Papers by Keyword: Electrochemical Properties

Abstract: Solid polymer electrolytes are recently investigated as alternatives to enhance the efficiency of lithium-ion batteries because of their inherent advantages. However, ionic transport through solid polymer electrolytes and mechanical properties of the electrolyte tend to be poorer compared with the liquid organic salt electrolytes. Granted, nanobased materials have attracted increased interest due to their ability to improve the properties of the electrolytes of lithium-ion batteries. This review is intended to highlight recent advances in utilizing nanomaterials in improving the electrochemical and mechanical characteristics of the solid electrolyte to enhance the performance of lithium-ion batteries. The synthetic techniques employed, as well as limitations of nanomaterials, are summarized. Recommendations for further development of novel functional nanomaterials for lithium-ion batteries are presented. Insight from this research will guide researchers in lithium battery technologies to make informed decisions, specifically when using nanobased materials.

Abstract: Cellulose polymer-based Solid Polymer Electrolytes (SPEs) have gained attention as an environmentally friendly and sustainable alternative for energy storage applications, particularly in lithium-ion batteries. The proper selection of electrolytes is crucial for enhancing the performance and stability of SPEs. This study presents a comparative analysis of LiBOB, LiPF₆ and LiTFSI electrolytes for cellulose-based solid polymer electrolytes (SPEs). The cellulose-SPEs were evaluated based on their mechanical and electrochemical performance. Our findings reveal that cellulose-LiTFSI exhibited the highest electrolyte uptake (784%) and electrolyte retention (88.69%), followed by cellulose-LiPF₆ (690% uptake and 87.34% retention), and cellulose-LiBOB (355.33% uptake and 78.04% retention). Morphological research reveals all SPEs exhibit porous structures and demonstrate contact with the electrolyte, however LiBOB cellulose does not effectively absorb the electrolyte. Heat treatment at 150°C for 4 hours demonstrated significant differences in thermal stability, where cellulose-LiBOB maintained structural integrity with negligible alteration in color, while cellulose-LiPF₆ and cellulose-LiTFSI darkened and underwent decomposition. The cellulose LiTFSI has the greatest electrochemical stability, with a potential window of 4.25 V, and the highest ionic conductivity, measuring 1.359 x 10-6 C/m. Conversely, cellulose LiBOB (3.37) has better electrochemical stability than LiPF₆ (2.91 V), while cellulose LiBOB has the lowest ionic conductivity (1.424 x 10^-7 C/m). These results suggest that electrolyte selection profoundly impacts the mechanical and electrochemical properties of cellulose-based SPEs, with LiTFSI showing best possibility for potential application in lithium-ion batteries.

Abstract: With the development of new energy vehicles, it is necessary to develope new fast charging cathode materials for lithium ion batteries. This paper reports a simple carbon thermal reduction routine to synthesize layered LiMoO₂ cathode for Li-ion batteries. Impurity-free micro-crystalline powders were synthesized by one-step method with a thermal treatment at 800^°C for 5 hrs under N₂ atmosphere. The structural, morphological and electrochemical properties of LiMoO₂ were characterized by using X-ray diffraction pattern (XRD), scanning electronic microscopy (SEM), charge/discharge cycling and electrochemical impedance spectroscopy (EIS). The diffraction results indicate that the prepared sample has a layered hexagonal structure related to α-NaFeO₂. The secondary particles are in order of 2.0 μm length on average with homogeneous distribution. The initial discharge capacity of LiMoO₂ is 110.9 mAh·g^-1 at 0.1 C, and the capacity can still remain 92.8 mAh·g^-1 after 100 cycles. The good cycling performance and high rate discharge performance are attributed to the smaller charge-transfer resistance revealed by EIS results.

Abstract: Seven multiphase YNi₃ and YN₄ based alloys have been prepared by arc-melting. Based on X-ray phase and structural analysis synthesized alloys depending on its composition contain intermetallics with PuNi₃, Gd₂Co₇ and CaCu₅ structure types. The influence of Y/La and Ni/Co/Mn/Al substitution on the discharge characteristics of the AB₃ and AB₄ electrodes was studied. Substitution Y by La and further Ni by Mn and Al lead to increasing discharge capacity from 40 to 341 mAh/g. Positive effect of Ni/Co/Al or Ni/Mn/Al substitution was also observed for the AB₃ electrodes. The high discharge capacities of 318 mAh/g and 340 mAh/g were seen for the YNi_2.65Co_0.2Al_0.15 and YNi_2.65Mn_0.2Al_0.15 electrodes.

Abstract: The TiO₂ nanotube arrays were prepared on Ti plate by anodizing technology, and then Co (OH)₂ nanoparticles in-situ grew into TiO₂ nanotubes with "Tube-particle bonding" nanocomposited structure. Co (OH)₂ nanoparticles with a particle size of 40.5±8 nm were infiltrated in the TiO₂ nanotube arrays, and the Co (OH)₂ outside the tube presented a nanosheet structure. The specific capacitance of the Co (OH)₂/TiO₂ nanotube array composite reached 260 F/g at the current density~1 A/g. The capacity retention rate was 82.5 % after 2,000 cycles at the current density~5 A/g. The high-rate performance of the Co (OH)₂/TiO₂ nanotube array composite reached 210 F/g at the current density~10 A/g.

Abstract: In this article the results of the negative electrode performance produced by La_0.7Mg_0.3Al_0.3Mn_0.4Co_0.5Ni_3.8 as-cast alloy adding 1 to 10% of carbon nanotube (CNT) or reduced graphene oxide (rGO) were investigated as Ni-MH batteries. The as cast alloy were investigated with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The CNT and rGO were characterized by high resolution SEM-FEG. The discharge capacity obtained during the electrochemical characterization showed that in the addition of 1% rGO the discharge capacity was 332 mAh and 1% CNT 364 mAh , being that the rGO batteries maintaining better cyclic stability during the electrochemical test.

Abstract: This paper investigates the physical properties and electrochemical properties of the innovative non-precious metal catalyst using different carbon types. The cathode catalyst for PEMFC (Proton Exchange Membrane Fuel Cell) is an important part of fuel cell because the reaction of the cathode is three times lower than the anode. Otherwise, the high cost of Pt/C catalyst for cathode needs to be replaced using low-cost material. Therefore, this research fabricated Pt free catalyst. FeCl₃.6H₂O was used as a metal precursor. Urea and PVP as a nitrogen (N) source were mixed with carbon. The variations of carbon are Graphite (Gt), Charcoal Active (CA), and Calcined Petroleum Coke (CPC). As prepared catalysts, were noted as Fe/N-Gt, Fe/N-CA, and Fe/N-CPC. Catalysts without nitrogen addition also were synthesized such as Fe-Gt, Fe-CA, and Fe-CPC for comparison. The electrochemical properties can be evaluated form Cycle Voltammograms (CV) curve. Graphite supported catalyst has anodic and cathodic peak otherwise has the lowest capacity. It means that the redox reaction occurs during CV measurement for Fe/N-Gt and Fe-Gt catalyst. Nitrogen addition of graphite supported catalyst has a higher current density than Fe-Gt catalyst. The morphology of the catalyst was identified by Scanning Electron Microscope (SEM). Different particle shape for carbon types can be observed by SEM image of obtained catalyst. Energy Dispersive X-Ray EDX to identify the chemical composition. Nitrogen-doped carbon caused the formation of Fe₂O₃ and it was determined by X-ray diffraction (XRD).

Abstract: Well-crystallized and nanosized LiFePO₄/C composite have been successfully synthesized by spray-drying under N₂ atmosphere. The morphology, physical and electrochemical properties of the LiFePO₄/C were tested and analyzed. The charge transfer resistances (Rct) and chemical diffusion coefficients of lithium ions (D_Li+) in LiFePO₄/C was systematically tested by EIS. The results show that the lithium ions diffusion coefficients obtained from EIS is 1.58×10^-14 cm²·s^-1. The assembled soft-packed cell with LiFePO₄/C show better rate capability and cycling stability. The average capacity retention of LiFePO₄/C soft-packed cell decreases to 100%, 98.9%, 96.5%, 92.4%, and 90.3% when current rate increases to 0.3, 0.5, 1, 2, and 3C, respectively. The capacity retention after 80 cycles is retained at more than 99%.

Abstract: Cobalt-free Li-rich Mn-based cathode materials are considered to be the next generation of Li-ion batteries due to low cost, high discharge capacities and high safety feature. However, there are still several serious issues that need to be solved urgently, such as low initial coulombic efficiency, low rate capability, poor cycling performance and voltage fading. Na doping or substitution is introduced to improve the electrochemical performance of Li_1.2Mn_0.6Ni_0.2O₂ cathode material, which is synthesized by sol-gel method. The effect of Na doping or substitution on the morphological, structural and electrochemical properties was systematically studied and analyzed by scanning electron microscope (SEM), X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cell test system and electrochemical workstation. These results illustrate that lattice layer spacing is enlarged by Na doping or substitution, which is beneficial for the diffusion of Li-ion, and the voltage fading is successfully suppressed. The best electrochemical properties were obtained when Na doping, which is attributed to the stronger structural stability and better reversibility of Li⁺ during the initial charge and discharge process.

Abstract: Zn-Al-Mg alloys with hypoeutectic microstructure were melted through a high frequency induction furnace. The content of aluminum and magnesium in the alloys were between 1% to 2%. Scanning electron microscopy (SEM) was utilized to analyze microstructure and phase, respectively. Effect of alloying element contents on corrosion resistance was studied. Results show that the Zn-Al-Mg alloys are almost covered by primarily solidified Zn rich block phase and fine lamellar binary and ternary eutectic microstructure exist between the Zn rich phase. The corrosion resistance was characterized through electrochemical test which indicates that increasing Al and Mg content in the Zn-Al-Mg alloys decline corrosion current density. For alloys with 1% Al, more magnesium means lower corrosion potential. For alloys with 2% Al, however, more magnesium suggests higher corrosion potential. In Nyquist curves of electrochemical impedance spectroscopy (EIS) test, Warburg impedance portion could be found for all alloys. With increasing alloying elements content in the Zn-Al-Mg alloys, charge transfer resistance in higher frequency remarkably increase, which implies higher corrosion resistance.