纳米SnO_2负极的电化学性质

Electrochemical Study of Nano-SnO_2 Anode

应用慢扫描循环伏安(CV)法和电化学阻抗谱(EIS)法分别研究了不锈钢电极在含有不同溶剂和锂盐电解液中的循环伏安行为和纳米SnO2复合电极在不同充放电状态下的界面阻抗和容抗。结果表明,纳米SnO2电极和碳负极相同,在首次放电过程中也存在电解液成分的不可逆还原,并造成一部分不可逆容量损失;提出了纳米SnO2电极首次放电的电化学反应过程是先在电极表面形成一层钝化膜(即SEI膜),Li+穿过膜与SnO反应生成金属Sn和非晶态的LiO,然后Sn再和Li+形成合金。

Slow scanning cyclic voltammetry was employed to study trolytes, solvents and lithium-salt. The impedance diagrams of nano-SnO2 anode/electrolyte interphase at different discharge states were analyzed with alternative current impedance spectroscopy. The results suggest that nonaqueous electrolyte reacts also on the surface of a nano-SnO2 anode as in lithium rechargeable batteries during the initial charge/discharge cycles, and results in the partial irreversible capacity loss. The electrochemical reaction of nano-SnO2 anode for lithium rechargeable batteries can be deduced as follows：a passivating film forms on the surface of nano-SnO2 particles first, then Li^＋ ions pass through the surface film and react with nano-SnO2 to produce amorphous Li2O and to form fine grains of Li-Sn alloys in the core region under-neath the passivation film.