Self-Healing Phenomenon Observed During Capacity-Control Cycling of Freestanding Si-Based Composite Paper Anodes for Li-Ion Batteries

A different strategy of capacity-control cycling under fixed upper and lower capacity/voltage limits is used in an attempt to seek an extended cycle life for Si nanoparticle–multiwalled carbon nanotube (Si–MW) electrodes for Li-ion batteries. For cells using Si–MW 1:1 (w/w) electrodes in the electrolyte of ethylene carbonate–diethyl carbonate–fluoroethylene carbonate (EC–DEC–FEC, 45:45:10 w/w/w) tested at a current of 1 mA, stable 326 charge/discharge cycles at a designated capacity of 506 mA h g –1 are attained. The new cycling protocol allows for the observation of a self-healing phenomenon by studying the specific capacities and charge/discharge end voltages. Prolonged cycling under capacity control (500 mA h g –1 ) and the interesting pattern of variations in the discharge/charge end voltage are successfully reproduced under different electrode/electrolyte and current conditions: Si–MW 3:2 in the electrolyte of DEC–FEC (1:1 w/w) at 1 mA (490 cycles), Si–MW 3:2 in DEC–FEC at 0.5 mA (483 cycles), and Si–MW 1:1 in DEC–FEC at 0.5 mA (576 cycles), which can be explained by applying the proposed self-healing mechanism as well.