With the rapid growth of the Internet of Things, the key trends in microelectronics are clear - miniaturization, flexibility, and integration are leading the way. Various microelectronic devices, including wearables, implants, micro-robots, and micro-sensors, have made significant advances and are set to become essential parts of our everyday lives. These tiny devices excel in complex tasks such as data processing and wireless signal transmission, paving the way for major innovations in areas like health monitoring, medical diagnosis, and disease treatment. However, powering these devices seamlessly requires an efficient energy supply unit. Our research is dedicated to developing microscale batteries, known as micro-batteries, with a special focus on 3D electrode designs to boost energy storage performance within the limited space of microscale devices. We particularly emphasize planar device configurations, which organize electrodes in an interdigitated electrode (IDE) pattern on the same substrate, resulting in a flat, efficient structure. This design offers significant benefits, such as improved control over critical battery properties like internal resistance and ionic diffusion distance, all without needing a separator. Most importantly, it provides a practical solution for reducing battery size and integrating them seamlessly with on-chip microelectronic devices. The processing and precise loading of energy materials onto microelectrodes are critical to optimizing charge storage performance. Our research centers on designing advanced 3D current collectors and utilizing electrodeposition and Microplotter techniques to specifically and selectively manipulate energy materials on these collectors.
Advanced 3D current collectors
Given the critical constraint of limited areal footprint in on-chip energy storage, a major challenge lies in enhancing energy performance without increasing device size. Equally important are improving ion transport, ensuring high electrical conductivity, and maintaining structural integrity for long-term operation. One promising strategy is the use of porous, periodic IDEs as current collectors, which support efficient active material loading - particularly beneficial for charge storage materials with inherently low conductivity. Electrodeposition from aqueous solutions is well-suited for fabricating such structures, leveraging the aqueous electrolyte’s wide solvent window to reduce metal ions without solvent degradation. However, at high cathodic overpotentials, H⁺ ions are also reduced to H₂ gas, forming bubbles that interfere with uniform metal deposition. Interestingly, these hydrogen bubbles can serve as dynamic templates during deposition - a process known as Dynamic Hydrogen Bubble Templating (DHBT). DHBT offers several advantages: it removes the need for additional templating agents or processing steps, generates pores in situ during deposition, and enhances efficiency while lowering material and operational costs. The method is versatile, scalable, and environmentally friendly, as it reuses hydrogen gas as a transient template. We apply DHBT to engineer porous IDEs for high-performance microscale energy storage systems.
All printed Micro-scale Energy Storage Systems
A key factor in advancing on-chip energy storage lies in the architecture of current collectors and the integration of high-performance electrode materials. While hybrid materials offer significant promise due to their synergistic charge storage capabilities, incorporating them into microscale electrodes - especially those with complex geometries - remains a major challenge. Traditional fabrication methods, such as electrodeposition, are often incompatible with these materials and unsuitable for flexible or irregular microelectrode designs. To overcome these limitations, we are leveraging the micro-plotter technique, an innovative direct-write approach that enables precise deposition of a wide range of hybrid materials onto microelectrodes, regardless of their pattern, shape, or substrate. This method offers several key advantages: Material Versatility, Design Flexibility, Scalability and Compatibility. Through the micro-plotter technique, we open new pathways for the fabrication of next-generation on-chip microscale energy storage devices, combining compactness, flexibility, and high performance in a fully printed, customizable format..
For Details:
Jingli Luo et al. Advanced Functional Materials DOI:10.1002/adfm.202417607 (2024)
Yijia Zhu et al., Small DOI: 10.1002/smll.202405733 (2024)
Nibagani Naresh et al. Advanced Functional Materials DOI:10.1002/adfm.202413777 (2024)
Nibagani Naresh et al. Nano Letters DOI:10.1021/acs.nanolett.4c03194 (2024)
Yujia Fan et al. Nano Letters DOI:10.1021/acs.nanolett.4c02539 (2024)
Yujia Fan et al., Chemical Engineering Journal 488, 150672 (2024)
Yijia Zhu et al., Chemical Engineering Journal 487, 150384 (2024)
Yijia Fan et al. Journal of Materials Chemistry A 12, 11710-11718 (2024)