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Hydrogel Ionic Diodes toward Harvesting Ultralow‐Frequency Mechanical Energy
Author(s) -
Zhang Yong,
Jeong Chang Kyu,
Wang Jianjun,
Chen Xin,
Choi Kyoung Hwan,
Chen LongQing,
Chen Wen,
Zhang Q. M.,
Wang Qing
Publication year - 2021
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202103056
Subject(s) - materials science , ionic bonding , diode , optoelectronics , nanowire , nanotechnology , self healing hydrogels , energy harvesting , electronics , ion , energy (signal processing) , electrical engineering , chemistry , statistics , mathematics , organic chemistry , polymer chemistry , engineering
Energy harvesting from human motion is regarded as a promising protocol for powering portable electronics, biomedical devices, and smart objects of the Internet of things. However, state‐of‐the‐art mechanical‐energy‐harvesting devices generally operate at frequencies ( > 10 Hz) well beyond human activity frequencies. Here, a hydrogel ionic diode formed by the layered structures of anionic and cationic ionomers in hydrogels is presented. As confirmed by finite element analysis, the underlying mechanism of the hydrogel ionic diode involves the formation of the depletion region by mobile cations and anions and the subsequent increase of the built‐in potential across the depletion region in response to mechanical pressure. Owing to the enhanced ionic rectification ratio by the embedded carbon nanotube and silver nanowire electrodes, the hydrogel ionic diode exhibits a power density of ≈ 5 mW cm −2 and a charge density of ≈ 4 mC cm −2 at 0.01 Hz, outperforming the current energy‐harvesting devices by several orders of magnitude. The applications of the self‐powered hydrogel ionic diode to tactile sensing, pressure imaging, and touchpads are demonstrated, with sensing limitation is as low as 0.01 kPa. This work is expected to open up new opportunities for ionic‐current‐based ionotronics in electronics and energy devices.