High-performance and safety of lithium-ion batteries enabled by NiO@PP separator

<title>Abstract</title> <p> Separator is a critical internal component, which can isolate the positive and negative electrodes, prevent short circuits, and allow lithium ions to pass freely, ensure safety and performance stability of battery. With the continuous improvement in the energy density of lithium-ion batteries, traditional polypropylene (PP) composite separators can no longer meet the growing demand for energy storage. To address this problem, this study proposes a simple method of modifying the conventional PP separators using an NiO coating to enhance the overall performance of PP separators. The results show that the separator with a 15 mm nickel oxide coating (NiO@PP-15) exhibits the best comprehensive performance. In 1C and 5C cycling tests, NiO@PP-15 demonstrates optimal stability, the slowest capacity decay, and more stable electrochemical performance. After a 5C cycle test, the NiO@PP-15 still has a battery capacity of 121.53 mAh g ^− 1 . Compared to the specific capacity of the PP separator (35.56 mAh g ^− 1 ), both the NiO@PP-5 (61.16 mAh g ^− 1 ) and NiO@PP-10 (110.33 mAh g ^− 1 ) also exhibited markedly superior electrochemical performance. These findings indicate that NiO coating not only improves the high discharge capacity but also enables cycling stability under high discharge rate conditions, which provided reliable technical support for high-energy-density and high-rate energy storage systems. </p>