Robust Conductive Adhesives: A Strategy Using Metal-Doped Poly(ionic liquid)s

Balancing conductivity, adhesion, and environmental stability remains a central challenge for next-generation conductive adhesives. Here, we report a facile metal-doping strategy for poly(ionic liquid) (PIL) adhesives, embedding Li+, Na+, or Ag+ salts within an ionic-liquid–polymer network to simultaneously reinforce interfacial binding and optimize ion transport. Systematic synthesis, multiscale characterization, and molecular dynamics simulations reveal that metal coordination sites concentrate at the polymer–substrate interface, yielding record adhesion strength up to 9.15 MPa on stainless steel for PIL-[Ag]. Electrochemical impedance spectroscopy shows that Li+-doped PIL exhibits an ultralow charge-transfer resistance of 0.24 MΩ, 3 orders of magnitude lower than that of conventional PILs. These adhesives also offer tunable electromechanical properties, ∼88% optical transparency, and reliable low-temperature performance (−50 °C), making them ideal for flexible electronics, wearable sensors, and smart interface applications.