Improving the electrical conductivity and electrochemical performance of LiMn2O4 by Sm gaseous penetration technology

Abstract

Aiming at the poor electrical conductivity and rate performance of LiMn2O4, the rare earth gaseous penetration technology was used to modify commercial LiMn2O4. XRD, SEM, TEM, FTIR, XPS and other characterization methods were used to investigate the resistivity, morphology, phase structure and electrochemical performance. ICP measurement and the mapping diagrams of TEM displayed that there was a small amount of Sm with evenly distribution after penetration. Sm-modified LiMn2O4 still maintained the standard spinel structure, Mn3+ was partially replaced by Sm3+ during the penetration process, the bond energy of Sm-O bond was stronger than that of Mn-O bond, which stabilized the spinel structure of LiMn2O4. The particle size of LiMn2O4 decreased after penetration, which can shorten the migration path of Li+ from the inside of the particle to the surface during the charge and discharge processes, and increase the charge transfer rate. The resistivity of LiMn2O4 reduced to 1.15 × 105 Ω·cm and the initial discharge specific capacity of Sm-modified LiMn2O4 was 110.9 mAh·g−1 at 0.1C. Moreover, Sm-modified LiMn2O4 exhibited excellent rate capabilities. This work is useful for providing a concrete method to improve the electrical conductivity and electrochemical performance of LiMn2O4 in industry.