Zhiwei Wang,Mingqiang Cheng,Jiaojiao Bu,Lei Cheng,Juanjian Ru,Yixin Hua,Ding Wang
Tin is one of the vital substances in the material and chemical industry. Deep eutectic solvent (DES) possesses excellent physicochemical properties for metal preparation. In this study, the electrochemical behavior of Sn(II) and metallic tin preparation in choline chloride-ethylene glycol (ChCl-EG) DES were investigated. Linear sweep voltammetry is carried out to study the effects of substrate material (Ni, Cu, Pt, C, Fe, Al, W, glassy carbon (GC) and Ti), temperature (313–353 K) and SnCl 2 concentration (10–100 mM) on the electrochemical behavior of Sn(II)/Sn. Results demonstrate that metallic tin is easier to be prepared on the Ni electrode, and increasing temperature and SnCl 2 concentration both facilitate the reduction of Sn(II). Electrospray ionization mass spectrometry (ESI-MS) shows that the main form of Sn(II) is [SnCl 3 ] - . Chronoamperometric tests indicate that with the increase of applied potential, the nucleation of Sn(II) on the nickel electrode becomes close to the instantaneous nucleation. Simultaneously, the nucleation rate and the number of active sites on the electrode surface increase significantly. Pure tin with a dendritic structure could be prepared with higher current efficiency of 96.4% and lower energy consumption of 320.5 kW·h·t −1 without any additives. All these studies provide a fundamental basis for the preparation of tin powders in ChCl-EG DES.
Zhiwei Wang,Juanjian Ru,Yixin Hua,Ding Wang,Jiaojiao Bu
High-pure Sn powders (99.99 wt%) with controllable morphologies are prepared by electrodeposition at various temperatures (313–353 K) in choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES). The electrochemical behavior of Sn(II)/Sn on nickel electrode has been investigated by cyclic voltammetry. Results demonstrate that the reduction of Sn(II) ions in ChCl-EG DES is a quasi-reversible process controlled by diffusion. The diffusion coefficients of Sn(II) ions are in the range of 0.893–3.189 × 10−7 cm2·s−1 at 313–353 K. Besides, the current efficiency and corresponding energy consumption during the electrodeposition of Sn powders at 353 K are calculated about 87.78% and 289.02 kW·h·t−1, respectively. The morphologies of Sn powders are gradually transformed from dendritic (27–43 μm) to tower cone-shaped and pagoda-shaped (40–155 μm) with the increasing of reaction temperature. Furthermore, the electrochemical performances of the as-prepared Sn electrodeposits as anodes for lithium ion batteries are also discussed. The Sn electrode obtained at 313 K in ChCl-EG DES, with uniform morphology and the finest size, shows a high discharge capacity of 1050 mA·h·g−1 at 0.1 A·g−1.
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