Controlling the water absorption and improving the high C-rate stability: a coated Li-ion battery separator using β-cyclodextrin as binder

The water absorption property of the coated separator directly affects the electrochemical performance of a Lithium-ion battery. For the water-based coated separator, the water absorption is directly dependent on the binder and ceramic components. In this work, β-cyclodextrin is chosen as the binder, and its hydrophilicity is regulated by chemical oxidation, while titanium dioxide (TiO 2 ) is used as the ceramic component. It is found that the water absorption of the coated separator using modified β-cyclodextrin is lower than that of commercial aqueous binders such as PVA. In addition, the Li-ion battery assembled with the coated separator shows better discharge capacity retention. At 8 C rate discharge, the discharge capacity of the battery using coated separator is measured at 123 mAhg − 1 , and the capacity retention is up to 88%. This work provides a new idea to modify the water-based coated separator with reduced water absorption in the storage stage.