3D-printed conductive hydrogels for flexible electrochemical energy storage: mechanisms, fabrication, and applications

Conductive hydrogels have emerged as crucial components for sophisticated flexible energy storage devices, such as batteries and supercapacitors, because of their customizable microstructures, mechanical versatility, and integrated electronic/ionic conductivity. Conventional fabrication methods face persistent challenges in balancing electrical performance with mechanical durability and constructing complex three-dimensional (3D) geometries. Three-dimensional-Printed addresses these limitations by enabling precise spatial control over material deposition and structural design. This review comprehensively analyses three critical aspects of 3D-printed conductive hydrogels: (1) Fundamental conduction mechanisms in electronic, ionic, and composite hydrogels, focusing on material optimization through nanoscale dispersion control and dynamic network design; (2) Advanced manufacturing methods including photopolymerization and direct ink writing, analyzing critical parameters including rheological behavior, printing resolution, and structural-functional synergy; (3) Groundbreaking applications in flexible energy storage, particularly supercapacitors with geometrically enhanced electrodes and batteries featuring self-healing zinc anodes. Persistent challenges in material compatibility, scalability trade-offs between resolution and speed, and interfacial stability are critically assessed. Future research directions focus on multifunctional ink development, multiscale structural engineering, and reliability optimization to enable customized, commercially viable flexible energy storage technologies.