Cheese-like porous SnP2O7 composite as a long-life and high-rate anode material for potassium-ion batteries

• Porous SnP 2 O 7 /rGO composite was synthesized by solvothermal-calcination method. • P-SPO/rGO delivers a high reversible capacity and excellent rate performance. • In-situ XRD and ex-situ TEM are employed to reveal the K + storage mechanism. The abundant reserve, low price, and low redox potential (-2.94 V vs . SHE) of potassium render potassium-ion batteries (PIBs) a potential for commercialization. However, developing suitable anode materials for PIBs remains an elusive challenge, and the low charge storage capacity of inserted anode materials also is not conducive to the realization of high energy density PIBs. In this work, a porous SnP 2 O 7 filled with rGO (P-SPO/rGO) composite material with both conversion and alloying reactions was prepared by solvothermal and calcination methods. Compared with bulk SnP 2 O 7 (B-SPO), P-SPO/rGO, used for the first time as an anode material for PIBs, delivers a high reversible capacity of 351.5 mAh g −1 , long cycling life and excellent rate performance due to the porous structure which can alleviate the large volume change of the material during the cycling processes. Ex-situ transmission electron microscope and in-situ X-ray diffraction were carried out to characterize the intermediate chemical reaction process during discharging/charging. All these findings not only suggest that P-SPO/rGO is a promising anode material for PIBs, but also point out a new direction for the development of anode materials for PIBs.