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 Bi 2 Se 3 nanosheets coated with nitrogen-doped carbon and wrapped with reduced graphene oxide (Bi 2 Se 3 @NC@rGO) is fabricated to boost K-ion storage. The Bi 2 Se 3 @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 K 2 Se 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 Bi 2 Se 3 @NC@rGO. The K-ion full cell is also assembled using K 2 Ni[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.