Multifunctional hydrogel with rigid–flexible synergy enables high-performance flexible supercapacitors and triboelectric nanogenerators

The integration of high energy density and robust mechanical flexibility in electrode materials remains a fundamental challenge for flexible energy storage devices. While manganese dioxide (MnO₂) offers high theoretical capacitance, its inherent rigidity and poor conductivity severely limit practical applications. Herein, we propose an innovative “rigid-flexible complementary” multi-level design strategy, constructing a multifunctional PVA-SA-PPy@MnO₂-PANI composite hydrogel. This architecture ingeniously integrates hollow-structured PPy@MnO₂ microspheres for enhanced active sites and electrolyte permeability, a dual-conductive-polymer network (PPy and PANI) for efficient electron transport, and a dynamic hydrogen-bonding matrix (PVA and SA) that confers remarkable mechanical strength (megapascal-level), exceptional flexibility, and intrinsic self-healing capability. The resulting hydrogel serves not only as a high-performance electrode for all-gel-state flexible supercapacitors, delivering an outstanding areal energy density of 10.4 mWh/cm 2 and excellent capacitance retention under extreme bending, but also as an effective tribo-positive layer in single-electrode triboelectric nanogenerators (TENGs), enabling stable energy harvesting. This work demonstrates a breakthrough material platform that successfully unifies high energy density, superior mechanical properties, self-healing, and dual energy storage/harvesting functionalities, paving the way for next-generation flexible and wearable electronics.