Toward Promising Turnkey Solution for Next-Generation Lithium Ion Batteries: Scale Preparation, Fading Analysis, and Enhanced Performance of Microsized Si/C Composites

A silicon/carbon composite with micron scale is prepared by a simple ball-milled mixing method and subsequent carbonization process. The composite electrode exhibits excellent electrochemical performance, delivering an initial reversible capacity of 441 mA h g–1 and Coulombic efficiency of 83.9%, respectively, along with high capacity retention of 97.1% after 200 cycles. Based on that, a LiCoO2/Si–C full cell is fabricated and the aging mechanism is investigated, where the results show that the significant capacity fading is primarily due to the loss of active lithium, related to the increased solid electrolyte interface (SEI) film forming on the surface of the anode. Addition of fluoroethylene carbonate (FEC) in the electrolyte can substantially inhibit the decomposition of electrolyte and reduce the loss of active lithium, thereby decreasing the cell internal resistance and increasing the cycling performance. Correspondingly, the capacity retention after 100 cycles increases from 36.7% to 76.8% for the cell with FEC added to the electrolyte.