Assessing the Performance of Biopolymers as Substrates for Flexible Printed Supercapacitors Containing Liquid Electrolytes

The environmental benefits of using supercapacitors to power the Internet of Things can be improved by replacing the fossil‐based substrate materials that they are traditionally manufactured from with sustainable biobased options. However, biobased materials tend to have poor barrier properties, which is an issue for supercapacitors that contain a liquid electrolyte. The aim of this study is to assess how well some common biobased polymers, such as polylactic acid (PLA), poly(3‐hydroxybutyrate) (PHB), or poly(3‐hydroxybutyrate ‐co ‐3‐hydroxyvalerate) (PHBV) would perform as substrates in printed supercapacitors, especially when it comes to their barrier properties. It is found that none of the unmodified biopolymers fulfill the requirements for the supercapacitors very well. The processability of the materials is good and the printability of the biopolymers is even better than the printability of the polyethylene terephthalate laminated with aluminum (PET+Al) used as a reference material. However, the barrier properties of the biopolymers do not reach the properties required of a supercapacitor operating in a vehicle. For this reason, it is clear that in order to manufacture a sustainable substrate suitable for a supercapacitor, the biobased polymers must be first modified in order to improve their barrier properties.