batterydata/paper-abstracts huggingface dataset:
The overcharge behaviour of AlPO4-coated LiCoO2 cathodes as a function of coating thickness is investigated in Li-ion cells at 1 and 2C overcharging rates. The AlPO4 coating thickness is controlled by the concentration of the coating solution. During 1C-overcharging to l2V, the 5V plateau region, which is indicative of both electrolyte oxidation and an exothermic reaction between the electrolyte and the cathode, decreases with increasing AlPO4 coating thickness (AlPO4 concentration). Therefore, a Li-ion cell containing a P100-coated LiCoO2 cathode (AlPO4 coating thickness estimated as 1000Å) does not show the 5V plateau, and displays the lowest cell external temperature of 60°C, even at 12V. This suggests that the reaction at the 5V plateau strongly influences the final external temperature of the cell. When a higher current is applied (2C), cells with bare or P10-coated LiCoO2 cathodes either burst or explode, and reach external temperatures of over 275°C. By contrast, cells with P30 and P100-coated cathodes show only a swollen external appearance with temperature profiles similar to those at the 1C-overcharging rate.
Prevention of thermal runaway and its propagation remains a technical barrier to the application of lithium-ion batteries. To mitigate thermal runaway in lithium-ion battery packs, heat sinks have been designed using various materials, such as phase-change materials or metal plates. In this study, aluminum plates were assembled into battery modules as heat sinks and the effect of plate thickness on thermal runaway mitigation was numerically investigated. A three-dimensional integrated multiphysics model was validated and calibrated with experimental data. It identified the mechanism and sequence of thermal runaway propagation in detail. Thermal mass and contact resistance are found to be the key design parameters for preventing thermal runaway propagation for the studied battery module configuration. In addition, this study provides further insights into the design of aluminum heat sinks for lithium-ion battery packs.
A scalable one-pot solvothermal route is presented for preparing tin disulfide (SnS2) nanosheets and nanoflowers. Urea, mercapto propionic acid as an organic additive, steers the growth of SnS2 nanosheets and thiourea (TU) orchestrates the formation hierarchical SnS2 nanoflowers. A time dependent experiment reveals the following growth mechanism: from SnO2 with a tetragonal rutile structure (1h), to SnS2 nanosheets and nanoflowers with a hexagonal crystal structure (12h). When SnS2 nanosheets and nanoflowers are incorporated into Li-ion battery half cells, both nanostructures exhibit excellent capacity retention and rate capability. SnS2 nanoflowers and nanosheets retained a capacity of 466 and 196mAhg−1 even at very high current density of 3000mAg−1 after 65 cycles. The outstanding reversible Li-ion storage responses and the visible blue-green photoluminescence shown by SnS2 nanosheets and nanoflowers are prime indicators of the potential these nanostructures have for not just energy storage and but also for energy harvesting applications.
The concept of a modular climbing caterpillar robot is inspired by the kinematics of real caterpillars. Two typical kinematics models and gaits are investigated based on the crawling motion of the inchworm and the tobacco hornworm. Due to the fixed constraints between the suckers and the wall, the gait of a caterpillar robot engages a changing kinematic chain which is from an open chain to a closed chain, and then to an open chain in order. During the open chain periods, an unsymmetrical phase method (UPM) is used to ensure the reliable attachment of the passive suckers to the wall. In the closed-chain state, a four-link kinematics model is adopted to fulfill the fixed constraints. By combining the two methods together, the complete joint control trajectories are acquired for a modular caterpillar robot with seven joints. At last, on-site tests confirm the proposed principles and the validity of the climbing gait.
LiCoPO4/C nanocomposites could be successfully prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment. X-ray diffraction analysis confirmed that the LiCoPO4/C nanocomposites were well crystallized in an orthorhombic structure with Pmna space group. Scanning electron microscopy and transmission electron microscopy with equipped energy dispersive spectroscopy verified that the LiCoPO4/C nanocomposites were the agglomerates of LiCoPO4 primary particles with a geometric mean diameter of 87nm, and the carbon was well distributed on the surface of the agglomerates. The LiCoPO4/C nanocomposites were used as cathode active materials for lithium batteries, and the electrochemical tests were carried out for the cell Li|1M LiPF6 in EC:DMC=1:1|LiCoPO4/C at various charge–discharge rates. The cells delivered first discharge capacities of 142 and 109mAhg−1 at 0.05 and 20C, respectively. Furthermore, the discharge capacity after 40cycles corresponded to 87% of initial one at 0.1C rate. The excellent rate capability of the cells is mainly due to the well distributed carbon on the LiCoPO4 agglomerates, and a much smaller lithium ion diffusion distance in the electrode.
It is known that the storage conditions influence the performance of a battery. The effect of temperature on the discharge capacity of silver oxide–zinc (AgO–Zn) cells is investigated quantitatively in the present study. 40Ah silver oxide–zinc cells are charged in two step constant current mode up to 2.05V and stored at temperatures in the range of −20°C to 60°C for charge stand periods of 1 day, 7 days and 15 days. Subsequently, the cells are discharged at 1C rate current until voltages of each cell reached 1.2V. Although the discharge capacity of these cells at and around room temperature is reasonable, at temperatures below 0°C the performance is poor. From 40°C to 60°C temperatures, the discharge capacities decreased with charge stand periods. The discharge capacities are not affected by the charge stand periods from −20°C to 30°C. Best performances in terms of the capacity and average midpoint voltage for different charge stand periods are obtained at 30°C. To identify the reasons for the poor performance at sub-ambient temperatures, electrochemical impedance studies are carried out on a fresh cell. The impedance data are analyzed using an equivalent circuit by Zman fitting software and the impedance parameters are evaluated. The resistances corresponding to mid-frequencies and low frequencies of Nyquist impedance plot exhibit a strong dependence on temperatures. The kinetic parameter namely, apparent exchange current density is calculated and discussed.
Graphene is a nanomaterial with many promising and innovative applications, yet early studies indicate that graphene may pose risks to humans and the environment. According to ideas of responsible research and innovation, all relevant actors should strive to reduce risks related to technological innovations. Through semi-structured interviews, we investigated the idea of graphene as a risk (or not) held by two types of key actors: graphene researchers and innovation advisors at universities, where the latter are facilitating the movement of graphene from the laboratory to the marketplace. The most common idea found is that graphene is not a risk due to, e.g., low toxicity, low amounts produced/used, and its similarity to harmless materials (being “just carbon”). However, some researchers and advisors also say that graphene is a risk, e.g., under certain conditions or due to a lack of risk-related information. We explain the co-existence of these seemingly contradictory ideas through (1) the semantic ambiguity of the word risk and (2) a risk/no-risk rhetoric, where risks are mentioned rhetorically only to be disregarded as manageable or negligible. We suggest that some of the ideas held by the researchers and innovation advisors constitute a challenge to responsible research and innovation regarding graphene. At the same time, we acknowledge the dilemma that the discourse of responsible innovation creates for the actors: denying graphene risks makes them irresponsible due to a lack of risk awareness, while affirming graphene risks makes them irresponsible due to their everyday engagement in graphene development. We therefore recommend more research into what researchers and innovation advisors should do in practice in order to qualify as responsible.
The fifth generation of mobile networks (5G) is the next major phase of mobile telecommunications that will enable the Networked Society. We describe the challenges and role of optical transport in the Networked Society. The paper covers the role of optical transport for 5G radio and SDN/NFV and the impact of integrated photonics with promise of low-cost DWDM which could serve as the basis for 5G transport satisfying requirements on performance, low cost and flexibility.
Modeling of secondary lithium batteries is reviewed in this paper. The models available to simulate the electrochemical and thermal behavior of secondary lithium batteries are discussed considering not only their electrochemical representation (transport phenomena and thermodynamics of the system), but also the mathematical techniques that have been used for solving the equations. A brief review of the governing equations for porous electrodes, and methods for solving these equations is also given.
A poly(2-acrylamido-2-methyl-1-propane-sulphonate) (PAMPS) ionomer containing both sodium and quaternary ammonium cations functionalised with an ether group, has been characterised in terms of its thermal properties, ionic conductivity and sodium ion dynamics. The ether oxygen was incorporated to reduce the Na+ association with the anionic sulfonate groups tethered to the polymer backbone, thereby promoting ion dissociation and ultimately enhancing the ionic conductivity. This functionalised ammonium cation led to a significant reduction in the ionomer Tg compared to an analogue system without an ether group, resulting in an increase in ionic conductivity of approximately four orders of magnitude. The sodium ion dynamics were probed by 23Na solid-state NMR, which allowed the signals from the dissociated (mobile) and bound Na+ cations to be distinguished. This demonstrates the utility of 23Na solid-state NMR as a probe of sodium dynamics in ionomer systems.
This study investigates the relationship between variability in cortical surface area and thickness of the pars opercularis of the inferior frontal gyrus and motor-inhibitory performance on a stop-signal task in a longitudinal, typically developing cohort of children and adolescents. Linear mixed-effects models were used to investigate the hypotheses that (1) cortical thinning and (2) a relatively larger cortical surface area of the bilateral pars opercularis of the inferior frontal gyrus would predict better performance on the stop-signal task in a cohort of 110 children and adolescents 4–13 years of age, with one to four observations (totaling 232 observations). Cortical thickness of the bilateral opercular region was not related to inhibitory performance. However, independent of age, gender, and total cortical surface area, relatively larger cortical surface area of the bilateral opercular region of the inferior frontal gyrus was associated with better motor-inhibitory performance. Follow-up analyses showed a significant effect of surface area of the right pars opercularis, but no evidence for an effect of area of left pars opercularis, on motor-inhibitory performance. These findings are consistent with the previous work in adults showing that cortical morphology of the pars opercularis is related to inhibitory functioning. It also expands upon this literature by showing that, in contrast to earlier work highlighting the importance of cortical thickness of this region in adults, relative cortical surface area of the pars opercularis may be related to developing motor-inhibitory functions during childhood and adolescence. Relationships between cortical phenotypes and individual differences in behavioral measures may vary across the lifespan.
A facile soft templating strategy has been developed for synthesizing hollow spheres of nanocarbon by hydrothermal process. In this soft templating strategy, poly (ethylene oxide)–poly (propylene oxide)–poly (ethylene oxide) block co-polymers are used as the template while α-cyclodextrin are employed as the carbon precursor. After hydrothermal treatment, the soft templates can be easily removed by pyrolysis of the as-prepared hollow spheres in argon. The resultant hollow spheres of nanocarbon exhibit both micro- and meso-pores in carbon wall with a specific surface area of ∼380 m2 g−1. Upon incorporation of permanganate (MnO4 −) into the hollow carbon spheres, nanocrystalline manganese dioxide (MnO2) is grown on the carbon surface, where the redox reaction between carbon and MnO4 − takes place, giving rise to the formation of hollow carbon–MnO2 hybrid particles. An appropriate control in the diffusion of MnO4 − into the core of hollow carbon spheres, nanocrystalline MnO2 can be successfully grown on both the external and internal surfaces of the hollow carbon structure. The carbon–MnO2 hybrid spheres are demonstrated as a promising candidate material for supercapacitor application.
LiNi0.5Mn1.5O4, which has a spinel framework structure, is a promising candidate for the cathode material of next-generation lithium-ion batteries with high energy density. We investigate the structural transition in Li x Ni0.5Mn1.5O4 (0 ≤ x ≤ 1) through first-principles calculations using the projector augmented wave method with the generalized gradient approximation. We calculate all the unique Li-site occupation configurations in a unit cell to obtain the total energies and the most stable structures for various compositions. Thermodynamic analysis shows that Li0.5Ni0.5Mn1.5O4 with x = 0.5 is the only stable phase for 0 < x < 1. The decomposition energy is lower than 0.1 eV for 0 < x < 0.5, but is distinctly higher for 0.5 < x < 1. The decomposition energy reaches 0.39 eV at x = 0.75. The ratios of the structures at room temperature are calculated from Boltzmann factors by using the energy differences between structures. The crystal structure of the unit cell changes gradually from x = 0 to 0.5, but changes markedly from x = 0.5 to 1. This first-principles study provides a general evaluation of the variation in the crystal structure with the composition of the bulk material, which affects the cyclability of the electrode.
1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide (VEIMTFSI) monomer was polymerized by dispersion polymerization in water in presence of an imidazolium-based ionic liquid crosslinker, leading to crosslinked polymeric ionic liquid nanoparticles. These nanoparticles were used as nanolatex binder to process Li-ion battery electrodes. Graphite electrodes were tested in half-cells vs lithium and showed excellent cycling performance for more than 7 months, although the irreversible capacity remained high in the initial cycles as compared with commercial electrodes. Sub-micrometric particles of ca. 200–300 nm of both carbon coated LiFePO4 (LFP) and Li4Ti5O12 (LTO) were also processed, leading to high coulombic efficiencies, although only the LTO electrodes allowed very stable cycling as well as practical performances.
Malignant glioneuronal tumors of the brain are rare and poorly characterized. Herein, we report the clinicopathologic features of three examples with unusual morphologies including both glial and neuronal differentiation. Hematoxylin and eosin-stained slides were reviewed in all cases. Immunohistochemical stains were performed on formalin-fixed, paraffin-embedded sections. Transmission electron microscopy (EM) was performed on both formalin-fixed (n = 1) and paraffin embedded tissue (n = 2). The immunogold technique for localization of GFAP was also performed. Two patients were male and one was female, age 66, 84, and 34 years, respectively. Radiologic studies demonstrated hyperdensity on CT (n = 3), multicentricity (n = 2), and a cortical based solid component with a cystic extension into underlying white matter (n = 2). At surgery, all three tumors were superficial and relatively circumscribed. Histologically, they were composed of large epithelioid cells (n = 3), spindle cells (n = 1), and poorly differentiated smaller cells with high nuclear/cytoplasmic ratios (n = 1). Brisk mitotic activity and coagulative non-palisading necrosis were present in all cases. The tumors were immunopositive for GFAP (n = 3), S-100 (n = 3), synaptophysin (n = 3), chromogranin (n = 3), Neu-N (n = 2), and neurofilament protein (n = 2). Stains for EMA were negative. EM demonstrated convincing neurosecretory granules in one case, some in filament-containing cells immunogold labeled for GFAP. Two patients expired 3–5 weeks after surgery. True malignant neoplasms with glial and neuronal differentiation do occur in the central nervous system of adults and may pursue a highly aggressive course. The use of minimal diagnostic criteria, e.g., immunoreactivity for a single antigen like neurofilament protein, may not be sufficient and should be discouraged.
Traditional nurse call systems used in residential care facilities rely on patients to summon assistance for routine or emergency needs. Wireless nurse call systems (WNCS) offer new affordances for persons unable to actively or consciously engage with the system, allowing detection of hazardous situations, prevention and timely treatment, as well as enhanced nurse workflows. This study aimed to explore facilitators and barriers of implementation of WNCSs in residential care facilities.
Safety issues have been a long-standing obstacle impeding large-scale adoption of next-generation high-energy-density batteries. Materials solutions to battery safety management are limited by slow response and small operating voltage windows. Here we report a fast and reversible thermoresponsive polymer switching material that can be incorporated inside batteries to prevent thermal runaway. This material consists of electrochemically stable graphene-coated spiky nickel nanoparticles mixed in a polymer matrix with a high thermal expansion coefficient. The as-fabricated polymer composite films show high electrical conductivity of up to 50 S cm−1 at room temperature. Importantly, the conductivity decreases within one second by seven to eight orders of magnitude on reaching the transition temperature and spontaneously recovers at room temperature. Batteries with this self-regulating material built in the electrode can rapidly shut down under abnormal conditions such as overheating and shorting, and are able to resume their normal function without performance compromise or detrimental thermal runaway. Our approach offers 103–104 times higher sensitivity to temperature changes than previous switching devices.
Falls in older adults with cancer are common, yet factors associated with fall-risk are not well-defined and may differ from the general geriatric population. This study aims to develop and validate a model of factors associated with prior falls among older adults with cancer.
Recently, spinel lithium titanate (Li4Ti5O12, LTO) has attracted attention as an anode material for lithium-ion batteries (LIBs). However, the poor electronic conductivity and low lithium-ion diffusion coefficient of LTO suppresses its electrochemical performance during quick charging. One possible way to improve the electrochemical performance is to reduce the LTO particle size to the nanometer range and modify the surface conductivity. In this study, LTO/C was synthesized by a one-step carbonization route without any specialized equipment using a resorcinol–formaldehyde (RF) resin as a carbon source, lithium acetate as a lithium source and polymerization catalyst, and commercial nano-sized TiO2 as a titanium source. The homogeneous mixing of the RF resin dissolved in water led to the uniform dispersion of the TiO2 and the Li source. The polymerization of the RF resin, TiO2, and dissolved Li source formed a closely structured matrix. LTO/C is comprised of crystalline LTO covered by a thin carbon layer. The RF resin plays an essential role in producing a suitable reaction field, preventing grain growth, and controlling the LTO primary particle size. The specific capacities of the LTO/C composite (carbon 15 wt%, carbonized at 900 °C) are 161 and 90 mAh/g at 0.1C and 25C, respectively. The composite shows improved electrochemical properties compared to commercial LTO.
Charging procedures at low temperatures severely shorten the cycle life of lithium ion batteries due to lithium deposition on the negative electrode. In this paper, cycle life tests are conducted to reveal the influence of the charging current rate and the cut-off voltage limit on the aging mechanisms of a large format LiFePO4 battery at a low temperature (−10 °C). The capacity degradation rates accelerate rapidly after the charging current reaches 0.25 C or the cut-off voltage reaches 3.55 V. Therefore the scheduled current and voltage during low-temperature charging should be reconsidered to avoid capacity degradation. Lithium deposition contributes to low-temperature aging mechanisms, as something needle-like which might be deposited lithium is observed on the surface of the negative electrode after disassembling the aged battery cell. To confirm our explanation, incremental capacity analysis (ICA) is performed to identify the characteristics of the lithium deposition induced battery aging mechanisms. Furthermore, the aging mechanism is quantified using a mechanistic model, whose parameters are estimated with the particle swarm optimization algorithm (PSO). The loss of reversible lithium originating from secondary SEI formation and dead lithium is confirmed as the cause of the aging.
The MoN nanoparticles in the size range of 20–30nm are dispersed onto the surface of nitrogen doped CNT (MoN/N-CNT) by annealing at 600°C kept under a constant flow of nitrogen gas for 4 hr. The N-doping of CNT is confirmed from the characteristic Raman shift. The as-synthesized nanoparticles display hexagonal MoN phase with sharp mesoporous internal structure and a high surface area of 369m2 g–1. As an anode material, the composite structure demonstrates high reversible capacity, long cycle life and excellent rate performance. A reversible capacity of 1232mAhg–1 is maintained after 200 cycles at a current density of 100mAg–1. When the electrode is tested at higher current densities of 1000, 1250 and 1500mAg–1 for 20 cycles each, it still holds a high specific capacity of 1184.7, 1096.5 and 989.5mAhg–1. This electrochemical performance is also compared with bare MoN, N-CNT, MoO2 and MoO2/functionalized-CNT anodes. The superior electrochemical performance is credited to the nitrogen doping of CNT which reduce the charge transfer resistance along with the higher conductivity of MoN due to the substitution of oxygen octahedral sites of MoO2 with nitrogen atoms.