Electrochromics for smart windows: Oxide-based thin films and devices

Rechargeable sodium-ion batteries (SIBs), as the most promising alternative to commercial lithium-ion batteries, have received tremendous attention during the last decade. Among all the anode materials for SIBs, metal sulfides/selenides (MXs) have shown inspiring results because of their versatile material species and high theoretical capacity. They suffer from large volume expansion, however, which leads to bad cycling performance. Thus, methods such as carbon modification, nanosize design, electrolyte optimization, and cut-off voltage control are used to obtain enhanced performance. Here, recent progress on MXs is summarized in terms of arranging the crystal structure, synthesis methods, electrochemical performance, mechanisms, and kinetics. Challenges are presented and effective ways to solve the problems are proposed, and a perspective for future material design is also given. It is hoped that light is shed on the development of MXs to help finally find applications for next-generation rechargeable batteries.

Advances and Challenges in Metal Sulfides/Selenides for Next-Generation Rechargeable Sodium-Ion Batteries.

ConspectusDeep eutectic solvents (DESs) represent an alternative class of ionic fluids closely resembling room-temperature ionic liquids (RTILs), although, strictly speaking, they are distinguished by the fact that they also contain an organic molecular component (typically, a hydrogen bond donor like a urea, amide, acid, or polyol), frequently as the predominant constituent. Practically speaking, DESs are attractive alternatives to RTILs, sharing most of their remarkable qualities (e.g., tolerance to humidity, negligible vapor pressure, thermostability, wide electrochemical potential windows, tunability) while overcoming several limitations associated with their RTIL cousins. Particularly, DESs are typically, less expensive, more synthetically accessible (typically, from bulk commodity chemicals using solvent/waste-free processes), nontoxic, and biodegradable.In this Account, we provide an overview of DESs as designer solvents to create well-defined nanomaterials including shape-controlled nanoparticles,...

Deep eutectic solvents: sustainable media for nanoscale and functional materials.

Carbon-oxide and carbon-sulfide nanocomposites have attracted tremendous interest as the anode materials for Li and Na ion batteries. Such composites are fascinating as they often show synergistic effect compared to their singular components. Carbon nanomaterials are often used as the matrix due to their high conductivity, tensile strength, and chemical stability under the battery condition. Metal oxides and sulfides are often used as active material fillers because of their large capacity. Numerous works have shown that by taking one step further into fabricating nanocomposites with rational structure design, much better performance can be achieved. The present review aims to present and discuss the development of carbon-based nanocomposite anodes in both Li ion batteries and Na ion batteries. The authors introduce the individual components in the composites, i.e., carbon matrices (e.g., carbon nanotube, graphene) and metal oxides/sulfides; followed by evaluating how advanced nanostructures benefit from the synergistic effect when put together. Particular attention is placed on strategies employed in fabricating such composites, with examples such as yolk–shell structure, layered-by-layered structure, and composite comprising one or more carbon matrices. Lastly, the authors conclude by highlighting challenges that still persist and their perspective on how to further develop the technologies.

A Review on Design Strategies for Carbon Based Metal Oxides and Sulfides Nanocomposites for High Performance Li and Na Ion Battery Anodes

ConspectusThe rational design and exploration of electrochromic devices will find a wide range of applications in smart windows for energy-efficient buildings, low-power displays, self-dimming rear mirrors for automobiles, electrochromic e-skins, and so on. Electrochromic devices generally consist of multilayer structures with transparent conductors, electrochromic films, ion conductors, and ion storage films. Synthetic strategies and new materials for electrochromic films and transparent conductors, comprehensive electrochemical kinetic analysis, and novel device design are areas of active study worldwide. These are believed to be the key factors that will help to significantly improve the electrochromic performance and extend their application areas.In this Account, we present our strategies to design and fabricate electrochromic devices with high performance and multifunctionality. We first describe the synthetic strategies, in which a porous tungsten oxide (WO3) film with nearly ideal optical modulati...

Next-Generation Multifunctional Electrochromic Devices

Scrupulous design and fabrication of advanced electrode materials are vital for developing high-performance sodium ion batteries. Herein, we report a facile one-step hydrothermal strategy for construction of a C-MoSe2/rGO composite with both high porosity and large surface area. Double modification of MoSe2 nanosheets is realized in this composite by introducing a reduced graphene oxide (rGO) skeleton and outer carbon protective layer. The MoSe2 nanosheets are well wrapped by a carbon layer and also strongly anchored on the interconnected rGO network. As an anode in sodium ion batteries, the designed C-MoSe2/rGO composite delivers noticeably enhanced sodium ion storage, with a high specific capacity of 445 mAh·g-1 at 200 mA·g-1 after 350 cycles, and 228 mAh·g-1 even at 4 A·g-1; these values are much better than those of C-MoSe2 nanosheets (258 mAh·g-1 at 200 mA·g-1 and 75 mAh·g-1 at 4 A·g-1). Additionally, the sodium ion storage mechanism is investigated well using ex situ X-ray diffraction and transmission electron microscopy methods. Our proposed electrode design protocol and sodium storage mechanism may pave the way for the fabrication of other high-performance metal diselenide anodes for electrochemical energy storage.
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https://link.springer.com/content/pdf/10.1007/s12274-020-3198-6.pdf

Erratum to: Facile fabrication of integrated three-dimensional CMoSe 2 /reduced graphene oxide composite with enhanced performance for sodium storage

The TiO2@PANI core/shell nanorod array is prepared by the combination of hydrothermal and electro-polymerization methods. A significant optical modulation (57.6% at 700 nm), high coloration efficiency (37.1 cm2 C–1), and good cycling performance (62.1% after 1000 cycles) are achieved for the TiO2@PANI core/shell nanorod array. The improved electrochromic properties are mainly attributed to the core/shell structure, formation of the donor–acceptor system, and the porous space among the nanorods, which can reduce the oxidation potential, make the ion diffusion easier and provide larger surface area for charge-transfer reactions. The data indicate great promise for the TiO2@PANI core/shell nanorod array as a potential multicolor electrochromic material.

Multicolor Electrochromic Film Based on TiO2@Polyaniline Core/Shell Nanorod Array

Co-doped NiO electrochromic nanoflake array films grown on FTO with antireflection ability have been synthesized by low temperature chemical bath deposition. Co doping has an influence on the growth and electrochromic properties of NiO nanoflake arrays. Noticeably, all the films show a very high transmittance at the bleached state in the region of visible light. Compared to the undoped NiO, the 1% Co-doped NiO nanoflake array film exhibits outstanding electrochromism, including large transmittance modulation (88.3%), high coloration efficiency (47.7 cm2 C−1), fast switching speed (3.4 s and 5.4 s), excellent reversibility and cycling durability at a wavelength of 550 nm. The enhanced electrochromic performances can be attributed to the synergetic effect contribution from low crystallization, oblique nanoflake array configuration and improved p-type conductivity by appropriate Co doping.

Co-doped NiO nanoflake array films with enhanced electrochromic properties

Growth of vertically aligned hierarchical WO3 nano-architecture arrays on transparent conducting substrates with outstanding electrochromic performance

Ding Zhou

Papers

Erratum to: Facile fabrication of integrated three-dimensional CMoSe 2 /reduced graphene oxide composite with enhanced performance for sodium storage

Multicolor Electrochromic Film Based on TiO2@Polyaniline Core/Shell Nanorod Array

Co-doped NiO nanoflake array films with enhanced electrochromic properties

Growth of vertically aligned hierarchical WO3 nano-architecture arrays on transparent conducting substrates with outstanding electrochromic performance

Efficient electrochromic materials based on TiO2@WO3 core/shell nanorod arrays