Integration of Polypyrrole Electrode into Piezoelectric PVDF Energy Harvester with Improved Adhesion and Over-Oxidation Resistance.

Kyungha Baik,Chung Hee Park,Sohyun Park,Changsang Yun

doi:10.3390/polym11061071

Abstract

Smart textiles for wearable devices require flexibility and a lightweight, so in this study, a soft polypyrrole (PPy) electrode system was integrated into a piezoelectric polyvinylidenefluoride (PVDF) energy harvester. The PVDF energy harvester integrated with a PPy electrode had the piezoelectric output voltage of 4.24–4.56 V, while the PVDF energy harvester with an additional aluminum-foil electrode exhibited 2.57 V. Alkaline treatment and chemical vapor deposition with n-dodecyltrimethoxysilane (DTMS) were employed to improve the adhesion between the PVDF and PPy and the resistance to over-oxidation in aqueous solutions. The PVDF film modified by an alkaline treatment could have the improved adhesion via the introduction of polar functional groups to its surface, which was confirmed by the ultrasonication. The surface hydrophobicity of the PPy electrode was enhanced by the DTMS coating, resulting in the improvement of the resistance to over-oxidation with a water contact angle of 111°. Even with the hydrophobic coating, the electrodes remained electroconductive and continued to transfer an electric charge, maintaining the piezoelectricity of the PVDF film. The developed electrode-integrated energy harvester is expected to be applied to smart textiles because it offers the advantages of efficient piezoelectric generation, flexibility, and durability.

Highlights

Many wearable devices have been made more wearable by incorporating them into garments or accessories, such as watches or bracelets [1,2,3,4,5]
PPy electrodes were combined with PVDF films for use in a flexible and practical
PPy electrodes were combined with PVDF films for use in a flexible and practical piezoelectric energy harvester

Summary

Introduction

Many wearable devices have been made more wearable by incorporating them into garments or accessories, such as watches or bracelets [1,2,3,4,5]. Stretchable, flexible, and lightweight electrical materials and elements are quite valuable for the fabrication of these devices. Piezoelectric materials become polarized when they undergo strain due to stress, which enables them to convert mechanical energy into electrical energy [12,13] Repetitive human motions, such as walking or bending at the knees or elbows, can induce energy transformation when applied to piezoelectric energy harvesters [14]. Since they are incorporated into clothing, piezoelectric energy harvesters for wearable devices should be flexible, lightweight, stretchable, biocompatible, and durable

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