Freestanding carbon fiber‐confined yolk‐shelled silicon‐based anode for promoted lithium storage applications

Abstract A flexible carbon fiber‐confined yolk‐shelled silicon‐based composite is reported as an anode material for lithium storage applications. Silicon nanoparticles (Si NPs) are confined by the N‐doped hollow carbon cages (Si‐NHC) and these uniform dispersed yolk‐shell‐structured Si‐NHC units were encapsulated by the carbon fibers within an interconnected three‐dimensional (3D) framework (Si‐NHC@CNFs). For the encapsulated yolk‐shelled Si‐NHC, the void space between the inner Si NPs and outer NHC can accommodate the structural changes of Si NPs during charging/discharging processes, leading to effectively improved structural stability and cycling life. More importantly, all the Si‐NHC units were bridged together through a conductive CNFs “highway” to enhance the overall conductivity and tap density further. As observed, Si‐NHC@CNFs exhibited an initial discharge capacity of 1364.1 mAh·g −1 at 1000 mA·g −1 and 678.9 mAh·g −1 at 2000 mA·g −1 . Furthermore, the reversible capacity was well maintained at 752.2 mAh·g −1 at 500 mA·g −1 after 6000 ultra‐long cycles.