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

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 (R_ct ) and solid electrolyte interface impedance (R_sei ), and increase the lithium ion diffusion coefficient (D_Li ), 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.