News Source: Advanced Research Institute of Multidisciplinary Science

Editor: News Agency of BIT

Translator: Long Xiaofei, News Agency of BIT

Huang Houbing, a distinguished researcher at the Advanced Research Institute of Multidisciplinary Science / School of Materials Science and Engineering has recently made outstanding achievements in the design of microstructures of ferroelectric materials by phase-field simulation. In cooperation with Qian Xiaoshi’s team from Shanghai Jiao Tong University, Huang published the research results entitled “High-entropy polymer produces a giant electrocaloric effect at low fields” in Nature as the corresponding author. By ingeniously designing the molecular defect-modified structure of relaxed ferroelectric materials, a polarized high-entropy polymer has been produced, which has significantly improved the giant electrocaloric (EC) effects under low electric fields and for the first time increased the life of the cooling cycle to over 1 million times. This is also the fourth full-length journal paper co-published by Huang Houbing’s research group following Science, 366, 475-479 (2019), Science, 374, 100-104 (2021) and Science, 371, 1050-1056 (2021).

The electrocaloric cooling effect is a unique physical phenomenon, which uses the reversible electric phase transition of the dielectric to form a thermodynamic cycle and transports heat against the temperature gradient. Based on solid-state cooling, electrocaloric cooling refrigeration technology has the characteristics of zero greenhouse effect potential, easy miniaturization/lightweight, high energy efficiency, etc. It is one of the important disruptive forward-looking technologies to achieve the “double carbon” goal. However, the current optimal refrigeration dielectric still requires a very high external electric field to produce an industrially usable cooling effect, and the high electric field can easily cause material aging and breakdown during the actual working process of the prototype. Therefore, how to increase the electricity-induced entropy change in the low electric field has become a critical research direction in the field.

Different from the current research paradigm that enhances the polarization strength of composite materials to improve the electric card effect, this paper takes the opposite approach and adopts the design of high-entropy polymers to improve the entropy change (increase the zero-field entropy). Driven by the same applied electric field (50 MVm-1), this polarized high-entropy material exhibits an electricity-induced entropy change nearly 4 times that of the state-of-the-art cooling polymer.

The advantage of the phase-field simulation method is to reveal the multi-physics coupling mechanism, which constructs a phase-field model of the ferroelectric multi-field coupling mechanism and reveals the physical mechanism of the complex interaction of polarization-response-heat multi-field coupling in ferric materials. The phase-field simulation revealed that the high-entropy polymer simultaneously increases the crystallinity of the system and reduces the grain size, so the number of polarized units in the material increases greatly; the coupling relationship between the domain structures is reduced, and the system has higher degrees of freedom and polarization entropy.

Figure 1. Huang Houbing’s research group, focusing on the micro-domain structure of ferroelectric materials to determine the ferroelectric properties, utilized phase-field simulation to reveal the microcosmic mechanism of ferroelectric domain flip and phase change.

In this study, Associate Professor Qian Xiaoshi of SJTU is the first author and corresponding author of the paper, Professor Hong Liang, Professor Huang Xingyi and Distinguished Researcher Huang Houbing of BIT are the co-corresponding authors, and postdoctoral researcher, Shi Xiaoming, from Advanced Research Institute of Multidisciplinary Science, BIT, is the collaborator.

Paper link: https://www.nature.com/articles/s41586-021-04189-5

Attached is the introduction of Distinguished Researcher Huang Houbing:

Huang Houbing, Distinguished Researcher, PhD supervisor from the Advanced Research Institute of Multidisciplinary Science, BIT, mainly engaged in the microcosmic structural evolution of phase-field simulation materials, has published more than 110 SCI papers in journals including Nature, Science, Adv. Mater., Adv. Func. Mater., Acta Mater., Sci. Bull and delivered invited reports on international conferences many times. The source code of the model developed by him has been integrated into the commercial software μ-Pro. He has successively presided over five projects including the General and Youth Program of the Natural Science Foundation of China, the sub-tasks of the key R&D plan of the Ministry of Science and Technology, and the "Youth Support Project" in Beijing. He also serves as the executive director of the board of directors for the “Phase Field and Integrated Computational Materials Engineering Conference”, a member of the Youth Work Committee of the China Silicate Society, the director of the Beijing Silicate Society, and a youth editor of Adv. Mater. Dev. etc.