Hierarchical bismuth composite for fast lithium storage: Carbon dots tuned interfacial interaction

Graphical abstract CDs are utilized as crucial structure-directing agents to elaborately design 3D cross-linked rod-like structured Bi2Se3/CDs composites. Computational simulations combined with experiments demonstrate that such robust 3D framework and the existence of interface Bi-O-C bond can simultaneously enhance the intrinsic sluggish kinetics and structural stability, endowing Bi2Se3/CDs anode with fast-charging capability and durable cycling life. Download : Download high-res image (205KB) Download : Download full-size image Advanced electrode materials for fast-charging lithium-ion batteries are of great significance to next-generation energy-storage systems. Herein, three-dimensional (3D) hierarchical rod-structured Bi2Se3/carbon dots (Bi2Se3/CDs) composite is elaborately designed for fast-kinetics lithium storage. It is proposed that CDs-induced self-assembly growth and site-selective ion-exchange transform nanosheets into cross-linked architecture. Such robust 3D framework provides efficient channels for electron/ion transport and sufficient inner space for volume variation as confirmed by theoretical prediction. Notably, the existence of interface Bi-O-C bond would effectively enhance its inherent bulk electronic conductivity and accelerate ionic transportation by narrowing the bandgap and reducing the Li+ migration energy barriers. Consequently, intrinsic sluggish kinetics and structural stability are simultaneously improved, endowing Bi2Se3/CDs composite electrode fast charging/discharging capability of 165 mAh g−1 at 20 A g−1 (corresponding to charge in ≈27 s) and excellent long-term durability with the capacity of 502 mAh g−1 over 950 cycles at 1 A g−1. Moreover, the intercalation-conversion-alloying type lithium storage mechanism of Bi2Se3/CDs is revealed by in-situ XRD. This work provides a train of thoughts for other CDs-tailored composites with tunable morphology and structure.