This study explores an efficient infrared (IR) heating technique to synthesize highly-crystalline LiNi0.8Co0.15Al0.05O2 (NCA) cathode materials for Li-ion batteries. One home-made IR induction ...reactor, equipped with medium-wave IR emitter array, is adopted to prepare the NCA powders at 700°C for a calcination period of 1–5h. Two kinds of preparation routes, ball milling and rheological-phase method, are used to prepare NCA precursors. The as-prepared NCA powders display well ordering of hexagonal two-dimensional layer structure with low degree of cation mixing under appropriate conditions: IR heating time (5h) and rheological-phase method. The NCA cathode exhibits an improved discharge capacity, fast Li+ diffusion rate, high rate capability, and good cycling stability. This improved performance mainly originates from low cation mixing, low defect level, and homogeneous particle size of NCA crystals. The carbon-coated NCA cathode offers high capacities of ca. 213 and 115mAhg−1 at 0.1 and 5C, respectively. Analyzed by the Randles-Sevcik plots, the diffusion coefficients in the NCA cathodes increase up to 1.73×10−8 and 5.82×10−9cm2s−1 for Li-extraction and Li-insertion, respectively. Accordingly, the IR heating route turns on a commercial feasibility to synthesize NCA cathode materials for Li-ion battery application.
Nanocomposites made of magnetic spinel oxide Co1+yAl2-yO4 nanoparticles (NPs) with y = 0.93, 1.20 and 1.34 dispersed in an amorphous SiO2 matrix were prepared by a sol-gel method. The average ...crystallite size DXRD of about 25 nm determined by X-ray diffraction (XRD) agrees well with the average particle size observed in transmission electron microscopy (TEM). Dynamic magnetic susceptibility measurements indicate a spin-glass-like behavior of the nanoparticles below the spin-glass (SG) transition temperature TC < 10 K. Field dependent magnetization exhibits weak ferromagnetism and shift of the magnetic hysteresis loop. On the basis of the observed magnetic properties, we propose a model of the core-shell structure of the Co1+yAl2-yO4 nanoparticles with the spin-glass phase in the core and weak ferromagnetism in the shell. The exchange bias field disappears above the spin-glass transition temperature TC, whereas the weak ferromagnetism persists also at temperatures above TC. The component of weak ferromagnetism is associated with the presence of Co vacancies in the nanoparticle spinel crystal lattice.
•Co1+yAl2-yO4 nanoparticles (NPs) exhibit spin-glass (SG) behavior below TC < 10 K.•Hysteresis loop recorded at T > TC reveals the existence of weak ferromagnetism (FM).•Weak FM is associated with the presence of Co vacancies in the NPs spinel lattice.•Horizontal shift of the hysteresis loop at T < TC is attributed to exchange bias effect.•A model of the NPs structure is proposed with SG in the core and weak FM in the shell.
We co-precipitated the precursor of a nickel-rich cathode material with high energy density—layered lithium nickel cobalt aluminum oxide (NCA, Li(NixCoyAl1−x−y)O2)—via a carbonate route, and we ...tested the cell performance of NCA synthesized from this precursor. The precursor for NCA had been previously co-precipitated via a hydroxide route, with a long residence time that caused low productivity. We obtained spherical precursor particles with uniform particle size distribution through the carbonate route. We found that the precursor has the form of (Ni0.8Co0.16Al0.04)(CO3)0.41(OH)1.18 and the precursor particles grow much faster than the hydroxide form with the same metal composition, (Ni0.8Co0.16Al0.04)(OH)2. The faster particle growth rate is attributed to the low solubility of the precursor in mild pH condition of co-precipitation (pH = 8.0). NCA from this precursor showed an initial discharge capacity of 183 mAh/g at 0.1C-rate, while retaining 91% of its capacity after 100 cycles representing improved performance over those of NCA from the hydroxide route with the same residence time. We believe faster particle growth, uniform particle size distribution, and morphology to be the reasons for the improved performance.
•Ni0.8Co0.16Al0.04(CO3)0.19(OH)1.62 was co-precipitated by using a carbonate process.•Ni0.8Co0.16Al0.04(OH)2 was also prepared by using a hydroxide process.•The carbonate process showed faster particle growth than the hydroxide process.•LiNi0.8Co0.16Al0.04O2 (NCA) was obtained from the two precursors and evaluated.•NCA from the carbonate process exhibited better electrochemical performances.
An in-situ chemical polymerization method maintaining a low temperature in the range of 0-5 °C was used to synthesize nanocomposites with different weight percentages of cobalt aluminum oxide (CAO) ...in polypyrrole (PPy). Structural, morphological, elemental, and particle size characterizations were done by employing X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM), respectively. The XRD analysis revealed the amorphous nature of pure PPy and the crystalline peaks of CAO along with the diminishing amorphous peak of PPy for the PPy/CAO nanocomposites. The SEM and TEM studies of PPy and PPy/CAO nanocomposites in powder form showed aggregates of the spherical particles with individual particle sizes of around 500 nm for pure PPy and in the range of 120-210 nm for the nanocomposites. The energy band gaps for pure PPy and the nanocomposites were analyzed by UV-VIS spectroscopy and were such that they can be considered for wide bandgap applications. Characterization of the temperature variation of the dc conductivity was carried out for all nanocomposites and found to be of the semiconductor type conduction. The humidity sensing properties of the pure PPy and its nanocomposites were studied and an improvement in the sensing properties of PPy by the addition of CAO was found.
Nickel-based oxide cathode material taking out from lithium-ion cell after storage for 2 years at 45
°C is analyzed by electron energy-loss spectroscopy in a scanning transmission electron microscope ...(STEM-EELS) and the result of STEM-EELS is compared with cobalt-based oxide cathode material which is treated as same manor as nickel-based oxide cathode material. The Ni-L
2,3 energy-loss near-edge structure (ELNES) spectra of nickel-based oxide cathode material show peak positions similar to original material before storage. This result indicates that nickel-based oxide material has no significant change in the surface structure. On the other hand, a remarkable shift to low energy is observed in the Co-L
2,3 ELNES spectra of the cobalt-based oxide cathode material after storage. The cycle test at 60
°C under the conditions of aggressive driving cycle (US06) mode for the nickel-based oxide cathode/graphite cell is also carried out. It is clear that cycle performance of the nickel-based oxide cathode/graphite cell is dependent on the depth of discharge (DOD).
This study investigates the synthesis of Ni0.80Co0.15(1−x)/0.95Alx(OH)2 (x = 0–0.2) materials by coprecipitation to understand the formation of layered double hydroxide (LDH) phases as influenced by ...Al content and synthesis route. Two routes were compared: the first method dissolved all the metal reagents into one solution before addition into the reaction vessel, while the second dissolved Al into a separate NaOH solution before simultaneous addition of the Ni/Co and Al solutions into the reaction vessel. The synthesized materials were characterized by Scanning Electron Microscopy, X-ray Diffraction, Inductively Coupled Plasma-Optical Emissions Spectroscopy and Thermogravimetric Analysis to understand the formation of LDH phases as influenced by Al content and synthesis method. It was found that as Al content increased, the amount of LDH phase present increased as well. No significant difference in LDH phase presence was observed for the two synthesis methods, but the morphologies of the particles were different. The method containing all the metals in one solution produced small particles, likely due to the continuous nucleation of Al(OH)3 disrupting particle growth. The method containing the separate Al in NaOH solution matched the morphology of the material with no Al, which is known to form desired large spherical particles under continuously stirring tank reactor synthesis conditions.
The method of obtaining composite electrolytic coatings (CEC) based on the nickel–cobalt–aluminum oxide system possessing high performance properties is considered in the work, since in engineering, ...automotive, instrument making, and other industries much attention is paid to the development of new materials possessing increased physical and mechanical properties. The use of such CEC will not only increase the reliability and durability of new machine parts and mechanisms and restore old ones, but in many cases will also replace defective alloyed steel and cast iron with cheaper metals. The article suggests a chloride electrolyte for the application of wear- and corrosion-resistant CEC nickel–cobalt–aluminum oxide–fluoroplastic. The effect of electrolysis regimes on the composition of the electrolyte and the concentration of alloying components on the physical and mechanical properties (wear resistance, corrosion resistance, microhardness, internal stresses, porosity, adhesion) of nickel–cobalt–alumina–fluoroplastic coatings is studied. The use of such coatings will expand the scope of their use as a wear- and corrosion-resistant coating in various friction nodes.
Chemical Lithium battery energy storage (BES) systems are considered as critical assets in providing flexibility and reliability for today's power and energy systems. However, BES degradation, which ...is due to the electrolyte reaction in lithium batteries, introduces some challenges to smart grid operators in terms of optimal charging/discharging management strategies. Although, considering degradation in BES operation can lead to long-term benefits, the associated uncertainties of renewable generations, load, and energy prices can pose a noticeable effect on BES operation optimality and accordingly affect the associated long-term benefits, if ignored. In fact, disregarding uncertainties in BES operation can lead to nonoptimal or even infeasible charging/discharging solutions, resulting in extra costs and even higher BES degradation rates. This paper presents an adaptive robust optimization approach to optimally characterize degradation in charging/discharging management of BES at the presence of uncertainties. The model is developed for a multi-energy system with electricity and natural gas as operating energy types. A Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2) battery is considered as the BES in the multi-energy system. Uncertainties of load, renewable generation, and energy prices are characterized with bounded interval through polyhedral uncertainty sets. The proposed model is solved through a column-and-constraint generation approach. A post-event analysis is conducted to evaluate the long-term performance of the proposed model. According to the obtained results, the proposed adaptive robust energy management model shows 18% growth in long-term benefit recovery and 15% reduction in loss of load, compare to deterministic model, considering battery degradation effects.
The intensities of the X-ray powder diffraction of cobalt aluminum oxides (spinel type) heat-treated at 1400°C and 1300°C under various partial pressures of oxygen (PO2) were measured. The optimum ...value of the fraction of tetrahedral sites occupied by aluminum (x), the fraction of tetrahedral sites occupied by vacancy (y), the fraction of octahedral sites occupied by vacancy (z), and the oxygen parameter (u) were determined as ones gave the best linearity in the relation between in (Iobs(hκl)/Icalc(hκl)) and sin2θhκl/λ2. The results are listed in Table 2. The values of x and u did not vary significantly with the condition of heat-treatment. It was concluded that 20-30% of tetrahedral sites were occupied by aluminum and the rest was occupied by cobalt in cobalt aluminum oxides, i.e. the cation distribution was intermediate between normal and inverse. In the photoacoustic spectra, the peaks of Co3+ ions in octahedral sites were observed for the samples heat-treated at high PO2 (Yogyo-Kyokai-Shi, 91, 131-36 (1983)). It was supposed that Co3+ ions were formed by the oxidation of Co2+ ions at high PO2, and that the defective spinel was formed by the change of the ratio of bivalent cations (Co2+ ions) to trivalent cations (Al3+ ions and Co3+ ions). The amount of Co3+ ions formed at high PO2 was estimated to be too small to affect the cation distribution in cobalt aluminum oxides.
PDF
