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A crystalline structure of LiCoO sample was synthesized at different stirring times via sol-gel method. This was followed by the electrochemical characterization of LiCoO in 5 M LiNO aqueous electrolyte. The hexagonal LiCoO was stirred for 30 h produced the highest peak intensity and smallest particle size. A morphological analysis showed the particle size distribution within the range of 0.32-0.47 μm. At lower scan rates of cyclic voltammetry, three pairs of redox peaks at E = 0.81/0.65, 0.89/0.83 and 1.01/0.95 V were observed. The peak separation was proportionally consistent with Li diffusion coefficients of 7.42 × 10 cm s (anodic) and 3.59 × 10 cm s (cathodic). For specific capacity, the LiCoO demonstrated a higher initial specific capacity (115.49 mA h g). A small difference (1.92 Ω) in the charge transfer resistance before and after a charge discharge analysis indicated that the Li ions had been well-diffused during the intercalation/de-intercalation process. [ABSTRACT FROM AUTHOR]

The layered compound LiCoO belonging to the ABO class exhibits a variety of interesting behaviors, and substitution adds a twist to the properties. Hence, the effect of partial substitution of Co with Fe on the high-temperature thermoelectric properties has been studied in detail. The X-ray diffraction patterns together with Rietveld refinement indicate formation of a single phase conforming to R $$ \overset{-}{3} $$ m space group in all the three cases, LiCoFeO with x = 0.01, 0.02, and 0.08. The electrical resistivity in all the compounds decreases by four orders of magnitude with increasing temperature from 300 to 1000 K, a semiconducting behavior. The Seebeck coefficient is found to be very high, >700 μV K in all the cases, and increases with increasing temperature and Fe substitution. The thermal conductivity, on the other hand, has been found to decrease with temperature in all the compounds from 3.5 W m K at room temperature to 1 W m K at 973 K, a consequence of phonon-phonon scattering. High resistivity of the compounds limits power factor indicating that carrier concentration and mobility need to be increased to realize a high figure-of-merit. [ABSTRACT FROM AUTHOR]

Kinetics of LiFePO, LiMnO, and LiCoO cathodes operating in 1 M LIPF solution in a mixture of ethylene carbonate and dimethyl carbonate was deduced from impedance spectra taken at different temperatures. The most striking difference of electrochemical impedance spectroscopy (EIS) curves is the impedance magnitude: tens of ohms in the case of LiFePO, hundreds of ohms for LiMnO, and thousands of ohms for LiCoO. Charge transfer resistances ( R ) for lithiation/delitiation processes estimated from the deconvolution procedure were 6.0 Ω (LiFePO), 55.4 Ω (LiCoO), and 88.5 Ω (LiMnO), respectively. Exchange current density for all the three tested cathodes was found to be comparable (0.55-1·10 mAcm, T = 298 K). Corresponding activation energies for the charge transfer process, $$ {E}_{ct}^{\#} $$ , differed considerably: 66.3, 48.9, and 17.0 kJmol for LiMnO, LiCoO, and LiFePO, respectively. Consequently, temperature variation may have a substantial influence on exchange current densities ( j ) in the case of LiMnO and LiCoO cathodes. [ABSTRACT FROM AUTHOR]

A moving-boundary model with activity correction for the diffusion of lithium in LiCoO electrodes and the electrochemical reaction on the surface of electrode particles was formulated in a reproduction of the discharge/charge voltage process in batteries that have a LiCoO cathode and a mesocarbon-microbead anode. Activity correction for the electrochemical reaction as well as the diffusion of lithium where the LiCoO structural phase transition occurs during discharge and charge was considered. An accurate representation of the discharge/charge voltage profiles was obtained by using the moving-boundary model with the activity correction. The activity correction incorporated into the moving-boundary model can improve the discontinuous gaps in the discharge voltage profiles at the surface of conjugate LiCoO electrode particles. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Operando measurements of the magnetic susceptibility χ during electrochemical charging of commercially used battery electrode materials are implemented in a superconducting quantum interference device magnetometer. The capability of this measurement set-up to study electronic and chemical processes in the electrode is exemplified by Li CoO cathodes, for which reversible variations of their susceptibility χ by more than a factor of 1.5 could be continuously monitored. From the variation of χ with Li-ion concentration x for 1> x≥0.77, where Pauli paramagnetism prevails, a linear increase of the electronic density of states with Li extraction is derived, indicating that the occurring nonmetal-metal transition is of Anderson-type. For x<0.77, the change of χ( x) was assigned to alterations of the Co oxidation state, with the slope of χ( x) revealing that in addition to Co also O undergoes partial oxidation during charging. The observed increase of χ at the beginning of the discharging process could be an indication for the formation of Co $^{2^{+}}$ at the electrode surface during reduction. [ABSTRACT FROM AUTHOR]

In applications of lithium ion batteries, it is a requisite to precisely appraise their fire and explosion hazards. In the current study, a fire calorimeter is utilized to test the combustion performance of two commercial 18650 lithium ion batteries (LiCoO and LiFePO) at different state of charge (SOC). Characteristics on thermal hazards of lithium ion batteries including surface temperature, time to ejection, mass loss, and heat release rate (HRR) are measured and evaluated. In case of thermal runaway, all the lithium ion batteries will rupture the can and catch fire even explode automatically. The solid electrolyte interface layer decomposition and the polymer separator shrinking are direct causes of the lithium ion battery fire. The experimental results show that the HRR and total heat generally rise as the SOC increases, whereas the time to first ejection and the time gap between first and second ejection decrease. LiCoO 18650 battery shows higher explosion risk than LiFePO 18650, as the former has released much more oxygen. The experimental combustion heats calculated and modified in the oxygen consumption method reveal that the internally generated oxygen have significant effect on the estimate of the heat, where the largest modified rate is 29.9 for 100 % SOC LiCoO 18650 battery. The results can provide scientific basis for fire protection during the storage and distribution of lithium ion batteries. [ABSTRACT FROM AUTHOR]

Used LiCoO material was renovated by means of ultrasound radiation under hydrothermal conditions. The optimal reaction condition for renovation process was obtained: temperature 120 °C, ultrasonic power 999 W, and ultrasonic method 'work 5 s-stop 2 s' and ultrasonic radiation time 10 h. The XRD, SEM, ICP-AES analysis, and charge-discharge test showed that the renovated LiCoO had a high degree of crystallinity, a fine-layered structure, good dispersion of particles, and improved electrochemical cycle performance. The first-time charge capacity and discharge capacity of renovated LiCoO were 132.6 and 131.5 mAh/g, respectively. The first-time charge and discharge efficiency was 99.2 %. After 20 cycles, the discharge capacity retention rate was 98.1 % which reaches or approaches the electrochemical properties of commercial batteries. [ABSTRACT FROM AUTHOR]

Kinetic characteristics of LiCoO cathode materials are studied using a Li-ion secondary cell incorporating a reference electrode. By carrying out electrochemical impedance spectroscopy (EIS) measurements at different state of charges (SOCs) and temperatures and obtaining d Q/d E vs. E curves, the activation energy, pre-exponential factor, and reaction rate constant of Li-ion insertion/deinsertion reactions are analyzed as a function of cathode potential. The kinetic behavior of Li-ion conduction, Li-ion solvation/desolvation, and charge transfer reactions of LiCoO and its dependency on the structural changes of LiCoO are studied. The charge transfer, Li-ion conduction, and Li-ion solvation/desolvation reactions exhibited a dependency on the structural changes of the cathode material. [ABSTRACT FROM AUTHOR]

Carbon-coated LiCoO and LiNiO compounds were prepared with a novel, fast, and very efficient microwave-assisted method within only minutes. This method provided highly dispersed LiCoO or LiNiO within a highly contacted carbon material. A remarkable high specific charge of about 179 and 270 A h kg was achieved for LiCoO and LiNiO, respectively. Moreover, due to the very high electrochemical stability about 89% for LiCoO and 97% for LiNiO, respectively, of the discharge capacity remained after about 1500 cycles. [ABSTRACT FROM AUTHOR]

Pure and rare earth oxides (SmO, LaO) coated LiCoO nanoparticles were prepared by acrylamide-assisted polymeric citrate and resin-coating processes, respectively. The prepared powders were characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and impedance spectroscopy. Powder X-ray diffraction patterns confirmed the formation of phase pure LiCoO with nanocrystallite size. X-ray fluorescence spectra confirm the presence of SmO and LaO in coated samples. The conductivity, dielectric and electric modulus studies of the samples were carried out at room temperature. Dielectric spectra of the samples show the decrease in dielectric constant with an increase in frequency of the applied field. The modulus studies indicate the non-Debye behavior of the samples, which is due to long-time slow polarization and relaxation of hopping charges. [ABSTRACT FROM AUTHOR]

The influence of the uppermost substrate layer on the structural properties of sputtered lithium cobalt oxide (LiCoO) is discussed in this work. For this purpose, bare, oxidized, and platinum-coated silicon wafers, as well as stainless steel and titanium sheets, were used as substrates. The resulting crystal structure of LiCoO deposited on these substrates was analyzed and discussed. The LiCoO thin films were deposited by RF magnetron sputtering with different film thicknesses. A subsequent annealing step at 700 °C was performed to induce the crystallinity of LiCoO. The crystal orientation was determined by X-ray diffraction. The obtained results show a strong dependency of LiCoO's crystal structure on the surface the film is deposited on. However, the strong influence of the film thickness reported in previous publications could not be observed. If LiCoO is deposited on the substrates with a metallic surface, a strong (003) preferential orientation is obtained for a wide range of film thicknesses. In contrast, sputtering of LiCoO on bare and on oxidized silicon wafers results in a (101) dominated crystal structure for the different film thicknesses. These experiments show the importance of the characterization of LiCoO's crystal structure in the intended battery setup. [ABSTRACT FROM AUTHOR]

Three-dimensionally ordered macroporous (3DOM) LiCoO was synthesized by colloidal crystal templating method using poly(methyl methacrylate) with the diameter of 232 nm as the template. The effects of roasting temperature on properties of LiCoO cathode materials were investigated by thermogravimetric analysis (TG-DTG), scanning electron microscope, X-ray diffraction, transmission electron microscopy, and electrochemical measurements. The results indicated that the synthesized 3DOM LiCoO calcined at 700 °C had better crystal framework and electrochemical properties. The 3DOM LiCoO samples presented higher rate capacity compared to commercial LiCoO with a specific discharge capacity of 151.2 mAh g at a current density of 1 C, and 92 % of the specific discharge capacity was retained after 50 charge-discharge cycling. [ABSTRACT FROM AUTHOR]

Nanoparticles of lithium cobalt oxide (LiCoO) and nanosheets of lithium vanadium oxide (LiVO) were synthesized by a citrate sol-gel combustion route. The physical characterizations of the electrodic materials were carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and also X-ray diffraction (XRD) measurements. Near spherical nanoparticles of ≈100 nm and compact nanosheets with a few nanometers thick were observed by SEM and TEM for LiCoO and LiVO, respectively. XRD data indicated that the as-prepared active materials presented pure phase of rhombohedral LiCoO with R-3m symmetry and monoclinic LiVO with p2/m symmetry. The kinetics of electrochemical intercalation of lithium ion into the nanoparticles of LiCoO and nanosheets of LiVO from 1.0 mol l LiNO aqueous solution were investigated by cyclic voltammetry and chronoamperometry. An aqueous rechargeable lithium-ion battery consisting of LiCoO nanoparticles as positive and LiVO nanosheets as negative electrode was assembled. This battery represented a discharge voltage of about 1 V with good cycling performance. [ABSTRACT FROM AUTHOR]

A commercial cathode material (LiCoO) was modified by doping with Zn to improve its performance in lithium battery. The structure and morphology of the doped cathode material were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The synthesized samples were characterized using X-ray photoelectron spectra (XPS), used to investigate the elementary states on the system. The electrical conductivity variations of doped powders were measured in the temperature range between 30 and 150 °C. The 3 mol% Zn-doped LiCoO sample shows the highest reversibility capacity (178 mA h g) after 30 cycles in the voltage window 3.0-4.5 V. [ABSTRACT FROM AUTHOR]

Mesoporous carbon (MC) was utilized to increase the mesoporosity of LiCoO composite cathode. Graphite powder (GP) was chosen as a standard of comparison because of its very low mesoporosity. Compared with MC, GP has similar particle size, lower specific surface area, and higher electronic conductivity. Acetylene black (AB) exists in the form of chains of nanoparticles. With all other factors held constant, the mixture of AB and MC (ABMC)-loaded LiCoO composite cathode (ABMC cathode) was superior to the mixture of AB and GP (ABGP)-loaded LiCoO composite cathode (ABGP cathode). The reason is described as follows. Both GP and MC form a conductive network with AB chains. ABGP cathode has higher electronic conductivity than ABMC cathode. But the ionic conductivity of the ABMC cathode is more easily enhanced than the ABGP cathode because the former has much greater mesoporosity. In addition, the mesopores absorb and retain electrolyte solution and then provide buffer lithium ions for quick electrochemical reactions, so shortening the lithium ion transfer path in the composite cathode. [ABSTRACT FROM AUTHOR]

We studied the microstructural and electrochemical properties of Ti-doped AlO (Ti-AlO) coated LiCoO thin films depending on the Ti composition. The 1.27 at.% Ti-AlO coated films had an amorphous structure with better conductivity than that of pure AlO films. The Ti-AlO coating layer effectively suppressed the dissolution of Co and the formation of lower Li conductivity SEI films at the interface between the LiCoO film and electrolyte. The Ti-AlO coating improved the cycling performance and capacity retention at high voltage (4.5 V) of the LiCoO films. The Ti-AlO coated LiCoO films showed better electrochemical properties than did the pure AlO coated LiCoO films. These results were closely related to the enhanced Li-conductivity and interfacial quality of the Ti-AlO film. [ABSTRACT FROM AUTHOR]

LiCoO polycrystalline thin film cathode was prepared by pulsed laser deposition (PLD). The higher power density of the excimer laser beam leads to the film consisting of highly crystallized cylindrical nanoparticles. Furthermore, the film thickness plays an important role on the film orientation as well as the diameter of the oxide cylinders. The film orientation was not fixed with (003) plane parallel to the substrate while the thickness was up to 300 nm. Meanwhile, the diameter of part of the cylindrical particles was increased due to a preferred growth induced by a driving force changing from surface energy to volume strain energy. The electrochemical tests indicate that flat charge/discharge plateaus corresponding to the first-order phase transition appear at around 3.85 V vs. Li/Li, resulting in high utilization of the active material and good capability retention. [ABSTRACT FROM AUTHOR]

The electronic structure of a solid electrolyte/solid electrode interface (SESEI) of an all-solid-state thin film battery was investigated. The thin film battery consisted of a LiPON solid electrolyte and a LiCoO cathode. The lithium phosphorus oxynitride (LiPON) electrolyte was RF sputtered in a step-by-step procedure onto the cathode and investigated by photoelectron X-ray-induced spectroscopy after each deposition step. An intermediate layer was found-composed of some new species-that differs in its chemical composition from the cathode as well as the LiPON solid electrolyte material and changes with growing layer thickness. In contrast, the electronic structure of the underlying cathode material remained predominantly unchanged. [ABSTRACT FROM AUTHOR]

Abstract: The several materials required for fabrication of thin-film solid-state rechargeable lithium batteries were deposited and characterized: A glassy lithium-phosphorus oxynitride electrolyte (LiPON) between a lithium (Li) anode and crystalline lithium-cobalt oxide cathode (LiCoO2), deposited by RF-sputtering. Ti/Pt layers, deposited by e-beam were used in contacts and a silicon nitride film (Si3N4), deposited by low temperature hot-wire CVD protects the battery. This technology allows batteries with a potential of 4.5 V, typical capacities of 50 μAcm−2 and chargedischarge rates up to 4C. Solid-state film batteries show faster charge rates and very high cycle life, compared with film polymer batteries, withstanding several thousands of cycles with no pronounced fading. [ABSTRACT FROM AUTHOR]

LiCoO2 xerogel hollow nanofibers were first prepared by co-electrospinning the sol precursor, and the polycrystalline LiCoO2 hollow nanofibers were obtained after calcination of the xerogel fibers. The obtained hollow nanofibers made up of 20∼30 nm nanocrystals were about 100 nm to several micrometers in outer diameter. The hollow nanofibers were detected by means of SEM, TEM, TG, DSC, FTIR, and XRD techniques. [ABSTRACT FROM AUTHOR]

A simple mechano-thermal coating procedure for the production of long-cycling LiCoO2 is described. Preformed nanoparticulate boehmite was used as the coating material. The coating procedure resulted in the cathode particles covered in a 20-30 nm thick kernel of boehmite, as revealed by TEM examination. XRD studies showed that the lattice parameter c diminished upon coating, indicating that a substitutional compound of the composition LixAlyCo1-yO2 may have formed upon calcination. SEM images, R-factor values from XRD studies and galvanostatic charge-discharge studies showed that a coating level of 1.0 wt % gave an optimal performance in capacity and cyclability. SEM images showed that above the 1.0 wt % coating level, the excess boehmite adhered to the coated cathode particles as sperules. ESCA depth profile analysis showed partial diffusion of aluminum from the surface to the interior. Galvanostatic cycling studies showed that at a coating level of 1.0 wt %, cyclability improved three- and twelve-fold for the two commercial LiCoO2 samples tested. Cyclic voltammetry revealed that the hexagonal-monoclinic-hexagonal phase transformations during cycling were suppressed in the coated cathode materials. [ABSTRACT FROM AUTHOR]

A simple mechano-thermal coating procedure for the production of long-cycling LiCoO2 is described. Preformed nanoparticulate boehmite was used as the coating material. The coating procedure resulted in the cathode particles covered in a 20-30 nm thick kernel of boehmite, as revealed by TEM examination. XRD studies showed that the lattice parameter c diminished upon coating, indicating that a substitutional compound of the composition LixAlyCo1-yO2 may have formed upon calcination. SEM images, R-factor values from XRD studies and galvanostatic charge-discharge studies showed that a coating level of 1.0 wt % gave an optimal performance in capacity and cyclability. SEM images showed that above the 1.0 wt % coating level, the excess boehmite adhered to the coated cathode particles as sperules. ESCA depth profile analysis showed partial diffusion of aluminum from the surface to the interior. Galvanostatic cycling studies showed that at a coating level of 1.0 wt %, cyclability improved three- and twelve-fold for the two commercial LiCoO2 samples tested. Cyclic voltammetry revealed that the hexagonal-monoclinic-hexagonal phase transformations during cycling were suppressed in the coated cathode materials. [ABSTRACT FROM AUTHOR]