Recycled additive manufacturing feedstocks for fabricating high voltage, low-cost aqueous supercapacitors

The first recycled conductive poly(lactic acid) (PLA) filament derived from post-industrial waste sources for additive manufacturing (AM) is reported herein, presenting a paradigm shift in plastic waste recycling, AM filament production, and AM energy storage architectures. Filaments utilizing a base of recycled PLA, carbon black (CB) as a conductive filler, and polyethylene glycol (PEG) as a plasticizer are used to produce aqueous AM symmetric supercapacitor platforms that can reach capacitance values 75 times higher than commercially available conductive PLA filaments. Furthermore, through the rapid prototyping capabilities of AM and GCode modification, it is seen that changing the electrode architecture from solid to a mesh with additional inter-layer spacing is able to further enhance electrode performance by 3.5 times due to improvements in the surface area, ion accommodating capabilities and faster ion diffusion. The symmetric full cell device is capable of delivering 7.82 mF cm−2, 4.82 µWh cm−2, and 433.32 µW cm−2 of capacitance, energy, and power density, respectively. Moreover, the material cost is £0.15 per electrode. This work represents a new direction for plastic waste recycling, in which low-value recycled base products can be manufactured into high-value end products in their second cycles

Exploring the role of the connection length of screen-printed electrodes towards the hydrogen and oxygen evolution reactions

Zero-emission hydrogen and oxygen production are critical for the UK to reach net-zero greenhouse gasses by 2050. Electrochemical techniques such as water splitting (electrolysis) coupled with renewables energy can provide a unique approach to achieving zero emissions. Many studies exploring electrocatalysts need to “electrically wire” to their material to measure their performance, which usually involves immobilization upon a solid electrode. We demonstrate that significant differences in the calculated onset potential for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can be observed when using screen-printed electrodes (SPEs) of differing connection lengths which are immobilized with a range of electrocatalysts. This can lead to false improvements in the reported performance of different electrocatalysts and poor comparisons between the literature. Through the use of electrochemical impedance spectroscopy, uncompensated ohmic resistance can be overcome providing more accurate Tafel analysis