Two-dimensional polymers made of carbonyl-bridged heterotriangulenes are promising anode materials for Li-ion batteries

Abstract

By means of first-principles calculations, we have explored the potential of two-dimensional (2D) polymers made of carbonyl-bridged triphenylamine (CTPA) and carbonyl-bridged triphenylborane (CTPB) as electrode materials for lithium-ion batteries (LIBs). Our investigations demonstrate that the carbonyl groups of 2D CTPB and CTPA are rather active to accommodate Li. Both 2D CTPA and CTPB show the transition from semiconductor to metal after combining with Li. The migration of Li through the pore space of 2D CTPB and CTPA is facilitated with a small diffusion barrier of 0.76 and 0.79 eV, respectively. 2D CTPB exhibits a high theoretical capacity of 760.86 mAh g−1 because it can accommodate Li at both the carbonyl sites and the surface sites of the skeleton, which is ascribed to the promotion of the electron-deficient B center. As a comparison, 2D CTPA can only combine with Li at the carbonyl sites and shows a capacity of 251.09 mAh g−1. With fast Li-diffusion ability, high capacity and low average operating voltage, 2D CTPA and CTPB are predicted to be promising non-metal anode materials for LIBs.