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In this study, within the defined orthogonal array of Taguchi design, the hydrothermal process parameters have been optimized for fabricating the smallest particle sized iron oxide (Fe2O3) particles. The finest particle size (210 nm) has been achieved when 0.02 M FeCl3 solution at pH 10 is hydrothermally treated for 90 min with an autoclave filling ratio of 100% (D3). Afterwards, to improve the physical properties of iron oxide particles, carbon black powder is added into the precursor solution as the seeding agent before the hydrothermal treatment. Structural and morphological analyses show that upon the existence of carbon in the precursor solution, C-supported Fe2O3 (D5) is fabricated. In the latter, carbon is present in graphitic form and no carbide formation is detected. Electrochemical test results verify that unlike to Fe2O3 (D3), C-supported Fe2O3 (D5) electrode performs lower charge transfer resistance and polarization leading to higher first coulombic efficiency, capacity retention, and improved rate performance, eventually. Thanks to the favorable characteristics of the latter, after 150 cycles, D5 performs 550, 390, and 333 mAh g−1 discharge capacities under loads of 50 mA g−1, 500 mA g−1, and 1.5 A g−1, respectively. Finally, to understand the contribution of capacitive and diffusion-controlled reactions to the total stored charge, an adopted sweep rate method has been used. The calculated voltammograms reveal that fabricating C-supported Fe2O3 particles led to improved rate performance because faradaic reactions that occur at the surface of the material prevail. [ABSTRACT FROM AUTHOR]

Locust Bean Gum (LBG, carob bean gum) was investigated as an environmentally friendly, natural, and water-soluble binder for cathode (LFP) and anode (LTO) in lithium-ion batteries (Li-ion). For the first time, we show LBG as an electrode binder and compare to those of the most popular aqueous (CMC) and conventional (PVDF) binders. The electrodes were characterized using TGA/DSC, the galvanostatic charge–discharge cycle test, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Thermal decomposition of LBG is seen to begin above 250 °C with a weight loss of about 60 wt% observed at 300 °C, which is sufficient to ensure stable performance of the electrode in a Li-ion battery. For CMC, weight loss at the same temperature is about 45%. Scanning electron microscopy (SEM) shows that the LFP–LBG system has a similar distribution of conductive carbon black particles to PVDF electrodes. The LTO–LBG electrode has a homogeneous dispersion of the electrode elements and maintains the electrical integrity of the network even after cycling, which leads to fast electron migration between LTO and carbon black particles, as well as ion conductivity between LTO active material and electrolyte, better than in systems with CMC and PVDF. The exchange current density, obtained from impedance spectroscopy fell within a broad range between 10−4 and 10−2 mA cm−2 for the LTO|Li and LFP|Li systems, respectively. The results presented in this paper indicate that LBG is a new promising material to serve as a binder. [ABSTRACT FROM AUTHOR]

A simple method was applied to control the morphology of LiMn2O4 and Li1.05Mn1.97Nb0.03O4 in the sintering process by premixing a suitable proportion of acetylene black in the raw material. Both specific discharge capacity and cycling stability of the samples were improved. The results demonstrated that the doped samples showed excellent electrochemical performance at both 25 °C and 55 °C. [ABSTRACT FROM AUTHOR]