Fabricating ion-conducting channel in SU-8 matrix for high-performance patternable polymer electrolytes

Advances in electrochemical energy storage technologies drive the need for battery safety performance and miniaturization, which calls for the easily processable polymer electrolytes suitable for on-chip microbattery technology. However, the low ionic conductivity of polymer electrolytes and poor-patternable capabilities hinder their application in microdevices. Herein, we modified SU-8, as the matrix material, by poly(ethylene oxide) (PEO) with lithium salts to obtain a patternable lithium-ion polymer electrolyte. Due to the highly amorphous state and more Li-ion transport pathways through blending effect and the increase in number of epoxides, the ionic conductivity of achieved sample is increased by an order of magnitude to 2.9 × 10⁻⁴ S·cm⁻¹ in comparison with the SU-8 sample at 50 °C. The modified SU-8 exhibits good thermal stability (> 150 °C), mechanical properties (elastic modulus of 1.52 GPa), as well as an electrochemical window of 4.3 V. Half-cell and microdevice were fabricated and tested to verify the possibility of the micro-sized on-chip battery. All of these results demonstrate a promising strategy for the integration of on-chip batteries with microelectronics.