Ethyl cyanoacrylate reinforced polyvinylidene fluoride separators for robust lithium ion batteries

Ideal separators of Li-ion batteries should possess key characteristics simultaneously, including high mechanical strength, high thermal stability and high electrolyte wettability. Herein a composite separator is proposed to realize these properties by directly incorporating ethyl cyanoacrylate (ECA) into a polyvinylidene fluoride (PVDF) polymer matrix. With significantly enhanced mechanical strength resulting from abundant hydrogen bonds in ECA and van der Waals forces between ECA and PVDF, the ECA-PVDF separator possesses high thermal tolerance and superior capability for electrolyte uptake. The half cell with a LiFePO4 cathode and ECA-PVDF composite separator delivers a high discharge capacity of 154.1 mA h g-1 with 98.4% capacity retention after 100 cycles at 1C (1C = 0.22 mA cm-2), which is attributed to the inherent structure of ECA that exhibits strong interaction with ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC).