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.