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We have synthesized carbon coated LiFePO4 (C-LiFePO4) and C-Li1.05FePO4 with 5 mol% excess Li via sol–gel method using oleic acid as a source of carbon for enhancing electronic conductivity and reducing the average particle size. Although the phase purity of the crystalline samples was confirmed by x-ray diffraction (XRD), the 57Fe Mössbauer spectroscopy analyses show the presence of ferric impurity phases in both stoichiometric and non-stoichiometric C-LiFePO4 samples. Transmission electron microscopy measurements show nanosized C-LiFePO4 particles uniformly covered with carbon, with average particle size reduced from ∼100 nm to ∼50 nm when excess lithium is used. Electrochemical measurements indicate a lower charge transfer resistance and better electrochemical performance for C-Li1.05FePO4 compared to that of C-LiFePO4. The aim of this work is to systematically analyze the nature of impurities formed during synthesis of LiFePO4 cathode material, and their impact on electrochemical performance. The correlation between the morphology, charge transfer resistance, diffusion coefficient and electrochemical performance of C-LiFePO4 and C- Li1.05FePO4 cathode materials are discussed.
Publisher Summary This chapter provides na overview of mercy batteries. It discusses different types of batteries, such as mercury-zinc batteries, mercury-indium-bismuth, and mercury-cadmium primary batteries. Mercury batteries have an appreciably higher energy-to-weight ratio than carbon-zinc batteries, resulting from the high energy density of the materials used in their construction. Thus mercury batteries are only one-third the size of conventional dry batteries of the same capacity. The ampere hour capacity of mercury cells and batteries is relatively unchanged with variation of discharge schedule and, to some extent, with variation of discharge current. They have a relatively fiat discharge characteristic. Mercuric oxide batteries are available with two formulations designed for different field usage. Further, mercury-indium-bismuth and mercury-cadmium batteries are alkaline systems recommended for applications where high reliability in particularly onerous long-term storage and use conditions is a prime requirement. For example, the particular advantage of mercury-cadmium is that it will show good performance at low temperatures even below -20°C, where most other primary systems just would not function. Typical applications include reactor and high-temperature processing, telemetry systems and military uses.
Although demand response (DR) potentially brings miscellaneous advantages, it is currently faced with challenges in its implementation due to customers’ difficulty in manually responding to the time-varying prices. This paper presents an optimal and automatic residential load commitment (LC) framework to achieve the household minimum payment. Problem decision variables are the operating status of responsive appliances and charging/discharging cycles of battery storage and plug-in hybrid electric vehicles (PHEVs). Storage capability in residential centers provide the customers with this opportunity to not only supply the local demand during the high price hours but also sell the energy back to the utility. The optimization-based LC shifts the responsive loads to inexpensive periods which rationally coincide with the valley of consumption profile. As a matter of fact, the peak to average ratio (PAR) of the load profile would likely decrease which, although might be unappealing to the customers, is desirable from the utility viewpoint. Direct load control (DLC) is also modeled by using the proposed LC approach. In the DLC program, a customer receives a rather fair tariff allowing the utility to control a set of specific devices. Customer inconvenience is considered as the factor restricting a complete DLC realization. Numerical simulations are conducted to illustrate the proposed notions and to verify the efficiency of the developed model.
Carbonized porous aromatic framework (CPAF) nanobeads with 75wt% S (SCPAF) were synthesized by a simple method. The surface areas of CPAF and SCPAF were 679.8m2·g−1 and 2.0m2·g−1 respectively, and the predominant micropores both centered at 0.46nm. The spherical morphology guaranteed high tap density of Li-S batteries. After S loading, the SCPAF nanobeads exhibited excellent electrochemical performances. It showed high initial capacity of 1397.3mAh∙g−1 at 0.2C, which is 83.4% of the theoretical value of sulfur. And at 0.5C, it shows 0.074% decay rate per cycle over 1000 cycles. The good rate capability and long-term cycling stability indicated CPAF nanobeads composite is a promising sulfur support for Li-S batteries.
The new compound Li1.65Na0.35Fe[PO4]F with the Li2Ni[PO4]F structure has been prepared from the analogous LiNaFe[PO4]F phase by ion exchange using LiBr in ethanol at 90 °C. The sample was characterized by powder X-ray diffraction, 57Fe Mӧssbauer spectroscopy, and electrochemical measurements. Li1.65Na0.35Fe[PO4]F crystallizes with orthorhombic symmetry, space group Pnma, with a = 10.5093(5) Å, b = 6.4999(2) Å, c = 11.0483(5) Å, V = 754.70(7) Å3, and Z = 8. The 57Fe Mӧssbauer data collected at different stages of galvanometric cycling confirmed that only 1 mol of alkali metal is extractable between 1.0 V and 5.1 V vs. Li+/Li with a discharge capacity between 135 and 145 mA h g−1. Li/Na electrochemical ion exchange occurs during cycling and leads to a lithium rich phase.
The hierarchical porous carbon materials with specific areas from 3425.688m2 g−1 to 988.768m2 g−1 and total pores volumes from 1.979cm3 g−1 to 0.434cm3 g−1 were prepared by carbonization of the polypyrrole precursor and activated with potassium hydroxide under different activation conditions. Among them, two kinds of hierarchical porous carbon materials with similar high specific surface area were investigated by SEM, TEM, XRD, BET and electrochemical methods after loading 70wt% sulfur in micropores, in order to study the key role of the micro-/mesoporous carbonaceous structure in influencing the electrochemical performance of sulfur. The test results show that the hierarchical porous carbon with higher mesopores content exhibited better cycle and rate performance after loading 70wt% sulfur, attributing to the efficient penetration of electrolyte and migration of Li+.
SiO x has emerged as an important alternative to silicon as the high capacity anode host to store lithium due to its smaller volume change upon lithiation. However, conventional synthesis methods generally require harsh reaction conditions, making its production in industrial scale much challenging. Herein, a safe, economical and scalable approach is developed for SiO x using highly abundant natural silica as starting material via a magnesio-mechanochemical reduction process induced by ball-milling. The as-prepared SiO x is intrinsically porous and comprised of mixed nano clusters of SiO2 and Si. Upon lithiation, SiO2 nano domains convert into lithium silicates and Li2O, which help to absorb Si volume expansion and participate in the formation of a stable solid electrolyte interface. Such synergistic effect leads to exceptional cycling stability up to 2000 cycles with 71.3% capacity retention under 4 A g−1. After blending with graphite, a high areal capacity of 2.64 mAh cm−2 demonstrates stable cycling of 89.7% retention over 200 cycles with an high initial Coulombic efficiency of 82.3%, implying the feasibility for practical applications. Structural and compositional characterizations reveal the involved chemistry and evolution mechanism of the formed solid electrolyte interface upon cycling, providing guidelines of designing future silicon-based materials for future Li-ion batteries.
Position represents a relevant attribute needed by many applications, whose contexts are characterized by pervasiveness of the objects/things in the considered scenarios. In order to infer positions of pervasive objects, which are neither equipped with any location-sensing technologies, nor are unable to locate themselves, it is needed to support them with an appropriate infrastructure, which allows to determine their position in a manner that is transparent to applications. In this work, we aim at extending the positioning service using an agent-based approach, in order to discover and localize different kinds of objects, exploiting cheap and embedded technologies. We describe the design and the implementation of a layered architecture, that supports the localization of devices, and simple pervasive and ubiquitous objects. A simulation tool has been develop to evaluate the proposed solution in different application scenarios of every-day life.
Facility experience primarily in drug-oriented fermentation equipment (producing small molecules such as secondary metabolites, bioconversions, and enzymes) and, to a lesser extent, in biologics-oriented fermentation equipment (producing large molecules such as recombinant proteins and microbial vaccines) in an industrial fermentation pilot plant over the past 15 years is described. Potential approaches for equipment design and maintenance, operational procedures, validation/verification testing, medium selection, culture purity/sterility analysis, and contamination investigation are presented, and those approaches implemented are identified. Failure data collected for pilot plant operation for nearly 15 years are presented and best practices for documentation and tracking are outlined. This analysis does not exhaustively discuss available design, operational and procedural options; rather it selectively presents what has been determined to be beneficial in an industrial pilot plant setting. Literature references have been incorporated to provide background and context where appropriate.
A series of novel room-temperature ionic liquid (RTIL) salts based on C n (MIm) i A and C n (TMA) i A (i =1, 2 as single- and double-cation form, respectively; n =4, 5, 6; A=BF4 −, TFSI−), where MIm, TMA, and TFSI indicate 3-methylimidazolium, trimethylammonium, and bis(trifluoromethanesulfonyl)imide, respectively, are synthesized varying the number of alkyl chains, e.g., butane (n =4), pentane (n =5), and hexane (n =6) in the main backbone. Ionic conductivities of each RTIL salt are measured after dissolving with propylene carbonate (PC) or acetonitrile (ACN) at the salt concentration of 0.5M. A supercapacitor containing activated carbon as an active material in the organic electrolyte containing ionic liquid salts is fabricated to evaluate the supercapacitive properties using cyclic voltammetry. It is found that the effects of counter-anions (BF4 − and TFSI−) and the number of cations (single- and double-cation) in RTIL salts on the supercapacitive property are of importance in determining their potential applications for energy storage devices.
TiO2 (anatase) nanocrystals were prepared and their surface was modified by sol–gel deposition of vanadium oxide species. The resulting surface-modified TiO2 combines the good properties of both materials and new, synergistic properties arise, resulting in an increased electrical conductivity, voltage window, specific capacitance, and cycling stability.
A novel methodology for lifetime prognosis of Li-ion cells is presented, covering the validity and accuracy assessment of the predictions. It is especially focused on the procedures for the evaluation of semi-empirical ageing model development process. Combined calendar and cycle ageing is investigated with dynamic and realistic complex operation profiles, as part of the stepwise validation methodology that is proposed. The dynamic validation approach allows identifying the sources of model errors by analysing how the individual stress factors are adjusted under non-constant profiles. The results correspond to a LFP-based 26650-size cell. The presented model is suitable for different applications, such as elevator or vehicle combined with vehicle-to-grid (V2G) use, with 1.4% root-mean-square error accuracy.
We compare POC fluxes estimated using 234Th/238U and 210Po/210Pb disequilibria at the DYFAMED site, northwestern Mediterranean Sea. We also compare the POC fluxes estimated from these two isotope pairs with fluxes below the euphotic zone measured in moored sediment traps. The POC flux at 200m estimated from 234Th and 210Po deficits and the POC/210Po or POC/234Th on >70μm filterable particles measured through three seasons (early spring, late spring, summer) ranged from 3.8 to 17.5mmol C/m2/d based on 234Th/238U and from 4.4 to 7.0mmol C/m2/d based on 210Po/210Pb disequilibrium. In comparison, sediment trap fluxes of POC at approximately 200m ranged from 0.2 to 6.0mmol C/m2/d over the same interval. Values of POC/210Po and POC/234Th ratios in sediment trap material collected in time series or separated according to settling velocity (SV) were generally lower than values in the >70μm filterable particles at the same depth. The variation in POC/210Po and POC/234Th in material separated according to SV showed no clear relationship with SV and was controlled more by particle composition and degree of degradation. Both 234Th and 210Po showed sustained deficits in late spring and summer, despite low fluxes recorded in the trap. Lateral processes (transport of particles along isopycnals or intrusion of shelf waters to the site) and violations of temporal assumptions (steady-state vs. non-steady-state) may be responsible for this disparity. Based on the results of this study, we conclude that 210Po/210Pb disequilibrium is as valid as 234Th/238U as a proxy for estimating POC flux in the ocean.
We demonstrate the synthesis of new Cu–Si1−x Ge x core–shell nanowire array electrodes by directly depositing Si1−x Ge x layer on the surface of pre-synthesized Cu nanowire arrays via co-sputtering method. When used as anodes of lithium-ion batteries, the Cu–Si1−x Ge x (x =0.4) nanowire array electrodes show excellent electrochemical performance in terms of cycle stability and rate capability, which is much better than that of planar electrodes. The improved performance can be attributed to the good strain accommodation, fast electron transport and good electrical contact of the nanowire array electrodes. The effect of Ge content and the thickness of alloy film on the electrochemical performance of the three-dimensional electrodes have also been investigated.
In a world constrained by climate change, it is of utmost relevance that energy technologies offer a low level of greenhouse gas (GHG) emissions at a comparatively low cost level. A literature overview is presented, which shows that the common view of PV systems contradicts its position as an economically viable key solution in reducing greenhouse gas (GHG) emissions. However, most of the found research is outdated and instead of being a region-oriented specific analysis, most of the research has focused on general cost level calculations. A simple methodology is introduced for estimating the climate change mitigation relevance of PV systems by calculating the avoided GHG emissions for specific representative PV applications in respective regions. The potential of GHG mitigation by PV systems is combined with the related economics based on discounted cash flow calculus. PV applications ranging from small PV systems in rural off-grid regions up to large scale PV power plants and commercial PV rooftop systems show financial benefits for avoided GHG emissions. Even in Germany, the costs of avoiding GHG emissions using residential rooftop systems are 17–70€/tCO2eq depending on the applied assumptions. These costs are distinctly lower than the 80€/tCO2eq threshold for the cost of climate change impacts. PV power plants in Germany show financial benefits of 19–93€/tCO2eq for avoiding GHG emissions. Summing up, PV systems are a highly attractive climate change mitigation option.
Thermoelectric (TE) technology is regarded as alternative and environmentally friendly technology for harvesting and recovering heat which is directly converted into electrical energy using thermoelectric generators (TEG). Conversely, Peltier coolers and heaters are utilised to convert electrical energy into heat energy for cooling and heating purposes The main challenge lying behind the TE technology is the low efficiency of these devices mainly due to low figure of merit (ZT) of the materials used in making them. The objective of this work is to carry out a comprehensive review of TE technology encompassing the materials, applications, modelling techniques and performance improvement. The paper has covered a wide range of topics related to TE technology subject area including the output power conditioning techniques. It is observed that the intensified research into TE technology has led to an outstanding increase in ZT, rendering the use TE devices in diversified application a reality. The performance improvements of TE devices have been mainly contributed by improved TE material research, TE device geometrical adjustments, design of integrated TE devices as well as the use of advanced TE mathematical models which have facilitated appropriate segmentation of TE modules using different materials. TE devices are observed to have booming applications in cooling, heating, electric power generation as well as hybrid applications. With the generation of electrical energy using TEG, not only does the waste heat provide heat source but also other energy sources like solar, geothermal, biomass, infra-red radiation have gained increased utilization in TE based systems. However, the main challenge remains in striking the balance between the conflicting parameters; ZT and power factor, when designing and optimizing advanced TE materials. Hence more research is necessary to overcome this and other challenge so that the performance TE device can be improved further.
This study investigates the electrochemical sodium insertion/extraction of NaxVS2, and NaxTiS2 in the voltage range where either intercalation (0.2≤x≤1) or displacement-conversion reaction (x>1) occurs. Both NaxVS2 and NaxTiS2 showed good reversible capacities, as high as ∼160mAh/g at an average voltage of ∼1.9V vs. Na in the region for the intercalation reaction (0.2≤x≤1). When sodium (Na) insertion was forced further to the x>1 composition, NaxVS2 exhibited the direct displacement-conversion reaction at 0.3V vs. Na without further Na intercalation, which contrasted with the wider lithium intercalation range of 0<x≤2 for LixVS2. The displacement-conversion reaction for NaxVS2 (x>1) was reversible with a specific capacity of above 200mAh/g up to 15 cycles, but the displacement reaction for NaxTiS2 (x>1) was not observed.
The electric double layer capacitor (EDLC) should have an almost indefinite life, because the EDLC is charged and discharged by the electrostatic adsorption and desorption of ions on electrodes whose processing involves mass transfers without a chemical reaction. However, the actual life of an EDLC is finite, such that its performance begins to slowly degrade and is significantly deteriorated at some point. We have investigated this phenomenon in detail by analyzing changes in the species of the EDLC during its life. We found that reactions on the positive and negative electrode occurred in phase with the consumption of oxygen, carbon in the electrode materials, and anions in the electrolyte during EDLC charging to change the electrode potentials and the abundance of ions on the electrodes. A product and/or disappearance by the side reactions deteriorated the performance of the active materials. Here we suggest a life process during the float charge of the EDLC and a directional concept for extending its life while comparing experimental data with theoretical models of EDLC charging.
This study brings a new insight into the interfacial compatibility of cathode binders with modified electrolytes in lithium–sulfur batteries. We compared the oxygen-containing binders sodium alginate (NaAlg) and sodium carboxymethyl cellulose (NaCMC) with the conventional oxygen-free polyvinylidene difluoride. The results revealed that the NaAlg and NaCMC binders strongly facilitated the decomposition of the electrolyte additive LiNO3 at potentials lower than 1.8 V. This is primarily attributed to the influence of oxygen-containing functional groups. However, when LiNO3 was absent from the electrolyte, the sulfur cathode with the NaAlg binder showed the most stable performance. To prevent LiNO3 decomposition and acquire stable cycling, the discharge voltage was limited to 1.8 V. At the conclusion of testing (100 cycles, voltage cutoff = 1.8 V), the NaAlg-based cathode maintained 608 mAh g−1 of capacity (52% of the initial capacity). This represented a 35% increase in the specific capacity obtained at the 100th discharge cycle with the cutoff voltage at 1.5 V. Our results suggest a rational choice of the binders used in sulfur composite cathodes.
In this work, we successfully developed a novel wet chemical method to prepare LiNi0.5Mn1.5O4 coated LiMn2O4 (LMO@LNMO), in which commercial LiMn2O4 produced by solid state reaction method was used as the starting material and a nitrate precursor containing Li, Ni and Mn was used to form LiNi0.5Mn1.5O4 coating layer. There is no precipitant, chelating agent and washing process needed. The effect of the calcination temperature and the mass ratio of LiMn2O4 and LiNi0.5Mn1.5O4 (mLMO:mLNMO) were systematically studied. LMO@LNMO was investigated by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), which showed that a completed coating layer was formed via the wet chemical method and some Ni2+ in LiNi0.5Mn1.5O4 were diffused to LiMn2O4 to form a Ni concentration-gradient structure after calcination. Typically, LMO@LNMO with the calcination temperature of 800°C and the mass ratio of 9:1 (mLMO:mLNMO) showed an initial discharge specific capacity of ∼100 mAh·g−1 between 3.0 and 4.3V vs. Li+/Li at 55°C, and greatly improved cyclic performance with a capacity retention of 81.9% over 400 cycles. The thermal safety of LMO@LNMO was also enhanced according to the differential scanning calorimetry (DSC) results.
We propose a facile, novel concept of mass transfer enhancement in flow batteries based on electrolyte guidance in rationally designed corrugated channel systems. The proposed fluidic networks employ periodic throttling of the flow to optimally deflect the electrolytes into the porous electrode, targeting enhancement of the electrolyte-electrode interaction. Theoretical analysis is conducted with channels in the form of trapezoidal waves, confirming and detailing the mass transport enhancement mechanism. In dilute concentration experiments with an alkaline quinone redox chemistry, a scaling of the limiting current with Re0.74 is identified, which compares favourably against the Re0.33 scaling typical of diffusion-limited laminar processes. Experimental IR-corrected polarization curves are presented for high concentration conditions, and a significant performance improvement is observed with the narrowing of the nozzles. The adverse effects of periodic throttling on the pumping power are compared with the benefits in terms of power density, and an improvement of up to 102% in net power density is obtained in comparison with the flow-by case employing straight parallel channels. The proposed novel concept of corrugated fluidic networks comes with facile fabrication and contributes to the improvement of the transport characteristics and overall performance of redox flow battery systems.