Yttrium-modified ultra-high Ni quaternary cathodes with enhanced high-potential and high-temperature performances

Ultra-high Ni quaternary cathodes (LiNi x Co y Mn z Al 1-x-y-z O 2 , 1 x 0.8) demonstrate superior cycling stability, positioning them as promising Ni-rich cathode candidates for next-generation lithium-ion batteries. However, increasing demand for higher energy density necessitates higher operation potential, which in turn exacerbates intrinsic challenges, such as poor chemical stability and diminished thermal stability. To address these challenges, an yttrium (Y) modification strategy has been carried out to enhance structural and interfacial stability. Compared to pristine, Y-modified samples show enhanced high-potential and high-temperature performances. In detail, it reveals a specific capacity of 228.5 mAh g −1 within an extended potential window of 3.0–4.5 V and retains 90.7% of its capacity after 200 cycles. When operated at an elevated temperature of 55 °C, it also presents a good capacity retention of 80.4%. The role of Y dopant has been systematically investigated using advanced techniques such as density functional theory (DFT) and in-situ experiments. Results indicate that Y primarily substitutes Ni sites, thereby stabilizing the oxygen framework to enhance cycling stability at a higher operation potential or elevated temperature. Moreover, the formation of surface-coated solid electrolyte layers effectively suppresses interfacial side reactions, contributing to improved cyclability under high-potential and high-temperature conditions.