A γ‐Boehmite Nanowhiskers ‐ Polyethylene Glycol 10000/Polyethylene Separator for Lithium‐Ion Batteries

Abstract In this study, a γ‐boehmite (γ‐AlOOH) – PEG/polyethylene (PE) lithium‐ion battery separator was fabricated using a dip‐coating method, with γ‐AlOOH nanowhiskers being synthesized directly through a hydrothermal process,and polyethylene glycol 10000 (PEG‐10000) was chosen for the first time as a dispersant for the γ‐AlOOH nanowhiskers in the PE coating slurry{Lee, 2014 #7}. Simultaneously, the membrane's performance was characterized, confirming the significant dispersion effect of PEG‐10000, resulting in a porosity as high as 64 % in the AlOOH‐PEG/PE, a substantial increase compared to the PE separator (40 %). The AlOOH‐PEG/PE separator maintains its structural integrity even after a 0.5 h test at 200 °C, showcasing outstanding stability and significantly improved safety. Besides, the LIB half cells assembled with the PE/AlOOH‐PEG separator exhibited remarkable performance, with a capacity of 73.9 % in power capability (at 5 C rate) and a 97.1 % discharge capacity retention rates in cycle performance (after 400 cycles, at 2 C rate). Furthermore, lithium iron phosphate (LiFePO 4 ) batteries utilizing the AlOOH‐PEG/PE separator demonstrated significantly enhanced cycling stability and rate capacity.