Effect of Current Collector and Pyrolysis Temperature on the Electrochemical Performance of Photoresist Derived Carbon Films

SU-8, an epoxy based negative photoresist has been demonstrated as a potential precursor to fabricate thin films and three-dimensional micropatterned arrays in glassy carbon. However, the use of silicon wafer as a substrate cum collector limits their use in real battery devices. In accordance with the commercial lithium ion battery architecture and also owing to enhanced conductivity, we have successfully demonstrated the use of stainless steel (SS) wafer as a current collector to prepare binder free SU-8 derived carbon thin films. Standard carbon microelectromechanical systems (C-MEMS) process parameters were tuned to obtain a uniform, crack-free carbon thin film on SS wafer upon pyrolysis. Further, we varied the final pyrolysis temperature to examine its effect on the microstructure and composition as characterized with X-ray diffraction, Small angle X-ray scattering, Raman spectroscopy and CHNS-O elemental analyzer respectively. The microstructural changes in the carbon films at different pyrolysis temperature were then correlated with their electrochemical performance as investigated using galvanostat charge/discharge experiments, impedance spectroscopy and cyclic voltammetry. Selection of an appropriate current collector and optimizing the pyrolysis temperature yielded excellent cyclic stability and coulombic efficiency with 400 mAh g−1 reversible capacity after 100 cycles, nearly double to as reported in the literature