Synthesis And Electrochemical Behavior Of Lifepo4/C With Air-Electrode For Aqueous Lithium Ion Battery

An aqueous rechargeable lithium ion battery (ARLB) has become a great solution to overwhelm the cost and safety issue of the conventional lithium ion battery with organic electrolyte. Recently, the in situ carbon layer was proven to avoid any direct contact between the nanoparticles and the environment, including O2 and H2O. This help to achieve high capacity battery with improved capacity retention in aqueous environment. A citric acid assisted sol-gel method is employed in this study to prepare carbon-coated lithium iron phosphate (LiFePO4/C) using different calcination temperatures (500–800 °C). The phase structure and elemental analyses confirmed the orthorhombic crystal structure of LiFePO4 surrounded by different amounts of carbon layer. The morphologies and physical absorption results proved the porous structure of LiFePO4/C with a mesoporous range. The calcination temperature influences the crystallite size, impurity phase, and surface area as the LiFePO4/C calcined at 700 °C offered the optimum properties. This finding was supported by the electrochemical behavior of LiFePO4/C in the ARLB system with an air-electrode. The LiFePO4/C calcined at 700 °C showed the highest current response for cyclic voltammetry and the lowest impedance (6.11 Ω) with a good discharge capacity (83 mA h g−1 at 1.0 C). In addition, good cycling stability was achieved as the LiFePO4/C maintained a discharge capacity of approximately 90 mA h g−1 within 30 cycles at 0.5 C. By contrast, bare LiFePO4, which was calcined at the same calcination temperature (700 °C), exhibited poor electrochemical performance with high capacity fading (45 % within 30 cycles at 0.5 C) because of high 2 impedance (18.98 Ω). The rate capability of the LiFePO4/C calcined at 700 °C was also compared with that of a platinum counter electrode; the air-electrode still showed better cycling behavior

Morphology study of electrodeposited zinc from zinc sulfate solutions as anode for zinc-air and zinc-carbon batteries

The morphology of Zinc (Zn) deposits was investigated as anode for aqueous batteries. The Zn was deposited from zinc sulfate solution in direct current conditions on a copper surface at different current densities. The morphology characterization of Zn deposits was performed via field emission scanning electron microscopy. The Zn deposits transformed from a dense and compact structure to dendritic form with increasing current density. The electrodeposition of Zn with a current density of 0.02 A cm−2 exhibited good morphology with a high charge efficiency that reached up to 95.2%. The Zn deposits were applied as the anode in zinc–air and zinc–carbon batteries, which gave specific discharge capacities of 460 and 300 mA h g−1, respectively

Electrophoretic Deposition of Graphene Oxide and Reduced Graphene Oxide on the Rutile Phase of TiO₂ Nanowires for Rapid Reduction of Cr (VI) under Simulated Sunlight Irradiation

Hexavalent chromium is very carcinogenic, and it is, therefore, important to remove it from wastewater prior to disposal. This study reports the photoreduction of Cr(VI) under simulated sunlight using graphene-derived TiO2 nanowire (TNW) composites. Electrophoretic deposition (EPD) of graphene oxide (GO) and reduced graphene oxide (rGO) was carried out on rutile phase TNWs. The TNWs were fabricated by thermal oxidation of titanium foil in the presence of 1M potassium hydroxide mist at 750 °C. The TNWs uniformly covered the surface of the titanium foil. EPD of GO or rGO was done as a function of time to produce deposits of different thicknesses. The photocatalytic performances of the GO/TNWs or rGO/TNWs were tested to reduce Cr(VI) under visible light. The performance of rGO/TNWs in reducing Cr(VI) was better than GO/TNWs. A 10-second-deposited rGO on TNW samples can reduce 10 mg/L Cr(VI) within 30 min under visible light, likely as a result of the high electron transfer from rGO to TNWs accelerating the Cr(VI) reduction

Electrophoretic Deposition of Graphene Oxide and Reduced Graphene Oxide on the Rutile Phase of TiO2 Nanowires for Rapid Reduction of Cr (VI) under Simulated Sunlight Irradiation

Hexavalent chromium is very carcinogenic, and it is, therefore, important to remove it from wastewater prior to disposal. This study reports the photoreduction of Cr(VI) under simulated sunlight using graphene-derived TiO2 nanowire (TNW) composites. Electrophoretic deposition (EPD) of graphene oxide (GO) and reduced graphene oxide (rGO) was carried out on rutile phase TNWs. The TNWs were fabricated by thermal oxidation of titanium foil in the presence of 1M potassium hydroxide mist at 750 °C. The TNWs uniformly covered the surface of the titanium foil. EPD of GO or rGO was done as a function of time to produce deposits of different thicknesses. The photocatalytic performances of the GO/TNWs or rGO/TNWs were tested to reduce Cr(VI) under visible light. The performance of rGO/TNWs in reducing Cr(VI) was better than GO/TNWs. A 10-second-deposited rGO on TNW samples can reduce 10 mg/L Cr(VI) within 30 min under visible light, likely as a result of the high electron transfer from rGO to TNWs accelerating the Cr(VI) reduction

Hexavalent Chromium Removal via Photoreduction by Sunlight on Titanium–Dioxide Nanotubes Formed by Anodization with a Fluorinated Glycerol–Water Electrolyte

In this paper, titanium–dioxide (TiO2) nanotubes (TNTs) are formed by anodic oxidation with a fluorinated glycerol–water (85% and 15%, respectively) electrolyte to examine the effect of fluoride ion concentration, time, and applied voltage on TNT morphologies and dimensions. For fluoride ion concentration, the surface etching increases when the amount of ammonium fluoride added to the electrolyte solution increases, forming nanotube arrays with a clear pore structure. At a constant voltage of 20 V, TNTs with an average length of ~2 µm are obtained after anodization for 180 min. A prolonged anodization time only results in a marginal length increment. The TNT diameter is voltage dependent and increases from approximately 30 nm at 10 V to 310 nm at 60 V. At 80 V, the structure is destroyed. TNTs formed at 20 V for 180 min are annealed to induce the TiO2 anatase phase in either air or nitrogen. When ethylenediaminetetraacetic acid is added as a hole scavenger, 100% hexavalent chromium removal is obtained after 120 min of sunlight exposure for nitrogen-annealed TNTs