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The increasing demand for energy, coupled with the continuing deterioration of the environment, has heightened people's desire for renewable energy storage technologies, such as rechargeable zinc‐air batteries (ZABs). However, the race for the developing ZABs usually focuses on the search for new materials, with less emphasis on electrode engineering and recycling. Herein, for the first time, a simple, scalable, and inexpensive electrode engineering and recycling strategy for ZABs is proposed based on the magnetic binder engineering of the cobalt‐implanted electrocatalysts. By manipulating the electrode with magnets, the ZAB can cycle for 1200 h (7200 cycles), and its anti‐pulverization behavior is revealed through in situ observation of a visual cell with an air electrode in the charged state. Moreover, the cobalt‐implanted electrocatalysts can be recycled from the spent ZABs using a magnetic force‐separation method. Additionally, the ZAB with the recycled electrocatalyst exhibits considerably prolonged cycling stability for over 500 h (ΔE = 0.86 V). This study not only enables the design of magnetic force‐engineered electrodes with improved battery performance but also provides sustainable solutions for recycling electrocatalysts for many possible applications beyond ZABs. [ABSTRACT FROM AUTHOR]

Garnet‐based solid‐state Li‐metal batteries (GSSBs) have the merits of high energy density and high safety. However, the realization of a stable and well‐matched Li|garnet interface for GSSBs remains challenging due to electron leakage and lithiophobic Li2CO3 impurity. To address these issues, herein, new surface chemistry is reported that converts the undesired Li2CO3 contaminant into an ultra‐thin lithium polyphosphate (Li‐PPA) layer through anhydrous polyphosphoric acid ‐induced in situ substitution reaction without damaging the water‐sensitive garnet electrolyte. In particular, the Li‐PPA interlayer not only facilitates the homogenous spreading of molten Li but also creates a robust electron‐blocking shield to suppress Li dendrite formation. As a result, the assembled Li symmetric cell exhibits a low interfacial impedance (4 Ω cm2) and high critical current density (1.8 mA cm−2) at 25 °C, which enables the cell to continuously cycle over 2500 h at 0.2 mA cm−2. Furthermore, the GSSBs paired with LiFePO4 deliver a high capacity of 149.3 mAh g−1 at 1 C and maintain 92.3% of the initial capacity after 500 cycles and can be used for solar energy storage, suggesting the feasibility of this interfacial engineering strategy for GSSBs. [ABSTRACT FROM AUTHOR]

Before the practical application of rechargeable Zn–air batteries (ZABs), a critical issue regarding the inherent slow reaction kinetics of the oxygen reduction (ORR) and oxygen evolution (OER) must be addressed. Here, we fabricate a cost‐effective bifunctional oxygen electrocatalyst with a self‐antistacking structure, where three‐dimensional (3D) Fe–Co bimetallic oxide particles (FeCoOx) are directly grown on 2D N‐doped graphene (NG). The in situ grown FeCoOx particles can alleviate the NG interlaminar restacking, ensuring abundant channels for diffusion of O2/OH− species, while the NG allows rapid electron flow. Benefiting from this self‐antistacking 3D‐on‐2D structure and synergetic electrocatalysis, FeCoOx@NG demonstrated excellent activity for both ORR and OER (ΔE = 0.78 V), which is superior to that of the binary mixtures of Pt/C and RuO2 (ΔE = 0.83 V). A homemade ZAB with 20%‐FeCoOx@NG delivers a specific capacity of 758.9 mAh g−1, a peak power density of 215 mW cm−2, and long‐term cyclability for over 400 h. These research results suggest that designing a bimetallic oxide/N‐doped carbon 3D‐on‐2D nanoarchitecture using an in situ growth strategy is an attractive and feasible solution to overcome electrocatalytic problems in ZABs. [ABSTRACT FROM AUTHOR]

Gel polymer electrolytes (GPEs) are intrinsically advantageous over rigid inorganic ones due to their easy processability and scalability. However, in terms of poor mechanical strength, GPEs can hardly satisfy the requirement of practical Li metal batteries. Herein, a novel one‐dimensional Cu‐metal–organic framework (MOF)‐filler‐reinforced GPE with the merits of high mechanical strength and high ionic conductivity is developed. When such GPE is used in Li symmetrical cells, small and stable Li‐plating/stripping overpotentials (~50 mV) can be maintained over 350 h at.3 mA/cm2. Benefitting from the above MOF‐filler‐reinforced GPE, a full cell with the Li metal anode and LiFePO4 cathode presents a stable cycling performance with a low capacity decay rate of.004% per cycle over 800 cycles at 1 C. [ABSTRACT FROM AUTHOR]

All‐solid‐state lithium batteries (ASSBs) have the potential to trigger a battery revolution for electric vehicles due to their advantages in safety and energy density. Screening of various possible solid electrolytes for ASSBs has revealed that garnet electrolytes are promising due to their high ionic conductivity and superior (electro)chemical stabilities. However, a major challenge of garnet electrolytes is poor contact with Li‐metal anodes, resulting in an extremely large interfacial impedance and severe Li dendrite propagation. Herein, an innovative surface tension modification method is proposed to create an intimate Li | garnet interface by tuning molten Li with a trace amount of Si3N4 (1 wt%). The resultant Li‐Si‐N melt can not only convert the Li | garnet interface from point‐to‐point contact to consecutive face‐to‐face contact but also homogenize the electric‐field distribution during the Li stripping/depositing process, thereby significantly decreasing its interfacial impedance (1 Ω cm2 at 25 °C) and improving its cycle stability (1000 h at 0.4 mA cm−2) and critical current density (1.8 mA cm−2). Specifically, the all‐solid‐state full cell paired with a LiFePO4 cathode delivered a high capacity of 145 mAh g−1 at 2 C and maintained 97% of the initial capacity after 100 cycles at 1 C. [ABSTRACT FROM AUTHOR]

The development of an air electrode that is flexible in physical property and highly active and durable at different geometric status for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of crucial importance for the rational design of flexible rechargeable Zn‐air batteries (ZABs). Considering their good elasticity, high conductivity, and superior thermal and chemical stability, carbon nanotubes have been widely used as a catalyst support in various electrocatalysts, while oxide or metal nanoparticles have been frequently deposited on the carbon nanotube substrate to perform as the active materials. Considering the poor contact between active materials and carbon nanotubes may introduce a challenge for long‐term operating stability, in particular in flexible devices, pure carbon electrocatalyst is highly appreciated. Herein, a free‐standing air electrode with cobalt nanoparticles encapsulated N‐codoped carbon nanotube arrays uniformly grown on the surface of carbon fiber cloth is developed by a two‐step in situ growth method. Such a carbon‐based electrode shows outstanding activity for both ORR and OER. The flexible ZAB with such air electrode shows superior flexibility and stability working under extreme bending conditions. Moreover, the polarization and round‐trip efficiency for the flexible battery is 0.67 V and 64.4% at 2 mA/cm2, respectively, even after being operated for 30 hours. This study provides a feasible way to design all carbon‐based free‐standing and flexible electrode and enlightens the electrode design for flexible energy conversion/storage devices. [ABSTRACT FROM AUTHOR]

Abstract: Host materials that can provide both a strong absorbability of soluble intermediate polysulfides and a high electronic conductivity are in high demand to realize practical applications of Li–S batteries. Here, the rational design of an N‐doped carbon comb (NCC) as a new type of sulfur host for Li–S batteries, delivering a favorable performance, particularly a good cycling stability and rate capability, is reported. A novel dodecylamine micelle‐induced self‐assembling method is first proposed for constructing the NCC host which is built from close‐packed hollow submicron carbon spheres. The interconnected carbon frameworks create good electrical conductive pathways. In addition, the high porosity and the N doping of the NCC host effectively suppress sulfur losses during cycling through synergistic physisorption and chemisorption effects. As a result, cathodes with 71 wt% of sulfur deposited in the NCC host possess superior capacities of 1090 and 553 mAh g−1 at 0.1 and 2 C, respectively. After 300 cycles at 1 C, a reversible capacity of 562 mAh g−1 is retained. Even at a high sulfur loading of 83 wt%, favorable performance is realized. [ABSTRACT FROM AUTHOR]

A sponge-like V2O5 nanomaterial is prepared by a freeze-drying method and evaluated as a cathode material for sodium-ion batteries. The sponge-like structure is self-assembled from V2O5 nanosheets that can sustain high pressure (400 times their own weight), thus leading to a high structure stability. The numerous macropores in the spongy structure can effectively soak up the electrolyte. Moreover, the exposed (001) facet of the nanosheets is favorable for charge transfer at the electrolyte/electrode interface. The thin nanosheets along the [001] axis provide short diffusion pathways for sodium ions. Electrochemical experiments show that the material has a high discharge capacity of 216 mAh g−1 at a current density of 20 mA g−1. In addition, the material shows a good capacity retention of 73 % in 100 charge-discharge cycles at a current density of 100 mA g−1. [ABSTRACT FROM AUTHOR]

Overall, the articles selected for publication in this special issue encompass a wide range of research topics related to deep learning for fuel cells and batteries according to both theoretical calculations and experimental results. Fuel cells and batteries, as two key types of energy conversion and storage devices, have recently attracted more and more attention. This special issue contains 14 contributions, including 11 research articles and 3 reviews, contributed from the experts working in the fields of fuel cells and batteries. [Extracted from the article]

Hierarchically porous, metallic RuO2 hollow spheres are applied as a carbon‐free cathode for Li–O2 batteries for the first time. They exhibit low charge potentials of ≈3.5 V, corresponding to overpotentials of 0.13/0.54 V in discharging and charging processes, a large reversible capacity of ≈1400 mAh g−1, and 100 cycles of full discharge and charge. [ABSTRACT FROM AUTHOR]

Porous carbon-free cathodes are critical to achieve a high discharge capacity and efficient cycling for rechargeable Li-O2 battery. Herein, we present a very simple method to directly grow nanoporous Ru (composed of polycrystalline particles of ∼5 nm) on one side of a current collector of Ni foam via a galvanic replacement reaction. The resulting Ru@Ni can be employed as a carbon- and binder-free cathode for Li-O2 batteries and delivers a specific capacity of 3720 mAh gRu−1 at a current density of 200 mA gRu−1. 100 cycles of continuous discharge and charge are obtained at a very narrow terminal voltage window of 2.75∼3.75 V with a limited capacity of 1000 mAh gRu−1. The good performance of the nanoporous Ru@Ni cathode can be mainly attributed to the effective suppression of the by-products related to carbon or binder, the good adhesion of the catalyst to the current collector, and the good permeation of O2 and electrolyte into the active sites of the nanoporous Ru with the open pore system. This new type electrode provides a snapshot toward developing high-performance carbon- and binder-free Li-O2 batteries. [ABSTRACT FROM AUTHOR]

Antireflection TiO2 nanoparticle film was fabricated on silica glass substrate by using directed cluster beam deposition method. Self-shadowing becomes a dominant growth mechanism for nanoparticle deposition at sufficiently large incident angles, which results in extremely porous nanoparticle stacking and yields excellent control over the refractive index profile. Inclined columnar and porous microstructure was confirmed with SEM and AFM. The TiO2 nanoparticle films show ultra-high transmittance, broadband and omnidirectional characters, which can be attributed to its porous structure and modulated refractive index. We also found that the film displays an angular selective optical transmittance. The highest antireflection enhancement of the light transmission can be obtained for light incidence along the nanoparticle columns. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Rigid‐flexible coupled composite polymer electrolytes (CPEs, e.g., polyethylene oxide/Li6.4La3Zr1.4Ta0.6O12, PEO/LLZTO) hold the promise of integrating the respective merits of organic polymer electrolyte and inorganic ceramic fillers to achieve better all‐solid‐state batteries (ASSBs), but commonly suffer from poor synergistic effect owing to the ionically/electronically resistive layer on the ceramic surface. Representatively, the Li2CO3 passivation layer‐isolated LLZTO not only contributes minimally to the Li+ conduction in PEO/LLZTO CPE, but also narrows the available electrochemical window. Herein, an interfacial reconstruction strategy is disclosed based on mild liquid‐phase chemical reaction and subsequent self‐assembly, allowing the detrimental Li2CO3 to fully react with succinic anhydride (SA), and simultaneously constructing a robust ultra‐thin lithium succinate (SALi) ionic conductor shell to eradicate its regeneration. Accordingly, the obtained PEO/LLZTO@SALi (PLS) CPE shows a high room‐temperature ionic conductivity (1.2 × 10−4 S cm−1), a wide electrochemical window (4.8 V), a notable Li+ transference number (0.37), as well as nonflammability and exceptional compatibility with Li metal in Li/Li symmetric cells (2000 h at 0.2 mA cm−2). More encouragingly, the Li/PLS CPE/LiFePO4 full ASSB maintains an ultrahigh capacity retention of 84.3% after 1400 cycles at room temperature. This work propels the design of high‐performance CPEs through the interfacial modulation of inorganic ceramic fillers. [ABSTRACT FROM AUTHOR]

The self‐catalyzed growth of nanostructures on material surfaces is one of the most time‐ and cost‐effective ways to design multifunctional catalysts for a wide range of applications. Herein, the use of this technique to develop a multicomponent composite catalyst with CoSx core encapsulated in an ultrathin porous carbon shell entangled with Co, N‐codoped carbon nanotubes is reported. The as‐prepared catalyst has a superior catalytic activity for oxygen evolution and oxygen reduction reactions, an ultralow potential gap of 0.74 V, and outstanding durability, surpassing most previous reports. Such superiority is ascribed, in part, to the unique 3D electrode architecture of the composite, which is favorable for transporting oxygen species and electrons and creates a synergy between the components with different functionalities. Moreover, the flexible solid Zn–air battery assembled with such an air electrode shows a steady discharge voltage plateau of 1.25 V and a round‐trip efficiency of 70% at 1 mA cm−2. This work presents a simple strategy to design highly efficient bifunctional oxygen electrocatalysts and may pave the way for the practical application of these materials in many energy conversion/storage devices. [ABSTRACT FROM AUTHOR]