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Advanced Functional Materials for Energy Harvesting and Storage Devices, Volume II

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A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D：Materials and Processing".

Deadline for manuscript submissions: closed (29 February 2024) | Viewed by 3610

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Special Issue Editors

Dr. Yongteng Qian

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Department of Physics and Interdisciplinary Course of Physics and Chemistry, Sungkyunkwan University, Suwon-si 16419, Republic of Korea
Interests: functional nanomaterials; flexible energy storage and conversion devices; supercapacitors; photocatalysis; electrocatalysis; nanogenerators
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Dae Joon Kang

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Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
Interests: synthesis of 2D atomic crystals and their device applications; synthesis of metal oxides and their device physics; electrohydrodynamic lithography; atomic layer deposition
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Very recently, the fabrication of energy-harvesting, storage, and conversion systems, including nanogenerators, supercapacitors, lithium-ion batteries, solar cells, photo/electro-catalysts, etc., has received remarkable attention and, in recent years, become a hot research topic. Up to now, numerous researchers have utilized different functional materials, including two-dimensional (2D) materials, MXenes, metal oxides, metal phosphides, metal sulfides, metal–organic frameworks, etc., as the active materials for energy-harvesting, storage, and conversion systems. However, there are still many challenges to overcome, such as the low output voltage of piezoelectric nanogenerators, the poor output current density of triboelectric nanogenerators, the poor power density of supercapacitors, the poor cyclic stability of lithium-ion batteries, the low conversion efficiency of solar cells, etc. Accordingly, this Special Issue seeks to showcase research papers and review articles that focus on novel developments in energy-harvesting, storage, and conversion systems.

Topics of interest include, but are not limited to:

Triboelectric nanogenerators;
Pyroelectric nanogenerators;
Piezoelectric nanogenerators;
Supercapacitors;
Lithium-ion batteries;
Solar cells.

We look forward to receiving your submissions!

Dr. Yongteng Qian
Prof. Dr. Dae Joon Kang
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Micromachines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

functional materials
energy-harvesting devices
energy storage and conversion devices
flexible devices

Related Special Issue

Advanced Functional Materials for Energy Harvesting and Storage Devices in Micromachines (9 articles)

Published Papers (3 papers)

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Research

15 pages, 1112 KiB

Open AccessArticle

Limit Efficiency of a Silicon Betavoltaic Battery with Tritium Source

by Mykhaylo Evstigneev, Mohammad Afkani and Igor Sokolovskyi

Micromachines 2023, 14(11), 2015; https://doi.org/10.3390/mi14112015 - 29 Oct 2023

Viewed by 892

Abstract

An idealized design of a silicon betavoltaic battery with a tritium source is considered, in which a thin layer of tritiated silicon is sandwiched between two intrinsic silicon slabs of equal width, and the excess charge carriers are collected by thin interdigitated n⁺ and p⁺ electrodes. The opposite sides of the device are covered with a reflecting coating to trap the photons produced in radiative recombination events. Due to photon recycling, radiative recombination is almost ineffective, so the Auger mechanism dominates. An analytical expression for the current–voltage curve is obtained, from which the main characteristics of the cell, namely, the open-circuit voltage, the fill factor, and the betaconversion efficiency, are found. The analytical results are shown to agree with the numerical ones with better than 0.1% accuracy. The optimal half-thickness of this device is found to be around 1.5 μm. The maximal efficiency increases logarithmically with the surface activity of the beta-source and has the representative value of 12.07% at 0.1 mCi/cm² and 14.13% at 10 mCi/cm². Full article

(This article belongs to the Special Issue Advanced Functional Materials for Energy Harvesting and Storage Devices, Volume II)

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12 pages, 3130 KiB

Open AccessArticle

The Influence of Preparation Temperature on the Different Facets of Bulk MgB₂ Superconductors

by Penghe Zhang, Yufeng Zhang, Chunyan Li, Yan Zhang, Shuangyuan Shen, Guanjie Ruan, Jiaying Zhang and Jacques Guillaume Noudem

Micromachines 2023, 14(5), 988; https://doi.org/10.3390/mi14050988 - 30 Apr 2023

Cited by 2 | Viewed by 1157

Abstract

Two MgB₂ samples were prepared using the spark plasma sintering (SPS) technique at different temperatures—950 °C (S1) and 975 °C (S2)—for 2 h under 50 MPa pressure to study the influence of preparation temperature on different facets, namely those perpendicular (PeF) and parallel (PaF) to the compression direction of uniaxial pressure during the SPS of MgB₂ samples. We analyzed the superconducting properties of the PeF and PaF of two MgB₂ samples prepared at different temperatures from the curves of the critical temperature (T_C), the curves of critical current density (J_C), the microstructures of MgB₂ samples, and the crystal size from SEM. The values of the onset of the critical transition temperature, T_c,onset, were around 37.5 K and the transition widths were about 1 K, which indicates that the two samples exhibit good crystallinity and homogeneity. The PeF of the SPSed samples exhibited slightly higher J_C compared with that of the PaF of the SPSed samples over the whole magnetic field. The values of the pinning force related to parameters h₀ and K_n of the PeF were lower than those of the PaF, except for K_n of the PeF of S1, which means that the PeF has a stronger GBP than the PaF. In low field, the most outstanding performance was S1-PeF, whose critical current density (J_C) was 503 kA/cm² self-field at 10 K, and its crystal size was the smallest (0.24 µm) among all the tested samples, which is consistent with the theory that a smaller crystal size can improve the J_C of MgB₂. However, in high field, S2-PeF had the highest J_C value, which is related to the pinning mechanism and can be explained by grain boundary pinning (GBP). With an increase in preparation temperature, S2 showed a slightly stronger anisotropy of properties. In addition, with an increase in temperature, point pinning becomes stronger to form effective pinning centers, leading to a higher J_C. Full article

(This article belongs to the Special Issue Advanced Functional Materials for Energy Harvesting and Storage Devices, Volume II)

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14 pages, 10726 KiB

Open AccessArticle

The Performance of the Two-Seeded GdBCO Superconductor Bulk with the Buffer by the Modified TSMG Method

by Yufeng Zhang, Chunyan Li, Ziwei Lou, Penghe Zhang, Yan Zhang, Shuangyuan Shen, Guanjie Ruan and Jiaying Zhang

Micromachines 2023, 14(5), 987; https://doi.org/10.3390/mi14050987 - 30 Apr 2023

Cited by 1 | Viewed by 1054

Abstract

The multiseeding technique is a method to grow large-sized REBa₂Cu₃O_7−δ (REBCO, where RE is a rare earth element) high temperature superconducting bulks. However, due to the existence of grain boundaries between seed crystals, the superconducting properties of bulks are not always better than those of single grain bulks. In order to improve the superconducting properties caused by grain boundaries, we introduced buffer layers with a diameter of 6 mm in the growth of GdBCO bulks. Using the modified top-seeded melt texture growth method (TSMG), that is, YBa₂Cu₃O_7−δ (Y123) as the liquid phase source, two GdBCO superconducting bulks with buffer layers with a diameter of 25 mm and a thickness of 12 mm were successfully prepared. The seed crystal arrangement of two GdBCO bulks with a distance of 12 mm were (100/100) and (110/110), respectively. The trapped field of the GdBCO superconductor bulks exhibited two peaks. The maximum peaks of superconductor bulk S_A (100/100) were 0.30 T and 0.23 T, and the maximum peaks of superconductor bulk S_B (110/110) were 0.35 T and 0.29 T. The critical transition temperature remained between 94 K and 96 K, with superior superconducting properties. The maximum J_{C, self-field} of S_A appeared in specimen b5, which was 4.5 × 10⁴ A/cm². Compared with S_A, the J_C value of S_B had obvious advantages in a low magnetic field, medium magnetic field and high magnetic field. The maximum J_{C, self-field} value appeared in specimen b2, which was 4.65 × 10⁴ A/cm². At the same time, it showed an obvious second peak effect, which was attributed to Gd/Ba substitution. Liquid phase source Y123 increased the concentration of the Gd solute dissolved from Gd211 particles, reduced the size of Gd211 particles and optimized J_C. For S_A and S_B under the joint action of the buffer and the Y123 liquid source, except for the contribution of Gd211 particles to be the magnetic flux pinning center with the improvement of J_C, the pores also played a positive role in improving the local J_C. More residual melts and impurity phases were observed in S_A than in S_B, which had a negative impact on the superconducting properties. Thus, S_B exhibited a better trapped field and J_C. Full article

(This article belongs to the Special Issue Advanced Functional Materials for Energy Harvesting and Storage Devices, Volume II)

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