Thin Coating of Microporous Organic Network Makes a Big Difference: Sustainability Issue of Ni Electrodes on the PET Textile for Flexible Lithium-Ion Batteries

Poly(ethylene terephthalate) fibers (PET-Fs) were coated with microporous organic networks (MONs) by the Sonogashira coupling of tetra(4-ethynylphenyl)methane with 1,4-diiodobenzene. Ni was deposited on the PET-F@MON via electroless deposition. Interestingly, although Ni on the PET-F showed a sharp decrease in conductivity in repeated bending tests, the PET-F@MON@Ni showed excellent retention of conductivity. We suggest that thin MON layers play roles of an efficient binder for Ni attachment to fibers and a structural buffer for the relaxation of bending strain. The positive effect of MON was supported by scanning electron microscopy studies of the PET-F@Ni or PET-F@MON@Ni retrieved after 2000 bending numbers. Although Ni on the PET-F showed severe detachment after bending tests, PET-F@MON@Ni retained the original morphologies. The pouch cells of lithium-ion batteries fabricated using PET-F@MON@Ni as the current collectors showed excellent performance against bending.