Phase transition driven tough hydrogel ionic thermoelectric cell with giant thermopower
Xiaofang Shi, Yingjie Li, Nan Shi, Chengyu Ji, Lei Hou, Yingkun Shi, Jie Xu, Yarong Lan, Qingcong Wei, Guanglei Ma, Peiyi Wu, Zhiguo Hu
Abstract
The application of quasi-solid ionic thermoelectric (i-TE) cells holds great potential for powering ubiquitous wearable electronics without the need for cables or batteries. However, their practical application is restricted by low thermopower. Herein, a temperature-responsive supramolecular hydrogel, P(N-acryloylsemicarbazide-co-acrylic acid) (PNA), has been developed as a i-TE cell that integrates good mechanical and electrochemical properties. The volume phase transition (VPT) of PNA i-TE cell can generate a substantial ion entropy difference, thereby enhancing both the redox reaction efficiency and ionic thermodiffusion rate. A single PNA i-TE cell can generate a thermopower of 2.04 volts with a temperature difference of 50 K. The Seebeck coefficient (Se), specific output power density ( $${P}_{\max }/{(\Delta T)}^{2}$$ ) and figure of merit (ZT) of PNA i-TE cell can reach up to 40.9 mV K−1, 35.2 mW m−2 K−2 and 1.33 respectively. This ionic hydrogel is promising for the design of high performance polymer based i-TE cells in an environmentally friendly and cost-effective manner. Quasi-solid ionic thermoelectric cells are promising for wearable electronics, though it is challenging to fabricate devices due to low thermopower. Here the authors report a supramolecular hydrogel to enhance the thermopower for wearable electronics.