Functional AlF3 modification over 5 V spinel LiCoMnO4 cathode for Li-ion batteries

Abstract

We report the improved electrochemical activity of the 5 V LiCoMnO4 (LCMO) cathode with the functionalization of AlF3 coating. LCMO@AlF3 is prepared by adopting the co-precipitation technique followed by a wet coating by altering the concentration of AlF3 by 1–3 wt.%. LCMO@AlF3 exhibits improvement in the electrochemical performance compared to pristine LCMO. In addition, LCMO@AlF3 exhibits superior electrochemical performance with specific capacities of 107, 102, and 95 mAh g−1 and retentions of 68, 77, and 74% after 100 cycles for 1, 2, and 3 wt.% AlF3 coating. However, pristine LCMO shows a specific capacity of 105 mAh g−1 with a retention of 48% after 100 cycles. Also, LCMO@AlF3 exhibits a decrement in the irreversible capacity loss (ICL) compared to pristine LCMO, which enhances the coulombic efficiency of the former compared to the latter. Further, the AlF3 coating of 2 and 3 wt.% has been optimized to exhibit excellent electrochemical performance. The diffusion coefficients are calculated from cyclic voltammetric and electrochemical impedance spectroscopic techniques and are in the order of ∼10−12 cm2 s−1. Further, in-operando and in-situ impedance studies are conducted to authenticate the electrochemical activity observed in half-cell studies. In full-cell assembly with Li4Ti5O12 (LTO) anode, the LCMO@AlF3: 2–3 wt.% exhibits better electrochemical performance compared to its bare configuration. In addition, the electrochemical activity at various temperature (−10 to 25 °C) conditions is performed and reported.