Chemomechanically Stable Ultrahigh-Ni Single-Crystalline Cathodes with Improved Oxygen Retention and Delayed Phase Degradations

• Published in: Nano letters Vol. 21; no. 22; pp. 9797 - 9804
• Main Authors: Wang, Chunyang, Zhang, Rui, Siu, Carrie, Ge, Mingyuan, Kisslinger, Kim, Shin, Youngho, Xin, Huolin L
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 24.11.2021
• Subjects: cathodes; chemomechanical; degradation; electrodes; ENERGY STORAGE; inhomogeneity; layers; lithium-ion batteries; MATERIALS SCIENCE; NANOSCIENCE AND NANOTECHNOLOGY; phase transitions; scanning transmission electron microscopy; single-crystalline; ultrahigh Ni; chemomechanical; degradation; lithium-ion batteries; ultrahigh Ni; single-crystalline; cathodes
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/acs.nanolett.1c03852

The pressing demand in electrical vehicle (EV) markets for high-energy-density lithium-ion batteries (LIBs) requires further increasing the Ni content in high-Ni and low-Co cathodes. However, the commercialization of high-Ni cathodes is hindered by their intrinsic chemomechanical instabilities and fast capacity fade. The emerging single-crystalline strategy offers a promising solution, yet the operation and degradation mechanism of single-crystalline cathodes remain elusive, especially in the extremely challenging ultrahigh-Ni (Ni > 90%) regime whereby the phase transformation, oxygen loss, and mechanical instability are exacerbated with increased Ni content. Herein, we decipher the atomic-scale stabilization mechanism controlling the enhanced cycling performance of an ultrahigh-Ni single-crystalline cathode. We find that the charge/discharge inhomogeneity, the intergranular cracking, and oxygen-loss-related phase degradations that are prominent in ultrahigh-Ni polycrystalline cathodes are considerably suppressed in their single-crystalline counterparts, leading to improved chemomechanical and cycling stabilities of the single-crystalline cathodes. Our work offers important guidance for designing next-generation single-crystalline cathodes for high-capacity, long-life LIBs.