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HighlightsThe Zn/MnO2 cell with inorganic colloidal electrolyte demonstrates unprecedented durability over 1000 cycles.For the cathode, the presence of the protective film can inhibit the dissolution of manganese element and the formation of irreversible by-products.For the anode, it can reduce the corrosion and de-solvation energy, inhibit the growth of dendrite and irreversible by-products.Zinc-ion batteries (ZIBs) is a promising electrical energy storage candidate due to its eco-friendliness, low cost, and intrinsic safety, but on the cathode the element dissolution and the formation of irreversible products, and on the anode the growth of dendrite as well as irreversible products hinder its practical application. Herein, we propose a new type of the inorganic highly concentrated colloidal electrolytes (HCCE) for ZIBs promoting simultaneous robust protection of both cathode/anode leading to an effective suppression of element dissolution, dendrite, and irreversible products growth. The new HCCE has high Zn2+ ion transference number (0.64) endowed by the limitation of SO42−, the competitive ion conductivity (1.1 × 10–2 S cm−1) and Zn2+ ion diffusion enabled by the uniform pore distribution (3.6 nm) and the limited free water. The Zn/HCCE/α-MnO2 cells exhibit high durability under both high and low current densities, which is almost 100% capacity retention at 200 mA g−1 after 400 cycles (290 mAh g−1) and 89% capacity retention under 500 mA g−1 after 1000 cycles (212 mAh g−1). Considering material sustainability and batteries’ high performances, the colloidal electrolyte may provide a feasible substitute beyond the liquid and all-solid-state electrolyte of ZIBs.

HighlightsThe interfacial engineering strategies of surface and electrolyte modifications for high-performance Zn metal anodes are reviewed.The reaction mechanisms for inhibiting dendrite growth and side reactions in interface engineering are systematically summarized.An outlook on future reference directions for new interface strategies to advance this field is provided.Due to their high safety and low cost, rechargeable aqueous Zn-ion batteries (RAZIBs) have been receiving increased attention and are expected to be the next generation of energy storage systems. However, metal Zn anodes exhibit a limited-service life and inferior reversibility owing to the issues of Zn dendrites and side reactions, which severely hinder the further development of RAZIBs. Researchers have attempted to design high-performance Zn anodes by interfacial engineering, including surface modification and the addition of electrolyte additives, to stabilize Zn anodes. The purpose is to achieve uniform Zn nucleation and flat Zn deposition by regulating the deposition behavior of Zn ions, which effectively improves the cycling stability of the Zn anode. This review comprehensively summarizes the reaction mechanisms of interfacial modification for inhibiting the growth of Zn dendrites and the occurrence of side reactions. In addition, the research progress of interfacial engineering strategies for RAZIBs is summarized and classified. Finally, prospects and suggestions are provided for the design of highly reversible Zn anodes.

The detrimental parasitic reactions and uncontrolled deposition behavior derived from inherently unstable interface have largely impeded the practical application of aqueous zinc batteries. So far, tremendous efforts have been devoted to tailoring interfaces, while stabilization of grain boundaries has received less attention. Here, we demonstrate that preferential distribution of intermetallic compounds at grain boundaries via an alloying strategy can substantially suppress intergranular corrosion. In-depth morphology analysis reveals their thermodynamic stability, ensuring sustainable potency. Furthermore, the hybrid nucleation and growth mode resulting from reduced Gibbs free energy contributes to the spatially uniform distribution of Zn nuclei, promoting the dense Zn deposition. These integrated merits enable a high Zn reversibility of 99.85% for over 4000 cycles, steady charge-discharge at 10 mA cm −2 , and impressive cyclability for roughly 3500 cycles in Zn-Ti//NH 4 V 4 O 10 full cell. Notably, the multi-layer pouch cell of 34 mAh maintains stable cycling for 500 cycles. This work highlights a fundamental understanding of microstructure and motivates the precise tuning of grain boundary characteristics to achieve highly reversible Zn anodes. The electrochemical performance of metal electrodes is significantly influenced by their grain boundary stability. Here, the authors propose a zinc-titanium two-phase alloy via grain boundary engineering to inhibit intergranular corrosion and tailor deposition behavior for stable aqueous zinc batteries.

The optimization of crystalline orientation of a Zn metal substrate to expose more Zn(0002) planes has been recognized as an effective strategy in pursuit of highly reversible Zn metal anodes. However, the lattice mismatch between substrate and overgrowth crystals has hampered the epitaxial sustainability of Zn metal. Herein, we discover that the presence of crystal grains deviating from [0001] orientation within a Zn(0002) metal anode leads to the failure of epitaxial mechanism. The electrodeposited [0001]-uniaxial oriented Zn metal anodes with a single (0002) texture fundamentally eliminate the lattice mismatch and achieve ultra-sustainable homoepitaxial growth. Using high-angle angular dark-filed scanning transmission electron microscopy, we elucidate the homoepitaxial growth of the deposited Zn following the “~ABABAB~” arrangement on the Zn(0002) metal from an atomic-level perspective. Such consistently epitaxial behavior of Zn metal retards dendrite formation and enables improved cycling, even in Zn||NH 4 V 4 O 10 pouch cells, with a high capacity of 220 mAh g −1 for over 450 cycles. The insights gained from this work on the [0001]-oriented Zn metal anode and its persistently homoepitaxial mechanism pave the way for other metal electrodes with high reversibility. The authors present a single [0001]-oriented Zn metal anode with high reversibility and demonstrate the significance of the Zn(0002) metal anode, characterized by a single crystalline orientation, for promoting ultra-sustainable homoepitaxial growth.

As a promising hydrogen carrier, formic acid (HCOOH) is renewable, safe and nontoxic. Although noble-metal-based catalysts have exhibited excellent activity in HCOOH dehydrogenation, developing non-noble-metal heterogeneous catalysts with high efficiency remains a great challenge. Here, we modulate oxygen coverage on the surface of Ti 3 C 2 T x MXenes to boost the catalytic activity toward HCOOH dehydrogenation. Impressively, Ti 3 C 2 T x MXenes after treating with air at 250 °C (Ti 3 C 2 T x -250) significantly increase the amount of surface oxygen atoms without the change of crystalline structure, exhibiting a mass activity of 365 mmol·g −1 ·h −1 with 100% of selectivity for H 2 at 80 °C, which is 2.2 and 2.0 times that of commercial Pd/C and Pt/C, respectively. Further mechanistic studies demonstrate that HCOO* is the intermediate in HCOOH dehydrogenation over Ti 3 C 2 T x MXenes with different coverages of surface oxygen atoms. Increasing the oxygen coverage on the surface of Ti 3 C 2 T x MXenes not only promotes the conversion from HCOO* to CO 2 * by lowering the energy barrier, but also weakens the adsorption energy of CO 2 and H 2 , thus accelerating the dehydrogenation of HCOOH. Developing non-noble-metal heterogeneous catalysts with high efficiency in HCOOH dehydrogenation is significant for the acquisition of hydrogen, but remains a great challenge. Here, the authors modulate oxygen coverage of Ti 3 C 2 T x MXenes to boost the catalytic activity toward HCOOH dehydrogenation.

Developing practical technical index of aqueous zinc metal batteries (ZMBs) is crucial to support safe large-scale energy storage. However, the realistic performance demonstration of ampere hour (Ah)-scale aqueous ZMBs under high mass loading and large areal capacity, which is the key to the industrial application of aqueous ZMBs, remains a critical challenge. In this paper, we propose a bilateral in-situ functionalization strategy in response to the issues that face high mass loading and large areal capacity of aqueous ZMBs. A gradient interface of Zn negative electrode was formed by directional adsorption and in-situ decomposition of organic sodium salt electrolyte additive. It avoids the influences from the fluctuation of electrolyte state and positive electrode dissolution, realizing uniform large-capacity plating/stripping in Ah-scale pouch cell. The positive electrode interface was also in-situ modified by electrolyte additive, which not only facilitated ion intercalation but also suppressed positive electrode dissolution through adsorption at the interface, thereby achieving high-loading stability. As a result, the cyclic stability in coin cell maintained more than 4000 cycles at 2 A g −1 , underscoring the superior compared to its counterpart. More importantly, the Ah-scale pouch cell can last more than 680 cycles with an accumulated capacity of 319.6 Ah. This work offers a roadmap for designing practical Ah-scale ZMB pouch cells. Large capacity vanadium-based aqueous zinc batteries present significant challenges at both electrodes. Here, authors propose a bifacial in-situ modification strategy to alleviate both severe vanadium dissolution and zinc dendrite growth, thereby enabling large capacity aqueous zinc metal batteries.

Highlights We first report on H 11 Al 2 V 6 O 23.2 with large layer spacing as cathode for aqueous zinc-ion battery, which accelerates the diffusion of Zn 2+ . The graphene-wrapped H 11 Al 2 V 6 O 23.2 nanobelts can improve electronic conductivity, and potentially inhibit the dissolution of elements in the aqueous electrolyte. H 11 Al 2 V 6 O 23.2 @graphene exhibits high capacity and stable cycling stability even at an ultra-high mass loading of ~ 15.7 mg cm −2 . Rechargeable aqueous zinc-ion batteries (AZIBs) have their unique advantages of cost efficiency, high safety, and environmental friendliness. However, challenges facing the cathode materials include whether they can remain chemically stable in aqueous electrolyte and provide a robust structure for the storage of Zn 2+ . Here, we report on H 11 Al 2 V 6 O 23.2 @graphene (HAVO@G) with exceptionally large layer spacing of (001) plane (13.36 Å). The graphene-wrapped structure can keep the structure stable during discharge/charge process, thereby promoting the inhibition of the dissolution of elements in the aqueous electrolyte. While used as cathode for AZIBs, HAVO@G electrode delivers ideal rate performance (reversible capacity of 305.4, 276.6, 230.0, 201.7, 180.6 mAh g −1 at current densities between 1 and 10 A g −1 ). Remarkably, the electrode exhibits excellent and stable cycling stability even at a high loading mass of ~ 15.7 mg cm −2 , with an ideal reversible capacity of 131.7 mAh g −1 after 400 cycles at 2 A g −1 .

HighlightsSmall cobalt nanoparticles are carefully encapsulated into a N-doped carbon shell (Co-NC) by calcining a Prussian blue analogue precursor.The presence of cobalt nanoparticles and Co-N bonds not only promotes adsorption behavior, but also reduces the diffusion energy barrier, enabling fast diffusion kinetics of K+ ions.The good diffusion kinetics and capacitive adsorption behavior of the Co-NC material synergistically contributes to enhanced potassium storage performances.Potassium-ion batteries (KIBs) have great potential for applications in large-scale energy storage devices. However, the larger radius of K+ leads to sluggish kinetics and inferior cycling performance, severely restricting its practical applicability. Herein, we propose a rational strategy involving a Prussian blue analogue-derived graphitized carbon anode with fast and durable potassium storage capability, which is constructed by encapsulating cobalt nanoparticles in nitrogen-doped graphitized carbon (Co-NC). Both experimental and theoretical results show that N-doping effectively promotes the uniform dispersion of cobalt nanoparticles in the carbon matrix through Co–N bonds. Moreover, the cobalt nanoparticles and strong Co–N bonds synergistically form a three-dimensional conductive network, increase the number of adsorption sites, and reduce the diffusion energy barrier, thereby facilitating the adsorption and the diffusion kinetics. These multiple effects lead to enhanced reversible capacities of 305 and 208.6 mAh g−1 after 100 and 300 cycles at 0.05 and 0.1 A g−1, respectively, demonstrating the applicability of the Co-NC anode for KIBs.

HighlightsA novel hydrogel with high water retention and Zn2+ transference number of 0.604 was constructed by copolymerizing sulfobetaine and acrylamide in Zn(ClO4)2 solution.The designed electrolyte configuration enables in situ generation of the organic–inorganic hybrid interface, which contributes to the electrodeposition uniformity and corrosion resistance of the anode.Zn–Zn and Zn–MnO2 cells based on hydrogel electrolyte exhibit outstanding cycling stability (over 3000 h under 0.5 mA cm−2/0.5 mAh cm−2 after two-time shelving).Aqueous zinc metal batteries are noted for their cost-effectiveness, safety and environmental friendliness. However, the water-induced notorious issues such as continuous electrolyte decomposition and uneven Zn electrochemical deposition remarkably restrict the development of the long-life zinc metal batteries. In this study, zwitterionic sulfobetaine is introduced to copolymerize with acrylamide in zinc perchlorate (Zn(ClO4)2) solution. The designed gel framework with hydrophilic and charged groups can firmly anchor water molecules and construct ion migration channels to accelerate ion transport. The in situ generated hybrid interface, which is composed of the organic functionalized outer layer and inorganic Cl− containing inner layer, can synergically lower the mass transfer overpotential, reduce water-related side reactions and lead to uniform Zn deposition. Such a novel electrolyte configuration enables Zn//Zn cells with an ultra-long cycling life of over 3000 h and a low polarization potential (~ 0.03 V) and Zn//Cu cells with high Coulombic efficiency of 99.18% for 1000 cycles. Full cells matched with MnO2 cathodes delivered laudable cycling stability and impressive shelving ability. Besides, the flexible quasi-solid-state batteries which are equipped with the anti-vandalism ability (such as cutting, hammering and soaking) can successfully power the LED simultaneously. Such a safe, processable and durable hydrogel promises significant application potential for long-life flexible electronic devices.

Highlights Hollow V 4+ -V 2 O 5 nanospheres are prepared by a novel and simple method using VOOH as the precursor. V 4+ -V 2 O 5 with mixed vanadium valences is firstly constructed as an electrochemically active cathode for aqueous zinc-ion batteries. The V 4+ -V 2 O 5 cathode exhibits a prominent cycling performance up to 1000 cycles and an excellent rate capability. A V 4+ -V 2 O 5 cathode with mixed vanadium valences was prepared via a novel synthetic method using VOOH as the precursor, and its zinc-ion storage performance was evaluated. The products are hollow spheres consisting of nanoflakes. The V 4+ -V 2 O 5 cathode exhibits a prominent cycling performance, with a specific capacity of 140 mAh g −1 after 1000 cycles at 10 A g −1 , and an excellent rate capability. The good electrochemical performance is attributed to the presence of V 4+ , which leads to higher electrochemical activity, lower polarization, faster ion diffusion, and higher electrical conductivity than V 2 O 5 without V 4+ . This engineering strategy of valence state manipulation may pave the way for designing high-performance cathodes for elucidating advanced battery chemistry.