Development of a processing route for the fabrication of thin hierarchically porous copper self-standing structure using direct ink writing and sintering for electrochemical energy storage application

The present study aims to develop a systematic processing route using direct ink writing (DIW) and pressureless sintering for fabricating hierarchically porous \(\text{ Cu }\) (HP-\(\text{ Cu }\)) electrodes. A 3D printable high particle loading \(\text{ Cu }\) ink \(> 95 {\text{wt}}\%\) with polylactic acid as a binder was prepared. Green \({\text{Cu}}\) samples using optimum value of \(\text{ Cu }\) loading, nozzle diameter, layer height, and printing speed as 97 \({\text{wt}}\%\), 0.2 \(\text{mm}\), 70% and 10 \(\text{mm}/\text{s}\) respectively were fabricated and subsequently sintered. A proper inter-particle bonding with 91% relative density and 215 \(\text{Mpa}\) ultimate compressive strength was achieved. Finally, a proof-of-concept study targeting the fabrication of thin HP-\(\text{ Cu }\) current collector was performed and the pore size of 154 ± 10 µm with a thickness of 200 µm was achieved successfully. Moreover, the prepared sample exhibited the highest coulombic efficiency of 95.86% for more than 400 h at 1 \({\text{mAcm}}^{-2}\) making it a potential candidate for energy storage applications.

Graphical abstract