Ambiently and Mechanically Stable Ionogels for Soft Ionotronics

Stretchable ionic conductors such as hydrogels and ionic-liquid-based gels (aka ionogels) have garnered great attention as they enable the development of soft ionotronics. Notably, soft ionotronic devices inevitably operate in humid environments or under mechanical loads. However, many previously reported hydrogels and ionogels, however, are unstable in environments with varying humidity levels owing to hydrophilicity, and their liquid components (i.e., ionic liquid, water) may leak easily from polymer matrices under mechanical loads, causing deterioration of device performance. This work presents novel hydrophobic ionogels with strong ionic liquid retention capability. The ionogels are ambiently and mechanically stable, capable of not absorbing moisture in environments with high relative humidity and almost not losing liquid components during long periods of mechanical loading. Moreover, the ionogels exhibit desirable conductivity (10⁻⁴–10⁻⁵ S cm⁻¹), large rupturing strain (>2000%), moderate fractocohesive length (0.51–1.03 mm), and wide working temperature range (−60 to 200 °C). An ionic skin is further designed by integrating the concept of sensory artificial skins and triboelectric nanogenerators, which can convert multiple stimuli into various types of signals, including resistance, capacitance, short-circuit current, and open-circuit voltage. This work may open new avenues for the development of soft ionotronics with stable performance.