Institute of Fundamental Technological Research

In this current work, the pristine LiNi0.5Mn1.5O4 (LNMO) and fluorine-doped LiNi0.5Mn1.5O4–xFx (x = 0.1; 0.2; 0.3) cathode materials were successfully synthesized through a facile spray-drying method. The performed morphological and structural characterizations revealed that the fluorine doping led to a partial conversion of Mn4+ to Mn3+ ions in LNMO structure and an increase of their average particle sizes. These characteristics made the LiNi0.5Mn1.5O3.9F0.1 cathode exhibited the best rate capability at high C-rates and cycling performance among all investigated LNMO-based electrodes. Its improved electrochemical properties resulted from excellent crystallinity, high Li+ diffusion coefficient, and low charge-transfer resistance. Moreover, the LiNi0.5Mn1.5O3.9F0.1 electrode was found to possess the excellent resistant against Mn dissolution at elevated temperature. According to its great thermal stability, an impressive capacity retention of 81.5% after 100-cycle at 0.2 C at elevated temperature was achieved. In terms of the facile synthesis approach, superior electrochemical performances, and great thermal stability, the LiNi0.5Mn1.5O3.9F0.1 electrode synthesized by the scalable spray-drying method can be regarded as a promising high-voltage cathode material for high-performance Li-ion batteries.

Cathode material, Fluorine doping, Spinel LiNi0.5Mn1.5O4, Spray-drying synthesis, Li-ion batteries

In this study, spinel LiNi0.5Mn1.5O4 (LNMO) was successfully decorated with Al2O3 thin film by using atomic layer deposition (ALD) approach and evaluated as a cathode material for high-temperature applications in lithium ion batteries (LIBs). To optimize the LNMO-Al2O3 electrodes operated at elevated temperature (55 °C), the effects of Al2O3 thicknesses adjusted by controlling the ALD deposition cycle were systemically investigated. According to the series of electrochemical results, the LNMO coated with the Al2O3 thin layer in the thickness of ca. 2 nm was achieved by using one-cycle ALD and the LNMO-Al2O3 electrode exhibited superior electrochemical stability (capacity retention up to 93.7% after consecutive 150 charge/discharge cycles at 0.5 C to the pristine LNMO electrode at elevated temperature. This can be attributed to two factors: (i) the decoration of Al2O3 thin layer could not contribute remarkably to extra resistance for charge transfer; (ii) Al2O3 thin film deposition could efficiently stabilize the growth of cathode electrolyte interface (CEI) and suppress the dissolution of transition metals. Therefore, these results verify that the LNMO-Al2O3 electrode could be regarded as a promising cathode material for high-voltage LIBs, especially at elevated temperature operation.

atomic layer deposition, Al2O3 coating, lithium nickel manganese oxide, lithium-ion battery, elevated temperature