Enhancing rate capability of amorphous silicon thin film anodes by n-type doping for lithium-ion batteries

Abstract

Abstract This study investigates the fabrication of low-resistivity n-type (nSi) and p-type (pSi) amorphous silicon (a-Si) thin films by magnetron sputtering and comparatively evaluates their electrochemical performance as anodes for thin film lithium-ion batteries (TFLIBs). Approximately 100 nm thick films were deposited and characterized. Electrical resistivity measurements confirmed significantly lower resistivity for the nSi film compared to the pSi film. Electrochemical testing revealed excellent cycling stability for both electrodes at 1 A/g and 4 A/g, nSi maintained 1204 mAh/g while pSi delivered 1132 mAh/g after 500 cycles. Notably, the nSi electrode exhibited superior rate capability, delivering a high capacity of around 1900 mAh/g even at 5 A/g, significantly outperforming the pSi electrode. Electrochemical impedance spectroscopy (EIS) indicated lower interfacial and charge-transfer resistance for nSi, correlating with its enhanced rate performance. These findings underscore the effectiveness of n-type doping in reducing resistivity and boosting the electrochemical performance, particularly the rate capability, of a-Si thin film anodes.