| Summary: | 碩士 === 逢甲大學 === 材料科學與工程學系 === 107 === In this report, we study the electrochemical performance of amorphous silicon as the anode for lithium ion batteries. Silicon has high theatrical capacity of 4200 mAh/g toward lithium metal. However, Li insertion/Li extraction of silicon electrode causes huge volume expansion. In this study, radio frequency (RF) magnetron sputtering is used to deposit amorphous silicon thin films on nickel foam current collectors. This flexible three-dimensional structure is found to relieve stress caused by the volume expansion. Furthermore, we sputter a SiNx thin film on silicon to be a buffer layer. From the potential window of 1.2 V - 0.01 V, long cycle test have been executed to investigate the electrochemical performances of various N-Si coated Si-based lithium ion batteries anode materials. The cycling stability is enhanced via nitride layer coating as silicon nitride films are converted to Li3N with covered Si thin films. After 300th cycle, the capacity retention is 96% and the discharge capacity is 1380 mAh/g due to low charge transfer resistance resulted from silicon nitride films. The results reveal that the inactive phase could be a good buffer layer for Si anodes.
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