Anchor and activate sulfide with LiTi2(PO4)2.88F0.12 nano spheres for lithium sulfur battery application

Abstract

Lithium–sulfur batteries are promising for next-generation energy storage devices due to the high energy density and low material cost. However, their development is hampered by the short cycling life and severe polarization induced by shuttle effect of polysulfides and sluggish kinetics of Li₂S. Herein, for the first time, LiTi₂(PO₄)_2.88F_0.12 (LTP-F_0.12) is proposed to anchor and activate sulfide based on its strong interaction with lithium polysulfide and rapid charge transfer behavior. By adding 10 wt% LTP-F_0.12 to the cathode, the discharge capacity and discharge rate performance were apparently improved, while the capacity retention of about 70% at 0.1C after 200 cycles was realized, which was much higher than that of pure SP–S cathode (lower than 50%). The activation energy (voltage polarization) was decreased by almost 40%. Additional capacity of 132 mA h g⁻¹ was also provided by the LTP-F_0.12 from 3.0 to 1.85 V. This study presents a new insight in promoting the polysulfide conversion kinetics in the sulfur cathode.