Morphology-Controlled Preparation of Sn Powders by Electrodeposition in Deep Eutectic Solvent as Anodes for Lithium Ion Batteries

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.