Interfacial Design for a 4.6 V High-Voltage Single-Crystalline LiCoO<sub>2</sub> Cathode.

Zhang, Jiaxun; Wang, Peng-Fei; Bai, Panxing; Wan, Hongli; Liu, Sufu; Hou, Singyuk; Pu, Xiangjun; Xia, Jiale et al. · Adv Mater · 2022

basic_science · Level V

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Abstract

Single-crystalline cathode materials have attracted intensive interest in offering greater capacity retention than their polycrystalline counterparts by reducing material surfaces and phase boundaries. However, the single-crystalline LiCoO<sub>2</sub> suffers severe structural instability and capacity fading when charged to high voltages (4.6 V) due to Co element dissolution and O loss, crack formation, and subsequent electrolyte penetration. Herein, by forming a robust cathode electrolyte interphase (CEI) in an all-fluorinated electrolyte, reversible planar gliding along the (003) plane in a single-crystalline LiCoO<sub>2</sub> cathode is protected due to the prevention of element dissolution and electrolyte penetration. The robust CEI effectively controls the performance fading issue of the single-crystalline cathode at a high operating voltage of 4.6 V, providing new insights for improved electrolyte design of high-energy-density battery cathode materials.