Improving the Cyclic Stability of LiNi0.5Mn1.5O4 at High Cutoff Voltage by Using Pyrene as a Novel Additive

Pyrene (PY) is first used as an additive to improve the cyclic stability of LiNi 0.5 Mn 1.5 O 4 at high cutoff voltage. After 300 cycles at room temperature (≈25 °C) and 100 cycles at elevated temperature (≈55 °C), the capacity retention of Li/LiNi 0.5 Mn 1.5 O 4 cells is 93.1% and 92.68% in the electrolyte containing 0.0025 wt% PY. However, in the base electrolyte, the capacity retention of the cells is 84.7% and 88.12%. The improved capacity retention is due to a thin and even cathode electrolyte interphase (CEI) film containing the poly‐PY on surface of LiNi 0.5 Mn 1.5 O 4 , which reduces the oxidation reaction of electrolyte, the dissolution of transition metal, and the interface impedance in subsequent cycles. In addition, the cross‐talk effect between the positive and negative electrodes is effectively avoided. The film derived from PY also improves the rate performance of cell at room temperature.