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 LiNi0.8Co0.1Mn0.1O2 (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.