Combined DFT and experiment: Stabilizing the electrochemical interfaces via boron Lewis acids

The incorporation of boron into carbon material can significantly enhance its capacity performances. However, the origin of the promotion effect of boron doping on electrochemical performances is still unclear, in part due to the inadequate exposure of boron configurations resulting from the complexity of traditional carbon materials. To overcome this issue, herein, a series of boron-doped graphene with highly-exposed boron configurations are prepared by tuning annealing temperature. Then the correlation between boron configurations and the electrochemical performances is investigated. The combination of density-functional theory (DFT) computation and NH₃-TPD/Py-FTIR indicates that the BCO₂ configuration formed on the surface of graphene is easier to accept lone-pair electrons than BC₂O and BC₃ configurations due to the stronger Lewis acidity. Such an electronic structure can effectively reduce the number of unstable electron donors and stabilize the electrochemical interface, which is proved by NMR, and critical for improving the electrochemical performances. Further experiments confirm that the optimized BG800 with the largest amount of BCO₂ configuration presents ultralow leak current, improved cyclic stability, and better rate performance in SBPBF₄/PC. This work would provide an insight into the design of high-performance boron-doped carbon materials towards energy storage.