Photolithographically Patterning of Iongel Electrolytes for On-Chip Electrochemical Devices with High Areal Number Density

On-chip electrochemical devices hold great promise for functional diversification through monolithic integration with semiconductor integrated circuits (ICs). However, their practical implementation is hindered by conventional liquid electrolytes, which are incompatible with standard IC fabrication processes. Although recently developed semi-liquid gel electrolytes enable on-chip deposition, their poor wafer-scale depositability and patternability severely restrict device miniaturization and high-density integration. Herein, we propose a photolithographic patterning method for ionic liquid gel (iongel) electrolytes to achieve high ionic conductivity and scaling capability simultaneously. A complete wafer-level iongel thin-film deposition and dry-etching fabrication workflow is developed. Leveraging the patterned iongel electrolyte, the fabricated on-chip electrochemical micro supercapacitors achieve record-high areal device density of 400 cells/cm² and areal voltage density of 800 V/cm², while retaining a stable areal capacitance density over 1.2 mF/cm² and satisfactory operational reliability.