Journals > > Topics > TOPLCAL SECTION: Electrochromic Materials and Devices (Contributing Editor: DIAO Xungang, WANG Jinmin)
TOPLCAL SECTION: Electrochromic Materials and Devices (Contributing Editor: DIAO Xungang, WANG Jinmin)|6 Article(s)
Qi ZHAO, Ke QIAO, Yongji YAO, Zhang CHEN, Dongchu CHEN, and Yanfeng GAO
Gel electrolytes are chemically stable, nonflammable and easy to encapsulate, however, their moderate ionic conductivity (10-4-10-5S·cm-1) hinders their further development for the usage in electrochromic devices (ECDs). Here, we developed a highly conductive hydrophobic SiO2/PMMA/PC/LiClO4 gel polymer electrolyte (H-SiO2 GPE). Electrochemical behaviors of ECDs were characterized by electrochemical impedance spectroscope (EIS), cyclic voltammetry (CV) and chronoamperometry (CA). Systematic analyses show that the ionic conductivity of the H-SiO2 GPE can reach 5.14 mS∙cm-1 (at 25 ℃) by introducing only 0.5wt% hydrophobic fumed SiO2. This increase is due to the good compatibility and hydrophobic-hydrophobic attractions between SiO2 additive and organic electrolyte, which promotes the dissociation of lithium perchlorate. Additionally, the viscosity as a function of shear rate for GPE with various fumed silica contents shows the behavior of shear thinning, which indicates the formation of a three-dimensional network structure. This structure provides ion transport channels, leading to a clearly improved switching speed for ECDs assembled with hydrophobic SiO2 GPEs (tbleaching=4 vs 8 s and tcoloring=14 vs 16 s). Similarly, the investigation of hydrophobic fumed SiO2 in liquid electrolyte is demonstrated that the ionic conductivity of LiClO4/PC liquid electrolyte without and with hydrophobic fumed SiO2 increases from 6.94 to 7.58 mS∙cm-1, respectively. Therefore, hydrophobic fumed SiO2 as a filler has a positive effect on electrolytes, and the proposal of the H-SiO2 GPE provides a new idea for offsetting the trade-off between a high ionic conductivity and easy leakage when applied in ECDs. Gel electrolytes are chemically stable, nonflammable and easy to encapsulate, however, their moderate ionic conductivity (10-4-10-5S·cm-1) hinders their further development for the usage in electrochromic devices (ECDs). Here, we developed a highly conductive hydrophobic SiO2/PMMA/PC/LiClO4 gel polymer electrolyte (H-SiO2 GPE). Electrochemical behaviors of ECDs were characterized by electrochemical impedance spectroscope (EIS), cyclic voltammetry (CV) and chronoamperometry (CA). Systematic analyses show that the ionic conductivity of the H-SiO2 GPE can reach 5.14 mS∙cm-1 (at 25 ℃) by introducing only 0.5wt% hydrophobic fumed SiO2. This increase is due to the good compatibility and hydrophobic-hydrophobic attractions between SiO2 additive and organic electrolyte, which promotes the dissociation of lithium perchlorate. Additionally, the viscosity as a function of shear rate for GPE with various fumed silica contents shows the behavior of shear thinning, which indicates the formation of a three-dimensional network structure. This structure provides ion transport channels, leading to a clearly improved switching speed for ECDs assembled with hydrophobic SiO2 GPEs (tbleaching=4 vs 8 s and tcoloring=14 vs 16 s). Similarly, the investigation of hydrophobic fumed SiO2 in liquid electrolyte is demonstrated that the ionic conductivity of LiClO4/PC liquid electrolyte without and with hydrophobic fumed SiO2 increases from 6.94 to 7.58 mS∙cm-1, respectively. Therefore, hydrophobic fumed SiO2 as a filler has a positive effect on electrolytes, and the proposal of the H-SiO2 GPE provides a new idea for offsetting the trade-off between a high ionic conductivity and easy leakage when applied in ECDs.
Journal of Inorganic Materials
- Publication Date: Feb. 20, 2021
- Vol. 36, Issue 2, 161 (2021)
Kailing ZHOU, Hao WANG, Qianqian ZHANG, Jingbing LIU, and Hui YAN
The dynamic process of ions transport in electrochromic WO3 film is usually studied by electrochemical impedance spectroscopy. However, the detailed features are hidden since the ions insertion into WO3 is a very complex process including structural deformation and phase transformations. Chronopotentiometry is an electrochemical characterization method that measures the response potential of a system under an imposed current. Compared to other dynamic characterization methods (impedance spectroscopy and CV), it allows direct access to the voltage contributions in different states of the solution-electrode system and has frequently been used to investigate kinetic effects such as adsorption and transport phenomena near electrode surface. In this study, chronopotentiometry is creatively applied to study ion transport kinetics and control ions insertion behavior in electrochromic WO3 film. The results suggest that a large ions insertion flux at the interface of WO3/electrolyte could broaden ions transport channels due to the fierce lattice expansion during Li+ions insertion process, which further improves the ions transportation kinetics and gifts a fast switching speed of optical performance. However, the repeating ions insertion/extraction behaviors at the interface of WO3/electrolyte for the long-term cycle process can reduce the size of WO3 grains as a “ball mill effect”. Especially, a large ions transport flux can aggravate the “ball mill effect”. Consequently, the structure of the WO3 film becomes very dense, which is unfavorable for ions transport and electrolyte permeation. This dense structure also leads to an irreversible accumulation of Li+ ions and LixWO3 in the WO3 host structure, resulting in a decay of optical modulation ability and electrochromic activity. This work offers an efficient method to analyze ion transport kinetics in intercalation materials and a new understanding of the relationship between ion transport behavior and cyclic stability of electrochromic materials. The dynamic process of ions transport in electrochromic WO3 film is usually studied by electrochemical impedance spectroscopy. However, the detailed features are hidden since the ions insertion into WO3 is a very complex process including structural deformation and phase transformations. Chronopotentiometry is an electrochemical characterization method that measures the response potential of a system under an imposed current. Compared to other dynamic characterization methods (impedance spectroscopy and CV), it allows direct access to the voltage contributions in different states of the solution-electrode system and has frequently been used to investigate kinetic effects such as adsorption and transport phenomena near electrode surface. In this study, chronopotentiometry is creatively applied to study ion transport kinetics and control ions insertion behavior in electrochromic WO3 film. The results suggest that a large ions insertion flux at the interface of WO3/electrolyte could broaden ions transport channels due to the fierce lattice expansion during Li+ions insertion process, which further improves the ions transportation kinetics and gifts a fast switching speed of optical performance. However, the repeating ions insertion/extraction behaviors at the interface of WO3/electrolyte for the long-term cycle process can reduce the size of WO3 grains as a “ball mill effect”. Especially, a large ions transport flux can aggravate the “ball mill effect”. Consequently, the structure of the WO3 film becomes very dense, which is unfavorable for ions transport and electrolyte permeation. This dense structure also leads to an irreversible accumulation of Li+ ions and LixWO3 in the WO3 host structure, resulting in a decay of optical modulation ability and electrochromic activity. This work offers an efficient method to analyze ion transport kinetics in intercalation materials and a new understanding of the relationship between ion transport behavior and cyclic stability of electrochromic materials.
Journal of Inorganic Materials
- Publication Date: Feb. 20, 2021
- Vol. 36, Issue 2, 152 (2021)
Huajing FANG, Zetian ZHAO, Wenting WU, and Hong WANG
Electrochromic materials with ability of changing color in response to periodically adjusted bias are an important class of optoelectric functional materials. The controllable modulation of light absorption and transmission can make a great contribution in applications such as smart windows, electrochromic displays and antiglare rear-view mirrors. In recent years, electrochromic technology has developed rapidly. However, the research so far mainly focuses on the traditional rigid electrochromic devices (ECD), mostly based on transparent conductive glass such as indium tin oxide (ITO) glass. The rigid electrochromic devices have some noticeable problems such as large thickness, poor conformability, low mechanical strength, high cost, etc., which hinder their further development of electrochromic technology and their forward commercialization. With the upsurge of developing flexible devices that can be used in wearable devices and e-skin, flexible electrochromic devices (FECD) have attracted extensive attention due to their possibility of foldability, wearability and even embeddability, and have become a research hotspot in the electrochromic field. Starting from the materials for preparing FECD, this review systematically summarizes the recent progress and trend of flexible electrochromic devices based on inorganic, organic, inorganic/organic composite and other new materials. The review also focuses on the research progress of up to date stretchable electrochromic devices. At the same time, challenges in performance improvement and practical application of flexible electrochromic devices at the present stage as well as the corresponding measures taken in the literatures are discussed. Finally, the key to the preparation and performance improvement of flexible electrochromic devices is defined, and the future development trend is prospected. Electrochromic materials with ability of changing color in response to periodically adjusted bias are an important class of optoelectric functional materials. The controllable modulation of light absorption and transmission can make a great contribution in applications such as smart windows, electrochromic displays and antiglare rear-view mirrors. In recent years, electrochromic technology has developed rapidly. However, the research so far mainly focuses on the traditional rigid electrochromic devices (ECD), mostly based on transparent conductive glass such as indium tin oxide (ITO) glass. The rigid electrochromic devices have some noticeable problems such as large thickness, poor conformability, low mechanical strength, high cost, etc., which hinder their further development of electrochromic technology and their forward commercialization. With the upsurge of developing flexible devices that can be used in wearable devices and e-skin, flexible electrochromic devices (FECD) have attracted extensive attention due to their possibility of foldability, wearability and even embeddability, and have become a research hotspot in the electrochromic field. Starting from the materials for preparing FECD, this review systematically summarizes the recent progress and trend of flexible electrochromic devices based on inorganic, organic, inorganic/organic composite and other new materials. The review also focuses on the research progress of up to date stretchable electrochromic devices. At the same time, challenges in performance improvement and practical application of flexible electrochromic devices at the present stage as well as the corresponding measures taken in the literatures are discussed. Finally, the key to the preparation and performance improvement of flexible electrochromic devices is defined, and the future development trend is prospected.
Journal of Inorganic Materials
- Publication Date: Feb. 20, 2021
- Vol. 36, Issue 2, 140 (2021)
Xiaolan ZHONG, Xueqing LIU, and Xungang DIAO
Electrochromic devices (ECDs) are the intelligent devices change color by applying electric potential, with the advantages of wide working temperature, high optical contrast, good reversible bistability, low driving voltage, and low energy consumption, which show great application potential in the field of dynamic smart windows, full-color electronic screens, anti-glare goggles, adaptive dual-stealth camouflage, and energy storage status visualization. Cathodically coloring material tungsten oxide and anodically coloring material nickel oxide are two widely studied inorganic electrochromic materials, and complementary electrochromic devices based on WO3 and NiO films have high commercial values in the application of large scale smart windows. Improving the performance of the complementary ECDs such as optical modulation range, response rate, cycle life and weather fastness has attracted much attention. This review focuses on the structural composition of complementary electrochromic devices and summarizes the recent research progress of the electrochromic full devices based on WO3 and NiO. Firstly, the electrochromic mechanism and decay mechanism of WO3 and NiO films are clarified, the effects and latest research progress of four strategies for film performance optimization that include optimizing preparation conditions, element doping modification, designing nanostructure, and introducing composite materials are discussed in detail. Secondly, according to the composition and structure design of the device, the classification system of the complementary electrochromic full device is introduced, and the influence of selection for each component material and the device structure on device overall performance are summarized. Finally, the application of the electrochromic device prospects and development trends are forecasted. Electrochromic devices (ECDs) are the intelligent devices change color by applying electric potential, with the advantages of wide working temperature, high optical contrast, good reversible bistability, low driving voltage, and low energy consumption, which show great application potential in the field of dynamic smart windows, full-color electronic screens, anti-glare goggles, adaptive dual-stealth camouflage, and energy storage status visualization. Cathodically coloring material tungsten oxide and anodically coloring material nickel oxide are two widely studied inorganic electrochromic materials, and complementary electrochromic devices based on WO3 and NiO films have high commercial values in the application of large scale smart windows. Improving the performance of the complementary ECDs such as optical modulation range, response rate, cycle life and weather fastness has attracted much attention. This review focuses on the structural composition of complementary electrochromic devices and summarizes the recent research progress of the electrochromic full devices based on WO3 and NiO. Firstly, the electrochromic mechanism and decay mechanism of WO3 and NiO films are clarified, the effects and latest research progress of four strategies for film performance optimization that include optimizing preparation conditions, element doping modification, designing nanostructure, and introducing composite materials are discussed in detail. Secondly, according to the composition and structure design of the device, the classification system of the complementary electrochromic full device is introduced, and the influence of selection for each component material and the device structure on device overall performance are summarized. Finally, the application of the electrochromic device prospects and development trends are forecasted.
Journal of Inorganic Materials
- Publication Date: Feb. 20, 2021
- Vol. 36, Issue 2, 128 (2021)
Hongwei FAN, Kerui LI, Chengyi HOU, Qinghong ZHANG, Yaogang LI, and Hongzhi WANG
Electrochromism is the phenomenon of reversible color/optical change of materials induced by redox reactions under an applied electric field. Since electrochromism was first introduced by Platt in 1961, electrochromic (EC) technology continues to develope due to its advantages of multiple colors energy saving and controllability, and was applied in many fields, for example, smart windows, displays, anti-dazzling rear view mirrors, etc. Recently, with the rapid development of optoelectronic and photoelectric technologies, highly integrated electronic devices attracted extensive interests, and the EC technology is developed towards functionalization and intellectualization. For example, self-powered EC devices (ECDs) were fabricated through integrating with the green energy technology, which further reduced the building energy consumption. Because of the visualization of the EC phenomena by naked eyes, the signal reading became more convenient for the sensors integrated with ECDs. In addition, because of similar device structure, electrochemical principles, active components with other functional devices, a lot of multifunctional EC technologies were explored based on single device, facilitating applications of ECDs in EC infrared control, EC energy storage, and EC actuation. In light of the recent emerging progress of EC technology, we reviewed multi-functional EC systems based on the integration of multiple devices and single device, respectively, including self-powered ECDs, EC sensors, infrared ECDs, and EC energy storage devices, etc. The integration modes, structure design and performance optimization were also summarized for different types of the multi-functional ECDs. At last, we introduced the challenges and potential pathway of multi-functional EC integration in the future. Electrochromism is the phenomenon of reversible color/optical change of materials induced by redox reactions under an applied electric field. Since electrochromism was first introduced by Platt in 1961, electrochromic (EC) technology continues to develope due to its advantages of multiple colors energy saving and controllability, and was applied in many fields, for example, smart windows, displays, anti-dazzling rear view mirrors, etc. Recently, with the rapid development of optoelectronic and photoelectric technologies, highly integrated electronic devices attracted extensive interests, and the EC technology is developed towards functionalization and intellectualization. For example, self-powered EC devices (ECDs) were fabricated through integrating with the green energy technology, which further reduced the building energy consumption. Because of the visualization of the EC phenomena by naked eyes, the signal reading became more convenient for the sensors integrated with ECDs. In addition, because of similar device structure, electrochemical principles, active components with other functional devices, a lot of multifunctional EC technologies were explored based on single device, facilitating applications of ECDs in EC infrared control, EC energy storage, and EC actuation. In light of the recent emerging progress of EC technology, we reviewed multi-functional EC systems based on the integration of multiple devices and single device, respectively, including self-powered ECDs, EC sensors, infrared ECDs, and EC energy storage devices, etc. The integration modes, structure design and performance optimization were also summarized for different types of the multi-functional ECDs. At last, we introduced the challenges and potential pathway of multi-functional EC integration in the future.
Journal of Inorganic Materials
- Publication Date: Feb. 20, 2021
- Vol. 36, Issue 2, 115 (2021)
Xungang DIAO
We have invited the most prestigious research groups in China to contribute to our special issue, and they are all leaders in the field of inorganic electrochromism researches. It is expected that these professional academic works can further promote the vigorous development of electrochromic research and industrialization technologies in China. On behalf of my colleagues in the field of electrochromism, I would like to express my sincere thanks and respect to the authors and editors who have made outstanding contributions to the special issue’s publication. We have invited the most prestigious research groups in China to contribute to our special issue, and they are all leaders in the field of inorganic electrochromism researches. It is expected that these professional academic works can further promote the vigorous development of electrochromic research and industrialization technologies in China. On behalf of my colleagues in the field of electrochromism, I would like to express my sincere thanks and respect to the authors and editors who have made outstanding contributions to the special issue’s publication.
Journal of Inorganic Materials
- Publication Date: Feb. 20, 2021
- Vol. 36, Issue 2, 113 (2021)
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