ScholarWorks@성균관대학교

초록

Mn-rich Li[Mn1- xFex]PO4 (LMFP) cathodes are promising candidates for next-generation lithium-ion batteries due to their structural stability and cost-effectiveness. However, under industrially relevant high-mass-loading conditions, they still suffer from severe performance degradation, particularly during fast charging. In this study, we systematically demonstrate that charge-transfer resistance, rather than bulk Li+ diffusivity, governs the kinetic limitations of LMFP electrodes with an areal capacity of similar to 3.5 mAh cm-2 (similar to 23 mg cm-2 mass loading). Surface analyses reveal that the buildup of electronically and ionically insulating LiF at the cathode-electrolyte interphase (CEI) is the primary cause of sluggish charge transfer, highlighting a previously overlooked detrimental role of LiF. Guided by this insight, we implement an interfacial engineering strategy that suppresses LiF formation at the CEI. Remarkably, the resulting high-mass-loading LMFP cathodes deliver a 1.6-fold increase in capacity at 5C and retain similar to 87% of their initial capacity after 100 cycles at 2C. Moreover, operando structural analysis reveals that electrodes with LiF-suppressed CEI maintain a robust single-phase transition during fast cycling, directly linking interfacial LiF suppression to significantly enhanced charge-transfer kinetics. This work highlights the critical importance of CEI engineering in enabling fast-charging Mn-rich olivine cathodes under practical, high-mass-loading conditions.

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