High-performance, safe, and stable micro energy storage devices (MESDs) are essential for the continued development of technologies ranging from micro-electro-mechanical systems (MEMS) to the Internet of Things (IoT). Among the critical components of MESDs, solid-state ionogel electrolytes (IEs)—a newly emerging class of ionic conductors—offer not only high spatial patterning resolution and excellent electrochemical performance, but also outstanding thermal and chemical stability. These features make IEs highly promising candidates for future applications in highly customised MESDs and their associated miniaturised systems. This work presents a comprehensive review of the fundamental principles, recent research advances, and practical applications of ionogel electrolytes in the field of MESDs.

In this study, ultrathin (~10 μm), photopatternable ionogel electrolytes featuring uniformly distributed nanoporous structures were successfully fabricated via ultraviolet (UV) photolithographic techniques and applied in both zinc-ion hybrid capacitors (ZHCs) and micro-supercapacitors (MSCs). The fabricated hybrid capacitor, based on a Zn/IE/activated carbon sandwich configuration, delivered an impressive specific capacity of 188 mAh g^-1 at a current density of 0.2 A g^-1. When integrated into planar micro-supercapacitor devices, the ionogel electrolyte-based system enabled a high operating voltage of 10 V within a compact area of 5 mm², achieving an energy density of 73.48 µWh cm^-2 and a power density of 35.2 mW cm^-2, demonstrating superior performance compared to MESDs below 10 μm. The superior performance is attributed to its tunable nanoporous architecture and the incorporation of ionic liquids, which together facilitate a high ionic conductivity of 3.36 × 10^-3 S cm^-1 while preserving spatial resolution at sub-10 μm dimensions. These findings clearly demonstrate the strong potential of ionogel electrolytes for next-generation miniaturised energy storage technologies, with further promise in the future advanced miniaturised devices.