Characterization and Performance of Graphite-Lithium Titanium Oxide Composites Used as Anodes in Lithium-Ion Batteries

Lithium titanium oxide used as the anode for lithium-ion batteries has some challenges such as its high electrical resistance and low lithium diffusion coefficient. To this end, graphite-lithium titanium oxide composites were prepared and the effect of synthesis parameters on half-cell and full-cell performance with NMC532 cathode was investigated. The best synthesis parameters included 5 h of milling, a heat treatment temperature of 850 degrees C, and graphite contents of 70 or 90 W/W%, resulting in full-cell capacity of 124.73 mA h g-1 and initial Coulombic efficiency (ICE) of 97.63 for 90% graphite content and the capacity of 116.14 mA h g-1 and ICE of 95.62 for 70% graphite content. The hall-cell capacity also improved to 311.23 Ma h g-1 and 290.51 mA h g-1 for 90% and 70% graphite content, respectively. The composites also improved the lithium diffusion coefficient, achieving a diffusion coefficient of 1.356x10-11cms-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1.356\times {10}<^>{-11}\text{cm}\, {\text{s}}<^>{-1}$$\end{document} for the composite anode compared to 2.968x10-14cms-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2.968\times {10}<^>{-14}\text{cm}\, {\text{s}}<^>{-1}$$\end{document} for LTO anode in full-cell configuration. The results of microstructural studies after charge and discharge cycles showed that composites containing LTO were successful in preventing the formation of lithium dendrite structures often observed on graphite anodes. The synthesis parameters were optimized for the first time with an emphasis on full-cell performance when paired with an NMC532 cathode. The proposed mechanism for this improved performance was ascribed to the formation of an LTO layer over the graphite anode, providing the advantages associated with LTO while minimizing the disadvantages by minimizing the length of lithium diffusion pathways in the LTO phase.