The integration of LiNi_0.8Co_0.1Mn_0.1O₂ coatings on separators for elevated battery performance

Improving the efficiency and safety of lithium-ion batteries (LIBs) with high-energy cathodes is crucial, yet challenging due to the limitations of commercial separators. Herein, we find that “giving” a portion of the Ni-rich LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) positive electrode to the Al₂O₃-coated polyethylene (PE) (PE/Al₂O₃) separator as an active and thick ceramic coating (> 10 µm) can more efficiently enhance the separator's wettability and thermal stability compared with the inert and thin (< 5 µm, typically 1~2 µm) Al₂O₃ coating. The NCM811 coating on the separator can take part in the electrochemical reaction and contribute capacity without increasing the cell dead weight. The NCM811-coated separator has a low thermal shrinkage of 0.8% at 160 °C and a high lithium-ion transfer number of 0.66. Notably, the NCM811-coated separator enhances electrochemical performance, delivering higher capacities compared to traditional PE and PE/Al₂O₃ separators. Furthermore, it effectively mitigates lithium dendrite formation, thereby bolstering LIB safety. Our findings demonstrate the potential of using active cathode materials as separator coatings to advance LIB technology with high-energy cathodes.