3D Hollow Porous Spherical Architecture Packed by Iron-Borate Amorphous Nanoparticles as High-Performance Anode for Lithium-Ion Batteries.

Three-dimensional hollow porous spherical architecture packed by iron-borate amorphous nanoparticles as an anode for lithium-ion batteries is first prepared through a simple method. The anode exhibits a high Coulombic efficiency and an ultralong cycle life under high rate, delivering outstanding reversible capacity of 1170 mAh g-1 after 360 cycles at 100 mA g-1 and 1160 mAh g-1 after 750 cycles at 200 mA g-1. The iron-borate anode has a prominent ultralong cycle life. The reversible capacity can still remain at about 600 mAh g-1 even after 3500 cycles at 2000 mA g-1, which maintains an outstanding capacity and delivers a much longer cycle life than that of the reported iron-based oxide anodes measured at same current density only within 1000 cycles. The hollow porous structure offers efficient electron-transport and Li+-diffusion paths and buffers the structural strains to alleviate excessive pulverization of the anode materials. Large specific surface area of the hollow porous structure increases the contact area between the anode and electrolyte, providing more reaction sites. More importantly, the amorphous characteristics of the iron-borate anode possess higher density of active sites and improved faster reaction kinetics. This work demonstrates that the hollow porous iron-borate particle anode allows mass production and is one of the most attractive anodes in energy-storage applications.