Effects of LiPON Thin-Film Coating on Thermal Behavior of Delithiated Li[sub 1−x](Ni[sub 0.53]Co[sub 0.2]Mn[sub 0.27])O[sub 2] Cathode

A lithium phosphorus oxynitride (LiPON) thin film, which is a solid ionic conductor, was deposited on a electrode to improve the thermal stability of the delithiated cathode. The LiPON thin films were deposited by radio-frequency magnetron sputtering. The thermal stability of electrochemically delithiated cathodes with electrolyte was investigated by differential scanning calorimetry (DSC), in which the cathode was charged to different upper cutoff voltages of 4.3, 4.5, and 4.7 V (vs ). The LiPON-coated cathodes exhibited an enhanced cycle performance for a high upper cutoff voltage, i.e., 4.7 V. However, the LiPON film appears to be thermally unstable as compared to the delithiated pristine electrodes, especially when charged to a higher upper cutoff voltage. As a result, the LiPON-coated electrodes exhibited a lower onset temperature and peak position of the exothermic peak in DSC scans than the pristine electrodes.