Synthesis of pomegranate-like Bi2Se3@C composite for high volume specific capacity lithium storage

Lithium-ion batteries (LIBs) with high volume specific capacity have promising applications in small/microelectronics. However, the contradiction between Li+ diffusion kinetics and material compaction density severely restricts its development. The layered bismuth selenide (Bi2Se3) with high conductivity and compaction density is a candidate material for LIBs with high volume specific capacity. In this work, Bi2Se3@C was synthesized by solvothermal and selenization methods, and the final product exhibits a high specific capacity (468 mAh g−1 at 0.1 A g−1, corresponding to 1862 mAh cm−3) and good cycling stability (358 mAh g−1 after 500 cycles at 0.5 A g−1, corresponding to 1445 mAh cm−3). The excellent electrochemical performance results from the special morphology of the carbon layer-coated Bi2Se3 nanospheres, and the carbon layer not only regulates the volume expansion of Bi2Se3 during cycling but also improves the electronic conductivity, which is also confirmed by density functional theory calculation. Ex-situ X-ray diffraction spectrum reveals that the crystal phase of Bi2Se3 changed from hexagon to orthogonal after the initial cycle.