In this paper, a hybrid Photovoltaic (PV)-fuel cell generation system employing an electrolyzer for hydrogen generation is designed and simulated. The system is applicable for remote areas or isolated loads. Fuzzy regression model (FRM) is applied for maximum power point tracking to extract maximum available solar power from PV arrays under variable insolation conditions. The system incorporates a controller designed to achieve permanent power supply to the load via the PV array or the fuel cell, or both according to the power available from the sun. Also, to prevent corrosion of the electrolyzer electrodes after sunset, i.e. when its current drops to zero, the electric storage device is designed so as to isolate the electrolyte from the electrolysis cell.
Using the multiphase lattice Boltzmann method (LBM), the electrolyte transport dynamics in the two-dimensional electrode structure of a lithium-ion battery are simulated. The effect of the compression ratio of a porous electrode on wettability is explored with respect to variations of porosity and particle shape. The electrolyte distribution in the electrode and the electrolyte saturation profile are examined in order to evaluate the wetting capability at various compression ratios. The results show that wettability in the electrode decreases as the compression ratio increases. In a highly compressed electrode, the through-plane permeation of liquid electrolyte is small. Thus, the electrolytes are mainly observed at the interface of the electrode and separator. The anode has lower wettability than the cathode due to the deformation of particle shape during the manufacturing process. Therefore, particle shape has a strong effect on wettability. The two-dimensional LBM approach used in this study characterizes the electrolyte transport phenomena inside the electrode and allows us to compare the wettability between the cathode and anode at various compression ratios.
The development of planar electrochemical multi-sensors for simultaneous determination of dissolved ions such as chloride, dissolved oxygen and electrical conductivity for the application, e.g. in biological liquids is reported. In this context, new and improved functional materials have been developed and technologies have been optimized in order to prepare micro sensor structures. Thick film and dispenser techniques were applied to print sensor structures and immobilized ionophores as well as reference systems. Sensor tests showed that the results are comparable to those of conventional sensors. With respect to a user-friendly calibration of different types of sensors, multi-buffer solutions have been developed for various sensor combinations.
Botryococcus braunii is known for its high hydrocarbon content, thus making it a strong candidate feedstock for biofuel production. Previous study has revealed that a high cobalt concentration can promote hydrocarbon synthesis and it has little effect on growth of B. braunii cells. However, mechanisms beyond the cobalt enrichment remain unknown. This study seeks to explore the physiological and transcriptional response and the metabolic pathways involved in cobalt-induced hydrocarbon synthesis in algae cells.
We present a simple, mass production of nonporous and nanoporous silicon nanowire anodes by combining block copolymer masks and metal catalytic etching. Carbon coated nanoporous silicon nanowire anodes exhibit a highly stable cycling performance with a reversible charge capacity of 1500 mA h g−1.
Electrocatalytic oxygen reduction reaction (ORR) is the vital process for next-generation electrochemical energy storage and conversion technologies, e.g., metal–air batteries and fuel cells. During the ORR, the O2* and O* intermediates principally combine with protons to form OOH* and OH* species, respectively, which are the proton-coupled electron transfer processes. Unfortunately, under alkaline conditions, the protons are essentially generated from the sluggish water dissociation process, which unavoidably limits the ORR kinetics. Herein, we design and synthesize a nitrogen-doped hierarchically porous carbon with homogeneously distributed ultrafine α-MoC nanoparticles (α-MoC/NHPC) as a model electrocatalyst. Theoretical investigations unveil that α-MoC on NHPC could efficiently reduce the energy barrier of the water dissociation process to generate protons, eventually promoting the proton-coupled ORR kinetics. In a 0.1 M KOH aqueous solution, α-MoC/NHPC exhibits excellent ORR performance with a high half-wave potential of 0.88 V (VS. reversible hydrogen electrode), which outperforms those for NHPC and commercial Pt/C. Moreover, as the air electrode in a zinc-air battery, α-MoC/NHPC presents a large peak power density of 200.3 mW cm−2 and long-term stability. Thereby, our approach to engineering proton-feeding centers paves a new avenue towards the understanding of ORR kinetics and the development of high-performance ORR electrocatalysts.
A series of ten chloroalkyl 1H-benz[de]isoquinoline-1,3-diones (naphthalimides) were synthesized and evaluated for antitumor activity. Amongst them, new compounds 2d and 2i carrying a 6-NO2 substituent in the aromatic portion of the molecule possessed significant antineoplastic activity. The most active compound 2i had elicited significant cytotoxicity in 15 human tumor cell lines namely Leukemia: MOLT-4, HL-60; Lymphoma: U-937; Colon: 502713, HT-29, SW-620, HCT-15, COLO-205; Liver: Hep-2; Prostate DU-145, PC-3; Breast: MCF-7; Neuroblastoma: IMR-32, SK-N-SH and Ovary: OVCAR-5 out of the 17 cell lines screened. Flow cytometric analysis performed to study the effect of compound 2i on the progression of cell cycle of MOLT-4 cells, revealed rise in sub-G1 fraction and concomitant accumulation of cells in S and G2/M phases, indicating apoptosis, mitotic arrest and/or delay in exit of daughter cells from mitotic cycle respectively. It also induced caspase-mediated apoptosis of MOLT-4 cells in a dose dependant manner. Light and electron microscopic studies revealed characteristic morphology of apoptotic MOLT-4 cells after in vitro treatment with 10 μM concentration of the compound. Apoptosis induction was also observed in HL-60 cells by compounds 2d and 2i to an extent much greater than camptothecin and cis-platin at 10 μM concentration. Both the compounds have shown minimal suppressive effect on human PBMC having high IC50 values of 3,582 and 1,536 μM respectively. These compounds inhibited DNA and RNA synthesis in murine ascites Sarcoma-180 tumor cells in vitro at 8 μM concentration. Above results indicate promising chemotherapeutic potential of the key compound 2i.
In this paper, we demonstrated the preparation and application of porous LiMn2O4 nanorods as cathode materials for rechargeable lithium-ion batteries. Solid-state lithiation of porous Mn2O3 nanorods, resulting from thermal decomposition of MnC2O4 precursor, led to the formation of porous LiMn2O4 nanorods with high crystallinity and phase purity. Without surface modification, the as-synthesized porous nanorods exhibited superior high-rate capability and cyclability to the counterpart nonporous nanorods and nanoparticles. An initial discharge capacity of 105 mAh g−1 could be delivered at 10 C rate, and capacity retention of about 90% was obtained after 500 cycles at this high rate. The durable high-rate capability was attributed to the unique porous one-dimensional (1D) nanostructure that gave rise to fast Li-intercalation kinetics and good structural stability for the spinel electrodes. The beneficial gains from 1D porous nanoarchitecture may enlighten the design and construction of new spinel-based electrode for high power applications.
Reduced graphene oxide (rGO) anchored spinel nickel cobalt binary sulfides nanosheets (NixCo3-xS4/rGO) with sandwich-like structure are synthesized via a facile hydrothermal process. The synergistic effect of nickel and cobalt on the superior electrochemical properties of the NixCo3-xS4/rGO nanocomposites is firstly illustrated in detail through the comparison of the phase structures, metal valent states and electrochemical behaviors of the nickel doped cobalt sulfide (Ni0.3Co2.7S4/rGO), cobalt doped nickel sulfide (Ni2.7Co0.3S4/rGO) and nickel cobalt binary sulfide (Ni1.5Co1.5S4/rGO). Results indicate that the fast valence change of nickel species mainly contributes the faradaic reaction of the active materials, while the cobalt species offer the high electronic conductivity and assist the charge transfer process. Due to the synergistic effect of cobalt and nickel, the Ni1.5Co1.5S4/rGO electrode with sandwich-like structure exhibits superior electrochemical performances, such as high specific capacity (347.5mAhg−1 based on metal sulfide), high areal specific capacity (4.3mAhcm−2), high cyclic stability (85.0% retention after 2000 cycles). An asymmetric device, with the Ni1.5Co1.5S4/rGO as positive material and a home-made activated carbon as negative material, delivers high energy density of 61.6Whkg−1 at the power density of 563.1Wkg−1 and still remains 49.3Whkg−1 even at high power density of 11.0kWkg−1.
We propose a new strategy to uniformly coat zeolitic imidazolate framework-8 (ZIF-8) on iron oxides containing no Zn to obtain an α-Fe2O3@ZIF-8 composite. After carbonization, the α-Fe2O3@ZIF-8 transforms into iron oxides@N-doped porous carbon (FeOx@NC). The uniform N-doped porous carbon layer gives rise to a superior electrical conductivity, highly-increased specific BET surface area (179.2 m2 g−1), and abundant mesopores for the FeOx@NC composite. When served as the LIB anode, the FeOx@NC shows a high reversible capacity (of 1064 mA h g−1 at 200 mA g−1), excellent rate performance (of 198.1 mA h g−1 at 10000 mA g−1) as well as brilliant long-term cyclability (with a capacity retention of 93.3% after 800 cycles), which are much better than those of the FeOx@C and pristine FeOx anodes. Specifically, the Li-ion intercalation pseudocapacitive behavior of the FeOx@NC anode is improved by this N-doped porous carbon coating, which is beneficial for rapid Li-ion insertion/extraction processes. The excellent electrochemical performance of FeOx@NC should be ascribed to the increased electrolyte penetration areas, improved electrical conductivity, boosted lithium storage kinetics, and shortened Li-ion transport length.
Electrochemical impedance spectroscopy (EIS) and in-situ intrinsic resistance measurements were applied to sandwiched disk graphite electrodes to investigate the mechanism of formation of irreversible capacity during initial galvanostatic or potentiostatic lithium intercalation into graphite in four different electrolyte formulations. The stability of the solid∣electrolyte interphase (SEI) film formed during pre-cycling eight times between 1.5 and 0.2 V versus Li∣Li+ in 1.0 M LiPF6+ethylene carbonate (EC) based electrolytes was studied using EIS and in-situ intrinsic resistance measurements during subsequent cycling in the same electrolyte between 0.4 and 0.0 V, and in 1 M LiPF6–propylene carbonate (PC) between 0.4 and 0.0 V. The purpose of the first set of results was to investigate the effect of the volume change resulting from stage transformation during Li intercalation–deintercalation on the stability of the previously formed SEI film. The second measurements were taken to study the reaction of the corresponding film in PC electrolyte. Results show that the two potential plateaus at around 0.9 and 0.6 V in the first galvanostic charge largely correspond to solvated Li intercalation into graphite with some contribution from the formation of the SEI film. In EC-containing mixtures, this solvent has little influence on co-intercalation at 0.9 V, but can effectively inhibit the process at 0.6 V. Potentiostatic charging at 0.2 or 0.7 V accelerates co-intercalation. Although the SEI film formed during cycling in EC-containing electrolytes can inhibit PC co-intercalation during subsequent cycles in the presence of this solvent, a new layer of different SEI film may also form.
In order to optimize the cycling performance of lithium–sulfur (Li–S) batteries, it is highly important to understand the structural and morphological changes of the sulfur cathode under operating conditions. In this work, a suitable cell for in-situ X-ray diffraction (XRD) analysis was designed to study the structural modifications on the cathode of Li–S batteries during electrochemical cycling. As a result, the formation of reaction products during charging and discharging was monitored in operando. The formation of dilithium sulfide (Li2S) and the recrystallization of sulfur during the first cycle could be identified. Moreover, these crystalline phases were semi-quantitatively determined by means of XRD analysis. Morphology changes of the cathode due to electrochemical cycling were characterized using scanning electron microscopy (SEM).