batterydata/paper-abstracts huggingface dataset:
High corrosion rate is one of the major obstacles that have to be overcome in order to establish practical application of primary alkaline Si–air batteries. At the current state of development the theoretical specific capacity of 3820 mAh/g is reduced to 120 mAh/g in long term operable alkaline Si–air batteries, with most of the capacity losses being due to corrosion reactions. In the present work the corrosion behavior of highly As-doped <100> oriented silicon wafers, that have proved stable performance as anode materials is summarized for a scope of conditions that may arise in battery operation. More specific, corrosion rates are presented and discussed with respect to (i) time dependence, (ii) influence of KOH electrolyte concentration, (iii) chemical vs. electrochemical corrosion, and (iv) corrosion under anodic potentials as present during the discharge of batteries. Corrosion rates were found to exhibit stable time profiles for immersion times longer than 8 h. With respect to concentration dependence, three ranges of KOH concentrations were identified. Within each range, the corrosion behavior is governed by similar mechanisms, but different limiting factors. Potentiodynamic measurements show that large part of the corrosion is chemical in nature. Under discharge conditions corrosion increases whereby the discharge potential, corrosion rates, and mass conversion efficiencies depend on KOH concentrations and discharge current densities.
Electrochemical double layer supercapacitor cells were fabricated and tested using composite electrodes of activated carbon with carbon black and poly(3,4-ethylenedioxythiophene) (PEDOT), and an organic electrolyte 1M TEABF4/PC solution. The effect of PEDOT on the performance of the EDLC cells was explored and the cells were characterised by electrochemical impedance spectroscopy (EIS), cyclic voltammetry and galvanostatic charge–discharge. A generalised equivalent circuit model was developed for which numerical simulations were performed to determine the properties and parameters of its components from the EIS data. It was found that the proposed model fitted successfully the data of all tested cells. PEDOT enhanced the electrode and cell capacitance via its pseudo-capacitance effect up to a maximum value for an optimum PEDOT loading and greatly increased the energy density of the cell while the maximum power density has been still maintained at supercapacitor levels. Furthermore, PEDOT replaced PVDF as a binder and harmful solvent release was reduced during electrode processing. Activated carbon–carbon black composite electrodes with PEDOT as binder were found to have specific capacitance superior to that of activated carbon–carbon black electrodes with PVDF binder.
Metal-organic frameworks (MOFs) and their derivatives are promising electrodes materials because of their various modular and controllable structures as well as their high specific surface areas and large internal pore volume. This review elaborates the recent advances in MOFs and MOF-derived materials for supercapacitor applications. Derivatives based on several typical MOFs are discussed with a focus on material synthesis strategies and corresponding supercapacitor performances if applied as electrode materials. Challenges and opportunities in MOFs-derived materials as supercapacitors are also highlighted, and further research directions are proposed to facilitate research and development in this area.
Despite technological advances in neonatology, premature children are still susceptible to disruptions in neurological development. The current study aimed to analyze the factors that influence motor development in prematurely born school-aged children in Brazil. This cross-sectional study involved 100 “apparently normal” children, aged 8–10 years, born at less than 35 weeks of gestation or with birth weight<1500g. Their motor development was assessed using the Movement Assessment Battery for Children (MABC-2). The children's neuropsychological and academic performance was assessed with the Token Test (TT) and Teste de Desempenho Escolar (TDE), respectively. Parents answered questions regarding the child's clinical history and behavior using the Strengths and Difficulties Questionnaire (SDQ) and family environment resources (RAF). Hierarchical multivariate analyses revealed that 39% of the children scored lower on the MABC-2, as compared to that expected for their age (manual dexterity: 49%; balance: 35%; throwing/catching a ball: 26%). Multivariate analysis indicated that the lower the birth weight, the maternal age at childbirth, and the RAF score, the greater was the chance of impairment on the MABC-2 scores. The probability of having an impairment MABC-2 scores was four times higher when the mother was not employed. We also found associations between MABC-2 scores and the tasks of tying shoes and opening/closing zippers and buttons. Factors related to children's home environments and birth weight are associated with deficient motor performance in prematurely born Brazilian school-aged children. Deficient motor skills were also associated with difficulty in performing functional tasks requiring greater manual dexterity.
In this paper, we report the growth of ultrathin Ni(OH)2 nanosheets on nickel foam at room temperature via a cost-effective and simple process, oxidizing fresh nickel foam in a wet environment followed by a morphology transformation in a mixed alkaline and oxidative solution without the need for any additional nickel sources, templates, or surfactants. When tested as electrode for a supercapacitor, the Ni(OH)2 nanosheets grown on nickel foam displayed excellent performance, demonstrating specific capacitance of 2384.3Fg−1 at a charge and discharge current density of 1Ag−1 and 1288.1Fg−1 at 5Ag−1 with a good cycling ability (~75% of the initial specific capacitance remained after 3000 cycles). The excellent electrochemical performance is attributed to its unique nanostructures, which may facilitate rapid ion transport near electrode surfaces, while allowing facile redox reactions associated with charge storage by the nanosheets. The demonstrated high specific capacity and the remarkable rate performance of the Ni(OH)2 nanosheets, together with the flexibility of the nickel foam substrate, make the three-dimensional nanostructured electrodes ideally suited for low-cost, high-performance supercapacitor applications.
Nowadays, the practical application of Li-S batteries is still inhibited by its inferior cycle stability caused by the shuttle effect. Herein, we report the design and fabricate of a fishbone based porous carbon (FBPC) for ultralong cycle life Li-S batteries. Prepared by carbonizing the tuna bone with activation process, FBPC is a heteroatoms-doped hierarchical porous carbon material which owns following merits: i) micropores of FBPC confine the dissolved polysulfides and offer adequate electrochemical reaction interface; ii) mesopores of FBPC not only facilitate infiltration of the electrolyte but also accommodates the volume expansion/contraction during the discharge/charge process; iii) the doped N/S/O heteroatoms increase the reactive sites, present strong polysulfides binding and improve the electroconductivity of carbon matrix. Li-S batteries with FBPC separator exhibit excellent cycling stability (0.064% capacity fading per cycle at 1C) and deliver a high discharge capacity of 1397.5mAhg−1 at 0.2C. Even after 700 cycles the capacity still retain as high as 599.9mAhg−1 at 1C. These superior performances as well as abundant precursor and facile preparation process represent the promising prospect of the designed FBPC being applied to the high-performance Li-S batteries.
Robots are traditionally bound by a fixed morphology during their operational lifetime, which is limited to adapting only their control strategies. Here we present the first quadrupedal robot that can morphologically adapt to different environmental conditions in outdoor, unstructured environments. Our solution is rooted in embodied AI and comprises two components: (1) a robot that permits in situ morphological adaptation and (2) an adaptation algorithm that transitions between the most energy-efficient morphologies on the basis of the currently sensed terrain. We first build a model that describes how the robot morphology affects performance on selected terrains. We then test continuous adaptation on realistic outdoor terrain while allowing the robot to constantly update its model. We show that the robot exploits its training to effectively transition between different morphological configurations, exhibiting substantial performance improvements over a non-adaptive approach. The demonstrated benefits of real-world morphological adaptation demonstrate the potential for a new embodied way of incorporating adaptation into future robotic designs.
Budding willow branches shaped Na3V2(PO4)3/C nanofibers were successfully synthesized by a simple electrospinning technique with Poly(vinyl pyrrilidone) (PVP). The Na3V2(PO4)3/C nanoparticles that anchored on the nanofibers surface seemed like the willow buds; the inner core of the nanofibers, which composed Na3V2(PO4)3, looked like willow twig and the uniform carbon layer was same with willow bark. Such special morphology played a vital role in improving cycle stability and rate capability of the electrode due to the conductive network built up by nanofibers. The Na3V2(PO4)3/C nanofibers cathode exhibited an initial specific capacity of 106.8 mAh g−1 at a current density of 0.2C, still stabling at 107.2 mAh g−1 after 125 cycles with excellent cycle stability. Moreover, a capacity retention of 95.7% was obtained when Na3V2(PO4)3/C nanofibers cycled stepwise from 0.2 to 2C. Good electrochemical performance should be ascribed to both the special morphology and preferential growth of the (113) plane. The simple synthesis technique and good electrochemical performance suggests that this material with the special shape of budding willow branches is a promising cathode for sodium ion batteries.
Latent storages utilising phase change materials (PCM) to store thermal energy offer a considerably higher energy density at a nearly constant temperature level in comparison to sensible storage systems. Despite this advantage, only a few latent storage technologies have been integrated successfully to the market. This may be due several engineering challenges and in particular the lack of a computationally fast and accurate mathematical model to facilitate the optimal incorporation of latent heat storages into an energy system. The presented study fills this gap and proposes a new, fast and experimentally validated mathematical modelling approach for latent heat storage units. The numerical model proposed combines high accuracy, low computational effort and numerical stability. The validation was performed with two different commercial latent storage units supplied by Sunamp Ltd. with a nominal phase change temperatures of 34 °C and of 58 °C. Both units use a salt hydrate based phase change material in combination with a fin-tube heat exchanger. The proposed model may be used for both fast system level performance investigations as well as latent storage design for a given application. It may therefore be implemented in commercial software packages such as TRNSYS [1] or Simulink [2].
To scale up power generation of the direct borohydride fuel cell (DBFC), 10-cell and 20-cell stacks have been constructed based on the single cell achievements. It has been found that the stacking loss of the DBFC is mainly caused by hydrogen evolution which leads to uneven fuel distribution in each cell of the stack. To reduce stacking loss, several efforts have been made to decrease hydrogen evolution influence on the stack performance. The anode preparation method has been modified from a dry-method to a wet-method. The influence of hydrogen evolution on stack performance can be alleviated by altering fuel supply manner. When hydrogen evolution is suppressed, an even distribution of cell voltage can be obtained and the maximum power of 10-cell stack reaches up to 229W.
Nanoimprint lithography (NIL) was used to fabricate electrodes with high specific Pt surface areas for use in micro-fuel cell devices. The Pt catalyst structures were characterized electrochemically using cyclic voltammetry and were found to have electrochemical active surface areas (EAS) ranging from 0.8 to 1.5m2 g−1 Pt. These NIL catalyst structures were tested in fuel cell membrane electrode assemblies (MEA) by directly embossing a Nafion 117 membrane. The features of the mold were successfully transferred to the Nafion and a 7.5nm thin film of Pt was deposited at a wide angle to form the anode catalyst layer. The resulting MEA yielded a very high Pt utilization of 15,375mWmg−1 Pt compared to conventionally prepared MEAs (820mWmg−1 Pt). Embossing pattern transfer was also demonstrated for spin casted Nafion films which could be used for new applications.
Metal–organic frameworks (MOFs) have received special attention in recent years as a result of their attractive and unique properties such as structure flexibility, high surface area, tunable pore size and functionalizable organic linkers and metal centres which have led to vast array of promising applications. Their properties can be improved to further enhance their performance by functionalization of the organic linkers, postsyntheic modification, and doping of nanomaterials into their frameworks. In this review, some recent synthetic methods for the preparation of MOFs are discussed, especially those that are applicable to CO2 adsorption. The second part of this paper discusses the applications of MOFs as heterogeneous catalyst for various CO2 conversion processes, with a view to address some of the challenges faced by the current technology of CO2 conversion which tend to be very energy intensive processes with high level of waste emission and cost. The current state of MOF commercialization for niche markets is also discussed.
To stabilize bromine during charging in zinc-bromide flow batteries, bromine-complexing agent is typically used as a supporting material in electrolyte. This paper describes the influences of the bromine-complexing agent on the electrochemical performances of the zinc deposition and dissolution process during charge and discharge. The surface morphologies before and after the zinc electrodissolution process are compared when using 1-Ethyl-1-methyl-pyrrolidinium bromide as a bromine-complexing agent in electrolyte, and the several measurements including surface chemical analysis are also performed in conjunction with the charge–discharge cell tests. Experimental results show that employing 1-Ethyl-1-methyl-pyrrolidinium bromide in electrolyte, through the formation of an electrostatic shield of 1-Ethyl-1-methyl-pyrrolidinium cations in-and-around the zinc dendrite during charging, provides powerful and effective effects yielding the uniformly flat formation of zinc as well as the prevention of zinc-dendrite growth. It also appears that the diffusion of 1-Ethyl-1-methyl-pyrrolidinium bromide on electrodeposited zinc produces not only two type morphologies of a melting-slurry agglomerate and a furrow ripple but also the change of chemical elemental composition, resulting in higher redox reaction reversibility and activity. Consequently, these results indicate that the propagation of zinc dendrite is mostly controlled by the diffusion rate of the 1-Ethyl-1-methyl-pyrrolidinium species on the zinc metallic surface.
A new phosphonamidate, bis(N,N-diethyl)(2-methoxyethoxy)methylphosphonamidate (DEMEMPA) has been synthesized as N-P collaborative flame retardant additive in electrolytes for lithium ion batteries (LIBs). It is found that adding 10vol.% of DEMEMPA to 0.9M LiPF6/EC/DMC can significantly inhibit the burning of electrolytes and provide a wide electrochemical window. Further studies indicate that the electrolytes with and without DEMEMPA have similar electrochemical behavior with natural graphite and LiFePO4 electrodes. These support the feasibility of using DEMEMPA as a flame retardant additive for LIBs.
This work presents results obtained from the production of low-cost carbons from expanded graphite (EG) and pinecone (PC) biomass, activated in potassium hydroxide (KOH) and finally carbonized in argon and hydrogen atmosphere. A specific surface area of 808m2 g−1 and 457m2 g−1 were measured for activated pinecone carbon (APC) and activated expanded graphite (AEG), respectively. The electrochemical characterization of the novel materials in a 2-electrode configuration as supercapacitor electrode shows a specific capacitance of 69Fg−1 at 0.5Ag−1, high energy density of 24.6Whkg−1 at a power density of 400Wkg−1. This asymmetric supercapacitor also exhibits outstanding stability after voltage holding at the maximum voltage for 110h, suggesting that the asymmetric device based on different carbon materials has a huge capacity for a high-performance electrode in electrochemical applications.
The heat generation behavior in the overcharge has been investigated experimentally for various lithium-ion cells. Generated heat flow was examined by calorimetric measurement for different charging rates as a parameter and discussed. It is clarified that the heat generation during the overcharge is almost proportional to charging current. It is considered that if the cooling system can remove the equivalent heat to electrical input, it is possible to prevent the thermal-runaway which originates from the overcharge.
Anatase TiO2 nanostructure coated and composited with N-doped carbon was simply fabricated by using acrylonitrile as carbon source. The carbon-coated composite with the TiO2 nanoparticles dispersed uniformly in the carbon matrix exhibits a high reversible capacity of 223.7 mAh g−1 after cycling 100 times at 100 mA g−1, excellent cycling stability and superior high rate performance (243.5, 219.0, 198.5, 175.8, 153.4 and 130.9 mAh g−1 at 100, 200, 400, 800, 1600 and 3200 mA g−1, respectively) when the carbonization temperature is around 550 °C. The synergistic effect of the combined coating and compositing the N-doped carbon is responsible for the outstanding electrochemical performance.
Here, we report that spherical C60 derivatives with well-defined molecular structures hold great promise to be advanced anode materials for lithium-ion batteries (LIBs). We studied four C60 molecules with various functional groups, including pristine, carboxyl, ester, and piperazine C60. The comparison of these C60s elucidated a strong correlation between functional group, overall packing (crystallinity), and the anode performance in LIBs. Specifically, carboxyl C60 and neutral ester C60 showed higher charge capacities than pristine C60, whereas positively-charged piperazine C60 exhibited lower capacity. The highest charge capacity was achieved on the carboxyl C60 (861mAhg−1 at 100th cycle), which is five times higher than that of pristine C60 (170mAhg−1), more than double the theoretical capacity of commercial graphite (372mAhg−1), and even higher than the theoretical capacity of graphene (744mAhg−1). Carboxyl C60 also showed a high capacity at a fast discharge-charge rate (370mAhg−1 at 5C). The exceptional performance of carboxyl C60 can be attributed to multiple key factors. They include the complex formation between lithium ions and oxygen atoms on the carboxyl group, the improved lithium-binding capability of C60 cage due to electron donating from carboxylate groups, the electrostatic attraction between carboxylate groups and lithium ions, and the large lattice void space and high specific area due to carboxyl functionalization. This study indicates that, while maintaining the basic C60 electronic and geometric properties, functionalization with desired groups can achieve remarkably enhanced capacity and rate performance for lithium storage.
Mechanical failure is an important reason for electrode degradation, especially for the anodes with large volume change during the electrochemical cycles. Plenty of studies prove that nanostructure materials under the critical size would significantly improve the stability of the electrodes. The commercial electrodes are inevitable defective during preparation, and the defect induced fractures will reduce the critical size. However, the mechanisms of this phenomenon are still unclear and lack of the support of precise experiments. In the present study, silicon islands under critical size are prepared and different types of defects with various curvatures are designed in the island electrodes. The in-situ experiments are employed to observe crack appearance, and the defects with higher curvatures are found to fail earlier than the others. Furthermore, the finite element analysis is used to quantitatively calculate the stress evolution around each defect. The results also show that the safe (no fracture) area of the electrodes is reduced by the defects with high curvature, and the critical failure state of charge could be obtained by the experiments and simulation data.
Enabling fast charging of lithium-ion batteries may accelerate the commercial application of electric vehicles (EVs). The fast charging, however, could lead to capacity fade, lithium plating, and thermal runaway. This paper develops an optimal multi-stage charging protocol for lithium-ion batteries to minimize capacity fade due to the solid-electrolyte interphase (SEI) increase, to maximize the SEI potential to decrease the lithium plating, and to reduce the temperature rise to avoid a thermal runaway situation. An electrochemical-thermal-capacity fade coupled model is developed to monitor the battery internal state. The dynamic programming (DP) optimization algorithm is employed to search for the suboptimal charging current profiles. The optimization results illustrate that the optimized charging current profile varies with the state of charge (SOC) and the cycle number. As compared to the constant current charging protocol, each optimized charging strategy can reduce the capacity fade ratio by 4.6%, increase the SEI potential by 57%, and reduce the temperature rise by 16.3% for over 3300 charging-discharging cycles, respectively.
A Si-based alloy as the negative electrodes of the Lithium-ion batteries (LIBs) possesses the advantages of high discharge capacity and better safety, but low electronic conductivity and poor property limit Si-based anode materials to commercialize for the LIBs. In this article, in order to solve the problems of poor conductivity and cycling instability, core-shell structured Si/Ni nanoparticles encapsulated in graphene nanosheet (Si@Ni-NP@GNS) has been proposed to enhance the electronic conductivity and cycling stability. The nanocomposite was characterized by using the measures of X-ray diffraction and transmission electron microscopy. The Si nano-particles as centre of sphere were coated with interconnected GNS and nickel-plated layer. The electrochemical performance was tested by cyclic voltammetry and galvanostatic charge-discharge tests. The nanocomposite behaves excellent specific capacity, outstanding cycle stability and perfect rate capability, the results show a reversible charge capacity of 2005 mA h g−1 after 50 cycles, which are superior to those of Si@GNS anode and Si@Ni-NP anode. We can be sure that the enhanced electrochemical performance is due to the core-shell structure, which interconnected GNS and nickel-plated layer act as buffer compound to avoid the excessive volume expansion and the electrode pulverization.