Additive manufacturing of polyaniline electrodes

Since the pioneering work of MacDiarmid and co-workers1, polyaniline (PANI) has been a promising material for numerous applications. PANI possess various desirable properties, such as tuneable conductivity, pseudocapacitance or biocompatibility. Combining these with the structural complexity and the design flexibility of additive manufacturing (AM) opens up new fields of applications, from energy storage to conductive implants. However, the AM of PANI is limited by its non-thermoformable character and poor processability2 and still remains in its early stages.

Recently developed AM techniques using thermal doping of PANI3 open up new possibilities for the use of PANI in AM. In this work, a novel process based on the thermal doping of PANI with dodecyl benzene sulfonic acid (DBSA) is used for the printing of electrodes for energy applications. For this, a fused filament deposition printer (Prusa i3 MK3S+) was modified with a custom made syringe extrusion system in order to print a viscous paste. PANI was synthesised using chemical oxidation and ultrasound at low temperatures, de-doped and mixed with DBSA to create a printable paste. Thermal pre-treatment of the paste and the use of the printer hot-bed enable solidification and thus printing of three dimensional conductive structures. The printing process was characterised and optimised in regards to pre-treatment time and temperature, hot bed temperature as well as nozzle distance from the hot bed. A fully 3D printed capacitor with PANI-DBSA electrodes and a solid electrolyte gel was fabricated and characterised in order to showcase the potential of this technique for electrochemical applications.

1 A. G. MacDiarmid, Angew. Chem. Int. Ed. 40 (2001) 2581-2590

2 F. Kazemi et al., Mater Today Chem. 16 (2020) 100249

3 F. Holness and A. D. Price, Smart Mater. Struct. 1 (2018) 015006