Mesoporous Silicon with Capacity‐Limited Lithiation: A Strategy for Stable High‐Capacity Lithium‐Ion Anodes

While silicon anodes offer a high theoretical capacity for lithium‐ion batteries, they face challenges related to severe volume expansion and mechanical degradation. Herein, mesoporous structuring is systematically coupled with capacity‐limited (partial) lithiation to improve the durability of high‐Si composite anodes (70% Si). Using galvanostatic cycling and ex situ scanning electron microscopy/thickness measurements on bulk‐Si and mesoporous‐Si (PSi) electrodes at four lithiation depths (100%, 66%, 50%, 33%), it is shown that PSi consistently delivers higher capacity retention over 100 cycles and exhibits markedly lower swelling. At 33% lithiation, PSi retains ≈94% of its initial capacity, outperforming bulk Si, and expands ≈141% compared to 315% for bulk Si under the same cycling conditions. These benefits result from the porous framework's ability to accommodate the volume changes and stabilize the solid electrolyte interface (SEI), reducing the risk of fracture and electrical connectivity loss. These findings contribute to the ongoing research on mesoporous silicon materials and support a higher Si fraction in graphite‐containing anodes, delivering greater energy density with maintained SEI stability and low swelling.