Freeze-drying-assisted fabrication of flexible graphene/SnO 2 for high-rate lithium-ion batteries

Graphene-based tin dioxide (SnO2) composite electrodes for flexible lithium-ion batteries (LIBs) have received tremendous attention due to advantages of lightweight, excellent mechanical flexibility, and superior electrochemical performance. However, the restacking of graphene nanosheets and agglomeration of SnO2 nanoparticles during the drying processes limit the infiltration of electrolyte and transfer of lithium ions across graphene plane and into graphene interlayers, resulting in low reversible capacity and inferior high-rate cycle performance. Herein, a facile synthetic method involving a freeze-drying technique coupled with a mild hydrothermal reduction treatment is employed to fabricate flexible graphene/SnO2 paper (FGSP) electrode. The results show that the use of freeze-drying technology can not only increase the spacing of graphene nanosheets but also alleviate the agglomeration of SnO2 nanoparticles, thus improving the rate and cycle performance of FGSP electrode. As anode material for LIBs, the obtained FGSP electrode delivers high specific capacity (740 mAh·g−1 at 100 mA/g), excellent rate capability (406 mAh·g−1 at 2 A/g), and stable cycling stability. It demonstrates that this synthetic methodology can provide a favorable strategy for the ingenious preparation of electrode materials for high-performance FLIBs.