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

Abstract 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.