Cyanometallic framework-derived dual-buffer structure of Sn-Co based nanocomposites for high-performance lithium storage

Tin (Sn)-based anodic materials have attracted tremendous attention in lithium-ion batteries (LIBs) owing to their high theoretical capacity and low potential (0.5 V versus Li/Li+). However, Sn-based anodic materials usually suffer from serious structural collapse and large volume expansion. To overcome this obstacle, herein, a dual-buffer structure of tin-cobalt (Sn-Co) alloy-based nanocomposite was designed through thermal annealing of a cyanometallic framework. The inactive Co acts as robust framework to buffer the volume expansion of Sn-Co alloy nanoparticles, and the reduced graphene oxide (rGO) matrix can reduce the aggregation of Sn-Co nanoparticles as well as alleviate the structure collapse of electrode during long-term cycling. As LIBs anodes, the Sn-Co/rGO composites exhibit a high reversible capacity (1055 mAh g−1 at 0.2 A g−1 after 250 cycles), good rate capability (320 mAh g−1 at 5 A g−1), and outstanding long-term cycling performance (720 mAh g−1 at 1 A g−1 after 600 cycles). When coupled with LiFePO4, the full battery can also display high electrochemical performance in terms of discharge capacity and cyclic stability.