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.