Papers by Keyword: Cathode Material

Abstract: High nickel content in nickel manganese cobalt (NMC811, LiNi_0.8Mn_0.1Co_0.1O₂) resulted in high capacity but low structural stability. Surface modification of NMC811 via silica (SiO₂) coating is known to counter this problem, leading to better electrochemical performance. In this work, silica was synthesized from rice husk through sol-gel method with alkaline extraction followed by acidification process. The resulting silica was coated onto commercially available NMC811 to modify its surface via solid-state reaction method. The characterization results showed that the silica coated NMC811 demonstrated a higher conductivity and lithium diffusion coefficient of 2.85 x 10^-5 S/cm and 2.52 x 10^-14 cm²/s, respectively, compared to that of bare NMC811 (8.17 x 10^-6 S/cm and 1.75 x 10^-15 cm²/s, respectively). This result confirms that the silica derived from rice husk can be used as a potential low-cost material to modify the surface and thus to increase the electrochemical performance of commercial NMC811.

Abstract: NaFePO₄, which is analogue to LiFePO_4, has been expected to show similar properties as LiFePO₄ that has a good cycle stability and excellent electrochemical performances. Here we report the synthesis of NaFePO₄ via sol-gel method and the structural study of NaFePO₄ as a cathode material for sodium-ion battery (SIB). The as-synthesized NaFePO₄ samples were calcined under air and argon atmosphere at the constant holding time of 10 hours with the variation of calcined temperature. In this report, we present the successfully synthesized NaFePO₄ based on XRD and SEM result. XRD results show the presence of NaFePO₄ as a major phase and some amount of secondary phase. SEM result indicates the plate-like particle which tends to agglomerate with the size range 2-5 .

Abstract: Li ion battery or LIB is an energy storage device that provides and store electrical energy and chemical energy, respectively. LIBs have been widely developed in the energy sector owing to their considerable high energy density, high capacity, and long-life cycle. In this study, the LiFePO₄/C cathode was synthesized from various precursors FeC₂O₄, FePO₄, Fe₃(PO₄)₂, Fe₂O₃ obtained via co-precipitation method, and continued with solid-state. The effects of precursors were studied in this study. The precursor and the resulting product were analyzed using XRD, FTIR, SEM, and EDX, while the electrochemical performance was tested using charge-discharge, cycle stability and rate capability. All precursors were successfully synthesized as evidenced by XRD, FTIR, SEM, and EDX characterization tests. Based on electrochemical performance test, the highest capacity that can be achieved is 109 mAh/g obtained from LFP with FeC₂O₄ precursor, with a reduction in capacity of 54.7% after 50 cycles.

Abstract: In order to increase the energy density of lithium-ion battery, the LiN_i0.8Co_0.1Mn_0.1O₂(NCM811) cathode material with higher Ni content has attracted much attention due to its advantages such as high energy density, low cost. However, there are some bottleneck problems about the NCM811 such as capacity fading, harsh storage conditions, poor thermal stability, poor safety, which limit its large-scale commercial use. This article reviews the urgent problems for NCM811 high nickel ternary materials, briefly describes several common synthesis methods, and focuses on the modification methods, such as element doping, surface coating and special core-shell structure for enhancing the electrochemical performances and explain the modification mechanism. Finally, we prospect the possible research development and commercial application of high nickel ternary material.

Abstract: Layered lithium iron hydroxysulfate, LiFeSO₄OH was recently proposed as a cathode material for lithium ion batteries (LIBs) made up of low cost and sustainable components. Here, we report ab-initio investigation into the structural properties of its sodium analogue, NaFeSO₄OH obtained from in-situ substitution of lithium (Li) with sodium (Na). A robust host structure for NaFeSO₄OH was discovered owing to strong Fe-O and S-O bonds, a good indicator for thermal stability and long cycle life. The Na ions are strongly held by the oxygen atoms, but the charge density map proves that the bond between the two is still ionic.

Abstract: In this work, the effect of carbon on the electrochemical properties of multi-walled carbon nanotube (MWCNT) functionalized Lithium iron manganese phosphate was studied. In an attempt to provide insight into the structural and electronic properties of optimized electrode materials a systematic study based on a combination of structural and spectroscopic techniques. The phosphor-olivine LiFe_0.5Mn_0.5PO₄, was synthesized via a simple microwave synthesis using LiFePO₄ and LiMnPO₄ as precursors. Cyclic voltammetry was used to evaluate the electrochemical parameters (electron transfer and ionic diffusivity) of the LiFe_0.5Mn_0.5PO₄ redox couples. The redox potentials show two separate distinct redox peaks that correspond to Mn²⁺/Mn³⁺ (4.1 V vs Li/Li⁺) and Fe²⁺/Fe³⁺ (3.5 V vs Li/Li⁺) due to interaction arrangement of Fe-O-Mn in the olivine lattice. The electrochemical impedance spectroscopy (EIS) results showed LiFe_0.5Mn_0.5PO₄-MWCNTs having high conductivity with reduced charge resistance. This result demonstrates that MWCNTs stimulates faster electron transfer and stability for the LiFe_0.5Mn_0.5PO₄ framework, which demonstrates favorable as a host material for Li⁺ ions.

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: Spinel LiMn₂O₄ is one of the promising cathode materials used in commercial Li-ion batteries. In this study, Ni was partially substituted in order to give the material LiMn_1.8Ni_0.2O₄, which was successfully synthesized using a self-propagating combustion (SPC) method. Results from Simultaneous Thermogravimetric Analysis (STA) show the small mass loss about 4.6%. The precursor then was calcined at temperature of 800 °C for 24 h, 48 h and 72 h. X-Ray Diffraction (XRD) confirms that the final products are pure and single phase with no impurities present. The morphology and crystallite size of pure samples are examined using Field Emission Scanning Electron Microscope (FESEM). The result shows that all the materials consist of crystalline particles with smooth surface and polyhedral shaped materials.

Abstract: Higher efficiency in raw material recycling is discussed as a key strategy to decrease the environmental impact of resource consumption and to improve materials’ availability in order to mitigate supply risks. However, particularly in the case of technology metals, demand is driven by specific emerging technologies from which recycling will not be possible before the end of their useful lifetimes. Hence, the availability of secondary materials is limited by the amount of obsolete products as well as their collection, separation and treatment during waste management and recycling. In this paper, we present the results of a dynamic material flow model for cobalt as a key raw material for lithium-ion batteries at an European level (EU28). This model aims at quantifying the current state of recycling and future recycling potentials from end-of-life (EoL) product flows. While it is expectable that obsolete large battery packs from (hybrid) electric vehicles will be efficiently collected in future, EoL Li-ion battery flows will remain dominated by smaller electronic equipment (smartphones, laptops etc.) in the coming years and the model results show a significant potential for improvements in collection and material recovery from EoL batteries in Europe. A major challenge will be the collection of smaller batteries and Waste Electrical and Electronic Equipment (WEEE) in general from which a significant share of total European cobalt demand could be recovered in the coming years.

Abstract: High energy density and rechargeable lithium ion batteries are attracting widely interest in renewable energy fields. The preparation of the high performance materials for electrodes has been regarded as the most challenging and innovative aspect. By utilizing a facile combustion synthesis method, pure nanostructure LiNi_0.5Mn_1.5O₄ cathode material for lithium ion batteries were successfully fabricated. The crystal phase of the samples were characterized by X-Ray Diffraction, and micro-morphology as well as electrochemistry properties were also evaluated using FE-SEM, electrochemical charge-discharge test. The result shows the fabricated LiNi_0.5Mn_1.5O₄ cathode materials had outstanding crystallinity and near-spherical morphologies. That obtained LiNi_0.5Mn_1.5O₄ samples delivered an initial discharge capacity of 137.2 mAhg^-1 at the 0.1 C together with excellent cycling stability and rate capability as positive electrodes in a lithium cell. The superior electrochemical performance of the as-prepared samples are owing to nanostructure particles possessing the shorter diffusion path for Li⁺ transport, and the nanostructure lead to large contact area to effectively improve the charge/discharge properties and the rate property. It is demonstrated that the as-prepared nanostructure LiNi_0.5Mn_1.5O₄ samples have potential as cathode materials of lithium-ion battery for future new energy vehicles.