Cu/Si雙層薄膜負極之相對厚度研究

The Study of Relative Thickness of Cu/Si Thin Film Cathodes

本研究採用具高電容量且蘊藏量豐富的矽作為薄膜鋰離子二次電池之負極材料。首先利用射頻磁控濺鍍系統設備來沉積奈米級的非晶矽薄膜，改善充放電過程中嚴重體積膨脹收縮的問題；緊接著再沉積銅之表面鍍層，此鍍層可減少矽遭受到電解液的破壞與在充電過程中產生不可逆反應而導致電容量損失，也可降低矽基地的體積膨脹問題，以提升其循環壽命。本研究分別利用厚度250、500、1000、2000 nm之非晶矽薄膜當作電池負極，並個別於其上鍍上8 nm之銅薄膜作為緩衝層，雖然銅鍍層會阻礙鋰離子的進出而降低電容量，但卻能提升電池的循環壽命。

Silicon is a promising anode material for lithium ion batteries due to the advantages of high electrical capacity and rich content on earth. Nano/amorphous silicon thin films were prepared by a radio frequency magnetron sputtering system. The nano/amorphous silicon thin film can improve the situation of severe volume change during the charging-discharging process. A copper layer was subsequently deposited on the silicon films. The copper layer reduced the electrolyte attack at silicon and prevent irreversible reactions that lead to a capacity loss during the charging-discharging process. The copper layer also relieve the volume expansion of the silicon matrix and improve the cycle life. In this study, the electrochemical performance of amorphous silicon anode thin films with thickness of 250, 500, 1000 and 2000 nm, coated with an 8 nm copper buffer layer on the surface of each film, were investigated. The results showed that the copper layer retarded the mobility of lithium ions and reduced the electrical capacity, but it can improve the cycle life of the battery.