▎ 摘　　要

The construction of an anode material with a conversion-alloying dual mechanism will facilitate the development of potassium-ion batteries (PIBs) with high-energy density. Here a Bi2Se3 nanosheets coated with nitrogen-doped carbon and wrapped with reduced graphene oxide (Bi2Se3@NC@rGO)is fabricated to boost K-ion storage. The Bi2Se3@NC@rGO composite with strong C-O-Bi bonding can provide superior electrode integrity and electrochemical kinetics by combining the synergistic effect of carbon encapsulation and graphene confinement. In situ X-ray diffraction and ex situ transmission electron microscopy analyses demonstrate that K-ion intercalation/deintercalation proceeds via both conversion and alloying/dealloying reactions based on 12-electron transfer per formula unit; the conversion product of K2Se can efficiently suppress the volume expansion during alloying/dealloying process to improve its stability. Hence, a high reversible capacity of 612.0 mAh.g(-1) at 100 mA.g(-1); a great rate capability with the capacity of 101.6 mAh.g(-1) at 5 A.g(-1), and an ultra-long cycling life of over 1000 cycles at 500 mA.g(-1) is achieved for the Bi2Se3@NC@rGO. The K-ion full cell is also assembled using K2Ni[Fe(CN)(6)] as the cathode, thereby contributing a high-energy density of 162.9 Wh.kg(-1) at 10 mA.g(-1) and a great cyclability.