Space-confined growth of Bi2Se3 nanosheets encapsulated in N-doped carbon shell lollipop-like composite for full/half potassium-ion and lithium-ion batteries

Metal Selenides with layer structure has obvious advantages to store guest alkaline metal ions, promote cycling stability and accelerate diffusion kinetics when applied as electrode for batteries. Among them, layer structured Bi2Se3 with large interlayer spacing is expect to have potential applications in rechargeable batteries. In this study, Bi2Se3 @NC composite with lollipop-like structure was synthesized by conveniently hydrothermal combined subsequent selenization process and then applied as high-performance anodes for both PIBs and LIBs. The synergistic effects between Bi2Se3 and N-doped carbon shell endow it excellent performances anode for PIBs (~ 201.2 mA h g−1 after 1200 cycles at 100 mA g−1, and 130.5 mA h g−1 after 2000 cycles at high current density of 1000 mA g−1). Bi2Se3 @NC also exhibited outstanding performance as anode for LIBs (~ 1005.8 mA h g−1 after 300 cycles at 100 mA g−1). The reaction kinetics analyses results revealed that pseudocapacitance contribution play important role for the excellent electrochemical performances. It is worth to note that the Bi2Se3 @NC//PTCDA-450 potassium-ion full cells were successfully assembled, and 122.3 mA h g−1 was remained after 200 cycles at 100 mA g−1 (the coulombic efficiency can keep at ~ 100%). In addition, ex-situ X-ray diffraction and HRTEM were adopted to explore the phase evolution of Bi2Se3 @NC during charge-discharge processes and density functional theory (DFT)-based first-principle calculations reveal that Bi2Se3 has a lower diffusion barrier and adsorption energy than that of Bi2O3. These results prove the merits of Bi2Se3 @NC and its application potential as suitable anode material for half/full PIBs and LIBs.