Aqueous Zn batteries that provide a synergistic integration of absolute safety and high energy density have been considered as highly promising energy‐storage systems for powering electronics. ...Despite the rapid progress made in developing high‐performance cathodes and electrolytes, the underestimated but non‐negligible dendrites of Zn anode have been observed to shorten battery lifespan. Herein, this dendrite issue in Zn anodes, with regard to fundamentals, protection strategies, characterization techniques, and theoretical simulations, is systematically discussed. An overall comparison between the Zn dendrite and its Li and Al counterparts, to highlight their differences in both origin and topology, is given. Subsequently, in‐depth clarifications of the specific influence factors of Zn dendrites, including the accumulation effect and the cathode loading mass (a distinct factor for laboratory studies and practical applications) are presented. Recent advances in Zn dendrite protection are then comprehensively summarized and categorized to generate an overview of respective superiorities and limitations of various strategies. Accordingly, theoretical computations and advanced characterization approaches are introduced as mechanism guidelines and measurement criteria for dendrite suppression, respectively. The concluding section emphasizes future challenges in addressing the Zn dendrite issue and potential approaches to further promoting the lifespan of Zn batteries.
Zinc‐based batteries demonstrate both intrinsic safety and high energy density compared with other metal batteries. Nevertheless, zinc‐dendrite issues such as special morphology and nucleation require unique protections, which develop rapidly and need further improvement. The remaining challenges are discussed and the future directions, i.e., dynamic contact, atomic‐level ionic flow mediation, dendrite protection under high depth of discharge, etc., are proposed.
When plants face an environmental stress such as water deficit, soil salinity, high temperature, or shade, good communication between above- and belowground organs is necessary to coordinate growth ...and development. Various signals including hormones, peptides, proteins, hydraulic signals, and metabolites are transported mostly through the vasculature to distant tissues. How shoots and roots synchronize their response to stress using mobile signals is an emerging field of research. We summarize recent advances on mobile signals regulating shoot stomatal movement and root development in response to highly localized environmental cues. In addition, we highlight how the vascular system is not only a conduit but is also flexible in its development in response to abiotic stress.
Limitations in water uptake in roots and sucrose supply from shoots under abiotic stress can be encoded into signals that regulate the growth and development of distant tissues.Root-localized stress signals trigger changes in xylem hydraulics, mobile peptides, reactive oxygen species (ROS), and Ca2+, which lead to remote effects and induce shoot stomatal closure.The mobility of HY5 protein and its downstream targets via the phloem conveys shoot-sensed light and temperature information to affect both primary and lateral root growth.Shoot-derived sucrose loading/unloading in the phloem is highly responsive to environmental changes, and triggers signaling pathways that regulate root development.Developmental plasticity of the vasculature in response to abiotic stresses is of key importance for long-distance transport of substances to assist plant stress resilience.
Featuring with low cost, exceptional inherent safety and decent electrochemical performance, rechargeable Zn-based batteries (RZBs) have attracted increased attention and revived research efforts ...recently as a compelling alternative battery chemistry to Li-ion. However, some challenges still stand in the way of the development of these energy storage systems, such as low operation voltage, instability of cathode materials as well as dissolution of Zn electrode, etc. In this review, we present a comprehensive overview of recent progress in different RZBs systems including mild electrolyte RZBs, alkaline RZBs, hybrid RZBs, Zn-ion capacitors and Zn air batteries. The fundamental chemistry of various RZB systems, different cathode materials, optimization of Zn anode as well as various types of electrolytes and their influence on the battery performance are summarized. The major issues of different components along with respective strategies to alleviate them are discussed, aiming at providing a general guide for design and construction of high-performance RZBs. Additionally, the development of RZBs with different features in the last few years are summarized. Finally, we discuss the limitations and challenges that need to be overcome, providing potential future research directions in the field of next-generation RZBs.
This manuscript presents a comprehensive overview of recent progress in different kinds of rechargeable Zinc batteries (RZBs) with an emphasis on the reaction mechanisms, cathode materials, variable electrolyte and Zn anodes. Display omitted
•A comprehensive review on the recent development of various rechargeable Zn batteries (RZBs) has been presented.•The reaction mechanisms, cathode materials, Zn anodes of various Zn battery systems that operate in different electrolytes was discussed and compared.•The major issues of different components along with respective strategies to alleviate them are discussed.•The development of flexible RZBs with different features and multiple functionalities in recent years are also summarized.
Rechargeable calcium-ion batteries are intriguing alternatives for use as post-lithium-ion batteries. However, the high charge density of divalent Ca
establishes a strong electrostatic interaction ...with the hosting lattice, which results in low-capacity Ca-ion storage. The ionic radius of Ca
further leads to sluggish ionic diffusion, hindering high-rate capability performances. Here, we report 5,7,12,14-pentacenetetrone (PT) as an organic crystal electrode active material for aqueous Ca-ion storage. The weak π-π stacked layers of the PT molecules render a flexible and robust structure suitable for Ca-ion storage. In addition, the channels within the PT crystal provide efficient pathways for fast ionic diffusion. The PT anode exhibits large specific capacity (150.5 mAh g
at 5 A g
), high-rate capability (86.1 mAh g
at 100 A g
) and favorable low-temperature performances. A mechanistic study identifies proton-assisted uptake/removal of Ca
in PT during cycling. First principle calculations suggest that the Ca ions tend to stay in the interstitial space of the PT channels and are stabilized by carbonyls from adjacent PT molecules. Finally, pairing with a high-voltage positive electrode, a full aqueous Ca-ion cell is assembled and tested.
Hydrogel materials are receiving increasing research interest due to their intriguing structures that consist of a crosslinked network of polymer chains with interstitial spaces filled with solvent ...water. This feature endows the materials with the characteristics of being both wet and soft, making them ideal candidates for electrolyte materials for flexible energy storage devices, such as supercapacitors and rechargeable batteries that are under intensive studies nowadays. More importantly, the highly abundant and tunable chemistries of these hydrogels allow the introduction of novel functionalities into the existing hydrogels so that it is possible to fabricate unprecedented energy storage devices with additional functions. Here, the state‐of‐the‐art advances of the hydrogel materials for flexible energy storage devices including supercapacitors and rechargeable batteries are reviewed. In addition, devices with various kinds of functions, such as self‐healing, shape memory, and stretchability, are also included to stress the critical role of hydrogel materials. Furthermore, the challenges embedded in the current technologies are also highlighted and discussed with the hope to continually boost future research for the fast‐developing field.
Hydrogel‐based electrolytes, as one of the core components in energy storage devices, introduce flexibility and additional functions, such as stretchability and self‐healing, to the devices. Consequently, improved adaptability to sophisticated and dynamic working environments could be endowed with the devices. The recent advancement of hydrogel‐based electrolytes for flexible and functional energy storage devices is reviewed and discussed.
The formation energies of oxygen vacancies at different surface and subsurface sites of anatase (101), anatase (001), and rutile (110) surfaces are calculated by the screened-exchange (sX) hybrid ...functional method. Our results show that the oxygen vacancy is more stable on the surface than subsurface for rutile (110), while it is a more stable subsurface than on the surface for anatase surfaces. These results are similar to those found by simple density functional theory, but now the sX hybrid functional gives the correct defect localizations. The defects introduce a gap state near the conduction band edge. For the most stable oxygen vacancy site at each TiO2 surface, the +2 charge state dominates over a wide range of Fermi energies.
Current aqueous Zn batteries (ZBs) seriously suffer from dendrite issues caused by rough electrode surfaces. Despite significant efforts in prolonging lifespan of these batteries, little effort has ...been devoted to dendrite elimination in commercial‐grade cathode loading mass. Instead, demonstrations have only been done at the laboratory level (≤2 mg cm−2). Additionally, new dilemmas regarding change of the proton‐storage behavior and interface pulverization have emerged in turn. Herein, hydrogen‐substituted graphdiyne (HsGDY), with sub‐ångström level ion tunnels and robust chemical stability, is designed as an artificial interface layer to address these issues. This strategy prolongs the symmetric cell lifespan to >2400 h (100 days), which is 37 times larger than without protection (63 h). The simulation of dual fields reveals that HsGDY can redistribute the Zn2+ concentration field by spatially forcing Zn2+ to deviate from the irregular electric field. During practical use, the as‐assembled full batteries deliver a long lifespan 50 000 cycles and remain stable even at a commercial‐grade cathode loading mass of up to 22.95 mg cm−2. This HsGDY‐protection methodology represents great progress in Zn dendrite protection and demonstrates enormous potential in metal batteries.
Aqueous Zn‐based batteries suffering from the dendrite issue show a short lifespan, especially at commercial‐grade cathode loading mass. Hydrogen‐substituted graphdiyne with ion tunnels is employed to eliminate dendrites, based on ion redistribution, achieving a long lifespan of 10 000 cycles at a cathode loading mass of 22.95 mg cm−2. This work sheds light on tackling the dendrite issue encountered by metal batteries.
Recently, wearable electronic devices including electrical sensors, flexible displays, and health monitors have received considerable attention and experienced rapid progress. Wearable ...supercapacitors attract tremendous attention mainly due to their high stability, low cost, fast charging/discharging, and high efficiency; properties that render them value for developing fully flexible devices. In this Concept, the recent achievements and advances made in flexible and wearable supercapacitors are presented, especially highlighting the promising performances of yarn/fiber‐shaped and planar supercapacitors. On the basis of their working mechanism, electrode materials including carbon‐based materials, metal oxide‐based materials, and conductive polymers with an emphasis on the performance‐optimization method are introduced. The latest representative techniques and active materials of recently developed supercapacitors with superior performance are summarized. Furthermore, the designs of 1D and 2D electrodes are discussed according to their electrically conductive supporting materials. Finally, conclusions, challenges, and perspective in optimizing and developing the electrochemical performance and function of wearable supercapacitors for their practical utility are addressed.
The rapid development of wearable electronics including flexible displays, medical sensors, and portable power has become a notable technology trend. The latest development and advancement of flexible and wearable supercapacitors that could power flexible electronics are reviewed. The representative achievements based on different types of electrode materials are summarized. Furthermore, the design and assembly of yarn/fiber‐shaped and planar supercapacitors are introduced.
Lithium/sulfur （Li/S） cells have great potential to become mainstream secondary batteries due to their ultra-high theoretical specific energy. The major challenge for Li/S cells is the unstable ...cycling performance caused by the sulfur＇s insulating nature and the high-solubility of the intermediate polysulfide products. Several years of efforts to develop various fancy carbon nanostructures, trying to physically encapsulate the polysulfides, did not yet push the cell＇s cycle life long enough to compete with current Li ion cells. The focus of this review is on the recent progress in chemical bonding strategy for trapping polysulfides through employing functional groups and additives in carbon matrix. Research results on understanding the working mechanism of chemical interaction between polysulfides and functional groups （e.g. 0-, B-, N- and S-） in carbon matrix, metal-based additives, or polymer additives during charge/discharge are discussed.
The ever-growing demand of portable and wearable electric devices requires energy storage devices with flexibility and wearable compatibility while not sacrificing the performance too much. This ...requires the electrode and electrolyte materials becoming robust and durable under mechanical deformations, which grants the polymers with inherent advantages. Therefore, polymers for supercapacitors, either as substrate/matrix or active materials have received prime concerns. Viewing from the requirements of the flexible and wearable supercapacitors, this review provides an essential guidance to choose and/or design the proper polymer materials for both electrode and electrolyte. More importantly, supercapacitors with additional functions that are achieved by utilizing polymer materials are also specifically highlighted.
PDF
