Regulation of Interstitial Buffering Space in Yolk-Shell Tin-Carbon Nanocomposites Used as Electrodes for Lithium-Ion Batteries

Tin-based anodic materials, benefiting from their large theoretical specific capacity and minimal operating potential, are considered high-development potential alternative anodes for lithium-ion batteries (LIBs). Nevertheless, the alloying-dealloying processes between tin (Sn) and lithium ions result in severe volume expansion, which leads to a poorly stabilized solid-electrolyte interface (SEI) layer and resultant inferior cycling performance, posing major obstacles to their commercialization. Herein, a structural regulation strategy was proposed to optimize the interstitial void buffer layer within yolk-shell structures to mitigate the lithiation-associated volume expansion. The tetraethyl orthosilicate-hydrolyzed SiO2 layer was located between Sn and the resin-derived carbon coating, whose thickness could be sophisticatedly optimized via regulating the hydrolysis durations. Following the carbonization and etching, an optimized buffer layer was encapsulated within a protective carbon shell (Sn@Void@C), which could effectively accommodate Sn's volume expansion during the alloying period, significantly enhancing its performance in electrochemical processes and structural stability. Specifically, the Sn@Void@C anode retained a high specific capacity of 720 mAh g-1 after 400 cycles at 0.2 C and demonstrated an outstanding capacity of 520 mAh g-1 after 500 cycles at 0.5 C. This work provides a facile and effective strategy for rationally designing tin-based anodes for lithium-ion batteries.