The performance and cycle life of Lithium-ion batteries (LIBs) are significantly influenced by the separator, a critical component. Traditional polyolefin separators can no longer meet the growing demand for energy storage. Coating conventional polyolefin separators with electrochemically inert ceramic materials can enhance stability but often increases weight and reduces battery capacity. This study introduces a novel separator coated with copper oxide (CuO), developed through a simple and efficient method. The CuO coating polypropylene (CuO@PP) separator demonstrates superior thermal resistance, enhanced electrolyte absorption, and increased porosity compared to conventional polypropylene (PP) separators. Additionally, the active participation of the CuO coating in electrochemical reactions during the charge-discharge process increases battery capacity. Results indicate that the CuO@PP separator provides an additional capacity of approximately 10 mAh g−1. The battery using the CuO@PP separator exhibited exceptional electrochemical properties in contrast to the traditional PP separator, with a first discharge capacity of 129.8 mAh g−1 at 10 C and a capacity retention rate of 92.4 % over 400 cycles at 10 C. Thus, enhancing the reliability and performance of LIBs by modifying the PP separator with a CuO coating presents a promising approach, offering novel perspectives for designing and manufacturing advanced battery separators.