Oxygen-deficient TiO2−x interlayer enabling Li-rich Mn-based layered oxide cathodes with enhanced reversible capacity and cyclability

• Published in: RSC advances Vol. 13; no. 25; pp. 16850 - 16859
• Main Authors: Yike Lei, Zhang, Yingchuan, Han, Yongkang, Ni, Jie, Zhang, Cunman, Xiao, Qiangfeng
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 05.06.2023; The Royal Society of Chemistry
• Subjects: Anions; Cathodes; Chemistry; Electrochemical analysis; Electrons; Interlayers; Oxide coatings; Oxygen; Photoelectrons; Redox reactions; Spectrum analysis; Titanium dioxide; X ray photoelectron spectroscopy
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d3ra02125d

The unique anion redox mechanism of Li-rich Mn-based layered oxide (LMLO) cathodes endows them with a higher specific capacity compared with conventional cathodes. However, the irreversible anion redox reactions can cause structural degradation and sluggish electrochemical kinetics in the cathode, resulting in a poor electrochemical performance in the batteries. Thus, to address these issues, a single-sided conductive oxygen-deficient TiO2−x interlayer was applied on a commercial Celgard separator as a coating layer towards the LMLO cathode. After coating TiO2−x, the initial coulombic efficiency (ICE) of the cathode increased from 92.1% to 95.8%, the capacity retention improved from 84.2% to 91.7% after 100 cycles, and the rate performance of the cathode was significantly enhanced from 91.3 mA h g−1 to 203.9 mA h g−1 at 5C. Operando differential electrochemical mass spectroscopy (DEMS) showed that the coating layer could restrain the release of oxygen in the battery, especially from the initial formation process. The X-ray photoelectron spectroscopy (XPS) results demonstrated that the favorable oxygen absorption by the TiO2−x interlayer benefitted the suppression of side reactions and cathode structural evolution and favored the formation of a uniform cathode-electrolyte interphase on the LMLO cathode. This work provides an alternative path to address the issue of oxygen release in LMLO cathodes.