Issue 42, 2021

Large polarization and record-high performance of energy storage induced by a phase change in organic molecular crystals

Abstract

Dielectrics that undergo electric-field-induced phase changes are promising for use as high-power electrical energy storage materials and transducers. We demonstrate the stepwise on/off switching of large polarization in a series of dielectrics by flipping their antipolar or canted electric dipoles via proton transfer and inducing simultaneous geometric changes in their π-conjugation system. Among antiferroelectric organic molecular crystals, the largest-magnitude polarization jump was obtained as 18 μC cm−2 through revisited measurements of squaric acid (SQA) crystals with improved dielectric strength. The second-best polarization jump of 15.1 μC cm−2 was achieved with a newly discovered antiferroelectric, furan-3,4-dicarboxylic acid. The field-induced dielectric phase changes show rich variations in their mechanisms. The quadruple polarization hysteresis loop observed for a 3-(4-chlorophenyl)propiolic acid crystal was caused by a two-step phase transition with moderate polarization jumps. The ferroelectric 2-phenylmalondialdehyde single crystal having canted dipoles behaved as an amphoteric dielectric, exhibiting a single or double polarization hysteresis loop depending on the direction of the external field. The magnitude of a series of observed polarizations was consistently reproduced within the simplest sublattice model by the density functional theory calculations of dipole moments flipping over a hydrogen-bonded chain or sheet (sublattice) irrespective of compounds. This finding guarantees a tool that will deepen our understanding of the microscopic phase-change mechanisms and accelerate the materials design and exploration for improving energy-storage performance. The excellent energy-storage performance of SQA was demonstrated by both a high recoverable energy-storage density Wr of 3.3 J cm−3 and a nearly ideal efficiency (90%). Because of the low crystal density, the corresponding energy density per mass Image ID:d1sc02729h-t1.gif (1.75 J g−1) exceeded those derived from the highest Wr values (∼8–11 J cm−3) reported for several bulk antiferroelectric ceramics Image ID:d1sc02729h-t2.gif, without modification to relaxor forms.

Graphical abstract: Large polarization and record-high performance of energy storage induced by a phase change in organic molecular crystals

Supplementary files

Article information

Article type
Edge Article
Submitted
19 May 2021
Accepted
05 Oct 2021
First published
06 Oct 2021
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2021,12, 14198-14206

Large polarization and record-high performance of energy storage induced by a phase change in organic molecular crystals

S. Horiuchi and S. Ishibashi, Chem. Sci., 2021, 12, 14198 DOI: 10.1039/D1SC02729H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements