Interconnected Silicon Hollow Nanospheres for Lithium-Ion Battery Anodes with Long Cycle Life

TLDR

Silicon is a promising anode material for lithium‑ion batteries because of its high theoretical capacity, but its large volume changes during cycling cause pulverization and rapid capacity fade, making long cycle life a major challenge. The authors introduce an interconnected silicon hollow nanosphere electrode designed to accommodate these volume changes without pulverization during cycling. The hollow nanosphere architecture allows the electrode to absorb large volume expansions, thereby maintaining structural integrity over repeated charge–discharge cycles. The electrode achieved an initial discharge capacity of 2725 mAh g⁻¹, retained over 92 % of its capacity after 700 cycles with less than 8 % degradation per 100 cycles, maintained 99.5 % Coulombic efficiency in later cycles, and demonstrated superior rate capability due to fast lithium diffusion in the interconnected hollow structure.

Abstract

Silicon is a promising candidate for the anode material in lithium-ion batteries due to its high theoretical specific capacity. However, volume changes during cycling cause pulverization and capacity fade, and improving cycle life is a major research challenge. Here, we report a novel interconnected Si hollow nanosphere electrode that is capable of accommodating large volume changes without pulverization during cycling. We achieved the high initial discharge capacity of 2725 mAh g–1 with less than 8% capacity degradation every hundred cycles for 700 total cycles. Si hollow sphere electrodes also show a Coulombic efficiency of 99.5% in later cycles. Superior rate capability is demonstrated and attributed to fast lithium diffusion in the interconnected Si hollow structure.