Waterborne spontaneous and robust coating of POSS nanoparticles on hydrophobic surfaces for application as an advanced separator in lithium ion batteries

Abstract

Waterborne spontaneous and robust coating of the catechol-functionalized polyoctahedral silsesquioxane (CA-POSS) is studied on the surface of hydrophobic substrates as a model organic-inorganic hybrid material. The CA-POSS was synthesized at room temperature, which readily produces an instant thin layer coating on the hydrophobic substrates such as mica film and polyethylene (PE) separator. The CA-POSS instantly forms nano-scale level coating with robust adhesion upon contact with the substrate surfaces in a basic aqueous medium at ambient conditions, unlike common coating methods that use prepared POSS particle dispersion. The surface roughness of the CA-POSS coated PE separator (PE-CAP) and mica was observed in AFM analysis. The PE-CAP separator showed highly enhanced hydrophilicity, electrolyte wettability, mechanical strength, and thermal stability. The PE-CAP separator is studied in lithium ion batteries (LIBs) using LiCoO2 cathode and Lithium metal anode has shown the highest specific capacity of ∼171.3 mAh g−1 with capacity retention of ∼99 % after 100 cycles in comparison to pristine PE separator (∼159.4 mAh g−1, 92 %).