Energy Conversion and Storage: From Materials to Devices

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

Deadline for manuscript submissions: closed (15 December 2023) | Viewed by 4930

Special Issue Editor


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Guest Editor
School of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Republic of Korea
Interests: heterogeneous catalysis; photocatalysis; biofuel production; energy storage materials

Special Issue Information

Dear Colleagues,

Conversion and storage of energy are key components of our modern energy landscape. A fast-expanding subject of study is the development of new materials and technology to increase the efficiency and sustainability of these processes. Materials and devices are being developed in the field of energy conversion to harness energy from renewable sources. Researchers are aiming to improve these technologies' efficiency and scalability, making them more competitive with traditional fossil fuels. Recently, one interesting area of research is the creation of novel photovoltaic materials, such as perovskite solar cells.

On the energy storage front, today’s demand is to increase the performance of fuel cells, batteries, supercapacitors, and other energy storage technologies by inventing materials and systems. This includes the creation of new electrode materials, electrolytes, and separators with the potential to improve energy density, charge/discharge rates, and overall longevity.

As a result, the goal of this Special Issue, titled “Energy Conversion and Storage: From Materials to Devices,” is to present research papers and review articles that highlight the current state of research as well as the most recent developments in the electrode materials and devices used in solar cells, batteries, and supercapacitors to maximize energy harvesting and storage.

Dr. Shalini Sahani
Guest Editor

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Keywords

  • renewable energy
  • solar cell
  • fuel cell
  • battery
  • supercapacitor

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Published Papers (4 papers)

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Research

11 pages, 2942 KiB  
Article
The Efficient Energy Collection of an Autoregulatory Driving Arm Harvester in a Breeze Environment
by Chao Zhang, Xinlong Yang, Boren Zhang, Kangqi Fan, Zhiming Liu and Zejia Liu
Micromachines 2023, 14(11), 2032; https://doi.org/10.3390/mi14112032 - 31 Oct 2023
Viewed by 991
Abstract
Breezes are a common source of renewable energy in the natural world. However, effectively harnessing breeze energy is challenging with conventional wind generators. These generators have a relatively high start-up wind speed requirement due to their large and steady rotational inertia. This study [...] Read more.
Breezes are a common source of renewable energy in the natural world. However, effectively harnessing breeze energy is challenging with conventional wind generators. These generators have a relatively high start-up wind speed requirement due to their large and steady rotational inertia. This study puts forth the idea of an autoregulatory driving arm (ADA), utilizing a stretchable arm for every wind cup and an elastic thread to provide adjustable rotational inertia and a low start-up speed. The self-adjustable rotational inertia of the harvester is achieved through coordinated interaction between the centrifugal and elastic forces. As the wind speed varies, the arm length of the wind cup automatically adjusts, thereby altering the rotational inertia of the harvester. This self-adjustment mechanism allows the harvester to optimize its performance and adapt to different wind conditions. By implementing the suggested ADA harvester, a low start-up speed of 1 m/s is achieved due to the small rotational inertia in its idle state. With the escalation of wind speed, the amplified centrifugal force leads to the elongation of the driving arms. When compared to a comparable harvester with a constant driving arm (CDA), the ADA harvester can generate more power thanks to this stretching effect. Additionally, the ADA harvester can operate for a longer time than the CDA harvester even after the wind has stopped. This extended operation time enables the ADA harvester to serve as a renewable power source for sensors and other devices in natural breeze environments. By efficiently utilizing and storing energy, the ADA harvester ensures a continuous and reliable power supply in such settings. Full article
(This article belongs to the Special Issue Energy Conversion and Storage: From Materials to Devices)
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13 pages, 4158 KiB  
Article
Conversion of CH4 and Hydrogen Storage via Reactions with MgH2-12Ni
by Young Jun Kwak, Myoung Youp Song and Ki-Tae Lee
Micromachines 2023, 14(9), 1777; https://doi.org/10.3390/mi14091777 - 16 Sep 2023
Viewed by 1077
Abstract
The main key to the future transition to a hydrogen economy society is the development of hydrogen production and storage methods. Hydrogen energy is the energy produced via the reaction of hydrogen with oxygen, producing only water as a by-product. Hydrogen energy is [...] Read more.
The main key to the future transition to a hydrogen economy society is the development of hydrogen production and storage methods. Hydrogen energy is the energy produced via the reaction of hydrogen with oxygen, producing only water as a by-product. Hydrogen energy is considered one of the potential substitutes to overcome the growing global energy demand and global warming. A new study on CH4 conversion into hydrogen and hydrogen storage was performed using a magnesium-based alloy. MgH2-12Ni (with the composition of 88 wt% MgH2 + 12 wt% Ni) was prepared in a planetary ball mill by milling in a hydrogen atmosphere (reaction-involved milling). X-ray diffraction (XRD) analysis was performed on samples after reaction-involved milling and after reactions with CH4. The variation of adsorbed or desorbed gas over time was measured using a Sieverts’-type high-pressure apparatus. The microstructure of the powders was observed using a scanning transmission microscope (STEM) with energy-dispersive X-ray spectroscopy (EDS). The synthesized samples were also characterized using Fourier transform infrared (FT-IR) spectroscopy. The XRD pattern of MgH2-12Ni after the reaction with CH4 (12 bar pressure) at 773 K and decomposition under 1.0 bar at 773 K exhibited MgH2 and Mg2NiH4 phases. This shows that CH4 conversion took place, the hydrogen produced after CH4 conversion was then adsorbed onto the particles, and hydrides were formed during cooling to room temperature. Ni and Mg2Ni formed during heating to 773 K are believed to cause catalytic effects in CH4 conversion. The remaining CH4 after conversion is pumped out at room temperature. Full article
(This article belongs to the Special Issue Energy Conversion and Storage: From Materials to Devices)
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16 pages, 7803 KiB  
Article
Marcus Theory and Tunneling Method for the Electron Transfer Rate Analysis in Quantum Dot Sensitized Solar Cells in the Presence of Blocking Layer
by Mohammad Javad Fahimi, Davood Fathi, Mehdi Eskandari and Narottam Das
Micromachines 2023, 14(9), 1731; https://doi.org/10.3390/mi14091731 - 3 Sep 2023
Cited by 7 | Viewed by 1107
Abstract
In this research study, the effects of different parameters on the electron transfer rate from three quantum dots (QDs), CdSe, CdS, and CdTe, on three metal oxides (MOs), TiO2, SnO2, and SnO2, in quantum-dot-sensitized solar cells (QDSSCs) [...] Read more.
In this research study, the effects of different parameters on the electron transfer rate from three quantum dots (QDs), CdSe, CdS, and CdTe, on three metal oxides (MOs), TiO2, SnO2, and SnO2, in quantum-dot-sensitized solar cells (QDSSCs) with porous structures in the presence of four types of blocking layers, ZnS, ZnO, TiO2, and Al2O3, are modeled and simulated using the Marcus theory and tunneling between two spheres for the first time. Here, the studied parameters include the change in the type and thickness of the blocking layer, the diameter of the QD, and the temperature effect. To model the effect of the blocking layer on the QD, the effective sphere method is used, and by applying it into the Marcus theory equation and the tunneling method, the electron transfer rate is calculated and analyzed. The obtained results in a wide range of temperatures of 250–400 °K demonstrate that, based on the composition of the MO-QD, the increase in the temperature could reduce or increase the electron transfer rate, and the change in the QD diameter could exacerbate the effects of the temperature. In addition, the results show which type and thickness of the blocking layer can achieve the highest electron transfer rate. In order to test the accuracy of the simulation method, we calculate the electron transfer rate in the presence of a blocking layer for a reported sample of a QDSSC manufacturing work, which was obtained with an error of ~3%. The results can be used to better interpret the experimental observations and to assist with the design and selection of the appropriate combination of MO-QD in the presence of a blocking layer effect. Full article
(This article belongs to the Special Issue Energy Conversion and Storage: From Materials to Devices)
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11 pages, 3259 KiB  
Article
A Harvester with a Helix S-Type Vertical Axis to Capture Random Breeze Energy Efficiently
by Chao Zhang, Boren Zhang, Jintao Liang, Zhengfeng Ming, Tao Wen and Xinlong Yang
Micromachines 2023, 14(7), 1466; https://doi.org/10.3390/mi14071466 - 21 Jul 2023
Cited by 1 | Viewed by 1102
Abstract
Breeze energy is a widely distributed renewable energy source in the natural world, but its efficient exploitation is very difficult. The conventional harvester with fixed arm length (HFA) has a relatively high start-up wind speed owing to its high and constant rotational inertia. [...] Read more.
Breeze energy is a widely distributed renewable energy source in the natural world, but its efficient exploitation is very difficult. The conventional harvester with fixed arm length (HFA) has a relatively high start-up wind speed owing to its high and constant rotational inertia. Therefore, this paper proposes a harvester with a helix s-type vertical axis (HSVA) for achieving random energy capture in the natural breeze environment. The HSVA is constructed with two semi-circular buckets driven by the difference of the drag exerted, and the wind energy is transferred into mechanical energy. Firstly, as the wind speed changes, the HSVA harvester can match the random breeze to obtain highly efficient power. Compared with the HFA harvester, the power coefficient is significantly improved from 0.15 to 0.2 without additional equipment. Furthermore, it has more time for energy attenuation as the wind speeds dropped from strong to moderate. Moreover, the starting torque is also better than that of HFA harvester. Experiments showed that the HSVA harvester can improve power performance on the grounds of the wind speed ranging in 0.8–10.1 m/s, and that the star-up wind speed is 0.8 m/s and output peak power can reach 17.1 mW. In comparison with the HFA harvester, the HSVA harvester can obtain higher efficient power, requires lower startup speed and keeps energy longer under the same time. Additionally, as a distributed energy source, the HSVA harvester can provide a self-generating power supply to electronic sensors for monitoring the surrounding environment. Full article
(This article belongs to the Special Issue Energy Conversion and Storage: From Materials to Devices)
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