Sn Film Electrode Research Articles

Selective separation of Y and Nd with similar electrochemical properties by pulsed electrolysis on Sn electrode

Selective separation of Y and Nd from LiCl-KCl melt was systematically investigated on W and Sn electrodes by various electrochemical methods. The electrochemical properties of Y and Nd on W and Sn film electrodes were firstly analyzed and compared by cycle voltammetry (CV), square wave voltammetry (SWV), reverse chronopotentiometry (RCP), etc. The results indicate that the deposition potentials of Y and Nd on W electrode are very close, while the deposition potential difference could reach 0.15 V on Sn film electrode. The selective separation of Y and Nd was conducted by potentiostatic electrolysis (PE) on W electrode assisted by Sn(II), and the product is composed of Sn and NdSn3 phases. In addition, the electrochemical properties and kinetic parameter of Y and Nd on liquid Sn electrode were also studied. The results prove that Nd has a more positive deposition potential, larger exchange current density and smaller reaction activation energy than Y, illustrating that Nd is more easily extracted on liquid Sn electrode. Thus, PE and potentiostatic electrolysis + pulse potential electrolysis (PE + PPE) were used to separate Y and Nd on liquid Sn electrode. The results show that the application of PPE effectively reduced the extraction efficiency of Y from 16.75 ± 1.50 % to 8.36 ± 1.13 %, and increased the separation factor β from 4.98 ± 0.46 to 9.64 ± 0.58.

Electrochemical Reaction of Sm(III) on Liquid Sn Electrode

The electrochemical study of Sm(III) ions was conducted on Sn film electrode in eutectic LiCl-KCl in the temperature range from 773 K to 923 K by a series of electrochemical techniques. The results of current reversal chronopotentiometry of Sm(III) on W electrode showed that the redox reaction related to Sm(III) is a kind of soluble/soluble system, which meant that Sm(III) was reduced to Sm(II) on W electrode. On Sn film electrode, the reduction of Sm(III) was found to be two-step process: Linear polarization (LP) and Tafel techniques were conducted to measure the exchange current density (j0) of Sm(II)/SmSn3 couple. The variation of j0 with temperature accords with the Arrhenius law, and the activation energy was evaluated to be 14.32 kJ mol−1 and 14.08 kJ mol−1, respectively. Moreover, the feasibility of extracting Sm on Sn film electrode was examined by constant potential electrolysis at −1.45 V in the LiCl-KCl-SmCl3-SnCl2 molten salt for 3 h. XRD result indicated the formation of SmSn3. Constant current and potential electrolysis were performed to extract metallic Sm on liquid Sn pool electrode. The alloy samples were characterized by SEM-EDS and XRD, which displayed the existence of SmSn3 and Sm4Sn3 phases in Sm-Sn alloys.

Magnesium Storage Performance and Surface Film Formation Behavior of Tin Anode Material

AbstractElectrochemical cycling performance of microsize bulk and thin film Sn electrodes up to 50 cycles in Mg half‐cell configuration, as well as Mg diffusivity and interfacial reaction behavior in a phenylmagnesium chloride (PhMgCl)/THF electrolyte are studied. The bulk Sn electrode delivers capacities of 321–289 mAh g−1 with capacity retention of 90 % and coulombic efficiencies higher than 99 % over 30 cycles, and thus demonstrates the potential of Sn anodes. The Sn film electrode shows good cycling ability. Surface analysis by XPS reveals that the surface of cycled electrodes is composed of a mixture of various inorganic salts of Sn and Mg formed by interfacial reactions between Sn and PhMgCl, and organic functionality produced by decomposition of THF, indicating surface film formation. The Mg2+ diffusivity of Sn is on the order of 10−11 cm2 s−1, which is four orders of magnitude lower than the Li+ diffusivity of Sn in Li‐ion batteries. Advanced material design for enhanced electronic conductivity and control of the interfacial chemistry for formation of a surface protective film are believed to be the keys to overcome such sluggish kinetics, increase the capacity, and improve the cycling performance.

Pulsed current electrodeposition parameters to control the Sn particle size to enhance electrochemical performance as anode material in lithium ion batteries

Abstract The Sn nanoparticles were synthesized through pulsed current electrodeposition in an acidic electrochemical bath containing polyvinylpyrrolidone (PVP) in order to control the electrodeposition rate of Sn reduction on copper collector electrode. The anode prepared at electrochemical bath containing PVP concentration of about 10 g·L−1 showed highest discharge capacity and cycleability as two main criteria in lithium ion batteries. Also, the pulsed current characteristics such as frequency and current density were investigated and 10 Hz and 20 mA·cm− 2, respectively, are obtained as the optimum parameters. The synthesis of Sn nanoparticles in such media was successfully developed. The sizes and morphologies of NPs were characterized by X-ray diffraction and scanning electron microscopy. Our findings indicated that the nanosized spherical particles with a diameter ranging from 80 to 100 nm could be formed at optimum concentration. The discharge capacity of synthesized Sn nanoparticles was obtained about 1350 mAh g− 1, indicating a 32% increase compared to the synthesized Sn particles with constant current electrodeposition method. Additionally, the discharge capacity of around 550 mAh g–1 is obtained in the 50th cycle, which shows an appropriate cycleability compared to the Sn film electrode prepared by a constant current electrodeposition. The discharge capacities obtained indicated a considerable improvement compared to similar works. The particles size of coated Sn on collector electrode is resulted from interplay between the rate of nucleation and growing rate of particles. PVP affects the kinetic of electrodeposition through surface capping and complexing of Sn2 + species.

Fabrication of Three-Dimensional Porous Sn Films as Anode for Li-Ion Batteries

A polystyrene spheres (PS) coated copper foil was adopted as a template to prepare three-dimensional (3D) porous Sn film electrode. The PS colloidal spheres were synthesized through emulsion polymerization and spin-coated on copper foil. Then Tin was electrodeposited on the template foil, following by etching in tetrahydrofuran to remove PS template. The obtained Sn film has a honeycomb-like porous structure and showed improved electrochemical performance.

Preparation of Co–Sn alloy film as negative electrode for lithium secondary batteries by pulse electrodeposition method

In order to easily and simply improve the cyclability of the Sn film negative electrode, we selected Co as a matrix metal and tried to prepare the Co–Sn alloy film negative electrode by a pulse electrodeposition method. The surface morphology of the deposit was almost the same as that of the Sn film, although aggregation partially occurred. The content rate of Co and Sn in the deposit was almost the same as the composition percentage in the electrodeposition bath. X-ray diffraction measurement showed that the deposited film could be assigned to a metastable Co–Sn alloy, while the co-deposition of crystalline Sn was not observed. The galvanostatic charge–discharge tests indicated that the discharge capacity and the charge–discharge efficiency of the Co 30.5Sn 69.5 alloy film electrode at the 1st cycle were 529.2 mAh g −1 and 87.9%, respectively. Furthermore, the film electrode showed a good cyclability and discharge capacity of 470.5–617.5 mAh g −1 during 50 cyclings. Alloying Sn with inactive Co could effectively improve the cyclability of the Sn film electrode prepared by the pulse electrodeposition method.

Electrochemical characteristics of Sn film prepared by pulse electrodeposition method as negative electrode for lithium secondary batteries

In order to improve the cyclability of Sn negative electrode, we tried preparing the Sn film negative electrode by a pulse electrodeposition. Based on the SEM observations, the crystal grains of the Sn film after the pulse electrodeposition were comparatively homogeneous and their grain size was ca. 1 μm. The discharge capacity and the charge–discharge efficiency at the 1st cycle were 679.3 mAh g −1 and 93.0%, respectively. The charge–discharge tests indicated that the initial electrochemical characteristic of Sn film electrode prepared by a pulse electrodeposition was much better than that of the Sn film electrode prepared by a constant current electrodeposition. The GD-OES profile suggested that Li + ions were easily extracted during the discharge reaction. In addition, it was found that no exfoliation of the film was observed after the 1st discharge though the cracking in the film was observed after the 1st discharge. Consequently, the Sn film electrode prepared by a pulse electrodeposition exhibited a better cyclability for the initial 10 cycles compared to the Sn film electrode prepared by a constant current electrodeposition. By reducing the particle size and repressing the morphological change, the initial electrochemical characteristics were considerably improved.

Surface layer formation on Sn anode: ATR FTIR spectroscopic characterization

Surface layer formed on Sn thin film electrode in 1 M LiPF 6/EC:DMC electrolyte was characterized using ex situ FTIR spectroscopy with the attenuated total reflection technique. IR spectral analyses showed that the immersion of Sn film in the electrolyte resulted in a chemical interfacial reaction leading to the passivation of Sn surface with primarily PF-containing inorganic surface species and small amount of organics. When constant current cycling was conducted with lithium cells with Sn film electrode at 0.1–1.0 V vs. Li/Li +, the interfacial reaction between Sn and electrolyte appeared significantly intensified that the features of PF-containing species became enhanced and new IR features of organic species (e.g. alkyl carbonate/carboxylate metal salts and ester functionalities) were observed. The surface layer continued to form with cycling, partly due to non-effective surface passivation as well as particle pulverization accompanied by enlargement of active surface area. Comparative IR spectral analyses indicated that the interfacial reaction between Sn and PF 6 − anion played a leading role in forming the surface layer, which is different from lithiated graphite that had mainly organic surface species. The data contribute to a better understanding of the interfacial processes occurring on Sn-based anode materials in lithium-ion batteries.