Adsorptive Shield\nDerived Cathode Electrolyte Interphase\nFormation with Impregnation on LiNi<sub>0.8</sub>Mn<sub>0.1</sub>Co<sub>0.1</sub>O<sub>2</sub> Cathode: A Mechanism-Guiding-Experiment Study

Lithium difluoro(oxalate) borate (LiDFOB) contributes\nactively\nto cathode–electrolyte interface (CEI) formation, particularly\nsafeguarding high-voltage cathode materials. However, LiNi<sub><i>x</i></sub>Co<sub><i>z</i></sub>Mn<sub><i>y</i></sub>O<sub>2</sub>-based batteries benefit from the LiDFOB and its\nderived CEI only with appropriate electrolyte design while a comprehensive\nunderstanding of the underlying interfacial mechanisms remains limited,\nwhich makes the rational design challenging. By performing ab initio\ncalculations, the CEI evolution on the LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>O<sub>2</sub> has been investigated. The findings\ndemonstrate that LiDFOB readily adheres to the cathode via semidissociative\nconfiguration, which elevates the Li deintercalation voltage and remains\nstable in solvent. Electrochemical processes are responsible for the\nsubsequent cleavage of B–F and B–O bonds, while the\nB–F bond cleavage leading to LiF formation is dominant in the\npresence of adequate Li<sup>+</sup> with a substantial Li intercalation\nenergy. Thus, impregnation is established as an effective method to\nregulate the conversion channel for efficient CEI formation, which\nnot only safeguards the cathode’s structure but also counters\nelectrolyte decomposition. Consequently, in comparison to utilizing\nLiDFOB as an electrolyte additive, employing LiDFOB impregnation in\nthe NCM811/Li cell yields significantly improved cycling stability\nfor over 2000 h.