batterydata/paper-abstracts huggingface dataset:
The poor cycle performance, low rate capability and thermo-instability limit the practical application of LiCoO2 as high-voltage cathode materials for lithium-ion batteries. Herein, we propose an integrated modification strategy which combines the advantages of elements doping, surface modifications and even the high Li+-diffusion of the coating layer. In this study, Li+-conductive Li2ZrO3 has been successfully coated on the surface of LiCoO2 (Li2ZrO3@LCO) through a synchronous lithiation strategy and the multiple effects of Li2ZrO3 coating on the structural and electrochemical performances of LiCoO2 as high-voltage cathode materials for Li-ion batteries have been discovered. In compared to bare LiCoO2, the cycle performance, polarization, rate capability and thermo-stability of Li2ZrO3@LZO have been significantly improved. Li2ZrO3@LCO shows a much higher capacity retention than bare LiCoO2 both at 25°C (85.2% vs.32.6% at 5C, 1C=200mAg−1) and 55°C (71.3% vs.13.9% at 5C), and the specific capacity at 10C has also been largely increased from 33.9mAhg−1 to 103.4mAhg−1. The enhancement of the electrochemical performances can be largely attributed to the multiple effects of Li+-conductive Li2ZrO3 coating: the alleviation of side reactions and transition metal dissolution, the enhancement of Li-ion diffusion coefficient and electronic conductivity, Zr4+ migration and doping, the resulting interplanar spacing expansion and the improvement of the layered structure stability.
As a high-potential and high-stability cathode material, LiVPO4F/C is modified by K+ and Zr4+ co-doping to significantly improve its high-rate and long-life performance. K+ assisted by Zr4+ slightly enlarges the unit cell volume to expand Li+ migration pathway. K+ substituting Li+ can also achieve pillar effect to increase the structural stability. Hall effect reveals that Zr4+ substituting V3+ is a donor doping, leading to the transformation of conductive type from p-type to n-type and a great increase of carrier density by 106 times. Therefore, the electronic conductivity (1.1 × 10−2 S cm−1) increases by a factor of ∼104. The charge transfer resistance decreases to 82.81 Ω and the Li+ diffusion coefficient (9.83 × 10−13 cm2 s−1) increases to 7 times that of undoped LiVPO4F/C. The discharge capacities of Li0.99K0.01V0.995Zr0.005PO4F/C at 0.1C and 1C are 143.3 mA h g-1 and 135.5 mA h g-1, respectively. The capacity retention at the charge/discharge rate of 10C is as high as 80.0% after 2000 cycles with an initial capacity of 108.1 mA h g-1. Even at the discharge rate of 60C (charging at 1C), the capacity reaches 105.7 mA h g-1.
In view of the growing concern about energy management issues, sodium ion batteries (SIBs) as cheap and environmentally friendly devices have increasingly received wide research attentions. The high current rate and long cycle-life of SIBs are considered as two key parameters determining its potential for practical applications. In this work, the rigid single-crystalline anatase TiO2 nanosheets (NSs) with a thickness of ∼4 nm has been firstly prepared, based on which a stable nanostructured network consisting of ultrathin anatase TiO2 NSs homogeneously anchored on graphene through chemical bonding (TiO2 NSs-G) has fabricated by hydrothermal process and subsequent calcination treatment. The morphology, crystallization, chemical compositions and the intimate maximum contact between TiO2 NSs and graphene are confirmed by TEM, SEM, XRD, XPS and Raman characterizations. The results of electrochemical performance tests indicated that the TiO2 NSs-G hybrid network could be consider as a promising anode material for SIBs, in assessment of its remarkably high current rate and long cycle-life aside from the improved specific capacity, rate capability and cycle stability.
Transition metal oxides with spinel structure have been intensively investigated for energy storage application such as electrochemical supercapcaitors. In the present work, nickel cobalt oxide (NiCo2O4) thin films have been systematically deposited using spray pyrolysis process. Compact and uniform thin films of spinel nickel cobalt oxide with particle size 10–20nm have been obtained by the oxidation of Ni and Co precursors. When evaluated as electrode for supercapacitor, the nanostructured NiCo2O4 thin film deposited at 350°C exhibit the best charge storage property exhibiting high specific capacitance of 752Fg−1 and excellent cycle stability over 1000 cycles. Moreover, nanostructured NiCo2O4 thin film demonstrated high power performance, excellent rate as well as long term cycling stability. The Ragone plots ascertain good power and energy densities for NiCo2O4 thin films. Therefore, NiCo2O4 thin film electrodes are very promising for application in supercapacitors.
To improve the cathodic performance of olivine-type LiMnPO4, we investigated the optimal annealing conditions for a composite of carbon with cation doping. Nanocrystalline and the cation-doped LiMn1−x M x PO4 (M=Ti, Mg, Zr and x =0, 0.01, 0.05 and 0.10) was synthesized in aqueous solution using a planetary ball mill. The synthesis was performed at the fairly low temperature of 350°C to limit particle size. The obtained samples except for the Zr doped one consisted of uniform and nano-sized particles. The performance of LiMnPO4 was much improved by an annealing treatment between 500 and 550°C with carbon in an inert atmosphere. A small amount of metal-rich phosphide (Mn2P) was detected in the sample annealed at 900°C. In addition, 1at.% Mg doping for Fe enhanced the rate capability in our doped samples. The discharge capacity of LiMn0.99Mg0.01PO4/C was 146mAh/g at 0.1mA/cm2 and 125mAh/g even at 2.0mA/cm2.
A flexible, self-standing graphene–Se@CNT composite film has been synthesized by a facile two-step assembly process. The film is directly employed as cathode for rechargeable Li–Se batteries without extra binders and conductive additives. It exhibits much higher reversible capacity and cycling stability (315 mAh g−1 after 100 cycles at 0.1 C) than graphene–Se composite film. The improved electrochemical performance is mainly attributed to the synergistic effects of graphene and CNT, which not only function as a flexible scaffold for strains/stresses release and volume expansion, but also offer a three-dimensional conductive architecture with open channels for electron transfer and Li ion diffusion, as well as strong confinement of soluble polyselenides.
As in other areas of international development, we are witnessing the proliferation of ‘traveling models’ developed by international experts and introduced in an almost identical format across numerous countries to improve some aspect of maternal health systems in low- and middle-income countries. These policies and protocols are based on ‘miracle mechanisms’ that have been taken out of their original context but are believed to be intrinsically effective in light of their operational devices.
Jet-milled natural Swedish graphite has been evaluated as an anode material for Li-ion battery applications, with a focus on rate capability of the material. The material was found to have a superior rate capability compared to other carbon materials with similar particle sizes. It could also intercalate and deintercalate lithium reversibly in an electrolyte based on propylene carbonate:ethylene carbonate (1:1). Jet-milling was found to increase the amount of rhombohedral phase (3R) in the material from 15 to 40%. However, after repeated electrochemical intercalation and deintercalation of lithium, the amount of 3R phase decreases to ∼5%. Neither rate capability nor PC-tolerance can therefore be correlated to the amount of 3R phase.
Vagus nerve stimulation (VNS) therapy has been reported to reduce seizure frequency in some children with drug-resistant epilepsy who are not suitable candidates for epilepsy surgery. It has been suggested that there may be positive cognitive and/or behavioral effects independent of seizure control. We describe the effects of VNS with respect to seizure frequency, cognition, and autistic symptoms and behavior in eight children and adolescents with medically intractable epilepsy and autism. In comparison to baseline, seizure frequency had not decreased in anyone in our series at the 2-year follow-up. In three cases, minor improvements in general functioning were noted, but there were no positive cognitive effects. This open prospective pilot study highlights the need for more prospective studies to prevent false expectations of improvement in this severely disabled group.
LiFePO4/C and LiFe0.96Pt0.04PO4/C nanocomposite cathode materials were synthesized using the sol–gel method in a nitrogen atmosphere. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Their electrochemical properties were investigated using galvanostatic charge/discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The XRD results indicate that substituting iron with platinum does not destroy the structure of LiFePO4, but expands the lattice parameters and enlarges the cell volume. The electrochemical results show that platinum doping improves the electrochemical performance of LiFePO4/C particles owing to the expansion of the lattice structure, which provides more space for Li ion diffusion. The, larger lattice structure parameters of the LiFe0.96Pt0.04PO4/C material result in a high discharge capacity of 166, 156, 142 and 140 mAh g−1 at rates of 0.2, 1, 5, and 10 C, respectively, as compared to 164, 150, 120, and 105 mAh g−1 for undoped LiFePO4/C.
The importance of micro-fuel cell has been increased with the demand for uninterrupted power source in today's power hungry portable electronics. Currently, there is aggressive research going on to commercialize the micro-fuel cell by many laboratories and companies. The three different fuels feeding systems, i.e. pure hydrogen, pure hydrocarbons (alcohol, i.e. methanol and ethanol; formic acid and ethylene glycol) and on-board hydrogen from reformed hydrocarbons like methanol or other compound like water can be used for operating the micro-fuel cells. The current status on the research and development of micro-fuel cell with all the above three types of fuels have been discussed. The different substrate materials used in micro-fuel cells for the suitability of the portable electronics have also been stated. The design aspects of micro-fuel cells and micro-reformers are discussed here. The current state of commercialization of micro-fuel cells for portable electronics has been reviewed based on the open literature. The hurdles to overcome in order to commercialize in full phase have been reported, whenever possible. Some very new technologies which can make the micro-fuel cell into a very promising system with a simple operation have also been focused.
Well-designed novel dual core-shell g-C3N4@Fe/Sr@g-C3N4 nanosphere (FSCN-NS) is originally reported in detail as high efficiency of oxygen reduction reaction (ORR) electrocatalyst in both acidic and alkaline media for fuel cell. The g-C3N4 as the catalyst carrier plays a critical role in facilitating the formation of the hierarchically porous architecture with large numbers of Fe3C, FeNx(x = 1–3), SrCN2 and SrC2 active ORR segments. Furthermore, g-C3N4 as catalyst protector has a stable supporting effect against chemical corrosion, ensuring stability and durability of the as synthesized FSCN-NS for ORR in fuel cell cathode. Additionally, the introduction of Sr can produce metal-nitrogen-carbon bonds to provide active ORR sites, contributes to the formation of the hierarchically porous nanostructure. Thus, FSCN-NS exhibits high ORR activity with the onset potentials of 1.06 V and 1.08 V in alkaline and acidic media, respectively. Notably, half-wave potential, limiting current density, methanol tolerance and durability are all better than that of commercial 20% Pt/C catalyst and most of previously reported materials derived from other metal-C/N nanostructure. Thus, FSCN-NS is as promising cheap candidate to solve the main problems of sluggish reaction kinetics of the ORR, high cost and low durability for fuel cells and metal-air batteries in energy conversion and storage devices.
A key challenge hindering the mass adoption of Lithium-ion and other next-gen chemistries in advanced battery applications such as hybrid/electric vehicles (xEVs) has been management of their functional performance for more effective battery utilization and control over their life. Contemporary battery management systems (BMS) reliant on monitoring external parameters such as voltage and current to ensure safe battery operation with the required performance usually result in overdesign and inefficient use of capacity. More informative embedded sensors are desirable for internal cell state monitoring, which could provide accurate state-of-charge (SOC) and state-of-health (SOH) estimates and early failure indicators. Here we present a promising new embedded sensing option developed by our team for cell monitoring, fiber-optic (FO) sensors. High-performance large-format pouch cells with embedded FO sensors were fabricated. This second part of the paper focuses on the internal signals obtained from these FO sensors. The details of the method to isolate intercalation strain and temperature signals are discussed. Data collected under various xEV operational conditions are presented. An algorithm employing dynamic time warping and Kalman filtering was used to estimate state-of-charge with high accuracy from these internal FO signals. Their utility for high-accuracy, predictive state-of-health estimation is also explored.
A synthesis of Li3V2(PO4)3 being a potential cathode material for lithium ion batteries was attempted via a glass-ceramic processing. A glass with the composition of 37.5Li2O–25V2O5–37.5P2O5 (mol%) was prepared by a melt-quenching method and precursor glass powders were crystallized with/without 10wt% glucose in N2 or 7%H2/Ar atmosphere. It was found that heat treatments with glucose at 700°C in 7%H2/Ar can produce well-crystallized Li3V2(PO4)3 in the short time of 30min. The battery performance measurements revealed that the precursor glass shows the discharge capacity of 14mAhg−1 at the rate of 1μAcm−2 and the glass-ceramics with Li3V2(PO4)3 prepared with glucose at 700°C in 7%H2/Ar show the capacities of 117–126mAhg−1 (∼96% of the theoretical capacity) which are independent of heat treatment time. The present study proposes that the glass-ceramic processing is a fast synthesizing route for Li3V2(PO4)3 crystals.
Current research in the field of future aircraft concepts aims at accommodating ambitious reduction goals set by national and international regulators. These concepts should be investigated not only with regard to aircraft efficiency, but also in terms of their compatibility with airline operations, existing ground handling procedures and airport infrastructure requirements, as these influence the overall performance of a future aircraft concept. This paper addresses this aspect, focusing on case studies concerning hybrid-electric and universally-electric aircraft concepts, analyzing implications for current ground handling operations at the airport. Current bottlenecks, such as capacity shortages, and potential areas of improvement are identified based on a state-of-the-art reference ground handling process. To this end, requirements of different stakeholders, including airports, airlines and ground handling providers, are outlined. In the next step, insights are contrasted with operational requirements of the future aircraft concepts under consideration. The paper stresses the anticipated challenges involved in aligning future aircraft requirements with current procedures, discusses the necessary adaptions to operational processes. The results highlight changes that need to be made to the current system before an aircraft can enter service, and provide an initial basis for the strategic planning of the stakeholders involved.
Graphene sheets (GNS) have been synthesized using a fast and effective microwave autoclave method in which the MnO2 nanoflakes are coated on the GNS in situ to form a composite material. The structures, compositions, and morphologies of the samples were characterized by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and electron microscopy. Application of the catalyst cathodes in Li–O2 batteries was also investigated. Compared with GNS cathode, dramatic improvements in the catalytic performance of the composite cathode have been obtained. This superior performance is attributed to the synergistic benefits from the GNS with three-dimensional structure and the MnO2 nanoflakes that cover them. The GNS not only increase the electrical conductivity of the composite cathode but also offer enough space for the tri-phase reaction and to buffer the volume changes during cycling. Due to their intrinsically high catalytic activity, the MnO2 nanoflakes could efficiently boost the oxygen reduction reaction and oxygen evolution reaction, improving the electrocatalytic performance of the MnO2/GNS composite as cathode for Li–O2 batteries.
Electrocatalytic water oxidation is key in energy storage technologies, but deeper mechanistic understanding is still required. Grimaud et al. show that surface oxygen atoms in a model oxide catalyst act as electrophilic centres for reactions and observe drastic reconstruction of the catalyst surface.
Co–Al mixed metal oxide (CoAl-MMO) has been used for surface modification of LiMn2O4 spinel by means of a co-precipitation method in an attempt to improve the electrochemical performance of LiMn2O4 at elevated temperature. The surface modified materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometry (EDS), Auger electron spectroscopy (AES) and galvanostatic charge–discharge cycling. After heat-treatment at 400°C, the CoAl-MMO coated LiMn2O4 shows better capacity retention at both 25°C and 55°C than the pristine LiMn2O4. The enhancement in electrochemical performance is mainly attributed to the CoAl-MMO coating layer which has the synergistic effect of cobalt and aluminum oxide species and could block the direct contact between the spinel cathode material and electrolyte resulting in Mn dissolution decrease.
To investigate the deposition and dissolution of the anodic deposited materials in the lead methanesulfonate flow battery, phase composition, grain and particle sizes, stoichiometry and conductivity of PbO2 are investigated, which are deposited at different positive electrode potentials. ΩWith the positive electrode potential increasing, the content of α-phase increases compared with β-phase’s by X-ray diffraction (XRD) analyses. Mean grain sizes are not apparently changed by calculation using Debye-Scherrer formula. But the particle sizes indeed become smaller with the positive electrode potential increasing, which are investigated using scanning electron microscope (SEM). Since the anodic deposited material is the compound in which oxygen deficiency in PbO2, X-ray photoelectron spectroscopy (XPS) is introduced to characterize the non-stoichiometry of PbO2 deposited at four typical positive electrode potentials, 1.5, 1.7，1.8 and 2.0 V vs. SCE. Here PbOx is utilized to represent this kind of compound. The highest value of x = 1.73 ± 0.03 in PbOx is obtained at 2.0 V vs. SCE, only x = 1.46 ± 0.02 for that electrodeposited at 1.5 V vs. SCE. It is also found that the polarization impedances of working electrodes covered by different PbOx layers decrease with the electrodeposition potential of PbOx increasing, which are 170，37，12 and 2.4 Ω respectively at 1.5, 1.7，1.8 and 2.0 V vs. SCE. By controlling the cell charge voltage of 2.15 V, corresponding to the positive electrode potential of 1.7 V vs. SCE, 261 cycling numbers have been achieved at the discharging current density of 40 mA cm-2 with a coulombic efficiency of more than 80 %.
Although solar photovoltaic technology is one of the matured technologies, its initial high cost and low efficiency have not made it fully attractive as an alternative option for electricity users. Hence it is very critical to utilize the maximum available solar power of the array and to operate the PV array at its highest energy conversion output. For this, the solar PV generating system has to operate at the maximum power output point. Since the maximum power point varies with radiation and temperature, it is difficult to maintain optimum power operation at all radiation levels. Over the years, many MPPT techniques have been advocated, developed and implemented. These methods vary in several aspects such as complexity, required number of sensors, convergence speed, cost, range of effectiveness, ease of hardware implementation etc. Although different methods have been developed by different research groups, very little literature is available, where different MPPT techniques/methods are compared in terms of energy capture, conversion efficiency, response time and reliability. This paper compares the performance of different MPPT methods that are currently used in a solar PV system and also advocates a new MPPT technique which offers better performance than the existing ones. The methodology adopted for analysis is as follows: Initially, a MATLAB based solar PV array model is first developed and validated; then, different MPPT techniques are employed on this PV array under varying temperature and insolation conditions to study the effectiveness of the particular MPPT technique under consideration.
La0.8Sr0.2CoO3 was coated on NiO (LSC–NiO) cathodes using a sol–gel method. Dissolution studies in molten Li2CO3 and K2CO3 (62:38mol%) at 650°C showed lower Ni dissolution than that of the conventional nickel oxide cathode. Impedance analysis showed that the behavior of the developed cathode is similar to that of nickel oxide. The LSC coated Ni cathode has an over potential of 109mV at an applied current density of 160mA/cm2. The LSC–NiO shows promise as an alternate cathode in molten carbonate fuel cells (MCFCs).
During the discharge of an aprotic Li/O2 battery solid products assemble inside of the gas diffusion electrodes (GDE). The distribution of these in dependence of pore size of the GDE is investigated by X-ray Photoelectron Spectroscopy (XPS). Depth profiling of the electrolyte facing side of the cathode reveal that macroporous electrodes are able to store discharge products homogeneously in the pore structure. Mesoporous GDE, however, develop a concentration gradient with large amounts of discharge product at the electrode/electrolyte interface and low amount in the bulk of the electrode. The investigation of the cross-section of these GDE reveals that most of the discharge products form near the oxygen facing side of the GDE. Here, the chemical compositions differ strongly from those at the electrolyte facing side. The high oxygen concentration and the limited lithium supply lead to the formation of lithium carbonate, lithium oxide and lithium fluoride. Also a thin layer of discharge product blocking further oxygen supply into the GDE through macroporous cracks is formed at the gas/electrolyte interface.