A pore-controllable polyamine (PAI) layer-coated polyolefin (PE) separator for pouch lithium-ion batteries with enhanced safety

A series of pore-controllable polyamine (PAI) layer-coated polyolefin (PE) separators (PAI-PE-1, PAI-PE-2, and PAI-PE-3) are prepared by using a phase-transfer and gravure-printing method and used to improve the safety of pouch lithium-ion batteries (LIBs) based on a PAI “guest-host transition” and PE “pore on-off” cooperative strategy. And the safety mechanism for the LIBs using PAI-PE-1, PAI-PE-2, and PAI-PE-3 separators with pore sizes of approximately 0.02, 0.17, and 0.85 μm is discussed. In the overcharge, nail, and hot box tests, the LIBs with PAI-PE separators all meet safety requirements, while the LIBs with PE separators exhibit either fire or smoke issues. The LIBs with PAI-PE-1 separators have the lowest temperature of 102 °C and the highest residual voltage of 3.97 V in the nail and hot box tests, respectively, and the LIBs with PAI-PE-3 separators have the lowest temperature of 129 °C in the overcharge test. The mechanism for the enhanced safety of LIBs with PAI-PE separators is ascribed to a PAI “guest-host transition” and PE “pore on-off” cooperative process. These results indicate that this pore-controllable PAI-PE separator has promising prospects in the application of LIBs with enhanced safety requirements.