Suppressing lattice expansion inLi1.17Mn0.51Ni0.15Co0.15Al0.02O2 cathode for enhanced electrochemical performance via Ti4+ Doping

Abstract

Layered lithium-rich oxides, characterized by their high safety, low cost, and high energy density, are widely regarded as potential contenders for cathode materials in energy storage technologies. Nevertheless, the practical implementation of these materials faces significant hurdles, with severe capacity degradation during cycling being the most intractable issue. In this study, Ti doping in the cathode is achieved by a high-temperature solid-phase approach to address these obstacles and enhance the performance of Li_1.17Mn_0.51Ni_0.15Co_0.15Al_0.02O₂ (LNCMA) cathode material. Notably, at 0.1C, LNCMA-2.5%Ti displayed a discharge capacity of 270.8 mAh·g⁻¹ with a coulombic efficiency of 84.9 %, whereas the pristine material delivered 224.3 mAh·g⁻¹ and 80.2 %. After 100 cycles at 0.5C, LNCMA-2.5%Ti material maintained an impressive capacity retention rate of 97.5 %, which is higher than the value for the pristine material (88.7 %). The exceptional electrochemical performance observed can be mainly attributed to the high bond energy of the Ti-O bond, which effectively reduces the lattice expansion of the material during cycling, stabilizes the lattice structure, and consequently suppresses voltage degradation while enhancing cyclic performance. Furthermore, the introduction of Ti into the lattice structure also widens the spacing between lithium layers, which consequently decreases the migration barrier and promotes the rate performance. Consequently, the LNCMA-2.5%Ti cathode displayed excellent rate performance with a specific capacity of 148 mAh·g⁻¹ at 5C. The electrochemical performance revealed above indicates a high potential for the material to be considered as a cathode option for high-energy batteries.