Extreme Rate Capability Cycling of Porous Silicon Composite Anodes for Lithium-Ion Batteries

Silicon-based anodes have the potential to increase the capacity of lithium-ion batteries but suffer from irreversible damage due to their volume expansion. Capacity-controlled cycling has emerged as a promising method for silicon-based anodes; however, few studies have evaluated how high C-rates affect cycle life under capacity-controlled cycling. Here, we examine how a repetitive cycling at high C-rates and long cycle numbers affects the electrochemical performance. This extreme rate capability test (cycling between C/5 and 8C for 560 cycles) illustrates the robustness of the silicon-composite anodes and indicates that the anode continues to perform well at C/5 for another 120 cycles after the 560-cycle-testing at 8C. When the C-rate increases, there is a drop in capacity, which can be attributed to an increase in the polarization resistance of the anode, which increases as the cell ages. The superior rate capability of silicon-composite anodes is promising for applications requiring fast charge-discharge rates.