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As the cathode materials for rechargeable lithium batteries, five commercial lithium cobalt oxide powders have been investigated for a comparative study. The X-ray diffraction analysis indicates that all these powders exhibit the α-NaFeO2 layered structure. The size distribution and morphology were analyzed by particle sedimentation method and scanning electron microscopy (SEM). Their electrochemical properties including cycleability and especially 3.6V plateau efficiency, a recently required control parameter, are compared. Two kinds of modifications, i.e. Li2CO3 coating and high-temperature treatment, have been applied to improve the electrochemical performance of one of these five powders. After the high-temperature treatment in air, cobalt oxidation-state becomes higher and Li(Li x Co1−x )O2 is formed. Both of the two modified means can significantly improve the 3.6V-plateau efficiency through suppressing the cell impedance rise during cycling. A general discussion on the factors influencing the plateau efficiency is also given.
To overcome the voltage decay upon cycling and increase the initial coulombic efficiency of the layered Li-rich Mn-based oxides, the double modification combining Na2S2O8 treatment with CaF2 coating has been first proposed in this study. The precondition Na2S2O8 treatment activates the Li2MnO3 phase gently and generates a stabilized three-dimensional spinel structure on the surface of particles, leading to a suppression of surface reaction and structure conversion during the subsequent electrochemical process. The mitigation of phase transformation for Na2S2O8-treated Li1.2Mn0.54Ni0.13Co0.13O2 alleviates the voltage decay and energy density degradation upon long-term charge-discharge cycling. In order to further restrain the capacity loss derived from the HF attack and manganese dissolution, 40 wt% Na2S2O8 treated-sample has been modified by an amorphous CaF2 layer with nano-scale thickness. The first-reported CaF2-coated/40 wt% Na2S2O8 treated-Li1.2Mn0.54Ni0.13Co0.13O2 presents excellent electrochemical properties with a high initial coulombic efficiency of 99.2%, a capacity retention rate of 89.2% after 200 cycles and a high-rate capability of 152.1 mAh g−1 at 3C. The double surface modification offers a smart design concept for Li-rich Mn-based oxides to meet the practical requirements for advanced lithium ion batteries in electric vehicles.
Nano-engineering of silicon anodes has contributed to the demonstration of a promising potential for high energy lithium ion batteries, through addressing the degradation of battery performance derived from severe volume changes during cycling. However, the practical use of nano-engineered silicon anodes is still stuck because of remaining challenges, such as the low tap density, poor scalability and inferior electrical properties. Herein, we successfully developed a new Fe–Cu–Si ternary composite (FeCuSi) by scalable spray drying and facile heat treatment. As a result, FeCuSi exhibited remarkable initial Coulombic efficiency (91%) and specific capacity (1287 mA h g−1). In order to exactly characterize the electrical properties of FeCuSi and directly compare them with industrially developed benchmarking samples such as silicon monoxide (SiO) and a silicon-metal alloy (Si2Fe), both half-cell and full-cell tests were performed with high electrode density (1.6 g cc−1) and high areal capacity (3.4 mA h cm−2). Overall, FeCuSi outperformed the benchmarking samples in terms of discharge capacity and capacity retention in high mass loading for 300 cycles.
Due to the increasing generation capacity of intermittent renewable electricity sources and an electrical grid ill-equipped to handle the mismatch between electricity generation and use, the need for advanced energy storage technologies will continue to grow. Currently, pumped-storage hydroelectricity and compressed air energy storage are used for grid-scale energy storage, and batteries are used at smaller scales. However, prospects for expansion of these technologies suffer from geographic limitations (pumped-storage hydroelectricity and compressed air energy storage), low roundtrip efficiency (compressed air energy storage), and high cost (batteries). Furthermore, pumped-storage hydroelectricity and compressed air energy storage are challenging to scale-down, while batteries are challenging to scale-up. In 2015, a novel compressed gas energy storage prototype system was developed at Oak Ridge National Laboratory. In this paper, a near-isothermal modification to the system is proposed. In common with compressed air energy storage, the novel storage technology described in this paper is based on air compression/expansion. However, several novel features lead to near-isothermal processes, higher efficiency, greater system scalability, and the ability to site a system anywhere. The enabling features are utilization of hydraulic machines for expansion/compression, above-ground pressure vessels as the storage medium, spray cooling/heating, and waste-heat utilization. The base configuration of the novel storage system was introduced in a previous paper. This paper describes the results obtained from a transient, analytical, physics-based thermodynamic system model used for the system design and evaluation of three design configurations (including base configuration). The system model captures real gas effects and all loss mechanisms. The model demonstrates an energy storage roundtrip efficiency of 82% and energy density of 3.59MJ/m3. Experimental evaluation of system performance and detailed cost-analysis will be presented in future publications.
Commercial 6.8 Ah lithium-ion cells with different ageing/status have been abused by external heating in an oven. Prior to the abuse test, selected cells were aged either by C/2 cycling up to 300 cycles or stored at 60 °C. Gas emissions were measured by FTIR and three separate vents were identified, two well before the thermal runaway while the third occurred simultaneously with the thermal runaway releasing heavy smoke and gas. Emissions of toxic carbon monoxide (CO), hydrogen fluoride (HF) and phosphorous oxyfluoride (POF3) were detected in the third vent, regardless if there was a fire or not. All abused cells went into thermal runaway and emitted smoke and gas, the working cells also released flames as well as sparks. The dead cells were however less reactive but still underwent thermal runaway. For about half of the working cells, for all levels of cycle ageing, ignition of the accumulated battery released gases occurred about 15 s after the thermal runaway resulting in a gas explosion. The thermal runaway temperature, about 190 °C, varied somewhat for the different cell ageing/status where a weak local minimum was found for cells cycled between 100 and 200 times.
Background Apathy is one hallmark of major depression (MDD). It is distinguished by lack of emotion, whereas other aspects of depression involve considerable emotional distress. Investigating both apathy and depression may increase the degree of treatment efficacy for both ailments together and apart. Objective Evaluate the differential effects of deep transcranial magnetic stimulation (DTMS) over the prefrontal cortex (PFC) on apathy and other aspects of depression in patients suffering from a depressive episode. Methods Fifty-four treatment-resistant MDD patients were evaluated with the Hamilton Rating Scale for Depression (HRSD), and then treated with DTMS. Apathy-related items from HRSD (ApHRSD) were compared with the remaining items from HRSD (DepHRSD). Antidepressant medications were withdrawn and active DTMS treatment was administered at 20 Hz, 5 days a week for 4 weeks. Changes in HRSD were recorded. Primary efficacy time point was 1 week after the end of active treatment. Results At screening, ApHRSD distribution was unimodal (moderate apathy), with low correlation (r = 0.17) between ApHRSD and DepHRSD. After treatment, a third had remitted apathy, and the correlation between ApHRSD and DepHRSD had dramatically increased (r = 0.83). Severe ApHRSD (≥ 7) at screening correlated with nonremission for both ApHRSD (R 2 = 0.1993, P = .0012) and DepHRSD (R 2 = 0.0860, P = .0334). Conclusions DTMS over the PFC improved both apathy and depression similarly. However, DTMS did not lead to MDD remission if ApHRSD at screening was ≥ 7 of 12. Further investigation using a larger sample will determine whether screening apathy at baseline could be used to predict efficacy of DTMS in MDD patients.
Increased usage of renewable energy resources is key for energy system evolution to address environmental concerns. Capturing variable renewable power requires the use of energy storage to shift generation and load demand. The integration of plug-in electric vehicles, however, impacts the load demand profile and therefore the capacity of energy storage required to meet renewable utilization targets. This study examines how the intelligence of plug-in electric vehicle (PEV) integration impacts the required capacity of energy storage systems to meet renewable utilization targets for a large-scale energy system, using California as an example for meeting a 50% and 80% renewable portfolio standard (RPS) in 2030 and 2050. For an 80% RPS in 2050, immediate charging of PEVs requires the installation of an aggregate energy storage system with a power capacity of 60% of the installed renewable capacity and an energy capacity of 2.3% of annual renewable generation. With smart charging of PEVs, required power capacity drops to 16% and required energy capacity drops to 0.6%, and with vehicle-to-grid (V2G) charging, non-vehicle energy storage systems are no longer required. Overall, this study highlights the importance of intelligent PEV charging for minimizing the scale of infrastructure required to meet renewable utilization targets.
The electrochemical behaviors of lithium difluoro(oxalate)borate (LiODFB) and LiBF4 blend salts in ethylene carbonate + dimethyl carbonate + ethyl(methyl) carbonate (EC + DMC + EMC, 1:1:1, by wt.) have been investigated for LiNi0.5Mn1.5O4 cathode in lithium-ion batteries. The electric conductivity tests are utilized to examine the relationship among solution conductivity, the electrolyte composition and temperature. Through cyclic voltammetry, charge–discharge test and AC impedance measurements, we compare the capacity and cycling efficiency of LNMO cathode in different electrolyte systems at different temperatures and discharge current rates. Scanning electron microscopy (SEM) analysis and X-ray photoelectron spectroscopy (XPS) are served to analyze the surface nature of LNMO cathode after cycles at elevated temperature. These results demonstrate that LNMO cathode can exert excellent electrochemical performance with the increase of LiODFB concentration at room temperature and elevated temperature and it is found that just slight LiBF4, mixed with LiODFB as blend salts, can strikingly improve the cyclability at −20 °C, especially in high-rate cycling. Grouped together, the optimum LiODFB/LiBF4 molar ratio is around 4:1, which can present an excellent affinity to LNMO cathode in a wide electrochemical window.
Sulfonated poly(ether ether ketone) has been investigated as an ionomer in the catalyst layer for direct methanol fuel cells (DMFC). The performance in DMFC, electrochemical active area (by cyclic voltammetry), and limiting capacitance (by impedance spectroscopy) have been evaluated as a function of the ion exchange capacity (IEC) and content (wt.%) of the SPEEK ionomer in the catalyst layer. The optimum IEC value and SPEEK ionomer content in the electrodes are found to be, respectively, 1.33meq.g−1 and 20wt.%. The membrane-electrode assemblies (MEA) fabricated with SPEEK membrane and SPEEK ionomer in the electrodes are found to exhibit superior performance in DMFC compared to that fabricated with Nafion ionomer due to lower interfacial resistance in the MEA as well as larger electrochemical active area. The MEAs with SPEEK membrane and SPEEK ionomer also exhibit better performance than that with Nafion 115 membrane and Nafion ionomer due to lower methanol crossover and better electrode kinetics.
Publisher Summary This chapter provides an overview of nickel batteries. Numerous types of nickel batteries are discussed, such as nickel-cadmium secondary batteries, nickel-hydrogen batteries, and sodium-nickel chloride secondary batteries. Specification of the types of batteries is provided according to its manufacturer. SAFT (Socirt6 des Accumulateurs Fixes et de Traction), a major manufacturer of alkaline batteries, produce a full range of sealed nickel-cadmium batteries, including open type (GPX) and semi-open type (VOK-VOKH-VHP), both of which are higher capacity types. SAFT also produce sealed cells and batteries and button cells. Varta supply a non-sealed double cell (DTN) for portable lamps. This battery is available in a capacity range 4.5-11 A h. It has a light weight, even voltage level, good capacity, long service life, lack of maintenance and low self-discharge rate. Yardney USA pioneered the development of nickel-zinc battery and are still the main suppliers. The original application was electric traction, and a number of road vehicles are now operating powered by Yardney experimental batteries.
A series of LiMn0.8Fe0.19Mg0.01PO4/C composites with different carbon content are synthesized and the effect of carbon content on properties of LiMn0.8Fe0.19Mg0.01PO4 is studied. The results show that the rate capability of LiMn0.8Fe0.19Mg0.01PO4/C is highly dependent on carbon content, and the LiMn0.8Fe0.19Mg0.01PO4/C with 10.5wt.% carbon exhibits the best coverage of carbon coating and the optimal rate performance. When the carbon content is reduced to 4.1wt.%, the obtained LiMn0.8Fe0.19Mg0.01PO4/C still has an excellent rate capability and can deliver a discharge capacity of 138.5 mAh g−1 at 1C, 121.7 mAh g−1 at 5C and 109.6 mAh g−1 at 10C. This is the best rate performance reported so far for low carbon coated LiMnPO4 based materials.
Magnesium – ion batteries have the potential for high energy density but require new types of electrolytes for practical application. Ionic liquid (IL) electrolytes offer the opportunity for increased safety and broader voltage windows relative to traditional electrolytes. We present here a systematic study of both the conductivity and oxidative stability of hybrid electrolytes consisting of eleven ILs mixed with dipropylene glycol dimethylether (DPGDME) or acetonitrile (ACN) cosolvents and magnesium bis(trifluoromethylsulfonyl)imide (Mg(TFSI)2). Our study finds a correlation of higher conductivity of ILs with unsaturated rings and short carbon chain lengths, but by contrast, these ILs also exhibited lower oxidation voltage limits. For the cosolvent additive, although glymes have a demonstrated capability of coordination with Mg2+ ions, a decrease in conductivity compared to acetonitrile hybrid electrolytes was observed. When cycled within the appropriate voltage range, the IL-hybrid electrolytes that show the highest conductivity provide the best cathode magnesiation current densities and lowest polarization as demonstrated with a Mg0.15MnO2 and Mg0.07V2O5 cathodes.
The article deals with the accumulation unit calculation deployed in renewable energy sources system. It is assumed that accumulation unit consists of a defined number of batteries. There are two cases which are analyzed and discussed in this article. The first case determines how many batteries have to be connected to store input energy. The second one determines how many batteries have to be connected to provide output energy to connected electronic devices.
In order to successively compete with supercapacitors, an ability of fast discharge is a must for lithium-ion batteries. From this point of view, stoichiometric and substituted lithium manganese spinels as cathode materials are one of the most prospective candidates, especially in their nanosized form. In this article, an overview of the most recent data regarding physico-chemical and electrochemical properties of lithium manganese spinels, especially, LiMn2O4 and LiNi0.5Mn1.5O4, synthesized by means of various methods is presented, with special emphasis of their use in high-rate electrochemical applications. In particular, specific capacities and rate capabilities of spinel materials are analyzed. It is suggested that reduced specific capacity is determined primarily by the aggregation of material particles, whereas good high-rate capability is governed not only by the size of crystallites but also by the perfectness of crystals. The most technologically advantageous solutions are described, existing gaps in the knowledge of spinel materials are outlined, and the ways of their filling are suggested, in a hope to be helpful in keeping lithium batteries afloat in the struggle for a worthy place among electrochemical energy systems of the 21st century.
As we are facing increasing challenges of diminishing fossil fuel and global warming, there is increasing interest in developing advanced and cost effective electrochemical energy storage devices for diverse applications including mobile power supply to portable electronics, electric vehicles (EVs) or hybrid EVs (HEVs). To this end, layered double hydroxides (LDHs) have gained considerable attention in the past decade as a unique class of electrode materials due to their multiple cations, flexible ion exchangeability and tunable compositions. With abundant slabs and electrochemically active sites, the LDHs can used to produce energy storage devices with both the double-layer capacitance and Faradaic pseudo-capacitance. In this review, we summarize and discuss recent progress in the synthesis of LDHs based materials for electrochemical energy storage devices including lithium ion batteries and electrochemical supercapacitors.
A series of polypyrrole-LiFePO4 (PPy-LiFePO4) composites were synthesised by polymerising pyrrole monomers on the surface of LiFePO4 particles. AC impedance measurements show that the coating of polypyrrole significantly decreases the charge-transfer resistance of LiFePO4 electrodes. The electrochemical reactivity of polypyrrole and PPy-LiFePO4 composites for lithium insertion and extraction was examined by charge/discharge testing. The PPy-LiFePO4 composite electrodes demonstrated an increased reversible capacity and better cyclability, compared to the bare LiFePO4 electrode.
An attempt has been made to evaluate comparatively the behavior of 2-methylaniline (2MA) and 3-methylaniline (3MA) during electrochemical homo- and copolymerization. As comonomer in the copolymerization bath with 2MA and 3MA 1,2-diaminobenzene (1,2-DAB), an aromatic diamine, was selected. Cyclic voltammetry was used both for the electrochemical synthesis and characterization of the homopolymers and copolymers on a gold electrode. In the copolymerization bath mixed solutions of the monomers having different concentrations of 1,2-DAB and a constant concentration of 2MA or 3MA were used. The voltammograms exhibit different behavior for different concentration ratios of the monomer in the feed. The homopolymers poly(2-methylaniline) (P2MA) and poly(3-methylaniline) (P3MA) show similar electrochemical properties. However, differences were observed in the properties between the copolymers of 2MA and 3MA with 1,2-DAB that could be due to the variation in the monomer units and orientation along the copolymer chains. The copolymerization of 1,2-DAB seems to be more facilitated when instead of 3MA, 2MA is present as comonomers. The effect of scan rate and pH on the electrochemical activity was studied. The copolymers are surface confined, electroactive and show good electrochemical activity even at pH=8.0 and pH=9.0 in case of poly(1,2-DAB-co-3MA) and poly(1,2-DAB-co-2MA), respectively. In situ conductivity measurements further support the differences in the structure of the copolymers of 1,2-DAB with 2MA and 3MA.
Expanding oil palm plantations have caused widespread deforestation and biodiversity loss in Southeast Asia, stigmatizing the industry around the world regardless of regional context. In Latin America, oil palm plantations are primarily replacing other agroindustrial land uses with uncertain implications for local biodiversity.
Improving the reversibility and energy efficiency of Li–CO2 electrochemistry would help in developing practical Li–air batteries capable of providing stable power supply in the presence of CO2. However, it is hard for most existing electrodes to convert CO2 effectively (high discharge capacity) and efficiently (low charge potential). Herein, we have, for the first time, identified the potential of metal–organic frameworks (MOFs) as porous catalysts in CO2 electrodes, taking advantage of their high capability for CO2 capture and monodispersed active metal sites for Li2CO3 decomposition. In particular, eight porous MOFs (Mn2(dobdc), Co2(dobdc), Ni2(dobdc), Mn(bdc), Fe(bdc), Cu(bdc), Mn(C2H2N3)2, and Mn(HCOO)2) and two nonporous materials (MnCO3 and MnO) were investigated. Among them, Mn2(dobdc) achieves a remarkable discharge capacity of 18022 mA h g−1 at 50 mA g−1, while Mn(HCOO)2 retains a low charge potential of ∼4.0 V even at 200 mA g−1 for over 50 cycles. The Li–CO2 electrochemistry on MOF electrodes was investigated with an arsenal of characterization techniques, including X-ray diffraction, scanning electron microscopy, electrochemical impedance spectroscopy, Raman spectroscopy and in situ differential electrochemical mass spectrometry. The findings provide useful design principles for improving the reversibility and energy efficiency of Li–CO2 electrochemistry and will herald the advent of practical technologies that enable energy-efficient utilization of CO2 for electrochemical energy storage and supply.
The global circulation of the Venus atmosphere is characterized at cloud level by a zonal super rotation studied over the years with data from a battery of spacecrafts: orbiters, balloons and probes. Among them, the Galileo spacecraft monitored the Venus atmosphere in a flyby in February 1990 in its route toward Jupiter. Since the flyby was almost equatorial, published analysis of zonal winds obtained from displacements of cloud elements on images obtained by the SSI camera [Belton, M.J.S., and 20 colleagues, 1991. Science 253, 1531–1536] stop at latitudes 50° north and south. In this paper we present new results on Venus winds based on a reanalysis of an extended set of images obtained at two wavelengths, 418 nm (violet) and 986 nm (near infrared), that sense different altitude levels in the upper cloud. Our main result is that we have been able to extend the zonal wind profile up to the polar latitudes: 70° N and 70° S at 418 nm and 70° N at 986 nm. Binned and smoothed profiles are given in tabular form. We show that the zonal winds drop in their velocity poleward of latitudes 45° N and 50° S where an intense meridional wind shear develops at the two cloud levels. Our data confirm the magnitude of this shear, retrieved previously from radio occultation data, but disagrees with it in the latitudinal location of the sheared region. The new wind data can be used to recalibrate the zonal winds retrieved from the previous measurements of the temperature field and the cyclostrophic balance assumption. The meridional profiles of the zonal winds at the two cloud levels are used to assess the vertical wind shear in the upper cloud layer as a function of latitude and locate the most unstable region.