Porous Fe1-S/C microspheres constructed by L-aspartic acid as high-performance anode material for lithium-ion batteries

Porous microspherical structure for metal oxides or sulfides as anode material exhibits dramatic advantages in improving electrochemical properties of lithium-ion batteries (LIBs). Herein, porous Fe1-xS microspheres with uniform size were synthesized through a hydrothermal reaction where L-aspartic acid molecules guide crystal growth and form secondary particles. The microsphere with perforated channels provides facile channels for the migration of Li+ and accommodates mechanical stress to suppress volume expansion. The residual carbon decomposed from the L-aspartic acid molecules in the final composite also facilitates the electron transfer and prevents polysulfides from dissolving into electrolyte. Thus, the Fe1-xS/C maintains superior structural stability in a long cycling with excellent reversible capacity at high rates. Specifically, the Fe1-xS/C electrode deliverers a capacity of 534 mAh g−1 at 20 A g−1 and lefts 810 mAh g−1 after 3000 cycles at 5 A g−1.