Tremella-like Hydrated Vanadium Oxide Cathode with an Architectural Design Strategy toward Ultralong Lifespan Aqueous Zinc-Ion Batteries

Multi-metal ions co-regulated vanadium oxide cathode toward long-life aqueous zinc-ion batteries

Interlayer intercalation engineering shows great feasibility to improve the structure stability of the layered oxides. Although high Zn-storage capability has been attained based on the pillar effect of multifarious intercalants, an in-depth understanding the synergistic effect of intercalated multiple metal ions is still in deficiency. Herein, alkali metal ion K+, alkaline earth metal ion Mg2+ and trivalent metal ion Al3+ are introduced into the VO interlayer of V2O5. Due to the different electronegativity and hydrated ion radius of K+, Mg2+ and Al3+, adjusting the relative proportions of these metal ions can achieve an appropriate interlayer spacing, stable layer structure and regular morphology, which facilitates the transport kinetics of Zn2+. Under the synergistic effect of pre-intercalated multi-metal ion, the optimal tri-metal ion intercalated hydrated V2O5 cathode exhibits a high specific capacity of 382.4 mAh g-1 at 0.5 A g-1, and long-term cycling stability with capacity retention of 86 % after 2000 cycles at the high current density of 10 A g-1. Ex-situ and kinetic characterizations reveal the fast charge transfer and reversible Zn2+ intercalation mechanism. The multi-ion engineering strategy provides an effective way to design desirable layered cathode materials for aqueous zinc-ion batteries.

Tailoring vanadium oxide crystal orientation for high-performance aqueous zinc-ion batteries

Due to the increasing demand for higher security and low-cost energy storage systems, the main research focus has been developing a suitable substitute for lithium-ion batteries. Aqueous zinc ion batteries (AZIBs) are considered the best alternative to lithium-ion batteries in large-scale energy storage devices. Owing to its high capacity, vanadate is a promising cathode material for AZIBs. The crystallographic orientation of cathode materials dramatically influences the rate performance and cycling life. Here, Mg0.57V5O12·2.3H2O (MgVO) with favorable (001) crystal orientation and significantly improved electrochemical performance is prepared by a simple stirring method. The crystal growth orientations of MgVO are altered by adjusting the aging time of the reactant solution. The (001)-orientated grain growth of MgVO delivers a 232.5 mA h g-1 capacity at 5 A g-1 with a 94% capacity retention rate after 1400 cycles. The zinc ion storage performance of MgVO demonstrates that the orientation-controlled method can design effective cathode materials for high-performance ZIBs.

Manipulating Zn Metal Texture with Guided Zincophilic Sites via Electrochemical Stripping for Dendrite-Free Zn Anodes

Constructing a three-dimensional (3D) structure along with Zn (002) texture selective exposure is a promising strategy to tackle the issues faced by Zn metal anodes. Herein, for the first time, we proposed an electrochemical stripping strategy to achieve controlled modification of the texture and microstructure of zinc foils in one step, building a hierarchical structure with (002) texture preferred exposed Zn (SZ). The SZ with favorable zincophilic properties not only can reduce the concentration polarization at the interface but also allow Zn to grow horizontally on the edge of the (002) texture by guiding the adsorption sites for Zn2+. Moreover, the honeycomb-like structure is beneficial to rearrange the distribution of the Zn2+ flux as well as alleviating stress changes during cycling. Thus, the SZ||Cu cell exhibits excellent stability with a Coulombic efficiency of 99.76% over 1800 cycles. The SZ||NaV3O8·xH2O cell with inconspicuous self-discharge effect maintains a high areal capacity of 3.67 mA h cm-2 even after 700 cycles with a low N/P ratio of 3.6. This work achieves texture architecture and structure designing on Zn foils simultaneously by metallurgical electrochemical methods and opens up a potential strategy to implement the practicality of zinc metal anodes.

Tremella-like Vanadium Tetrasulfide as a High-Performance Cathode Material for Rechargeable Aluminum Batteries

Rechargeable aluminum batteries (RABs) are gaining widespread attention for large-scale energy storage applications as a result of their high energy densities, high security, and abundance. The key to sustain the progress of RABs lies in the quest for the proper cathode materials with prominent capacity and reversible cycle life. Herein, we propose a tremella-like VS₄ as a cathode material aiming to tackle this problem. Obtained from a morphology modification process, VS₄ with a unique nanosheet structure provides sufficient active sites for intercalation and conversion reactions, shortens the transport paths for charge carrier ions, and facilitates the infiltration process for electrolyte. The RAB with the VS₄ cathode exhibits excellent electrochemical performance, including outstanding specific capacity (407.9 mAh g^-1) and stable cycling performance (∼300 cycles at a high current density). The energy storage mechanism has been comprehensively investigated and is confirmed to be a combination of the intercalation/deintercalation of Al³⁺ and AlCl₄^- ions and conversion reaction by various techniques and DFT calculation. Our study not only provides a peculiar and simple strategy for the rational design of metal sulfide cathode materials with high capacity and long-term stability but also proposes a specific energy storage mechanism that guides the development of cathode materials of RABs in the future.

Multifunctional Electrolyte Additive Enables Highly Reversible Anodes and Enhanced Stable Cathodes for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) are charming devices for large-scale power grid energy storage because of their characteristics of environment friendliness, low cost, high abundance, and safe operation. However, the inferior reversibility of the anode and the loss of cathode capacity always hinder the application of AZIBs. Herein, we propose a simple multifunctional electrolyte additive, diethylenetriamine (DETA), which can inhibit the formation of zinc dendrites and the occurrence of side reactions on the anode, reconstruct the solvated structure and uniform ion flux in the electrolyte, restrain the dissolution of active materials, and induce the crystal transformation on the cathode concurrently. Molecular dynamics Simulation and density functional theory both verified the extraordinary efficacy of DETA. With the assistance of DETA, the Zn anode gained a life of up to 2000 h, and the cathode with commercial V₂O₅ retained a capacity of 125.2 mA h g^-1 at the 1000th discharge process. From the perspective of practical application, this work can open up the application prospect of AZIBs in large-scale energy storage and provide reference for the subsequent works. The findings will greatly promote the application of AZIBs in large-scale energy storage and provide more inspiration for future research.

Recent Advances and Challenges Toward Application of Fibers and Textiles in Integrated Photovoltaic Energy Storage Devices

Flexible microelectronic devices have seen an increasing trend toward development of miniaturized, portable, and integrated devices as wearable electronics which have the requirement for being light weight, small in dimension, and suppleness. Traditional three-dimensional (3D) and two-dimensional (2D) electronics gadgets fail to effectively comply with these necessities owing to their stiffness and large weights. Investigations have come up with a new family of one-dimensional (1D) flexible and fiber-based electronic devices (FBEDs) comprising power storage, energy-scavenging, implantable sensing, and flexible displays gadgets. However, development and manufacturing are still a challenge owing to their small radius, flexibility, low weight, weave ability and integration in textile electronics. This paper will provide a detailed review on the importance of substrates in electronic devices, intrinsic property requirements, fabrication classification and applications in energy harvesting, energy storage and other flexible electronic devices. Fiber- and textile-based electronic devices for bulk/scalable fabrications, encapsulation, and testing are reviewed and presented future research ideas to enhance the commercialization of these fiber-based electronics devices.

Open-Framework Metal Oxides for Fast and Reversible Hydrated Zinc-Ion Intercalation

The development of high capacity and stable cathodes is the key to the successful commercialization of aqueous zinc-ion batteries. However, significant solvation penalties limit the choice of available positive electrodes. Herein, hydrated intercalation is proposed to promote reversible (de)intercalation within host materials by rationally designing a matching electrode. In contrast to previously reported works, the as-prepared electrode (NHVO@CC) can achieve fast and reversible intercalation of hydrated zinc ions in the interlayer gap, leading to a high capacity of 517 mAh g^-1 at 0.1 A g^-1 and excellent electrode stability for long-term cycling. Besides, as a consequence of the flexibility of the NHVO@CC electrode, a quasi-solid-state battery was achieved with equally advantageous electrochemical behavior under various bending states. The proposed hydrated cation direct insertion/extraction sets up an efficient way of developing high-performance positive electrodes for aqueous batteries.

A Comprehensive Understanding of Interlayer Engineering in Layered Manganese and Vanadium Cathodes for Aqueous Zn-ion Batteries

Rechargeable aqueous zinc-ion batteries (AZIBs) hold a budding technology for large-scale stationary energy storage devices due to their inherent safety, cost-effectiveness, eco-friendly, and acceptable electrochemical performance. However, developing a cathode material with fast kinetics and durable structural stability for Zn 2+ intercalation is still an arduous challenge. Compared with other cathode materials, layered manganese/vanadium (Mn/V) oxides that feature merits of adjustable interlayer spacing and considerable specific capacity have attracted much interest in AZIBs. However, the intrinsic sluggish reaction kinetics, inferior electrical conductivity, and notorious dissolution of active materials still obstruct the realization of their full potentials. Interlayer engineering of pre-intercalation is regarded as an effective solution to overcome these problems. In this review, we start from the crystal structure and reaction mechanism of layered Mn/V oxide cathodes to critical issues and recent progress in interlayer engineering. Finally, some future perspectives are outlined for the development of high-performance AZIBs.