Transparent Metal-Organic Framework-Based Gel Electrolytes for Generalized Assembly of Quasi-Solid-State Electrochromic Devices

Recent Advance in Electrochromic Materials and Devices for Display Applications

Electrochromic devices (ECDs) possess the performance advantages in terms of color adjustability, low power consumption, and visual friendliness, emerging as one of the ideal candidates for energy-efficient smart windows, next-generation displays, and wearable electronics. The optical and electrical characteristics of ECDs can be adjusted by modifying the materials or structure of devices. This review summarizes the recent developments of innovative technologies and key materials of ECDs for display applications, highlighting the key issues and development trends in this area.

Electrochemical immunosensor based on AuNPs/Zn/Ni-ZIF-8-800@graphene for rapid detection of aflatoxin B1 in peanut oil

Peanut oil is a basic food raw material in life. However, aflatoxin contamination in peanut oil is considered to be one of the most serious food safety problems in the world. Based on AuNPs/Zn/Ni-ZIF-8-800@graphene composite, a simple, efficient and sensitive electrochemical immunosensor was developed to detect aflatoxin B1 (AFB1) in peanut oil. The bare glassy carbon electrode was modified by graphene, bimetallic organic framework material (Zn/Ni-ZIF-8-800), chitosan and gold nanoparticles. The electrochemical immunosensor was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) and cyclic voltammetry (CV), and the electrochemical signal changes after antibody and AFB1 binding were investigated in detail. Under the optimal conditions, the linear range of the electrochemical immunosensor was 0.18-100 ng/mL, and the detection limit was 0.18 ng/mL. In addition, the prepared sensor has high selectivity and long-term stability, which lays a foundation for the simple, rapid and sensitive detection of AFB1 in peanut oil.

Electrochemical Actuators with Multicolor Changes and Multidirectional Actuation

Electrochemical (EC) actuators have garnered significant attention in recent years, yet there are still some critical challenges to limit their application range, such as responsive time, multifunctionality, and actuating direction. Herein, an EC actuator with a back-to-back structure is fabricated by stacking two membranes with bilayer V₂ O₅ nanowires/single-walled carbon nanotubes (V₂ O₅ NWs/SWCNTs) networks, and shows a synchronous high actuation amplitude (about ±9.7 mm, ±28.4°) and multiple color changes. In this back-to-back structure, the inactive SWCNTs layer is used as a conductive current collector, and the bilayer network is attached to a porous polymer membrane. The dual-responsive processes of V₂ O₅ nanowires (V₂ O₅ NWs) actuation films and actuators are also deeply investigated through in situ EC X-ray diffraction and Raman spectroscopy. The results show that the EC actuation of the V₂ O₅ NWs/SWCNTs film is highly related to the redox behavior of the pseudocapacitive V₂ O₅ NWs layer. At last, both V₂ O₅ NWs and W₁₈ O₄₉ nanowires (W₁₈ O₄₉ NWs)-based EC actuators are constructed to demonstrate the multicolor changes and multidirectional actuation induced by the opposite lattice changes of V₂ O₅ NWs and W₁₈ O₄₉ NWs during ionic de-/intercalation, guiding the design of multifunctional EC actuators in the future.

Electrochemically-Matched and Nonflammable Janus Solid Electrolyte for Lithium-Metal Batteries

Solid-state batteries based on ceramic electrolytes are promising alternatives to lithium-ion batteries with better safety and energy density. While solid electrolytes such as the garnet-type Li₇La₃Zr₂O₁₂ (LLZO) are chemically stable with lithium metal, their rigidity leads to poor interfacial contact with the cathodes. Nonflammable organic phosphates, however, are characterized by a liquid nature and can immerse the conventional porous cathodes to form a good contact. However, the phosphates are unstable with lithium metal anodes. We design a quasi-solid Janus electrolyte based on the ceramic LLZO and a trimethyl phosphate (TMP) gel which combines the best of both worlds. The electrochemical window of the Janus electrolyte is significantly extended compared with the TMP to accommodate the lithium metal anode. The contact between the cathode and the electrolyte is maintained by the semifluid nature of the TMP gel. A lithium-metal battery with such a Janus electrolyte can stably cycle at room temperature at 1C while still retaining a capacity of 115 mAh g^-1 over 100 times. In contrast, the batteries based on LLZO and TMP individually cannot function properly. More importantly, despite the quasi-solid nature, the battery does not contain flammable functional parts and can alleviate the safety concerns of current batteries containing organic-type electrolytes. This work provides a simple but effective strategy for safe, inexpensive, and energy-dense solid-state batteries.

Physical Simulation Model of WO3 Electrochromic Films Based on Continuous Electron-Transfer Kinetics and Experimental Verification

Tungsten oxide (WO₃) electrochromic devices have attracted a lot of interest in the energy conservation field and have shown a preliminary application potential in the market. However, it is difficult to quantitatively direct experiments with the existing electrochromic theoretical models, which can restrict the further development of electrochromism. Here, an electrochromic physical simulation model of WO₃ films was built to solve the above problem. Experimentally, the actual electrochromic kinetics of WO₃ in the LiClO₄/propylene carbonate electrolyte was determined as a continuous electron-transfer process by cyclic voltammetry measurement and X-ray photoelectron spectroscopy analysis. Theoretically, the continuous electron-transfer process, Li⁺-ion diffusion process, and the transmittance change process were described by a modified Butler-Volmer equation, Fick's law, and charge versus coloration efficiency/bleaching efficiency coupling equation, respectively. The comparisons between theoretical and experimental data were conducted to verify this model. The shape of the simulated current curves was basically consistent with that of experiments. Besides, the difference of transmittance between the simulation and experiments was less than 8%. The difference between theory and experiment was attributed to the influence of the electric double layer and the actual reaction interface. The success of the simulation was attributed to the accurate description of the electrochromic process by continuous electron-transfer kinetics. This model can be applied in the research of electrochromic mechanisms, experimental result prediction, and novel device development due to its clear physical nature.