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Silicon suboxide (SiOx) is a promising anode material for lithium ion batteries (LIBs), due to its high specific capacity, small volume variation and superior cycle performance. Herein, we demonstrated the determining roles of oxygen contents on the behavior of SiOx upon lithium by means of thin-film type electrodes. The SiOx thin-film anodes with different oxygen contents were prepared by sputtering with Cu foil as substrates. XRD and Raman investigations reveal that these SiOx films are amorphous. As anodes, it is found that increasing oxygen contents in SiOx endows an enhanced cycle stability, but does harm to their initial Coulombic efficiency and capacity. Among all the a-SiOx film anodes (x = 0.4, 0.7, 1.1 and 1.5), the SiO0.7 electrode with a thickness of 450 nm exhibits excellent cycle performance and rate capability, with a high initial discharge capacity of 463 μAh cm−2 μm−1 at the current density of 64 μA cm−2 and a high capacity retention of 90% after 300 cycles. This superior performance is ascribed to that the in-situ formed lithium oxide/silicates compounds during discharge effectively alleviates the large volume change of Si components, but also suppresses the electron leakage from the surface of active particles, shutting down the further decomposition of electrolytes and then the formation of thick solid interphase layer. These results will provide inspirations for designing high-performance Si based anodes for lithium ion batteries.

Hematite (Fe2O3) nanoparticles and reduced graphene oxide (rGO) were supersonically sprayed onto copper current collectors to create high-performance, binder-free lithium ion battery (LIB) electrodes. Supersonic spray deposition is rapid, low-cost, and suitable for large-scale production. Supersonic impact of rGO sheets and Fe2O3 nanoparticles on the substrate produces compacted nanocomposite films with short diffusion lengths for Li+ ions. This structure produces high reversible capacity and markedly improved capacity retention over many cycles. Decomposition of lithium oxide generated during cycling activates the solid electrolyte interface layer, contributing to high capacity retention. The optimal composition ratio of rGO to Fe2O3 was 9.1 wt.%, which produced a reversible capacity of 1242 mAh g−1 after N = 305 cycles at a current density of 1000 mA g−1 (1C).

Density functional theory calculations are performed to investigate the role of lithium salts regarding the oxygen reduction reaction (ORR) occurred in non-aqueous electrolyte in Li-air batteries. This study is useful to elucidate the influence of ion-conducting lithium salts on ORR kinetics. The Li + -O bonding, binding energy, Gibb's free energy, heat of formation energy, and IR spectra with increase in dimethyl sulfoxide (DMSO) solvent molecules in the primary solvation shell reveal that lithium trifluoromethanesulfonate (LiCF 3 SO 3 ) is the most stable in dimethyl sulfoxide (DMSO) as compared to lithium hexafluorophosphate (LiPF 6 ) and lithium bis(trifluoromethanesulfonimide (LiN(CF 3 SO 2 ) 2 ). Infrared spectroscopic (IR) data confirm the formation of lithium peroxide (Li 2 O 2 ), lithium oxide (Li 2 O), and lithium carbonate (Li 2 CO 3 ) as discharge products on the micro-electrode surface in non-aqueous electrolyte containing lithium salts. The infrared (IR) analysis reveals that the lithium trifluoromethanesulfonate/dimethyl sulfoxide (LiCF 3 SO 3 /DMSO) electrolyte is primarily assumed to be the most favorable for ORR kinetics. In order to study the kinetics of oxygen reduction reaction at the oxygen cathode of non-aqueous Li-air battery with three Li salts in dimethyl sulfoxide (DMSO), we calculate thermodynamic properties of the reactions held during the formation of lithium peroxide (Li 2 O 2 ) and lithium oxide (Li 2 O). The Gibb's energy and heat of formation of these reactions indicate that lithium trifluoromethanesulfonate/dimethyl sulfoxide (LiCF 3 SO 3 /DMSO) electrolyte plays a key role in oxygen reduction reaction mechanism compared to other two.

Sulfated zirconia was successfully synthesized and uniformly coated onto a nickel-rich layered lithium oxide (LiNi0.8Co0.1Mn0.1O2), and investigated with a view to its potential use as a cathode material in Li-ion batteries. The uniformity of this sulfated zirconia coating was confirmed through electron microscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy. Furthermore, the electrochemical properties of the sulfated-zirconia-coated LiNi0.8Co0.1Mn0.1O2 electrode were found to be greatly improved compared to those of pristine LiNi0.8Co0.1Mn0.1O2 and zirconia-coated LiNi0.8Co0.1Mn0.1O2, especially at elevated temperature (60 °C). These results are directly attributed to the sulfated zirconia coating, which is effective in reducing side reactions by preventing direct contact between the active materials and electrolyte solutions, as well as forming a more stable solid electrolyte interphase (SEI) layer on the active material surface.

{AA2099-T8} aluminium alloy was anodized at a current density of 5 {mA/cm} 2 to selected voltages in 0.1 M ammonium pentaborate electrolyte at 293 K. It was found that the growth of barrier-type anodic film on the alloy was accompanied by oxidation of intermetallics, formation and rupture of oxygen gas-filled voids in the anodic film and healing of the anodic film at the sites of rupture. It was revealed that the formation of oxygen gas-filled voids was related to the oxidation of copper-rich nanoparticles in the copper-enriched layer at the film/alloy interface, and that the oxidation process of copper-rich nanoparticles depended on grain orientation. Further, the significantly reduced Pilling-Bedworth ratio for formation of anodic lithium oxide compared with that for formation of anodic alumina resulted in the formation of fine voids at the alloy/film interface and sequentially, detachment of the anodic film from the alloy surface. ?? 2012 Elsevier Ltd.

The electrochemical reaction mechanisms of tridymite FePO4 with Li ions were studied in the voltage range of 2.4–0 V. The lithiation/delithiation of FePO4 was found to be similar to that of binary 3d-metal oxides, which involve the formation and decomposition of Li2O along with the reduction and oxidation of nanoscale 3d-metal nanoparticles. In the first discharge, FePO4 was reduced to metallic Fe nanoparticles dispersed in a lithium compound matrix consisting of Li3PO4 and Li2O. In the subsequent charge, these metallic Fe nanoparticles were partially oxidized to FeO by the decomposition of Li2O. The Li3PO4 matrix was inactive during the change of potential from 0 to 2.4 V. It is notable that the re-oxidation of metallic Fe occurred only in the case of small nanoparticles, and the large Fe particles remained electrochemically inert during the reversible reaction. © 2007 Elsevier Ltd. All rights reserved.

The Li + ion-exchange reaction of K + -type α-K 0.14 MnO 1.93 · n H 2 O containing different amounts of water molecules ( n = 0–0.15) with a large (2 × 2) tunnel structure has been investigated in a LiNO 3 –LiCl molten salt at 300 °C. The Li + ion-exchanged products were examined by chemical analysis, X-ray diffraction, and transmission electron microscopy measurements. The K + ions and the hydrogens of the water molecules in the (2 × 2) tunnels of α-MnO 2 were exchanged by Li + ions in the molten salt, resulting in the Li + -type α-MnO 2 containing different amounts of Li + ions and lithium oxide (Li 2 O) in the (2 × 2) tunnels with maintaining the original hollandite structure. The electrochemical properties and structural variation with initial discharge and charge–discharge cycling of the Li + ion-exchanged α-MnO 2 samples have been investigated as insertion compounds in the search for new cathode materials for rechargeable lithium batteries. The Li + ion-exchanged α-MnO 2 samples provided higher capacities and higher Li + ion diffusivity than the parent K + -type materials on initial discharge and charge–discharge cyclings, probably due to the structural stabilization with the existence of Li 2 O in the (2 × 2) tunnels.

Li[Ni1/3Co1/3Mn1/3]O2 cathode material for lithium ion batteries was prepared by mixing metal hydroxide, (Ni1/3Co1/3Mn1/3)(OH)2, with 6% excess LiOH followed by calcinations. The (Ni1/3Co1/3Mn1/3)(OH)2 with secondary particle of about 12 μm was prepared by hydroxide co-precipitation. The tap density of the obtained Li[Ni1/3Co1/3Mn1/3]O2 powder was 2.56 ± 0.21 g cm−3. The powder was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), particle size distribution (PSD) and galvanostatic charge–discharge cycling. The XRD pattern of Li[Ni1/3Co1/3Mn1/3]O2 revealed a well ordered hexagonal layered structure with low cation mixing. Secondary particles with size of 13–14 μm and primary particles with size of about 1 μm can be identified from the SEM observations. In the voltage range of 2.8–4.3 V, the initial discharge capacity of the Li[Ni1/3Co1/3Mn1/3]O2 electrode was 166.6 mAh g−1, and 96.5% of the initial capacity was retained after 50 charge–discharge cycling.

LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode powders with fine size and spherical shape were prepared by solid-state reaction method using the Ni–Co–Al–O precursor powders with fine size and spherical shape. The Ni–Co–Al–O precursor powders with fine size and filled inner structure were prepared by spray pyrolysis from the spray solution with drying control chemical additive (DCCA), citric acid and ethylene glycol. The one LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode powder with fine size and spherical shape was formed from the one precursor powder with spherical shape and filled morphology. The mean size of the spherical shape LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode powders was 1.1 μm. The initial discharge capacity of the LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode powders prepared from the spray solution with citric acid, ethylene glycol and DCCA was 200 mAh g −1 . The cycle properties of the cathode powders prepared from the spray solution with and without additives were compared.

LiNi 0.5 Mn 1.5 O 4− δ cathode materials with two different structures ( F d 3 ¯ m and P 4 3 32) were synthesized by ultrasonic spray pyrolysis method. The X-ray diffraction (XRD) data was confirmed that face-centered spinel ( F d 3 ¯ m ) transformed into primitive simple cubic ( P 4 3 32) structure by annealing process at 700 °C. In spite of two electrons operated cut-off voltage range between 2.0 and 5.0 V, LiNi 0.5 Mn 1.5 O 4 with P 4 3 32 structure has better electrochemical behaviors than the cathode with simple cubic F d 3 ¯ m structure. Ex situ XRD study of the electrode revealed that LiNi 0.5 Mn 1.5 O 4 ( P 4 3 32) has reversible crystal transformation between fully lithiated state (2.0 V) and delithiated state (5.0 V) whereas LiNi 0.5 Mn 1.5 O 4− δ ( F d 3 ¯ m ) showed irreversible phase transformed at two voltage region. The LiNi 0.5 Mn 1.5 O 4− δ ( F d 3 ¯ m ) has voltage drop was occurred after 20th cycled compared without any voltage drop of the P 4 3 32 structure.

Li x Mn 2 O 4 (LMO) and Li x Mn 2 O 4 –0.5ZrO 2 (LMZO) thin films have been fabricated by radio-frequency (rf) sputtering deposition combined with conventional annealing method. The structures and surface morphology of thin films are characterized by X-ray diffraction, transmission electron microscopy, selected area electron diffraction and scanning electron microscopy techniques. It is shown that the addition of mass quantity of ZrO 2 in LMZO can control the grain growth of nano-crystalline LMO. The electrochemical performances of all-solid-state thin film lithium batteries (TFBs) based on these thin films as cathodes are examined by cyclic voltammetry (CV), galvanostatic mode and alternate-current impedance measurements. Our results demonstrated that the addition of electrochemically inactive ZrO 2 could significantly overcome the disadvantage of two distinct plateaus in 3 and 4 V regions. LMZO is expected to become a promising cathode material for future TFBs.

{sup 13}C-carbon black substituted composite LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} cathodes were tested in model electrochemical cells to monitor qualitatively and quantitatively carbon additive(s) distribution changes within tested cells and establish possible links with other detrimental phenomena. Raman qualitative and semi-quantitative analysis of {sup 13}C in the cell components was carried out to trace the possible carbon rearrangement/movement in the cell. Small amounts of cathode carbon additives were found trapped in the separator, at the surface of Li-foil anode, in the electrolyte. The structure of the carried away carbon particles was highly amorphous unlike the original {sup 12}C graphite and {sup 13}C carbon black additives. The role of the carbon additive, the mechanism of carbon retreat in composite cathodes and its correlation with the increase of the cathode interfacial charge-transfer impedance, which accounts for the observed cell power and capacity loss is investigated and discussed.

The mechanism transition of lithium transport through a Li 1− δ Mn 2 O 4 composite electrode caused by the surface-modification and temperature variation was investigated using the galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and the potentiostatic current transient technique. From the analyses of the ac-impedance spectra, experimentally measured from unmodified Li 1− δ Mn 2 O 4 and surface-modified Li 1− δ Mn 2 O 4 with MgO composite electrodes, the internal cell resistance of the MgO-modified Li 1− δ Mn 2 O 4 electrode was determined to be much smaller in value than that of the unmodified electrode over the whole potential range. Moreover, from the analysis of the anodic current transients measured on the MgO-modified Li 1− δ Mn 2 O 4 electrode, it was found that the cell-impedance-controlled constraint at the electrode surface is changed to a diffusion-controlled constraint, which is characterised by a large potential step and simultaneously by a small amount of lithium transferred during lithium transport. This strongly suggests that the internal cell resistance plays a significant role in determining the cell-impedance-controlled lithium transport through the MgO-modified Li 1− δ Mn 2 O 4 electrode. Furthermore, from the temperature dependence of the internal cell resistance and diffusion resistance in the unmodified Li 1− δ Mn 2 O 4 composite electrode measured by GITT and EIS, it was concluded that which mechanism of lithium transport will be operative strongly depends on the diffusion resistance as well as on the internal cell resistance.

The intercalation and deintercalation mechanisms of lithium into V2O5 thin films prepared by thermal oxidation of vanadium metal have been studied by X-ray photoelectron spectroscopy (XPS) using a direct anaerobic and anhydrous transfer from the glove box (O2 and H2O

The heat generation of LiMn2O4, Li1.156Mn1.844O4, and Li1.06Mn1.89Al0.05O4 spinel cathode materials in a half-cell system was investigated by isothermal micro-calorimetry (IMC). The heat variations of the Li/LiMn2O4 cell during charging were attributed to the LiMn2O4 phase transition and order/disorder changes. This heat variation was largely suppressed when the stoichiometric spinel was doped with excess lithium or lithium and aluminum. The calculated entropy change (dE/dT) from the IMC confirmed that the order/disorder change of LiMn2O4, which occurs in the middle of the charge, was largely suppressed with lithium or lithium and aluminum doping. The dE/dT values obtained did not agree between the charge and the discharge at room temperature (25 °C), which was attributed to cell self-discharge. This discrepancy was not observed at low temperature (10 °C). Differential scanning calorimeter (DSC) results showed that the fully charged spinel with lithium doping has better thermal stability.

Metal-doped spinel lithium manganese oxides were successfully synthesized via co-precipitation. The synthesized Li1.05M0.05Mn1.9O4 (M = Ni, Mg, Al) had highly crystalline cubic spinel phase with the space group Fd3m, as confirmed by X-ray diffraction study. From scanning electron microscopic observation, it was found that the prepared materials had spherical morphology with high tap-density. The Li1.05M0.05Mn1.9O4 (M = Ni, Mg, Al) electrode exhibited improved cycling performance at elevated temperature. Especially, the Li1.05Al0.05Mn1.9O4 showed capacity retention of 91.5% during 100 cycles at elevated temperature (55 °C). Also the thermal stability of the Li1.05M0.05Mn1.9O4 (M = Ni, Mg, Al) was also significantly improved.

Electrochemical performance of an aqueous rechargeable lithium battery (ARLB) containing a LiV 3 O 8 (negative electrode) and LiCoO 2 (positive electrode) in saturated LiNO 3 aqueous electrolyte was studied. These two electrode materials are stable in the aqueous solution and intercalation/deintercalation of lithium ions occurs within the window of electrochemical stability of water. The obtained capacity of this cell system is about 55 mAh/g based on the mass of the positive electrode, which is lower than the corresponding one in the non-aqueous lithium ion battery. However, its specific capacity can be compared with those of the lead acid and Ni–Cd batteries. In addition, initial results show that this cell system is good in cycling.

The optimized composition of PVdF-co-HFP–LiAlO 2 based micro-porous nano-composite polymer electrolyte membranes (MPNCPEMs) was prepared with a preferential polymer dissolution process. Nitrogen adsorption isotherms and SEM micrographs showed that the enhanced ionic conductivity of polymer electrolyte was due to increase in pore-size, surface area and pore density, results an increase in the electrolyte uptake. The ac-impedance spectroscopy showed that the room temperature ionic conductivity of PVdF-co-HFP–LiAlO 2 based polymer electrolyte membranes increased with the removal of PVA content and attained the maximum ionic conductivity of 8.12 × 10 −3 S cm −1 . The prepared MPNCPEM of high ionic conductivity was subjected into LSV study. Finally, the electrode/electrolyte interfacial resistance was evaluated by monitoring the impedance response at different time intervals.

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High-rate performances of a lithium-ion battery after storage at elevated temperature are investigated electrochemically by means of three-electrode system. The high-rate capability is decreased significantly after high-temperature storage. A 3 C discharge capacities after room-temperature storage and 60 °C storage are 650 and 20 mAh, respectively. Lithium-ion diffusion in lithium cobalt oxide cathode limits the battery's capacity and the results show that storage temperature changes this diffusion behavior. Transmission electron microscopy (TEM) images show that many defects are directly observed in the cathode after storage compared with the fresh cathode; the structural defects block the diffusion within the particles. Electrochemical impedance and polarization curve indicate that mass-transfer (diffusion) dominates the discharge capacity during high-rate discharge.

An in situ electrochemical atomic force microscopy (EC-AFM) cell was developed to study surface and dimensional changes of individual LixCoO2 crystals during lithium de-intercalation. Discrete Li2CO3 particles having 50–250 nm in diameter and 5–15 nm in height were observed on the surface of stoichiometric LiCoO2 crystals and they were shown to gradually dissolve into the LiPF6-containing electrolyte. The dimensional change of individual LixCoO2 crystals along the chex. axis was monitored in situ during lithium de-intercalation. Evidence of surface instability or structural instability was not found in LixCoO2 single crystals upon de-intercalation to 4.2 V versus Li.

LiNi0.5Mn1.5O4 spinels coated with various amounts of fumed silica have been synthesized and investigated as cathode materials for high-voltage lithium-ion batteries at the elevated temperature (55 degrees C). The morphology and structure of the coated LiNi0.5Mn1.5O4 samples were characterized by XRD, TEM and EDX. It was found that the surfaces of the coated LiNi0.5Mn1.5O4 samples are covered with a porous, amorphous, nanostructured SiO2 layer. The results of electrochemical experiments showed that the SiO2-coated LiNi0.5Mn1.5O4 samples display obviously improved capacity retention rate, and the improvement effect enhances with the increase of SiO2 content. The XPS results revealed that the surfaces of the SiO2-coated LiNi0.5W1.5O4 cathode materials have relatively low content of LiF, and this is mainly responsible for their improved electrochemical cycling stability. (c) 2007 Elsevier Ltd. All rights reserved.

Highly crystalline spinel LiMn 2 O 4 was successfully synthesized by annealing lithiated MnO 2 at a relative low temperature of 600 °C, in which the lithiated MnO 2 was prepared by chemical lithiation of the electrolytic manganese dioxide (EMD) and LiI. The LiI/MnO 2 ratio and the annealing temperature were optimized to obtain the pure phase LiMn 2 O 4 . With the LiI/MnO 2 molar ratio of 0.75, and annealing temperature of 600 °C, the resulting compounds showed a high initial discharge capacity of 127 mAh g −1 at a current rate of 40 mAh g −1 . Moreover, it exhibited excellent cycling and high rate capability, maintaining 90% of its initial capacity after 100 charge–discharge cycles, at a discharge rate of 5 C, it kept more than 85% of the reversible capacity compared with that of 0.1 C.

CeO 2 -coated LiMn 2 O 4 spinel cathode was synthesized using two-step synthesis method. All the samples exhibited a pure cubic spinel structure without any impurities in the XRD patterns. The results of the electrochemical performances on CeO 2 -coated electrode are compared to those of electrodes based on LiMn 2 O 4 spinel without CeO 2 coating. CeO 2 -coated LiMn 2 O 4 cathode improved the cycling stability of the electrode. The capacity retention of 2 wt% CeO 2 -coated LiMn 2 O 4 was more than 82% after 150 cycles between 3.0 and 4.4 V at room temperature and 82% after 40 cycles at elevated temperature of 60 °C. The amounts of dissolved manganese-ions in CeO 2 -coated LiMn 2 O 4 significantly are smaller than pristine LiMn 2 O 4 systems especially at elevated temperatures. Surface-modified LiMn 2 O 4 can suppress the dissolution reaction of manganese-ions at elevated temperature and clearly improve the cyclability of the spinel LiMn 2 O 4 cathode materials.

A novel cathode material, lithium decavanadate Li 6 V 10 O 28 with a large tunnel within the framework structure for lithium ion battery has been prepared by hydrothermal synthesis and annealing dehydration treatment. The structure and electrochemical properties of the sample have been investigated. The novel material shows good reversibility for Li + insertion/extraction and long cycle life. High discharge capacity (132 mAh/g) is obtained at 0.2 mA/cm 2 discharge current and potential range between 2.0 and 4.2 V versus Li + /Li. AC impedance of the Li/Li 6 V 10 O 28 cell reveals that the cathode process is controlled mainly by Li + diffusion in the active material. The novel material would be a promising cathode material for Li-ion batteries.

LiNi1−xCoxO2 (x = 0, 0.1, 0.2) cathode materials were successfully synthesized by a rheological phase reaction method with calcination time of 0.5 h at 800 °C. All obtained powders are pure phase with α-NaFeO2 structure (R-3m space group). The samples deliver an initial discharge capacity of 182, 199 and 189 mAh g−1 (25 mA g−1, 4.35–3.0 V), respectively. The reaction mechanism was also discussed, which consists of a series of defect reactions. As a result of these defect reactions, the reaction of forming LiNi1−xCoxO2 takes place in high speed.

LiNi 0.5 Mn 1.5 O 4 thin films were prepared by pulsed laser deposition (PLD) on stainless steel substrates. The growth of the films has been studied as a function of substrate temperature and oxygen partial pressure in deposition, using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). Electrochemical properties of LiNi 0.5 Mn 1.5 O 4 thin film cathodes were investigated using cyclic voltammetry and galvanostatic charge/discharge against a lithium anode. The initial capacity and capacity retention of the films are highly dependent on the crystallinity and purity of the films. LiNi 0.5 Mn 1.5 O 4 thin films grown at 600 °C in an oxygen partial pressure of 200mTorr are well crystallized with high purity, exhibiting excellent capacity retention between 3 and 5 V with a LiPF 6 -based electrolyte.

Lithium transport through the partially inactive fractal Li 1 − δ Mn 2 O 4 film electrode under the cell-impedance-controlled constraint was theoretically investigated by using the kinetic Monte Carlo method based upon random walk approach. Under the cell-impedance-controlled constraint, all the potentiostatic current transients calculated from the totally active and partially inactive fractal electrodes hardly exhibited the generalised Cottrell behaviour and they were significantly affected in shape by the interfacial charge-transfer kinetics. In the case of the linear sweep voltammogram determined from the totally active and partially inactive fractal electrodes, all the power dependence of the peak current on the scan rate above the characteristic scan rate deviated from the generalised Randles–Sevcik behaviour. From the analyses of the current transients and the linear sweep voltammograms simulated with various values of the simulation parameters, it was further recognised that the cell-impedance-controlled lithium transport through the partially inactive fractal Li 1 − δ Mn 2 O 4 film electrode strongly deviates from the generalised diffusion-controlled transport behaviour of the electrode with the totally active surface, which is attributed to the impeded interfacial charge-transfer kinetics governed by the surface inhomogeneities including the fractal dimension of the surface and the surface coverage by active sites and by the kinetic parameters including the internal cell resistance.

The rapid thermal annealing (RTA) process was employed to obtain crystalline LiCoO2 thin films. XRD analyses of the LiCoO2 thin film show increased crystallinity with an increase in the RTA time. The Auger electron spectroscopic analysis of the LiCoO2 film strongly suggests that the RTA process is more advantageous to obtain a stable inter layer between the substrate and the deposited film and between each deposited layer than the conventional annealing process. All-solid-state thin film cells composed of Li/lithium phosphorous oxynitride (Lipon)/LiCoO2 systems were fabricated using the LiCoO2 cathode treated with RTA. The optimum condition of RTA would be 900 s at 650 °C, which exhibited a good rate capability for high power applications. Two cells were connected in parallel to obtain a higher discharge current, and they showed a specific capacity of 38.4 μAh cm−2 μm−1 even at a 25C rate (current density: 7.96 mA cm−2).

LiNi 0.5 Mn 1.5 O 4 was prepared by a spray drying and post-annealing process. The re-annealing treatment in O 2 could not only decrease the Mn 3+ content, but also increased the reversible capacity and significantly improve the rate capability compared to the untreated material. Moreover, the cyclic performance of the LiNi 0.5 Mn 1.5 O 4 depends on both the cycling rate and operating temperature, which was ascribed to the difference between the phase transition rates between cubic I ↔ cubic II and cubic II ↔ cubic III.

LiCoO_2 and LiMn_2O_4 cathodes were studied by X-ray diffractometry (XRD) and electron diffraction after ageing in the charged state at elevated temperature. Some cathodes were stopped at different times during ageing and XRD measurements were taken to monitor changes in the crystal structure over ageing time. The results indicate that Li-ions intercalate into the cathodes lattice during ageing thus decreasing the available discharge capacity. Analysis of electron diffraction patterns of LiCoO_2 and LiMn_2O_4 retrieved from the cathodes after ageing shows that irreversible crystallographic transformations have taken place in both electrodes. Dark field imaging illustrates that LiCoO_2 forms a layer of spinel phase on its surface. In LiMn_2O_4 a tetragonal distorted spinel is observed when the cathode has been in the 3 V regime for considerable length of time.

Solid state glass electrolyte, x Li 2 O-(1 − x )( y B 2 O 3 -(1 − y )P 2 O 5 ) glasses were prepared with wide range of composition, i.e. x = 0.35 – 0.5 and y = 0.17 – 0.67. This material system is one of the parent compositions for chemically and electrochemically stable solid-state electrolyte applicable to thin film battery. Lithium ion conductivity of Li 2 O–B 2 O 3 –P 2 O 5 glasses was studied in the correlation to the structural variation of glass network by using FTIR and Raman spectroscopy. The measured ionic conductivity of the electrolyte at room temperature increased with x and y . The maximum conductivity of this glass system was 1.6 × 10 −7 Ω −1 cm −1 for 0.45Li 2 O–0.275B 2 O 3 –0.275P 2 O 5 at room temperature. It was shown that the addition of P 2 O 5 reduces the tendency of devitrification and increases the maximum amount of Li 2 O added into glass former without devitrification. As Li 2 O and B 2 O 3 contents increased, the conductivity of glass electrolyte increased due to the increase of three-coordinated [BO 3 ] with a non-bridging oxygen (NBO).

Spherical Li[Ni 0.4 Co 0.2 Mn (0.4-x) Mg x ]O 2-y F y (x=0, 0.04, y=0, 0.08) with phase-pure and well-ordered layered structure have been synthesized by heat-treatment of spherical [Ni 0.4 Co 0.2 Mn 0.4-x Mg x ]O 4 precursors with LiOH·H 2 O and LiF salts. The average particle size of the powders was about 10-15 μm and the size distribution was quite narrow due to the homogeneity of the metal carbonate, [Ni 0.4 Co 0.2 Mn (0.4-x) Mg x ]CO 3 (x=0, 0.04) precursors. Although the Li[Ni 0.4 Co 0.2 Mn 0.36 Mg 0.04 ]O 1.92 F 0.08 delivered somewhat slightly lower initial discharge capacity, however, the capacity retention, interfacial resistance, and thermal stability were greatly enhanced comparing to the Li[Ni 0.4 Co 0.2 Mn 0.4 ]O 2 and Li[Ni 0.4 Co 0.2 Mn 0.36 Mg 0.04 ]O 2 .

Layered Li 1+x (Ni 0.3 Co 0.4 Mn 0.3 )O 2-δ (x=0, 0.03 and 0.06) materials were synthesized through the different calcination times using the spraydried precursor with the molar ratio of Li/Me = 1.25 (Me = transition metals). The physical and electrochemical properties of the lithium excess and the stoichiometric materials were examined using XRD, AAS, BET and galvanostatic electrochemical method. As results, the lithium excess Lι 1.06 (Ni 0.3 Co 0.4 Mn 0.3 )Ο 2-δ could show better electrochemical properties, such as discharge capacity, capacity retention and C rate ability, than those of the stoichiometric Li 1.00 (Ni 0.3 Co 0.4 Mn 0.3 )Ο 2-δ . In this paper, the effect of excess lithium on the electrochemical properties of Li 1+x (Ni 0.3 Co 0.4 Mn 0.3 )O 2-δ materials will be discussed based on the experimental results of ex situ X-ray diffraction, transmission electron microscopy (TEM) and galvanostatic intermittent titration technique (GITT).

Co, Ni and Mn K-edge XAFS investigation of LiCo1/3Ni1/3Mn1/3O2 as alternative cathode material to commercially used LiCoO2 in lithium rechargeable battery has been performed. Parameters of a local atomic structure such as radii of metal–oxygen and metal–metal coordination shells and disorder in those shells have been determined. It has been found that the radius of the first coordination shell (metal–oxygen) as well as a local disorder in the second shell (metal–metal) around each of the 3d-metals are in a good agreement with obtained for superlattice model of [ √ 3 × √ 3] R30 ◦ type in triangular lattice of sites by first principle calculation. Other parameters of the local atomic structure around Co, Ni and Mn atoms do not provide evidence for presence of superstructure in LiCo1/3Ni1/3Mn1/3O2. © 2006 Published by Elsevier Ltd.

The electrochemical properties of LiNi 0.8 Co 0.2 O 2 coated with ZrO 2 by three different coating processes (ball-milling, sol-gel method, simple grinding) were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Results showed that the ZrO 2 coating significantly improved the capacity retention of the cathode by suppressing the impedance growth at the interface between electrodes and electrolyte and the best cyclability was obtained in the case of employing the simple grinding for the ZrO 2 coating. On the other hand, the initial capacities of the ZrO 2 -coated LiNi 0.8 Co 0.2 O 2 cathode were slightly decreased.

Usefulness of W substitution for improvement of battery performance of LiMn2O4 cathode was investigated. Small amounts of tungsten were incorporated into LiMn2O4 spinel instead of available Mn. For this purpose, two sources of tungsten (metallic W or WO3) were examined. W concentration and source have significant influence on both morphology and electrochemical behavior of W-substituted LiMn2O4 spinels. W substitution of LiMn2O4 spinel can lead to the formation of uniform spinel particles and improved battery performance. Cyclic voltammetric behaviors of the samples were examined in an aqueous solution, and Li diffusion process was investigated for different cases. The best case was the LiW0.01Mn1.99O4 spinel prepared from metallic W powder, as exhibits excellent rate capability, but better cycleability was observed for the LiW0.01Mn1.99O4 spinel prepared from WO3. This means that because of significant influence of the dopant source, this parameter should be chosen in respect with the desire improvement.

Li 2 O–B 2 O 3 –P 2 O 5 glass soot was fabricated from aqueous precursor solution of a CH 3 CO 2 Li·2H 2 O and BCl 3 , POCl 3 by the flame-assisted ultrasonic spray hydrolysis. The aqueous precursor solution of the lithium acetates was first atomized with an ultrasonic vibrator (1.7 MHz). B 2 O 3 and P 2 O 5 were formed from BCl 3 and POCl 3 by oxy-hydrogen flame. Their properties were investigated by SEM, XRD, TGA–DSC and impedance analyzer. The formed particles in glass soot had spherical shape and the size of approximately 50–100 nm. XRD analysis revealed that the amorphous phase and crystalline phases were mixed in glass soot and the crystalline phases were B(OH) 3 and B 2 O 3 . The crystalline B(OH) 3 and B 2 O 3 found in glass soot completely disappeared by heat treatment. Conductivity was measured by complex impedance method using impedance analyzer and the conductivity was 10 −8 S/cm.

Properties of LiMn 2 O 4 thin films deposited on polished stainless steel substrates at 400 °C and 200 mTorr of oxygen by pulsed laser deposition have been characterized by electrochemical measurements and physical analyses. The film was mainly composed of nano-crystals less than 100 nm. A maximum specific capacity of 141.9 mAh/g cycled between 3.0 and 4.5 V with a current density of 20 μAh/cm 2 has been achieved. The film exhibited an excellent cycling stability up to 500 cycles. The low charge-transfer resistance at high potentials as revealed by AC impedance resulted in high charge/discharge potential and more capacity. The effect of overdischarge was limited and Jahn–Teller effect was overcome to a significant extent in this nano-crystalline film. Ex situ XRD, Raman and XPS provided supporting evidence in the changes in structure, reactivity and cycling stability of nano-crystalline LiMn 2 O 4 film cathodes under different charge/discharge states and cycling tests. SEM images also revealed the stability of the surface topography after a long-term cycling test.

LiNi1/3Co1/3Mn1/3O2 cathode materials have been coated with Al2O3 nano-particles using sol–gel processing to improve its electrochemical properties. The X-ray diffraction (XRD) pattern of the as-prepared Al2O3 nano-particles was indexed to the cubic structure of the γ-Al2O3 phase and had an average size of ∼4 nm. The XRD showed that the structure of LiNi1/3Co1/3Mn1/3O2 was not affected by the Al2O3 coating. However, the Al2O3 coatings on LiNi1/3Co1/3Mn1/3O2 improved the cyclic life performance and rate capability without decreasing its initial discharge capacity. These electrochemical properties were also compared with those of LiAlO2-coated LiNi1/3Co1/3Mn1/3O2 cathode material. The electrochemical impedance spectroscopy (EIS) was studied to understand the enhanced electrochemical properties of the Al2O3-coated LiNi1/3Co1/3Mn1/3O2 compared to uncoated LiNi1/3Co1/3Mn1/3O2.

Lithium transport through LiCoO2/Li1−δMn2O4 bilayer film electrode prepared by radio-frequency (rf) magnetron sputtering was investigated in a 1 M solution of LiClO4 in propylene carbonate. From the analyses of the AC-impedance spectra experimentally measured from the Li1−δMn2O4 single-layer and LiCoO2/Li1−δMn2O4 bilayer film specimens, the internal cell resistance of the LiCoO2/Li1−δMn2O4 bilayer film electrode was determined to be smaller in value than that of the Li1−δMn2O4 single-layer film electrode over the whole potential range, which can be accounted for by the kinetic facility for the interfacial charge-transfer reaction in the presence of the more conductive LiCoO2 surface film. Moreover, from the analyses of the anodic current transients measured from both the film specimens, it was suggested that the cell-impedance-controlled constraint at the electrode surface is changed to the diffusion-controlled constraint simultaneously characterised by the large potential step and the small amount of lithium transferred during lithium transport. In addition, in the case of the LiCoO2/Li1−δMn2O4 bilayer film electrode, it was found that the critical value of the applied potential step needed for the mechanism transition is reduced, which strongly indicates that the internal cell resistance plays a significant role in determining the cell-impedance-controlled lithium transport. Furthermore, from the comparison of the cathodic current transients measured on the Li1−δMn2O4 single-layer film specimens with various thicknesses, it was experimentally verified that the diffusion resistance is explicitly distinguished from the internal cell resistance.

Planetary explorations of human beings necessitate the research of the influence of -radiation on lithium-ion cells. In this study, the radioactive Co-60 was used as the radiation source. The electrochemical performances of LiCoO2/graphite full cells and LiCoO2/Li half-cells with a LiPF6based electrolyte were measured before and after the radiation. The structural and compositional changes of the cell components were evaluated by means of X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), and 1 H nuclear magnetic resonance spectroscopy ( 1 H NMR). The experimental results indicate that the cell performance is substantially deteriorated after the radiation due to two aspects of changes, i.e. radiation-induced defects in LiCoO2 and production of carboxyl in the electrolyte. The cell degradation is more pronounced for the LiCoO2/C full cells than for LiCoO2/Li half-cells owing to the reaction between active lithium and the carboxyl. © 2006 Elsevier Ltd. All rights reserved.

The surface of spinel LiMn 2 O 4 was modified with TiO 2 by a simple sol–gel method to improve its electrochemical performance at elevated temperatures and higher working potentials. Compared with pristine LiMn 2 O 4 , surface-modification improved the cycling stability of the material. The capacity retention of TiO 2 -modified LiMn 2 O 4 was more than 85% after 60 cycles at high potential cycles between 3.0 and 4.8 V at room temperature and near to 90% after 30 cycles at elevated temperature of 55 °C at 1 C charge–discharge rate. SEM studies shows that the surface morphology of TiO 2 -modified LiMn 2 O 4 was different from that of pristine LiMn 2 O 4 . Powder X-ray diffraction indicated that spinel was the only detected phase in TiO 2 -modified LiMn 2 O 4 . Introduction of Ti into LiMn 2 O 4 changed the electronic structures of the particle surface. Therefore a surface solid compound of LiTi x Mn 2− x O 4 may be formed on LiMn 2 O 4 . The improved electrochemical performance of surface-modified LiMn 2 O 4 was attributed to the improved stability of crystalline structure and the higher Li + conductivity.

Layered Li[Ni (1− x )/3 Mn (1− x )/3 Co (1− x )/3 Cr x ]O 2 materials with x = 0, 0.01, 0.02, 0.03, 0.05 are prepared by a solid-state pyrolysis method. The oxide compounds were calcined with various Cr-doped contents, which result in greater difference in morphological (shape, particle size and specific surface area) and the electrochemical (first charge profile, reversible capacity and rate capability) differences. The Li[Ni (1− x )/3 Mn (1− x )/3 Co (1− x )/3 Cr x ]O 2 powders were characterized by means of X-ray diffraction (XRD), charge/discharge cycling, cyclic voltammetry, and SEM. XRD experiment revealed that the Li[Ni (1− x )/3 Mn (1− x )/3 Co (1− x )/3 Cr x ]O 2 ( x = 0, 0.01, 0.02, 0.03, 0.05) were crystallized to well layered α-NaFeO 2 structure. The first specific discharge capacity and coulombic efficiency of the electrode of Cr-doped materials were higher than that of pristine material. When x = 0.02, the sample showed the highest first discharge capacity of 241.9 mAh g −1 at a current density of 30 mA g −1 in the voltage range 2.3–4.6 V, and the Cr-doped samples exhibited higher discharge capacity and better cycleability under medium and high current densities at room temperature.

A new methodology that combines the sol–gel method and a template approach is used to synthesize porous LiNi 1− x Co x O 2 films. Conventional films are obtained through the sol–gel method. The films are used to evaluate the influence of this new methodology on the electrochemical performance. It was observed, from X-ray diffraction analysis on the conventional film that a further increase in the annealing temperature to 450 °C leads to a more ordered system indicated by the presence of characteristics LiNi 1− x Co x O 2 diffraction patterns. Above this temperature no significant modification in the X-ray patterns is observed in the porous film. We concluded, using other experimental techniques including cyclic voltammetry, electrochemical impedance and charge/discharge tests) that electrochemical properties, such as, oxidation and reduction charges and charge/discharge capacity of LiNi 1− x Co x O 2 are significantly improved in the porous film, which demonstrates the feasibility of the proposed methodology.

Spinel LiMn 2 O 4 films were obtained by spin-coating the lithium/manganese acetates-containing precursor solution on a Pt-coated silicon substrate. The effect of chitosan addition in the acetates-containing precursor solution on the formation of the LiMn 2 O 4 films was investigated by TG/DTA, FT-IR spectroscopy, glancing-angle XRD and cyclic voltammetry. It was demonstrated that the addition of chitosan is very beneficial to the deposition of a single-phase LiMn 2 O 4 film due to the fact that chitosan is able to chelate with lithium/manganese ions and form a stable complex compound. Moreover, the electrochemical measurements also showed that the deposited LiMn 2 O 4 film from the chitosan-added precursor solution exhibits a higher discharge capacity of 134 mAh/g at 1 C and a better rate performance (86.4% of the discharge capacity at 1 C can be maintained when the discharge rate increases from 1 up to 8 C) in comparison with one from the chitosan-free solution.

New vanadate compounds having the molecular structure LixMg1−xV2−xMoxO6 (0 ≤ x ≤ 1) were studied. Six samples were prepared by sol–gel process from precursor using the following ratios of x = 0, 0.2, 0.4, 0.6, 0.8 and 1, respectively. These samples were labeled S1, S2, S3, S4, S5 and S6. The final process of firing occurred at 750 °C for 18 h in air. The prepared materials were characterized by XRD, SEM, IR, electron spin resonance (ESR) and magnetic measurements. The morphologies of S1, S2, S5 and S6 are prismatic as they have monoclinic crystal structures. S3 and S4 differ in the crystal morphology from the other previous samples due to their triclinic crystal lattice structure. IR spectra revealed that the bond lengths of the vanadyl groups νV O, νsy V–O and σV–O increase in the same direction from S1 to S6. The data of the ESR explain the existence of V4+ beside V5+ in S1, S4 and S6 and also presence of Mo5+ with Mo6+ in S4 and S6. S4 exhibited better magnetic susceptibility and saturated magnetization than the other samples. The first specific discharge capacities of the samples were performed. S4 showed the maximum specific capacity of 265 mAh g−1 in comparison with the other samples. Cyclic voltammogram of S4 exhibited the highest current intensity in comparison with the other samples. This sample showed two peaks at 0.53 and 1.3 V versus Li/Li+ characterizing double de-insertions of two lithium atoms from Li1.6Mg0.4V1.4Mo0.6O6−x and Li0.6Mg0.4V1.4Mo0.6O6, respectively. Also, two additional peaks were characterized for the oxidation of Mo5+ to Mo6+ and V4+ to V5+ at 3.5 and 4 V, respectively.

We report on electrochemical properties of NiO-blended spinel Li1.1Mn1.9O4 at elevated temperature (60 °C). Thus, we employed two kinds of NiO powders, those are, larger particle size (>10 μm) and submicron-sized NiO powders obtained by a ball-milling. These NiO powders were blended to the spinel Li1.1Mn1.9O4 as an additive for fabrication of cathode. The resulting discharge capacity for the larger NiO particle-blended Li1.1Mn1.9O4 had similar electrochemical properties to the bare Li1.1Mn1.9O4. On the other hand, submicron-sized NiO-blended Li1.1Mn1.9O4 brought about slightly increased capacity and excellent capacity retention, maintaining its initial capacity of 99.2% at 25 °C and 94% at 60 °C when Li metal was employed as the anode. In Li-ion cell using graphite as the anode, the capacity retention was of about 80% during cycling at 60 °C, whereas C/Li1.1Mn1.9O4 cell retained around 68% of its initial capacity. Such improved properties would be ascribed to the HF scavenging into the electrolyte by presence of the submicron-sized NiO particles in Li1.1Mn1.9O4 cathode.