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Employing metal anodes can greatly increase volumetric/gravimetric energy density versus a conventional ion-insertion anode. However, metal anodes are plagued by dendrites, corrosion, and interfacial side reactions issues. Herein, a compact and flexible amorphous MOF layer was successfully synthesized and used as protective layer on metal anode aqueous zinc-ion battery (AZIB). Compared with the crystalline MOF layer, the unique amorphous MOF layer can inhibit dendrite growth at the grain boundary and eliminate ions migration near the grain boundary, showing high interfacial adhesion and large ion migration number (tZn2+ = 0.82). Besides, the amorphous MOF layer can effectively depress unfavored behaviors, e.g., corrosion of zinc anode, hydrogen evolution reaction, and dendrite growth on zinc surface. The prepared Zn anode with the amorphous MOF layer exhibited an ultra-long cycle life (ten months, 7000 h) and a low voltage (< 40 mV) at 1 mA cm-2 in a symmetrical cell. Even at 10 mA cm-2, it still showed a high stability for more than 5500 cycles (1200 h). The enhanced performance is realized for full cells paired with a MnO2 cathode. Besides, a flexible symmetrical battery with the Zn@A-ZIF-8 anode exhibited a good cyclability under different bending angle (0°, 90°, and 180°). Moreover, various metal substrates were successfully coated with compact A-ZIF-8. The A-ZIF-8 layer can obviously improve the stability metal anodes, including Zn, Mg and Al. The results not only demonstrate the high potential of amorphous MOFs decorated Zn anodes for AZIBs, but also propose a new family of protective layers for metal anodes.

By manipulating the Zn2+ coordination environment, electrolytes with diverse Zn2+–En configurations effectively inhibit zinc dendrite growth and side reactions.

The slow hydrogen oxidation reaction (HOR) kinetics under alkaline conditions remains a critical challenge for the practical application of alkaline exchange membrane fuel cells. Herein, we design Ru/RuO

Poor cyclic stability and low rate performance due to dramatic volume change and low intrinsic electronic conductivity are the two key issues needing to be urgently solved in silicon (Si)-based anodes for lithium-ion batteries. Herein, a novel tin (Sn)-bonded Si anode is proposed for the first time. Sn, which has a high electronic conductivity, is used to bond the Si-anode material and copper (Cu) current collector together using a hot-pressed method with a temperature slightly above the melting point of Sn. The cycling performance of the electrode is studied using a galvanostatic method. Nanoindentation and peeling tests are conducted to measure the mechanical strength of the electrodes. Direct current polarization and galvanostatic intermittent titration techniques are applied to assess the conductivity of the composites. Electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy are conducted to evaluate the effect of the coating layer on the cycling ability of the composites. The Sn-bonded Si anodes show superior cycling stability and high rate performance with an improved initial Coulombic efficiency. Analyses reveal that the low-melting-point Sn helps to markedly improve the electronic conductivity of the electrodes and serves as a metallic binder as well to enhance the adhesive strength of the electrode. It is hopeful that this novel Sn-bonded Si anode provides a new insight for the development of advanced Si-based anodes for LIBs.

A major fraction of secondary energy consumed for our daily activities, such as electricity and low-grade heat sources, emanates from the conversion of fossil fuels in power plants. In the seawater desalination processes, the energy efficiency is usually expressed in kWh electricity or kWh of low-grade heat per unit volume of water produced. Although kWh energy unit provides a quantitative measure of input energy, it has subtly omitted the embedded quality of supplied energy to desalination plants. In assuming the equivalency across dissimilar energy forms, it results in a thermodynamic misconception that has eluded the desalination industry hitherto, i.e., not all units of derived energy are created equal. An incomplete energy efficacy approach may result in the inferior selection of desalination processes to be deployed;—a phenomenon observed in the trend of installed desalination capacity globally. Operating a less efficient desalination plant over its lifespan would create much economic burdens including a higher unit cost of water, higher CO2 emissions and greater brine discharge to the environment. This book chapter clarifies the key concept and a thermodynamic framework to rectify the misconception in energy consumption, permitting energy planners and designers to optimize deployment of future desalination plants for energy sustainability. We have derived conversion factors to convert assorted derived energies into standard primary energy for fair comparison.

ispartof: ACS MATERIALS LETTERS vol:4 issue:9 pages:1721-1725 status: published

By using ethylenediamine (En) as a complexing agent, the impact of various Zn

Hydrogen production from water electrolysis is severely restricted by the poor reaction kinetics of oxygen evolution reaction (OER). In this work, a series of two-dimensional (2D) composites MOF/Ti

Precise manipulation of the interactions between different components represents the frontier of heterostructured electrocatalysts and is crucial to understanding the structure-function relationship. Current studies, however, are quite limited. Here, we report targeted modulation of the atomic-level interface chemistry of Pt/NiO heterostructure via an annealing treatment, which results in substantially enhanced hydrogen electrocatalysis kinetics in alkaline media. Specifically, the optimized Pt/NiO heterostructure delivers by far the highest specific exchange current density of 8.1 mA cmPt-2 for hydrogen oxidation reaction. X-ray spectroscopy results suggest Pt-Ni interfacial bonds are formed after annealing, inducing more significant electron transfer from NiO to Pt. Also, the regulated interface chemistry, as proven by theoretical calculations, optimizes the binding behaviors of hydrogen and hydroxyl species. These findings emphasize the importance of interface engineering at the atomic level and inspire further explorations of heterostructured electrocatalysts.

Boosting the alkaline hydrogen evolution and oxidation reaction (HER/HOR) kinetics is vital to practicing the renewable hydrogen cycle in alkaline media. Recently, intensive research has demonstrated that interface engineering is of critical significance for improving the performance of heterostructured electrocatalysts particularly toward the electrochemical reactions involving multiple reaction intermediates like alkaline hydrogen electrocatalysis, and the research advances also bring substantial non-trivial fundamental insights accordingly. Herein, we review the current status of interface engineering with respect to developing efficient heterostructured electrocatalysts for alkaline HER and HOR. Two major subjects—how interface engineering promotes the reaction kinetics and what fundamental insights interface engineering has brought into alkaline HER and HOR—are discussed. Specifically, heterostructured electrocatalysts with abundant interfaces have shown substantially accelerated alkaline hydrogen electrocatalysis kinetics owing to the synergistic effect from different components, which could balance the adsorption/desorption behaviors of the intermediates at the interfaces. Meanwhile, interface engineering can effectively tune the electronic structures of the active sites via electronic interaction, interfacial bonding, and lattice strain, which would appropriately optimize the binding energy of targeted intermediates like hydrogen. Furthermore, the confinement effect is critical for delivering high durability by sustaining high density of active sites. At last, our own perspectives on the challenges and opportunities toward developing efficient heterostructured electrocatalysts for alkaline hydrogen electrocatalysis are provided.

The cathode materials for sodium ion batteries (SIBs) are intrinsically unstable due to their oxidation by electrolyte solution at high voltage; thus, developing novel solid permeable interfaces as passivation layers is critical to avoid these side oxidation reactions and increase the cycling durability of SIBs. Nevertheless, the abuse of passivation layers can hinder the Na+ transfer and further impact the rate capability. Herein, we demonstrated an effective approach that utilized konjac glucomannan (KGM) biopolymer as a multifunctional binder to build stable solid permeable interface films to achieve high-performance for Na3V2(PO4)3/C (NVP) cathodes. Compared with polyvinylidene difluoride (PVDF), the strong adhesion and solid permeable interface films of KGM protect the integrity of the electrodes. The unique conductive network and rich polar functional groups enable KGM to enhance the transfer of electrons and Na+ ions at the interfaces. Thanks to the multiple functions of KGM offering adhesion strength, a conductive network and a solid permeable interface, the NVP cathode exhibited a reversible capacity of 108.0 mA h g−1 at 0.5C (1C = 117 mA g−1). At a high rate of 50C, NVP profited from KGM to show a good capacity of 63.1 mA h g−1 and a high durability of 10 000 cycles with a small fading rate of 0.00259% per cycle. Hard carbon‖NVP full batteries, using KGM as the cathode binder, possessed a high specific energy of 137.7 W h kg−1, indicating the potential applications of KGM as an environmentally friendly binder for achieving high-rate capacity and long-term cycling durability of SIBs.

The creation of drag-reducing surfaces in deformed tubes is of vital importance to thermal management, energy, and environmental applications. However, it remains a great challenge to tailor the surface structure and wettability inside the deformed tubes of slim and complicated feature. Here, we describe an electrochemical anodization strategy to achieve uniform and superhydrophobic coating of TiO2 nanotube arrays throughout the inner surface in deformed/bend titanium tubes. Guided by a hybrid carbon fibre cathode, conformal electric field can be generated to adaptatively fit the complex geometries in the deformed tube, where the structural design with rigid insulating beads can self-stabilize the hybrid cathode at the coaxial position of the tube with the electrolyte flow. As a result, we obtain a superhydrophobic coating with a water contact angle of 157° and contact angle hysteresis of less than 10°. Substantial drag reduction can be realised with an overall reduction up to 25.8 % for the anodized U-shaped tube. Furthermore, we demonstrate to spatially coat tubes with complex geometries, to achieve energy-saving liquid transportation. This facile coating strategy has great implications in liquid transport processes with the user-friendly approach to engineer surface regardless of the deformation of tube/pipe.

Recently, resonance coupling between plasmonic nanocavity and two-dimensional semiconductors has attracted considerable attention. Most of the previous studies have focused on demonstrating this effect with light scattering or reflection spectroscopy, while the photoluminescence (PL) spectrum can help ascertain the underlying physics. Here, we report on the light-emitting characteristics of a monolayer WS2 flake coupled with a plasmonic gold nanorod. We construct a heterostructure by integrating an individual gold nanorod on top of a small piece of monolayer WS2, where the WS2 area is determined by the projected area of the nanorod. In such a heterostructure, the background PL from the uncoupled WS2 can be suppressed, which allows us to characterize the resonance coupling effect using correlated single-particle dark-field (DF) scattering and PL spectroscopies. Distinct mode splitting and anticrossing dispersion are observed in the scattering spectra, which originate from the resonance coupling between the excitons in the WS2 and plasmon resonance in the gold nanorod. In addition, a 1187-fold enhancement is obtained for the light emitted from the heterostructure relative to that of the pristine monolayer WS2. The emission spectra are broadened with mode-splitting features at room temperature, which can be further decomposed into two resonance modes using a coupled mode analysis. Moreover, two PL modes are polarized along the longitudinal axis of the gold nanorod. These findings show the potential of the designed individual gold nanorod-monolayer WS2 heterostructure as a platform for studying the resonance coupling effect between plasmon resonance and two-dimensional excitons.

The pursuit for high-energy and intrinsically safe energy storage is significantly driving the development of solid-state alkali metal batteries. The interfacial contact between the metal anode and the solid electrolyte plays a key role in enabling stable cycling of solid batteries. However, the sluggish alkali atom replenishment rate during stripping unavoidably leads to the interface deterioration that destroys the initial physical contact by forming interfacial voids and triggering the dendrite growth. Herein, a hybrid bulk Na anode approach is proposed by incorporating an ion-conducting phase into a metallic Na matrix, constructing an abundant interfacial electrochemical reaction area and enabling a balanced Na replenishment and consumption to minimize cycle-induced interface deterioration. Specific attention is paid to the effects of the second phase on the wettability and creep ability of hybrid Na metal. A high critical current density (3.1 mA cm-2) and long cycling life (6000 h in 0.5 mA cm-2) are achieved for the symmetric cells. Full cells coupling the hybrid anode with the Na3V2(PO4)3/C cathode deliver excellent cyclability over 7300 cycles at a high rate of 5 C. The viewpoint of balancing the consumption and replenishment rate of metal atoms paves a new way for designing cycle-stable anode/electrolyte interface in solid-state batteries.

Future innovations and developments in advanced rechargeable batteries require atomic-scale observation and understanding of the failure mechanisms of secondary batteries. Unfortunately, battery chemistry is highly sensitive to air or moisture and cannot stand electron beam radiation at high dose rates essential for atomic-scale resolution, hence limiting the use of conventional electron or optical microscopes. Recently, cryogenic electron microscopy (cryo-EM) has shown that battery-sensitive materials and interface/interphases can be protected, stabilized, and imaged under cryogenic conditions, facilitating novel insights into key components and phenomena that have a substantial impact on the cell operation. Herein, we highlight the significance and essential role of cryo-EM in characterizing sensitive battery materials (such as Li/Na/K metal anodes, sulfur, lithiated silicon, etc.), key components and interfaces, and summarize the recent contributions and discoveries enabled by cryo-EM. The chemistries and evolving nanostructures at electrode/electrolyte interphase in various electrolytes (both solid and liquid), hosts, artificial interphases, and temperature ranges for lithium-based batteries, and beyond are discussed in detail. Finally, the conclusions and the perspectives on the future direction of cryo-EM in analyzing the battery materials and interfaces are briefly discussed. We believe that the insights and discoveries obtained from this characterizing tool will provide guidelines for developing energy materials with improved electrochemical performance.

Li- and Mn-rich layered oxides (LMROs) are considered the most promising cathode candidates for next-generation high-energy lithium-ion batteries. The poor cycling stability and fast voltage fading resulting from oxygen release during charging, however, severely hinders their practical application. Herein, a strategy of introducing an additional redox couple is proposed to eliminate the persistent problem of oxygen release. As a proof of concept, the cycling stability of Li

Comparing with the massive efforts in developing innovative catalyst materials system and technologies, structural design of cells has attracted less attention on the road toward high‐performance electrochemical CO2 reduction reaction (eCO2RR). Herein, a hybrid gas diffusion electrode‐based reaction cell is proposed using highly porous carbon paper (CP) and graphene aerogels (GAs), which is expected to offer directional diffusion of gas molecules onto the catalyst bed, to sustain a high performance in CO2 conversion. The above‐mentioned hypothesis is supported by the experimental and simulation results, which show that the CP + GA combined configuration increases the Faraday efficiency (FE) from ≈60% to over 94% toward carbon monoxide (CO) and formate production compared with a CP only cell with Cu2O as the catalyst. It also suppresses the undesirable side reaction–hydrogen evolution over 65 times than the conventional H‐type cell (H‐cell). By combining with advanced catalysts with high selectivity, a 100% FE of the cell with a high current density can be realized. The described strategy sheds an extra light on future development of eCO2RR with a structural design of cell‐enabled high CO2 conversion.

Rechargeable aqueous Zn-ion battery has been considered as a key complement to the existing battery technologies due to its intrinsic merits such as operational safety and cost saving. However, issues of dendrite growth and accompanied water consumption hinder its further development. In this work, we utilize a chelating agent, 2-Bis(2-hydroxyethyl) amino-2-(hydroxymethyl)-1,3-propanediol (BIS-TRIS), to regulate the solvation sheath structure of Zn2+. Benefiting from such zinc-chelating coordination, Zn2+ 2D diffusion can be restricted and the altered deposition kinetic has contributed to the inhibition of the dendrite growth. In addition, partial substitution of water in solvation shell with chelator can also greatly suppress the competitive hydrogen evolution reaction (HER). Consequently, a stable symmetric Zn cell with lifetime more than 1000 h at a current density of 1 mA cm−2 is achieved. Moreover, the aqueous Zn/MnO2 battery with BIS-TRIS as electrolyte additive delivers an 86% capacity retention after 600 cycles at 500 mA g−1. This zinc-chelating coordination based facile strategy opens a new window for the future development in dendrite-free Zn anode.

Highlights A cooperative solvation/surface engineering approach is reported to achieve the reversible Mg plating/stripping in conventional carbonate electrolytes.Benefitting from the strategy, Mg2+ can easily overcome the reduced desolvation barrier and penetrate the Mg2+-conducting polymer coating, deposited on the Mg metal anode successfully, promoting the application of magnesium anode in carbonate electrolytes toward high-energy rechargeable batteries. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00716-1., Magnesium metal anode holds great potentials toward future high energy and safe rechargeable magnesium battery technology due to its divalent redox and dendrite-free nature. Electrolytes based on Lewis acid chemistry enable the reversible Mg plating/stripping, while they fail to match most cathode materials toward high-voltage magnesium batteries. Herein, reversible Mg plating/stripping is achieved in conventional carbonate electrolytes enabled by the cooperative solvation/surface engineering. Strongly electronegative Cl from the MgCl2 additive of electrolyte impairs the Mg…O = C interaction to reduce the Mg2+ desolvation barrier for accelerated redox kinetics, while the Mg2+-conducting polymer coating on the Mg surface ensures the facile Mg2+ migration and the effective isolation of electrolytes. As a result, reversible plating and stripping of Mg is demonstrated with a low overpotential of 0.7 V up to 2000 cycles. Moreover, benefitting from the wide electrochemical window of carbonate electrolytes, high-voltage (> 2.0 V) rechargeable magnesium batteries are achieved through assembling the electrode couple of Mg metal anode and Prussian blue-based cathodes. The present work provides a cooperative engineering strategy to promote the application of magnesium anode in carbonate electrolytes toward high energy rechargeable batteries. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00716-1.

The electrochemical conversion reaction, usually featured by multiple redox processes and high specific capacity, holds great promise in developing high-energy rechargeable battery technologies. However, the complete structural change accompanied by spontaneous atomic migration and volume variation during the charge/discharge cycle leads to electrode disintegration and performance degradation, therefore severely restricting the application of conventional conversion-type electrodes. Herein, latticed-confined conversion chemistry is proposed, where the "intercalation-like" redox behavior is realized on the electrode with a "conversion-like" high capacity. By delicately formulating the high-entropy compounds, the pristine crystal structure can be preserved by the inert lattice framework, thus enabling an ultra-high initial Coulombic efficiency of 92.5% and a long cycling lifespan over a thousand cycles after the quasistatic charge-discharge cycle. This lattice-confined conversion chemistry unfolds a ubiquitous insight into the localized redox reaction and sheds light on developing high-performance electrodes toward next-generation high-energy rechargeable batteries.

Electrocatalysts with high activity and long-term stability for the hydrogen oxidation reaction (HOR) under alkaline conditions is still a major challenge for anion exchange membrane fuel cells (AEMFCs). Herein, a heterostructured Ir@Pd electrocatalyst with ultrasmall Ir nanoclusters (NCs) epitaxially confined on Pd nanosheets (NSs) for catalyzing the sluggish alkaline HOR is reported. Apparent charge redistribution occurs across the heterointerface, and both experimental and theoretical results suggest that the electrons transfer from Pd to Ir, which consequently greatly weakens the hydrogen binding on Pd. More interestingly, the interfacial epitaxy results in the formation of Ir/IrO2 Janus nanostructures, where the partially oxidized Ir species away from the interface further optimize the hydroxyl adsorption behavior. The unique Ir@Pd heterostructure eventually shows an optimal balance between hydrogen and hydroxyl adsorption, and hence exhibits impressive HOR activity with an exchange current density of up to 7.18 mA cm-2 in 0.1 m KOH solution. In addition, the Ir@Pd electrocatalyst exhibits negligible activity degradation owing to the confinement effect of the unique epitaxial interface.

Large volume changes (∼300%) during cycling and low electronic conductivity of silicon (Si) always lead to the failure of the Si anode for lithium-ion batteries. In this paper, we report a facile method to fabricate Si/Ti3SiC2 composites by one-step sand-milling process. Ti3SiC2 is used as a mechanical strengthening and high conductive matrix for Si-based anode for the first time. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are conducted to characterize the structure and morphology of the Si/Ti3SiC2 composites. Capacity and cycling performance are studied by galvanostatic method. Nanoindentation test is performed to measure the elastic modulus and hardness of the electrodes. Electrochemical impedance spectroscopy (EIS) and four-probe electronic conductivity measurement are used to assess the effect of Ti3SiC2 on the electronic conductivity of Si anode. Electrochemical investigations show that both cycling stability and rate performance of Si/Ti3SiC2 anodes are significantly improved comparing with those of the pure Si anode. SEM, nanoindentation and four-probe electronic conductivity measurement results reveal that the Ti3SiC2 can not only significantly enhance the electronic conductivity of the Si/Ti3SiC2 anodes but also maintain the integrity of the electrode during cycling by markedly increasing the elastic modulus and hardness of the electrodes.

The future trend toward flexible electronics creates a demand for flexible power sources using rechargeable batteries, where freestanding and flexible electrodes are of critical importance. The utilization of high capacity anode materials like metal sulfides in flexible batteries is highly desirable for the miniaturization of electronic devices but is nevertheless very challenging in the fabrication of an electrode that is freestanding and flexible. Herein, a universal electrospinning strategy to fabricate freestanding and flexible metal sulfides@carbon electrodes is proposed based on the formation of chelate complexes between l-cysteine and metal cations. Taking SnS as a model material, flexible fiber electrodes are realized with SnS nanoparticles well embedded in the continuous and interwoven carbon fibers. As freestanding electrodes for lithium and sodium storage, a high capacity, good rate capability, and excellent cycling stability are simultaneously achieved. Such a strategy is also successfully extended to the fabrication of Ni 3S 2/C fibers and Fe 7S 8/C fibers, suggesting the universality in fabricating freestanding and flexible high capacity electrodes.

Developing high-capacity electrode materials is most vital to high-energy rechargeable batteries. The conversion reaction-based anode materials deliver substantially higher theoretical capacities in respect to intercalation-based materials. However, the sluggish conversion reaction kinetics is a big obstacle to deliver high practical capacity and rate capability, which is particularly severe for sodium storage. Herein, we implement an interface engineering approach by designing hetero-interfaces to enhance conversion reaction. As a proof of concept, Sb2S3-SnS2 hetero-nanostructures are synthesized and show greatly improved electrochemical performance in terms of specific capacity and rate capability. The DFT calculations reveal that the hetero-interfacial electric field prompts sodium ions pump into the interfaces, which greatly reduces the activation barrier and hence accelerates reaction kinetics. The Sb2S3-SnS2 hetero-interface serves therefore as a “reservoir” and fast diffusion channel for sodium or lithium ions. The obtained results provide important insights into engineering efficient hetero-nanostructures towards fast conversion reaction kinetics for rechargeable batteries.

Although tremendous progress has been made in preparing sulfur nanoparticles to achieve high-rate lithium sulfur (Li-S) batteries, the synthetic methods involved are usually toxic, complicated and costly. To solve the above problem, a simple and green method through high pressure steam is developed to prepare sulfur nanoparticles (