Characterization and Corrosion Resistance Behavior of Pure Ni Coatings & Ni-V2O5 Nano composite Coatings Developed by DC & PC Methods of Electrodeposition

Pure nickel (Ni) coating and nickel – vanadium pentoxide (Ni-V2O5) nanocomposite coatings have been developed on mild steel substrates by direct current (DC) & pulse current (PC) methods of electrodeposition using sulfamate electrolyte bath by optimizing all the suitable parameters. The surface morphology and texture characterization of pure Ni coating and Ni-V2O5nanocomposite coatings were analyzed by spectroscopic techniques such as Scanning Electron Microscopy (SEM) equipped with an attachment for Energy Dispersive Spectrometry (EDS) & X-ray Diffraction (XRD) spectroscopy analysis. The SEM study confirmed surface morphology of the pure Ni coating was changed by the incorporation of V2O5 nanoparticles in the nickel metal matrix and chemical composition of all the coatings was determined by EDS. XRD study proved highly corrosion resistant nanocomposites show preferred orientation towards (111) plane. The corrosion rate of all the coatings was investigated in 3.5% corrosive medium using electrochemical techniques such as Tafel extrapolation and AC impedance. The coatings developed by PC show enhanced corrosion resistance behavior compare to coatings developed by DC. The 0.125g/L Ni-V2O5nanocomposite coating obtained by PC show more widened semicircle with high Rp value and has more positive shift with high corrosion resistance during AC impedance and Tafel extrapolation analysis respectively. The coatings developed by PC showed improved micro hardness compare to coatings developed by DC during micro hardness testing of all the coatings.

VxG Pattern-Based Analysis and Battery Deterioration Diagnosis

This paper presents the results of an analysis using the direct current internal resistance (DCIR) method on a nickel-cobalt-manganese oxide (NCM)-based battery with a nominal capacity of 55.6 Ah. The accelerated degradation test was performed on V0G, V1G, and V2G patterns, representing existing simple power supply, smart charging control, and bi-directional charge/discharge control, respectively. We assumed V0G, V1G, and V2G patterns and conducted charging and discharging experiments according to the set conditions. According to the pattern repetition, changes in the internal resistance of DCIR and AC-impedance were analyzed and battery deterioration was diagnosed. By comparing DCIR and AC-impedance, we confirmed that the changes in internal resistance has a similar trend. In particular, we propose a new DCIR analysis method in the “stop-operation” part rather than the traditional DCIR method. In the case of traditional DCIR method, time is required for the battery to stabilize. However, the newly proposed DCIR analysis method has the advantage of diagnosing the deterioration of the battery during system operation by analyzing the internal resistance without the stabilization time of the battery.

Lithium-Ion Battery Real-Time Diagnosis with Direct Current Impedance Spectroscopy

The health and safety of lithium-ion batteries are closely related to internal parameters. The rapid development of electric vehicles has boosted the demand for online battery diagnosis. As the most potential automotive battery diagnostic technology, AC impedance spectroscopy needs to face the problems of complex test environment and high system cost. Here, we propose a DC impedance spectroscopy (DCIS) method to achieve low-cost and high-precision diagnosis of automotive power batteries. According to the resistance–capacitance structure time constant, this method can detect the battery electrolyte resistance, the solid electrolyte interphase resistance and the charge transfer resistance by controlling the pulse time of the DC resistance measurement. Unlike AC impedance spectroscopy, DCIS does not rely on frequency domain impedance to obtain battery parameters. It is a time-domain impedance spectroscopy method that measures internal resistance through a time function. Through theoretical analysis and experimental data, the effectiveness of the DCIS method in battery diagnosis is verified. According to the characteristics of DCIS, we further propose a fast diagnostic method for power batteries. The working condition test results show that this method can be used to diagnose online battery life and safety.

Electrochemical Analysis of Nano- and Micro-Sized Pore Formed Ti–6Al–4V Alloys in Solution Containing Ca, P, Mn, and Si Ions via Plasma Eletrolytic Oxidation for Bio-Implant Materials

The purpose of this study was to investigate electrochemical analysis of nano- and micro-sized pore formed Ti–6Al–4V alloys in solution containing Ca, P, Mn and Si ions via plasma eletrolytic oxidation for bio-implant materials. The coatings were produced on Ti–6Al–4V alloy for dental implant using the plasma electrolytic oxidation (PEO) method in electrolytes with the various concentration of 0, 5, and 20% Mn and Si, respectively. Electrochemical potentiodynamic polarization and AC impedance behaviors were carried out in 0.9% NaCl solution at 36.5 ± 1 °C using potentiostat (Potentiostat, EG&G, 362) and electrochemical impedance spectroscope (EIS, EG&G, 1025). The potentiodynamic polarization test with a scan rate of 1.667 mV s-1 was carried out from –1500 mV to 2000 mV. The frequency range used for EIS was 102–105 Hz. The amplitude of AC signal was 10 mV and 5 points per decade was used. From the potentiodynamic polarization test, PEO treated alloy in electrolyte containing Ca, P, Mn, and Si show a lower corrosion potential than that on the bulk surface. In the case of Mn and Si doped surface, the corrosion resistance increase compared to non-doped surface with Mn and Si elements, and the current density was lower than that of the bulk surface. From the AC impedance test, in the case of Mn and Si doped surface, polarization resistance values were higher than other specimens, and nano- and micro-sized pores were covered with corrosion product consisted Mn and Si elements.

New g-C3N4/GO/MoS2 composites as efficient photocatalyst for photocathodic protection of 304 stainless steel

Photocathodic protection is an economical and environmental metal anticorrosion method. In this research, we successfully synthesized the g-C3N4/GO (15 wt%)/MoS2 catalytic materials by a facile hydrothermal method. The results show that as-prepared g-C3N4/GO (15 wt%)/MoS2 composites prominently enhanced the photocatalytic activities for the photocathodic protection of 304 stainless steel compared with the corresponding pristine g-C3N4 and MoS2. Notably, the AC impedance results demonstrated that the Rct value of 304 SS coupled with g-C3N4/GO (15 wt%)/MoS2 decreased to 35.66 Ω•cm2, which is 29 and 37 times lower than that of g-C3N4 and MoS2 alone. In addition, g-C3N4/GO (15 wt%)/MoS2 provided the highest current density (77.19 μA•cm2) for the 304 SS, which is 4 times of pristine g-C3N4. All results indicate that as-prepared g-C3N4/GO (15 wt%)/MoS2 photocatalysts have exhibited distinct enhancement on photocathodic protection performance. An optimum decorating amount of MoS2 onto g-C3N4 forms heterojunction of g-C3N4/MoS2, which favors the separation of electrons and holes efficiently. Meanwhile, the addition of GO further promotes the separation and transfer of photo-induced carriers.