A detailed electrochemical study and investigation of a Fe-P glycine bath as a function of the temperature and glycine concentrations and current density, and their resulting corrosion and mechanical behavior is presented. A low addition of glycine to the electrolyte led to a drastic increase of the P content. At low Fe-P deposition rates, heterogeneous rough deposits with morphological bumps and pores were observed. By increasing the Fe-P deposition rate, the number of pores were reduced drastically, resulting in smooth coatings. Increasing the P content led to the formation of nanocrystalline grains from an “amorphous-like” state. Coatings with higher P contents exhibited better corrosion resistance and hardening, most likely attributed to grain boundary strengthening.
In this work, we present the characterization and electrochemical performance of various ternary silicon oxycarbide/graphite/tin (SiOC/C/Sn) nanocomposites as anodes for lithium-ion batteries. In binary SiOC/Sn composites, tin nanoparticles may be produced in situ via carbothermal reduction of SnO2 to metallic Sn, which consumes free carbon from the SiOC ceramic phase, thereby limiting the carbon content in the final ceramic nanocomposite. Therefore, to avoid drawbacks with carbon depletion, we used graphite as a substitute during the synthesis of precursors. The ternary composites were synthesized from liquid precursors and flake graphite using the ultrasound-assisted hydrosilylation method and pyrolysis at 1000 °C in an Ar atmosphere. The role of the graphitic component is to ensure good electric conductivity and the softness of the material, which are crucial for long term stability during alloying–dealloying processes. The presented approach allows us to increase the content of the tin precursor from 40 wt.% to 60 wt.% without losing the electrochemical stability of the final material. The charge/discharge capacity (at 372 mA g−1 current rate) of the tailored SiOC/C/Sn composite is about 100 mAh g−1 higher compared with that of the binary SiOC/Sn composite. The ternary composites, however, are more sensitive to high current rates (above 372 mA g−1) compared to the binary one because of the presence of graphitic carbon.
The influence of glycine on the iron phosphorous alloy electrodeposition was investigated by electrochemical quartz microbalance (EQMB), in-situ external reflection FTIR spectroscopy, and electrochemical impedance spectroscopy (EIS) measurements. An increase of glycine concentration leads to a decrease of the iron-phosphorous alloy electrodeposition rate and an increase of hydrogen evolution. Strong adsorption of glycine species, such as H 2 (gly) þ , H(gly) ± or/and Fe(gly) þ , have been observed during the hydrogen evolution and the Fe-P deposition reaction. Due to the concurrent hydrogen evolution the pH attains higher values at the interface than in the electrolyte bulk (pH2.5). The formation of adsorbed Fe(gly) þ and of the chelate complex Fe(gly) 2 in solution avoids the precipitation of Fe(OH) 2 in the pH range between 2.5 and ca. 7 at the interface. The phosphorous content of the iron phosphorous alloy deposit increases with the glycine concentration. This is due to a lower deposition rate of iron caused by the adsorption of Fe(gly) þ , while the hypophosphite reduction rate to phosphorous increases.
Fe-W-P coatings were deposited from a newly developed electrolytic bath. The effect of plating parameters, such as electrolyte current density and pH has been studied. It was found that the pH has a very strong effect on the phosphorous content of the coatings. Metallic-like, non-powdery alloys of Fe-W-P deposits with no cracks (lowly stressed) can be obtained at a lower pH (<3), exhibiting high phosphorus (up to 13 at.%) and low tungsten (6 at.%) contents. At a higher pH (>3), the composition changes to low phosphorus and high tungsten content, showing a matte, greyish, and rough surface. The applied current density also influences the morphology and the amount of phosphorous content. The deposits showed an amorphous structure for all samples with soft ferromagnetic properties.
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