Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150915

150915 - Controlling Porosity of Electrosprayed Polyimide Films Through Co-Solvent Blending 

Polyimide (PI) has been identified as a potential material for lithium-ion battery (LIB) separators due to its hydrophilic behavior, thermal stability, and mechanical strength. These properties make PI an attractive option for improving the performance and safety of LIBs. PI is effectively applied through an advanced additive manufacturing technique known as electrospray deposition (ESD). ESD is a technique that uses a high-voltage electric field to atomize charged droplets from a liquid solution onto a substrate, forming a uniform thin film or coating as the solvent evaporates. This method allows for precise control over the thickness and uniformity of the deposited film. However, despite these advantages, the lack of finer control over pore size, porosity, and morphology of PI-coated separators has been a significant limitation. These factors are critical because they directly impact the charge/discharge capacity and cycle life performance of LIBs, which are key metrics for evaluating battery efficiency and longevity. This study aims to address these limitations by investigating the characteristics of 1% PI blended with 1,2-dichloroethane (DCE) and chloroform in a 2:1 ratio. The blend is sprayed at four different flow rates (0.3, 0.5, 0.75, and 1 mL/hour) to determine how flow rate affects porosity. The PI coatings are deposited onto silicon wafers via self-limiting electrospray deposition (SLED), a variation of ESD that provides enhanced control over the deposition process. To evaluate the porosity, thickness, and morphology of the co-solvent blended sprayed PI films, we utilized a combination of scanning electron microscopy (SEM), optical microscopy, and spectroscopic microreflectometry. Porosity measurements for samples sprayed between 0.3 to 1 mL/hour are evaluated and a nearly 30% decrease in porosity is observed between the lowest and highest flow rate. In addition, for the lowest flow rate, which is expected to have the smallest features, we explored decreasing the porosity from the observed 80% toward the ideal 50% through blending in high boiling point solvents. A qualitative assessment of the resulting film morphologies are also captured using SEM. If finer control of porosity is achieved, it can allow for more efficient ion transport between the anode and cathode, thereby effectively enhancing the battery’s charge and discharge rates. Further research can also explore different co-solvent blends that can be sprayed at even lower flow rates to explore patterns in porosity. By optimizing these parameters, it may be possible to develop PI-based separators that offer superior performance and greatly improved reliability for next-generation LIBs.

Presenting Author: Emily Li Rutgers University - New Brunswick

Presenting Author Biography: My name is Emily A. Li and I am a rising sophomore at Rutgers University - New Brunswick majoring in Electrical Engineering. I currently work as an undergraduate research assistant at the Hybrid Micro/Nanomanufacturing Laboratory led by Professor Jonathan P. Singer.

Authors:

Emily Li Rutgers University - New Brunswick
Robert Green-Warren Rutgers University - New Brunswick
Isha Shah Rutgers University - New Brunswick
Jonathan Singer Rutgers University - New Brunswick