Зависимость электрохимических параметров композитных SiO/C-анодов для литий-ионных аккумуляторов от состава и температуры синтеза

The results of a study of anodes obtained by carbonization of silicon monoxide by means of a reaction with solid-phase fluorocarbon CF0.8 are presented. Charge/discharge voltage profiles were studied at different currents depending on the composition and temperature of the synthesis of composites. The irreversible losses of the 1st cycle and the contribution to them of intrinsic losses due to the formation of lithium oxide and its silicates and losses associated with the formation of SEI are analyzed. A difference has been established in the behavior of anodes made of SiO carbonized by annealing with CF0.8 at T=800°C (SiO/C composite) and silicon monoxide annealed with CF0.8 at T>1000°C, at which disproportionation occurs simultaneously with the carbonization of SiO (d-SiO/C composite). The difference consisting in a higher discharge capacity, a higher Coulomb efficiency, and better rate capability of d-SiO/C is explained by a change in the composition of the SiOx matrix that occurs during the disproportionation process. The effect of the formation of d-SiO/C anodes by preliminary lithiation with a low current, after which the electrodes can be charged and discharged with much higher currents, has been discovered. The effect is explained by the amorphization of silicon crystallites and the increasing diffusion coefficient of lithium

Li2O-Based Cathode Additives Enabling Prelithiation of Si Anodes

Low first-cycle Coulombic efficiency is especially poor for silicon (Si)-based anodes due to the high surface area of the Si-active material and extensive electrolyte decomposition during the initial cycles forming the solid electrolyte interphase (SEI). Therefore, developing successful prelithiation methods will greatly benefit the development of lithium-ion batteries (LiBs) utilizing Si anodes. In pursuit of this goal, in this study, lithium oxide (Li2O) was added to a LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode using a scalable ball-milling approach to compensate for the initial Li loss at the anode. Different milling conditions were tested to evaluate the impact of particle morphology on the additive performance. In addition, Co3O4, a well-known oxygen evolution reaction catalyst, was introduced to facilitate the activation of Li2O. The Li2O + Co3O4 additives successfully delivered an additional capacity of 1116 mAh/gLi2O when charged up to 4.3 V in half cells and 1035 mAh/gLi2O when charged up to 4.1 V in full cells using Si anodes.

Monitoring of Lithium Contents in Lithium Ores and Concentrate-Assessment Using X-ray Diffraction (XRD)

Lithium plays an increasing role in battery applications, but is also used in ceramics and other chemical applications. Therefore, a higher demand can be expected for the coming years. Lithium occurs in nature mainly in different mineralizations but also in large salt lakes in dry areas. As lithium cannot normally be analyzed using XRF-techniques (XRF = X-ray Fluorescence), the element must be analyzed by time consuming wet chemical treatment techniques. This paper concentrates on XRD techniques for the quantitative analysis of lithium minerals and the resulting recalculation using additional statistical methods of the lithium contents. Many lithium containing ores and concentrates are rather simple in mineralogical composition and are often based on binary mineral assemblages. Using these compositions in binary and ternary mixtures of lithium minerals, such as spodumene, amblygonite, lepidolite, zinnwaldite, petalite and triphylite, a quantification of mineral content can be made. The recalculation of lithium content from quantitative mineralogical analysis leads to a fast and reliable lithium determination in the ores and concentrates. The techniques used for the characterization were quantitative mineralogy by the Rietveld method for determining the quantitative mineral compositions and statistical calculations using additional methods such as partial least square regression (PLSR) and cluster analysis methods to predict additional parameters, like quality, of the samples. The statistical calculations and calibration techniques makes it especially possible to quantify reliable and fast. Samples and concentrates from different lithium deposits and occurrences around the world were used for these investigations. Using the proposed XRD method, detection limits of less than 1% of mineral and, therefore down to 0.1% lithium oxide, can be reached. Case studies from a hard rock lithium deposit will demonstrate the value of mineralogical monitoring during mining and the different processing steps. Additional, more complex considerations for the analysis of lithium samples from salt lake brines are included and will be discussed.

CALCULATION AND ANALYSIS OF EFFECTIVE ATOMIC NUMBER USING AUTO ZEFFECTIVE METHOD FOR BORO-SILICATE GLASS SERIES GLASS [Li O – B O – SiO 2 2 3 2 – XO] WITH THIRD (5D) D-BLOCK (HF–HG) TRANSITION METALS ELEMENTS (X)

The impact of the doping of the transition metals with Lithium Oxide provides signicant data in Boro-silicate materials. Hence their comprehensive study with Lithium in Boro-silicate glass studied in the present paper. Z-effective shows non consistence in study respective to energy and even more anomalous with respective to the atomic number at lowest energy levels (0.01 MeV). Variations in Z-effective are high with increase in energy among all 5d metals used in given series of glass. For 1 to 100 MeV a small variation observed in data as it ranges 9 to 21 (Zeffective). Even variation is symmetrical within the 5d transition metals except for Hf (72) and Ta (73)

Effect of RF magnetron sputtering parameters on the optimization of the discharge capacity of ternary lithium oxide thin films

The increasing demand for lithium-ion batteries has stimulated the investigation of new compounds in order to reduce the costs and the toxicity of their cathodes. Materials constituted of ternary lithiated oxide compounds are a successful alternative to cobalt-rich cathodes. The main disadvantage of ternary compound materials (TCM) is that the maximum amount of electrical charge is only achieved at high redox potentials, a limiting factor if we consider the current development in electrolyte technology. In this work, we investigated the influence of sputtering deposition parameters on the charge capacity of TCM thin films, restraining their electrochemical potential to conventional values. To do so, we analyzed the impact that small changes in crystalline and morphological structures have on the charge capacity at low cell potentials. For this, we performed the RF magnetron sputtering of TCM thin films, and carried out a factorial design of experiments to investigate their electrochemical properties, while limiting the charging potential to 4.20 V vs. Li|Li+. The films were deposited onto a rigid and conductive substrate with different parameters (power and pressure at room temperature). Electrochemical results showed that the discharge capacity is strongly influenced by the deposition parameters, reaching 250 mAh g− 1 even at 4.20 V vs. Li. This value is superior to the ones of the conventional cobalt cathode and the bulk ternary electrode. Both deposition parameters exhibited a synergic dependency, which means that they need to be simultaneously varied for a response optimization. The discharge capacity of the analyzed samples was highly affected by the surface morphology of the film and its crystallographic properties, and not by its elemental composition. High discharge capacity was obtained without additional thermal treatments, which favors the manufacture of films over polymeric substrates for future electronic applications.

Effect of Zinc Oxide on the Efficiency Enhancement of Al/Li2O/PSi/Si/Al solar cell

In this paper, electrochemical etching of the p-type silicon wafer is used to prepare p-type porous silicon with current density of 10 mA.cm− 2 for 10 minutes. Field Emission Scanning Electron Microscopy (FESEM) has been used to study porous silicon layer surface morphology. Zinc oxide and lithium oxide nanoparticles are prepared separately by chemical precipitation method and simple precipitation method, respectively and deposited on glass substrates by drop casting method. Moreover,, the structural properties of the films were analyzed by using XRD and SEM. The XRD results showed that the ZnO and Li2O films are polycrystalline with hexagonal wurtzite structure and cubic structure, and preferred orientation along (101) and (003) planes, respectively. Using Scherrer's formula, the crystallite size was measured and it was found that ZnO and Li2O thin films have a crystallite size of 22.04 and 45.6 nm respectively. Surface topography of the prepared thin films is studied by using Scanning Electron Microscopy (SEM). Later, certain proportions of both materials were mixed and deposited on porous silicon using drop casting method at thickness of 1.4 µm. After that, the characteristics of the solar cell were investigated. Mixing zinc oxide nanoparticles in particular proportions with lithium oxide played a major role in increasing the solar cell's performance. The highest prepared film efficiency was obtained at mixing ratio (0.5: 0.5) for (ZnO: Li2O) and its value was (11.09 %).