화학공학소재연구정보센터
Materials Chemistry and Physics, Vol.136, No.2-3, 863-867, 2012
Electrochemical performance of Si@TiN composite anode synthesized in a liquid ammonia for lithium-ion batteries
High-efficiency Si@TiN composite anode was synthesized by a homogeneous reduction reaction in the liquid ammonia, then calcinated at 950 C for 2 h in vacuum. The crystal structure and morphology of the obtained in-situ coated composites were characterized by XRD, FESEM. The results showed that the micron-sized Si particles were almost coated by the TiN nanoparticles with the average size of 50 nm, while the morphology of Si@TiN composite was almost unchanged over 50 discharge-charge cycles. The electrochemical performances of Si@TiN composite anode were studied by galvanostatic discharge-charge tests, cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). The CV curves showed that the two redox peaks remained stable and were attributed to the alloying/dealloying process of Li with active Si particles. It could be seen from the EIS curves that the charge transfer resistance (R-ct) for fresh was larger than that for the 50th cycle, which was mainly because the electrons and Li ions conducted on the electrode surface more difficultly for fresh. The cycle stability of the as-prepared Si@TiN composite anode was investigated, with the result showing that the cycling performance was stable and optimal at a rate of 0.2 C. The initial charge capacity was as high as 3226.99 mAh g(-1), which was kept as 467.02 mAh g(-1) over 50 cycles. (c) 2012 Elsevier B.V. All rights reserved.