Papers by Keyword: Li-Ion Batteries

Abstract: Li-ion batteries generate significant heat during operation, which leads to an increase in temperature and, consequently, a reduction in the battery's efficiency and lifespan. In this study, different cooling methods are simulated for the thermal management of the battery. The cooling using air and liquids is investigated with laminar flow at varying velocities. Results indicated that the use of water/glycol is more effective than air and mineral oil.

Abstract: This work numerically studies the thermal management of a Li-ion battery pack using Phase Change Materials (PCMs) with two different modelling approaches. Specifically, the results obtained with the Enthalpy-Porosity method, implemented in the tool STAR-CCM+, are compared with those yielded by the Apparent Heat Capacity formulation, employed by COMSOL Multiphysics. Both models are first validated against benchmark cases found in the literature. The study then focuses on the thermal behaviour of a battery pack composed of four 21700 Li-ion battery cells, cooled using the paraffinic PCM RT35. The numerical results show that, while natural convection in the liquid PCM accelerates the melting process, it leads to a non-uniform temperature distribution, particularly disadvantageous for cells located in the upper part of the battery pack. In addition, although both numerical approaches show good agreement between their results, especially in capturing the overall thermal behaviour, some minor differences in the temperature profiles during the PCM phase change still emerge.

Abstract: The cathode material of the lithium-ion battery in this study is LiNi_0.5Mn_0.3Co_0.2O₂ (NMC532) with a mole ratio of Ni, Mn, and Co respectively 5:3:2. The purpose of this research was aimed for direct using of MHP as the nickel source to NMC532 as cathode material can greatly reduce the overall production cost due to shorter supply chain of nickel which is beneficial for commercialization of cathode material. The Mix Hydroxide Precipitate (MHP) was leached by acetic acid to earn nickel acetate. Then, to make NMC532 by co-precipitation method, the nickel acetate was reacted with MnSO₄.H₂O, CoSO₄.7H₂O, and C₂H₂O₄.2H₂O. Based on the XRD and FTIR analysis, NMC532 exhibited a high crystalline layered structure with no observable impurity peaks even with the presence of impurities such as other metals or organic groups contained in MHP. SEM images showed homogenous particles with polycrystalline morphology. Charge-discharge analysis performed in cylindrical cell type 18650 showed promising results such as excellent cycle performances with specific charge capacity 179.14 mAh/g and specific discharge capacity 111.19 mAh/g. The rate ability could perform stable in every current density (0.1C, 1C, 4C, 8C, and 16C) and retested again in 0.1C with the initial capacity 90.89 mAh/g. The overall process can be considered as cheap and economically attractive to be adapted at industrial scale.

Abstract: Ni-rich layered oxide cathode materials LiNi_xCo_yMn_zO₂ (x>0.6) have been widely used in high specific energy Li-ion batteries. Compared with polycrystalline LiNi_xCo_yMn_zO₂, single crystal Ni-rich cathode materials have attracted much attention for their unique advantages. However, they also suffer from some drawbacks, such rapid capacity decay and intragranular crack during cycling. In order to enhance the structure and electrochemical performance of single crystal LiNi_0.8Co_0.1Mn_0.1O₂ (SC811), different amount of aluminium (1 mol%, 2 mol% and 3 mol%) is utilized to substitute the materials. Physical characterizations of SC811 show the successful synthesis and Al doping of the single-crystal materials as well as lower Li/Ni intermixing after Al doping. Electrochemical tests illustrate that the single-crystal materials doped with 2mol% Al (2Al-SC811) shows superior electrochemical performance, and maintains 83.5 % of the initial discharge capacity after 100 cycles at 1 C in comparison with 68.9 % of the pristine SC811. It is hoped this work should shed light on the development of advanced cathode materials for Li-ion batteries.

Abstract: Lithium iron phosphate (LiFePO₄) batteries have received much attention because they can provide higher power density with abundant raw materials, better safety, low toxicity, and high thermal stability. In general, the production of LiFePO₄ cathodes uses polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent. These components are expensive, toxic, and can adversely affect the environment. Therefore, to address these shortcomings, the solvent and binder were replaced in this study. The solvent in the current study is water. The water soluble binders employed in this study are carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR). Suitable electrode formulations were investigated to obtain high performance cylindrical Li-ion batteries. As a result, a formulation with a ratio of LiFePO₄:AB:KS6:SBR:CMC equal to 90:3:3:2.677:1.333 was used. It has a high specific discharge capacity, 120 mAh/g. This NMP-based cathode can yield about 145 mAh/g, which is slightly higher than a water-based LiFePO₄ cathode.

Abstract: Significant demand of Li-ion batteries (LIBs) is raising awareness of future LIBs wastes which are highly required to be reprocessed, reused or recycled. In this research, copper foil waste from spent LIBs are upcycled as an anode material, CuO. Hydrometallurgical route was applied to selectively dissolve copper foils where nitric acid, maleic acid and acetic acid were used as the leaching agents while oxalic acid were used to precipitate copper into copper oxalate which is a precursor to CuO. CuO was obtained by calcination of copper oxalate at high temperature. Based on XRD and FTIR analysis, Copper (II) oxalate dihydrates is successfully obtained while SEM images of the samples confirmed micron sized agglomerates which is consist of submicron primary particles. XRD analysis of CuO samples obtained from various leaching process confirmed that a pure CuO is successfully synthesized from nitric acid leaching process while CuO from acetic acid and maleic acid leaching has Cu₂O and Cu phase. CuO and 10%CuO@graphite sample from nitric acid leaching were used as sole anode and composite anode in a LiNi_0.8Co_0.1Mn_0.1O₂(NCM) battery, respectively. The initial columbic efficiency of CuO anode was far inferior to CuO@graphite. However, CuO@graphite had higher specific charge-discharge capacity with the value of 347.8 mAh/g compared to pure graphite (286.5 mAh/g). In conclusion, Cu-foils are a promising source of CuO to enhance the capacity of commercial graphite anode.

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: LiV₃O₈ layered structure was successfully synthesized by a conventional solid-state approach and subsequent heat-treated at 400, 450, 500 and 550 oC. The samples were characterized by XRD, SEM, TEM, BET. Electrochemical performance of LiV₃O₈ was investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge. The results showed that high purity of LiV₃O₈ with layered structure was formed. The morphology of the samples were mixed between nanorods and nanosheets structure. For electrochemical performance, results showed that LiV₃O₈ heat-treated at 500 oC performed a highest charge and discharge capacity of 212 and 172 mAh g^-1, respectively. From electrochemical performance results made them a good candidate for cathode material for lithium-ion batteries application.

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: Tin oxide is the most promising material for thin film anodes of Li-ion batteries due to its cycling performance and high theoretical capacity. It is assumed that lithium-tin oxide can demonstrate even higher performance. Lithium-silicon-tin oxide nanofilms were prepared by atomic layer deposition (ALD), using the lithium bis (trimethylsilyl) amide (LiHMDS), tetraethyltin (TET) as a metal containing reagents and ozone or water or oxygen plasma as counter-reactants. Monocrystalline silicon (100) and stainless steel (316SS) were used as supports. The thicknesses of the nanofilms were measured by spectral ellipsometry (SE) and scanning electron microscopy (SEM). It was found that oxygen plasma is the most optimal ALD counter-reactant. The composition and structure were studied by Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS) and X-ray diffraction (XRD). The nanofilms contain silicon as impurity, whose source is the ALD precursor (LiHMDS). The nanofilms deposited on stainless steel have shown the high Coulombic efficiency (99.1-99.8%) and cycling performance at a relatively high voltage (0.01 to 2.0V).