A Porous Mooncake-Shaped Li4 Ti5 O12 Anode Material Modified by SmF3 and Its Electrochemical Performance in Lithium Ion Batteries.

Abstract

Reasonably designing and synthesizing advanced electrode materials is significant to enhance the electrochemical performance of lithium ion batteries (LIBs). Herein, a metal-organic framework (MOF, Mil-125) was used as a precursor and template to successfully synthesize the porous mooncake-shaped Li4 Ti5 O12 (LTO) anode material assembled from nanoparticles. Even more critical, SmF3 was used to modify the prepared porous mooncake-shaped LTO material. The SmF3 -modified LTO maintained a porous mooncake-shaped structure with a large specific surface area, and the SmF3 nanoparticles were observed to be attach on the surface of the LTO material. It has been proven that the SmF3 modification can further facilitate the transition from Ti4+ to Ti3+ , reduce the polarization of electrode, decrease charge transfer impedance (Rct ) and solid electrolyte interface impedance (Rsei ), and increase the lithium ion diffusion coefficient (DLi ), thereby enhancing the electrochemical performance of LTO. Therefore, the porous mooncake-shaped LTO modified using 2 wt % SmF3 displays a large specific discharge capacity of 143.8 mAh g-1 with an increment of 79.16 % compared to pure LTO at a high rate of 10 C (1 C=170 mAh g-1 ), and shows a high retention rate of 96.4 % after 500 cycles at 5 C-rate.