Effect of Fluorine-Containing Additive on the Electrochemical Properties of Silicon Anode for Lithium-Ion Batteries

Silicon anode is a promising candidate as an alternative to the conventional graphitic anode in lithium-ion batteries. In this work, silicon anode is modified by NH 4 F using a facile method in air. The concentration of NH 4 F on the electrochemical performance is systematically checked. The 5wt%NH 4 F-modified silicon anode exhibits enhanced cycle and rate performances, the first discharge specific capacity is 3958 mAh·g -1 with 86.45% as the coulombic efficiency at 0.4A·g -1 . The capacity can maintain at 703.3 mAh·g -1 after 50 cycles, exhibiting a much better cycle stability than pristine silicon anode (329.9 mAh·g -1 after 50 cycles). SEM images confirm that NH 4 F can alleviate the volume expansion of silicon since LiF can be generated at the surface which is beneficial to the stability of solid-electrolyte interphase (SEI).