N-Doped Carbon Nanonecklaces with Encapsulated BiOCl Nanoparticles as High-Rate Anodes for Lithium-Ion Batteries

The unique two-dimensional layered structure of BiOCl makes it highly promising for energy storage applications. In this study, we successfully synthesized BiOCl nanoparticles encapsulated in N-doped carbon nanonecklaces (BiOCl NPs/N-CNNs) using well-established electrospinning and solvothermal substitution. As an anode material for lithium-ion batteries, BiOCl NPs/N-CNNs exhibited enhanced rate performance, delivering a capacity of 220.2 mA h g^-1 at 8 A g^-1. Furthermore, it demonstrated remarkable long cycle stability, retaining a capacity of 200.5 mA h g^-1 after 9000 cycles with a discharge rate of 8.0 A g^-1. The superior electrochemical performance can be attributed to the stacked layered structure of BiOCl, facilitated by van der Waals force, as well as the ingenious nanonecklace structures. These structures not only provide fast ion diffusion pathways but also enhance electrolyte penetration and offer more active sites for Li⁺ insertion and extraction. Additionally, the nanonecklace structure prevents the aggregation of nanopolyhedra, promoting the complete reaction of BiOCl with Li⁺. Moreover, the unique nanopolyhedron structure alleviates the stress caused by the volume expansion of Bi nanoparticles during cycling and reduces the internal resistance of the electrode.