Identification of the Key Structure Factor to Achieve High Energy Density in Spinel LiNi 0.5 Mn 1.5 O 4

作者：Yingbo Deng, Zengzhu Li, Honghao Wang, Lunhua He, Bingkai Zhang, Mingjian Zhang · 发表于：Chemistry of Materials · 年份：2024 · DOI：10.1021/acs.chemmater.4c01571 · 被引用次数：3 · 研究领域：Advancements in Battery Materials、Ferroelectric and Piezoelectric Materials、Multiferroics and related materials

Extending the lower cutoff potential of spinel LiNi 0.5 Mn 1.5 O 4 to 2 V holds the potential to significantly increase the energy density from approximately 600 to around 900 W h/kg by utilizing an extra ∼2.7 V plateau. However, precisely adjusting the length of the ∼2.7 V plateau has proven to be a challenging task, and the decisive structural factor has remained elusive. In this study, a thorough and comparative investigation employing time-of-flight neutron powder diffraction, aberration-corrected scanning transmission electron microscopy, combined with theoretical calculations, has unveiled, for the first time, the key structural feature influencing the length of the ∼2.7 V plateau, a specific point defect, that is, Ni occupation at the 16 c octahedral site. It drives Li ions at the neighboring 8 a tetrahedral site to move to the 16 c site and accelerates the T1 → T2 phase transition, resulting in a shorter ∼2.7 V plateau. Ultimately, the cathode material with the vacant 16 c site exhibits a prolonged ∼2.7 V plateau, achieving a higher energy density of approximately 900 W h/kg than that of the cathode material with ∼5.4% Ni at the 16 c site (around 800 W h/kg). These findings offer valuable insights for achieving high-energy-density and cost-effective spinel cathodes through meticulous microstructure regulation.