Potassium-ion batteries (PIBs) are considered as potential replacements to lithium-ion batteries for large scale energy storage applications due to abundant potassium resources and low cost. However, it is a rough road to find suitable materials with high capacity and cycling stability due to the large K ion radius. In this study, a simple method, electrodeposition, is used to anchor SnO2 nanoparticles on three dimensional carbon foam (SnO2@CF) as a freestanding anode for PIBs. The prepared freestanding SnO2@CF electrode features a three dimensional (3D) conductive carbon frame and SnO2 nanoparticles, which can enhance electron transfer, prevent SnO2 from losing electrical contact after large volume changes and facilitate electrolyte infiltration and K ion transfer. As expected, SnO2@CF delivers a high K storage specific capacity, and outstanding cycling stability (231.7 mA h g−1 after 400 cycles at 1 A g−1) and rate performance (371.4, 307.6, 247.3 and 143.5 mA h g−1 at 0.5, 1, 2 and 5 A g−1, respectively). Meanwhile, the phase transition of the SnO2@CF electrode is tracked during the charge and discharge processes in PIBs. This study provides a facile method to prepare freestanding electrode materials and a promising anode material for PIBs.
