Papers by Keyword: LiCoO₂

Abstract: Energy storage devices are the demand of the new era for flexible portable electronics. Considering the importance of renewable energy and environmental issues. We utilized LiCo_1-xZn_xO₂ (x=0.0, 0.1) nanoparticles with an average crystallite size of 31-45nm that were embedded in nanofibers formed by the electrospinning technique. Sol-gel techniques were used to make them. PVP polymer was used as a binder to support the backbone frame of the nanofibers. We have characterized our synthesized material to examine its structural, morphological, and electrical properties. XRD of synthesized material tells us about the rhombohedral structure of the R3m space group symmetry. FTIR spectroscopy was used to study the functional groups and vibrations in synthesized material. SEM results confirmed the formation of nanoparticles embedded in nanofibers. In AC analysis, we have discussed dielectric constant, tangent loss, and AC conductivity. The electrical properties of synthesized LiCo_1-xZn_xO₂ (x=0.0, 0.1) nanofibers were studied in a frequency range of 100Hz to 3MHz and found that AC conductivity is high of nanoparticles embedded nanofibers of LiCo_0.9Zn_0.1O₂ i.e., 4.2 x10^-5 (S/m) that plays a crucial role for the supercapacitors and as a cathode material in Lithium-ion batteries(LIBs).

Abstract: The effect of Cr and Ni substitution on electrochemical performance of layered LiCo_0.9M_0.1O₂ (M=Cr and Ni) has been investigated. Partial substituted of LiCo_0.9Cr_0.1O₂ and LiCo_0.9Ni_0.1O₂ has been synthesized using a self-propagating combustion (SPC) method with annealing temperature of 700 ̊ C for 24 h. The starting materials used were metal nitrates and citric acid act as a combustion agent. The phase and crystalinity of the materials were characterized using X-Ray Diffraction (XRD) and results showed that the single phase and pure materials were obtained with no impurity peaks were detected. The morphology and particle sizes of samples also analyzed using Field Emission Scanning Electron Microcopy (FESEM). The electrochemical performances of the materials were measured by its charge-discharge cycling which carried out in the voltage range of 2.5 V to 4.5 V. The results from charge-discharge studies found that LiCo_0.9Ni_0.1O₂ has better specific discharge capacity compared with LiCo_0.9Cr_0.1O₂.

Abstract: LiCo_0.9X_0.1O₂ (where X=Mn and Fe) were synthesized using self-propagating combustion (SPC) method using citric acid as a combustion agent. The precursors of LiCo_0.9X_0.1O₂ were annealed at a temperature of 800 °C at 24 h. The phase and crystalinity of the materials were characterized using X-Ray Diffraction (XRD). All the materials were observed to be single and pure phase with no impurity peaks detected. The morphology and particle sizes of the materials were also analyzed using Field Emission Scanning Electron Microcopy (FESEM). Finally, the electrochemical performance of the materials was studied using charge-discharge cycling in the voltage range of 2.5 to 4.3 V. Based on the results from charge-discharge studies, Mn substituted cathode materials exhibit better specific discharge capacity compared with Fe substituted cathode materials.

Abstract: In this work, we investigated the influence of passivation coating of aluminum oxide on cycle life of lithium-ion batteries. Al2O3 was synthesized by atomic layer deposition directly on the porous electrodes based on LiCoO2. More than 800 charge-discharge cycles were done. No increase of internal resistance due to Al2O3 coating was observed. According to the results, electrodes coated by aluminum oxide have better cycle life.

Abstract: A new lithium cobalt oxyhydroxide compound has been successfully synthesized. This new compound has been found to be related to the low temperature LiCoO₂ (LT-LiCoO₂) spinel structure formed at low processing temperatures. With the use of a modified sol-gel approach, this compound with the composition of LiCo₂O₃(OH) can be successfully synthesized at around 150 °C. Structural analyses using powder X-ray diffraction (XRD) and selected area electron diffraction (SAED) suggest a cubic-spinel structure, which is also supported by FT-IR and TG/DTA analyses. In addition, from the TEM morphological analysis, a very fine nanograined LiCo₂O₃(OH) powder with an average grain size of 5 nm has been obtained. From these results, the presence of OH or water at low processing temperatures promotes a favorable formation of this structure. At higher temperatures (>400 °C), the phase transforms to a layered high-temperature LiCoO₂ (HT-LiCoO₂) structure with the excess cobalt precipitated as Co₃O₄ as suggested by the in-situ high temperature XRD analysis.

Abstract: LiCoO₂ is a well-known cathode material used in commercial Li-ion batteries but it has its own limitations in terms of cost and toxicity. Improvement of the material by partial substitution of Co with other transition metals is one of the alternative and effective ways to overcome the limitations and improve the electrochemical performance of cathode materials. The transition metal element used for the substitution has to be cheaper and non-toxic thus Mn is chosen here. LiCo_(1-x)Mn_xO₂ (x= 0.1, 0.2, 0.3) we synthesized by a novel route using a self-propagating combustion (SPC) method. The samples are analyzed using X-Ray Diffraction (XRD) for phase purity and Field Emission Scanning Electron Microscopy (FESEM) for morphology and particle size studies. The materials obtained are phase pure. In terms of electrochemical activity, though it does not show better first cycle discharge capacity, the Mn doped materials have improved capacity retention. Results showed that LiCo_0.9Mn_0.1O₂ and LiCo_0.8Mn_0.2O₂ exhibited less than 8 % capacity loss in the 20th cycle compared to 12 % for LiCoO₂.

Abstract: The chemical and mineralogical characterizations of cobalt precursor recovered from spent lithium-ion batteries with incineration process was analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It indicates that Co exists in the form of LiCoO₂. However, after thermal treatment, complex products including LiCoO₂, Co₃O₄, and Co₂AlO₄ etc. generated, in which Co₃O₄ has strong signal. The XPS spectra shows that Li_(1-x)CoO₂ and LiCoO₂ are the main chemical state of Co in the original sample, but after thermal treatment, the chemical state changes to Co₃O₄. Besides, there are undecomposed Li_(1-x)CoO₂, CoF₃ and Co. Analyses indicate that Co is enriched after thermal treatment and chemical state of some Co have been certified.

Abstract: In the present work, spent LiCoO₂ was processed to remove impurities by ultrasound with the aim to renovate its electrochemical characteristics. The composition and amount of organic materials remained in the LiCoO₂ particle surface were characterized by GC-MS, FT-IR and TGA, respectively. The morphology and particle sizes of PVDF (Polyvinylidene fluoride) was analyzed by SEM. Experimental results show that ultrasonic cavitation could be effectively used to remove organic substance stuck on LiCoO₂ surface. At room temperature, the spent LiCoO₂ was successfully remove impurities, including EC (Ethylene carbonate) and PVDF, with ultrasound applied for 12 h. It can be considered that most of the PVDF (82.0 wt.%) has decomposed under ultrasonic irradiation. Furthermore, the EC has completely decomposed under such ultrasonic irradiation.

Abstract: A new LiCoO₂ recovery technology from leaching solution of spent Li-ion batteries was studied in this paper. Leaching solution contained many metals, such as Cu, Co and Fe. Copper was removed through replacement by iron powder followed by iron precipitation in goethite method. The experimental results show that Cu can be removed 99% at least through replacement by Fe powder, and the removal of Fe can achieve 99% by goethite method. The optimum Cu removal conditions are that temperature is 50 °C, Fe_mol/Cu_mol=1.5,reaction time is 30 min. The optimum Fe removal conditions are that terminal precipitation pH is 4, temperature is 90 °C, reaction time is 6 h. The remainder Co can be mixed with Li₂CO₃,LiOH•H₂O and LiAc•2H₂O to adjust the Li/Co molar ratio to 1.00. The new LiCoO₂ was obtained by calcining the mixture at 850°C for 12 h in the air. Structure and morphology of the recycled powders and resulted sample were observed by XRD and SEM technique, respectively. The layered structure of the LiCoO₂ synthesized by adding Li₂CO₃ is best, and it is found to have the best characteristics as cathode material in terms of charge–discharge capacity and cycling performance.

Abstract: LiCoO2 is the most studied cathode material for lithium batteries. The doping effect gives a better cycle life in such materials. Apart from the doping effect, the preparation technique also plays an important role. Presently, the layer structured Cu doped LiCoO2 cathode material has been prepared via microwave assisted sol gel route; better cycle life and capacity retention have been attained. It was found that this method could reduce the synthesis time to 30 minutes. The espousal of the microwave method in synthesis could develop a highly efficient, low cost process for synthesis. The surface morphology of the material has been observed using SEM and it is inhomogeneous in nature. The capacity retention is higher than that of pure LiCoO2 material. Compositional analysis was made through EDX. The Cu doped material has a voltage plateau about 4.0V which is obtained from the cyclic voltammetry.