Ion Transport Nanotube Assembled with Vertically Aligned Metallic MoS2 for High Rate Lithium‐Ion Batteries

Metallic phase molybdenum disulfide (MoS₂) is well known for orders of magnitude higher conductivity than 2H semiconducting phase MoS₂. Herein, for the first time, the authors design and fabricate a novel porous nanotube assembled with vertically aligned metallic MoS₂ nanosheets by using the scalable solvothermal method. This metallic nanotube has the following advantages: (i) intrinsic high electrical conductivity that promotes the rate performance of battery and eliminates the using of conductive additive; (ii) hierarchical, hollow, porous, and aligned structure that assists the electrolyte transportation and diffusion; (iii) tubular structure that avoids restacking of 2D nanosheets, and therefore maintains the electrochemistry cycling stability; and (iv) a shortened ion diffusion path, that improves the rate performance. This 1D metallic MoS₂ nanotube is demonstrated to be a promising anode material for lithium‐ion batteries. The unique structure delivers an excellent reversible capacity of 1100 mA h g^?1 under a current density of 5 A g^?1 after 350 cycles, and an outstanding rate performance of 589 mA h g^?1 at a current density of 20 A g^?1. Furthermore, attributed to the material's metallic properties, the electrode comprising 100% pure material without any additive provides an ideal system for the fundamental electrochemical study of metallic MoS₂. This study first reveals the characteristic anodic peak at 1.5 V in cyclic voltammetry of metallic MoS_2. This research sheds light on the fabrication of metallic 1D, 2D, or even 3D structures with 2D nanosheets as building blocks for various applications.     

Hierarchically Multiscale Vertically Oriented NiFeCo Nanoflakes for Efficient Electrochemical Oxygen Evolution at High Current Densities

Crucial advancements in versatile catalyst systems capable of achieving high current densities under industrial conditions, bridging the gap between fundamental understanding and practical applications, are pivotal to propel the hydrogen economy forward. In this study, vertically oriented hierarchically multiscale nanoflakes of NiFeCo electrocatalysts are presented, developed by surface modification of a porous substrate with nano-structured nickel. The resulting electrodes achieve remarkably low overpotentials of 139 mV at 10 mAcm⁻² and 248 mV at 500 mAcm⁻². Further, scaled-up electrodes are implemented in a water-splitting electrolyser device exhibiting a stable voltage of 1.82 V to deliver a constant current density of 500 mA cm⁻² for over 17 days. Moreover, the role of the unique structures on electrochemical activity is systematically investigated by fractal analysis, involving computation of structure factors such as Minkowski connectivity, fractal dimension, and porosity using scanning electron microscope images. It is found that such structures offer higher surface area than typical layered double hydroxide structures due to morphological coherence that results in a superhydrophilic surface, while the base Ni layer boosts the charge transfer. This study demonstrates a Ni/NiFeCo(OH)_x heterostructure with highly porous morphology, a key to unlocking extremely efficient oxygen evolution reaction activity with exceptional stability. Moreover, fractal analysis is presented as a valuable tool to evaluate the electrochemical performance of catalysts for their structured morphology.     

Fast Charge-Transfer Rates in Li-CO2 Batteries with a Coupled Cation-Electron Transfer Process

Li-CO₂ batteries with a high theoretical energy density (1876 Wh kg⁻¹) have unique benefits for reversible carbon fixation for energy storage systems. However, due to lack of stable and highly active catalysts, the long-term operation of Li-CO₂ batteries is limited to low current densities (mainly <0.2 mA cm⁻²) that are far from practical conditions. In this work, it is discovered that, with an ionic liquid-based electrolyte, highly active and stable transition metal trichalcogenide alloy catalysts of Sb_0.67Bi_1.33X₃ (X = S, Te) enable operation of the Li-CO₂ battery at a very high current rate of 1 mA cm⁻² for up to 220 cycles. It is revealed that: i) the type of chalcogenide (Te vs S) significantly affects the electronic and catalytic properties of the catalysts, ii) a coupled cation-electron charge transfer process facilitates the carbon dioxide reduction reaction (CO₂RR) occurring during discharge, and iii) the concentration of ionic liquid in the electrolyte controls the number of participating CO₂ molecules in reactions. A combination of these key factors is found to be crucial for a successful operation of the Li-CO₂ chemistry at high current rates. This work introduces a new class of catalysts with potential to fundamentally solve challenges of this type of batteries.     

A Low-Cost Al(OH)3-Modified Fire-Retardant and Shuttle-Limiting Separator for Safe and Stable Lithium–Sulfur Batteries

Lithium–sulfur battery (LSB) possesses high theoretical energy density, but its poor cycling stability and safety issues significantly restrict progress in practical applications. Herein, a low-cost and simple Al(OH)₃-based modification of commercial separator, which renders the battery outstanding fire-retardant and stable cycling, is reported. The modification is carried out by a simple blade coating of an ultrathin composite layer, mainly consisting of Al(OH)₃ nanoparticles and conductive carbon, on the cathode side of the separator. The Al(OH)₃ shows strong chemical absorption ability toward Lewis-based polysulfides and outstanding fire retardance through a self-decomposition mechanism under high heat, while the conductive carbon material acts as a top current collector to prevent dead polysulfide. LSB using the Al(OH)₃-modified separator shows an extremely low average capacity decade per cycle during 1000 cycles at 2 C (0.029%, 1 C = 1600 mA g⁻¹). The pouch cell exhibiting high energy density (426 Wh kg⁻¹) can also steadily cycle for more than 100 cycles with high capacity retention (70.2% at 0.1 C). The effectiveness and accessibility of this Al(OH)₃ modification strategy will hasten the practical application progress of LSBs.     

Tailoring Interfacial Charge Transfer of Epitaxially Grown Ir Clusters for Boosting Hydrogen Oxidation Reaction

The sluggish kinetics of hydrogen oxidation reaction (HOR) is one of the critical challenges for anion exchange membrane fuel cells. Here, we report epitaxial growth of Ir nanoclusters (<2 nm) on a MoS₂ surface (Ir/MoS₂) and optimize the alkaline HOR activity via tailoring interfacial charge transfer between Ir clusters and MoS₂. The electron transfer from MoS₂ to Ir clusters can effectively prevent the oxidation of Ir clusters, which is not the case for carbon-supported Ir nanoclusters (Ir/C) synthesized using the same method. Moreover, the HOR performance of the Ir/MoS₂ can be further optimized by tuning the hydrogen binding energy (HBE) via a precise annealing treatment. A substantial exchange current density of 1.28 mA cm_ECSA⁻² is achieved in the alkaline medium, which is ∼10 times over that of Ir/C. The HOR mass-specific activity of Ir/MoS₂ heterostructure is as high as 182 mA mg_Ir⁻¹. The experimental results and density functional theory calculations reveal that the significant improved HOR activity is attributed to the decreased HBE, which highlights epitaxial growth is an effective way for boosting catalytic activity of heterostructured catalysts.     

Pseudocapacitive Charge Storage in Thick Composite MoS2 Nanocrystal‐Based Electrodes

A synthesis methodology is demonstrated to produce MoS₂ nanoparticles with an expanded atomic lamellar structure that are ideal for Faradaic‐based capacitive charge storage. While much of the work on MoS₂ focuses on the high capacity conversion reaction, that process is prone to poor reversibility. The pseudocapacitive intercalation‐based charge storage reaction of MoS₂ is investigated, which is extremely fast and highly reversible. A major challenge in the field of pseudocapacitive‐based energy storage is the development of thick electrodes from nanostructured materials that can sustain the fast inherent kinetics of the active nanocrystalline material. Here a composite electrode comprised of a poly(acrylic acid) binder, carbon fibers, and carbon black additives is utilized. These electrodes deliver a specific capacity of 90 mAh g^?1 in less than 20 s and can be cycled 3000 times while retaining over 80% of the original capacity. Quantitative kinetic analysis indicates that over 80% of the charge storage in these MoS₂ nanocrystals is pseudocapacitive. Asymmetric full cell devices utilizing a MoS₂ nanocrystal‐based electrode and an activated carbon electrode achieve a maximum power density of 5.3 kW kg^?1 (with 6 Wh kg^?1 energy density) and a maximum energy density of 37 Wh kg^?1 (with 74 W kg^?1power density).     

Self‐Limited on‐Site Conversion of MoO3 Nanodots into Vertically Aligned Ultrasmall Monolayer MoS2 for Efficient Hydrogen Evolution

MoS₂ has emerged as a promising alternative electrocatalyst for the hydrogen evolution reaction (HER) due to high intrinsic per‐site activity on its edge sites and S‐vacancies. However, a significant challenge is the limited density of such sites. Reducing the size and layer number of MoS₂ and vertically aligning them would be an effective way to enrich and expose such sites for HER. Herein, a facile self‐limited on‐site conversion strategy for synthesizing monolayer MoS₂ in a couple of nanometers which are highly dispersed and vertically aligned on 3D porous carbon sheets is reported. It is discovered that the preformation of well‐dispersed MoO₃ nanodots in 1–2 nm as limited source is the key for the fabrication of such an ultrasmall MoS₂ monolayer. As indicated by X‐ray photoelectron spectroscopy and electron spin resonance data, these ultrasmall MoS₂ monolayers are rich in accessible S‐edge sites and vacancies and the smaller MoS₂ monolayers the more such sites they have, leading to enhanced electrocatalytic activity with a low overpotential of 126 mV at 10 mA cm^?2 and 140 mV at 100 mA mg^?1 for HER. This state‐of‐the‐art performance for MoS₂ electrocatalysts enables the present strategy as a new avenue for exploring well‐dispersed ultrasmall nanomaterials as efficient catalysts.     

Vertically Oriented MoS2 with Spatially Controlled Geometry on Nitrogenous Graphene Sheets for High‐Performance Sodium‐Ion Batteries

Inspired by the great success of graphite in lithium‐ion batteries, anode materials that undergo an intercalation mechanism are considered to provide stable and reversible electrochemical sodium‐ion storage for sodium‐ion battery (SIB) applications. Though MoS₂ is a promising 2D material for SIBs, it suffers from deformation of its layered structure during repeated intercalation of Na⁺, resulting in undesirable electrochemical behaviors. In this study, vertically oriented MoS₂ on nitrogenous reduced graphene oxide sheets (VO‐MoS₂/N‐RGO) is presented with designed spatial geometries, including sheet density and height, which can deliver a remarkably high reversible capacity of 255 mA h g^?1 at a current density of 0.2 A g^?1 and 245 mA h g^?1 at a current density of 1 A g^?1, with a total fluctuation of 5.35% over 1300 cycles. These results are superior to those obtained with well‐developed hard carbon structures. Furthermore, a SIB full cell composed of the optimized VO‐MoS₂/N‐RGO anode and a Na₂V₃(PO₄)₃ cathode reaches a specific capacity of 262 mA h g^?1 (based on the anode mass) during 50 cycles, with an operated voltage range of 2.4 V, demonstrating the potentially rewarding SIB performance, which is useful for further battery development.     

Multi-Interface Engineering of Self-Supported Nickel/Yttrium Oxide Electrode Enables Kinetically Accelerated and Ultra-Stable Alkaline Hydrogen Evolution at Industrial-Level Current Density

The development of highly active and robust non-noble-metal electrocatalysts for alkaline hydrogen evolution reaction (HER) at industrial-level current density is the key for industrialization of alkaline water electrolysis. Herein, a superhydrophilic self-supported Ni/Y₂O₃ heterostructural electrocatalyst is constructed by a high-temperature selective reduction method, which demonstrates excellent catalytic performance for alkaline HER at high current density. Concretely, this catalyst can drive 10 mA cm⁻² at a low overpotential of 61.1 ± 3.7 mV, with a low Tafel slope of 52.8 mV dec⁻¹. Moreover, it also shows outstanding long-term durability at high current density of 1000 mA cm⁻² for 500 h in 1 m  KOH, evidently exceeding the metallic Ni and Pt/C(20%) catalysts. The superior HER activity can be attributed to the multi-interface engineering of the Ni/Y₂O₃ electrode. Construction of Ni/Y₂O₃ heterogeneous interface with dual active sites lowers the energy barrier of water dissociation and optimizes the hydrogen adsorption energy, thus synergistically accelerating the overall HER kinetics. Also, its superhydrophilic self-supported electrode structure with the firm electrocatalyst-substrate interface and weakened electrocatalyst-bubble interfacial force ensures rapid charge transfer, prevents catalyst shedding, and expedites the H₂ gas bubble release timely, further enhancing the catalytic activity and stability at high current density.     

Battery‐like Supercapacitors from Vertically Aligned Carbon Nanofiber Coated Diamond: Design and Demonstrator

To fabricate battery‐like supercapacitors with high power and energy densities, big capacitances, as well as long‐term capacitance retention, vertically aligned carbon nanofibers (CNFs) grown on boron doped diamond (BDD) films are employed as the capacitor electrodes. They possess large surface areas, high conductivity, high stability, and importantly are free of binder. The large surface areas result from their porous structures. The containment of graphene layers and copper metal catalysts inside CNFs leads to their high conductivity. Both electrical double layer capacitors (EDLCs) in inert solutions and pseudocapacitors (PCs) using Fe(CN)₆^3?/4? redox‐active electrolytes are constructed with three‐ and two‐electrode systems. The assembled two‐electrode symmetrical supercapacitor devices exhibit capacitances of 30 and 48 mF cm^?2 at 10 mV s^?1 for EDLC and PC devices, respectively. They remain constant even after 10 000 charging/discharging cycles. The power densities are 27.3 and 25.3 kW kg^?1 for EDLC and PC devices, together with their energy densities of 22.9 and 44.1 W h kg^?1, respectively. The performance of these devices is superior to most of the reported supercapacitors and batteries. Vertically aligned CNF/BDD hybrid films are thus useful to construct high‐performance battery‐like and industry‐orientated supercapacitors for future power devices.     

3D Printed Sodium-Ion Batteries via Ternary Anode Design Affording Hybrid Ion Storage Mechanism

Sodium-ion batteries (SIB), as one of the most appealing grid-scale energy storage devices, have to deal with the trade-off between the capacity output and rate performance. Utilizing 3D-printed (3DP) anode materials with hybrid sodium storage mechanism and elevated mass loading is promising yet poorly explored. Herein, the design of a prototype ternary composite is reported, MoS₂@Bi/N-doped carbon, as a sodium storage candidate to achieve high reversible capacity (604 mAh g⁻¹ at 0.1 A g⁻¹ with an initial output of 709 mAh g⁻¹) and outstanding rate capability (169.6 mAh g⁻¹ at 15 A g⁻¹), outperforming the state-of-the-art reports. This is realized by delicate structural and interfacial engineering of the composite anode, markedly synergizing the conversion-typed MoS₂, alloy-typed Bi, and adsorption-typed N-doped carbon. Theoretical simulations and operando instrumental analysis elaborate the reasons of the boosted electrochemical performance. Encouragingly, a fully 3DP SIB affording an areal mass loading of up to 11.7 mg cm⁻² is demonstrated, retaining a capacity of 114 mAh g⁻¹ at 1.0 A g⁻¹. This work would facilitate the design of 3DP SIB devices with the employment of advanced electrodes harnessing hybrid ion storage features.     

MoS2 Nanosheets Vertically Aligned on Carbon Paper: A Freestanding Electrode for Highly Reversible Sodium‐Ion Batteries

The development of sodium‐ion batteries for large‐scale applications requires the synthesis of electrode materials with high capacity, high initial Coulombic efficiency (ICE), high rate performance, long cycle life, and low cost. A rational design of freestanding anode materials is reported for sodium‐ion batteries, consisting of molybdenum disulfide (MoS₂) nanosheets aligned vertically on carbon paper derived from paper towel. The hierarchical structure enables sufficient electrode/electrolyte interaction and fast electron transportation. Meanwhile, the unique architecture can minimize the excessive interface between carbon and electrolyte, enabling high ICE. The as‐prepared MoS₂@carbon paper composites as freestanding electrodes for sodium‐ion batteries can liberate the traditional electrode manufacturing procedure, thereby reducing the cost of sodium‐ion batteries. The freestanding MoS₂@carbon paper electrode exhibits a high reversible capacity, high ICE, good cycling performance, and excellent rate capability. By exploiting in situ Raman spectroscopy, the reversibility of the phase transition from 2H‐MoS₂ to 1T‐MoS₂ is observed during the sodium‐ion intercalation/deintercalation process. This work is expected to inspire the development of advanced electrode materials for high‐performance sodium‐ion batteries.     

Stretchable Zn-Ion Hybrid Capacitor with Hydrogel Encapsulated 3D Interdigital Structure

To enhance the areal energy density of current flexible energy storage devices, hybrid capacitors combining the advantages of supercapacitors and batteries are proposed and further enhanced by incorporating the 3D interdigital structure design. However, uneven electric field distribution and hindered ion diffusion kinetics due to the non-electroactive components in these devices limit the enhancement of areal electrochemical performances when expanding the electrodes longitudinally. Herein, hydrogels with high ionic conductivity and high mechanical stability are designed to accommodate Zn²⁺-containing electrolytes and integrated with Ti₃C₂T_x-MXene electrodes to assemble flexible Zn-ion hybrid capacitors (ZIHCs). Fully encapsulated by ionic conductive hydrogels, 3D interdigital electrodes enable omnidirectional ion transport and unimpeded ionic accessibility, facilitating adequate electrode reactions, rapid energy storage, and uniform energy distribution. Hence, the all-hydrogel-encapsulated ZIHC achieved a 50-fold increase in capacitance with a quadrupled electrode thickness, exhibiting a large areal capacitance of 1432 mF cm⁻² and an energy density of 389.7 µWh cm⁻² without sacrificing power density and rate performance. Finite element simulations further illustrate the uniform distribution of potential, electric field intensity, and energy density in this structure. In addition, the device shows great stability under deformation, excellent adhesion, and underwater workability, demonstrating great promise for next-generation wearable energy storage devices.     

How chloride functions to enable proton conduction in photosynthetic water oxidation: Time-resolved kinetics of intermediates (S-states) in vivo and bromide substitution

Chloride (Cl⁻) is essential for O₂ evolution during photosynthetic water oxidation. Two chlorides near the water-oxidizing complex (WOC) in Photosystem II (PSII) structures from Thermosynechococcus elongatus (and T. vulcanus) have been postulated to transfer protons generated from water oxidation. We monitored four criteria: primary charge separation flash yield (P* → P⁺Q_A⁻), rates of water oxidation steps (S-states), rate of proton evolution, and flash O₂ yield oscillations by measuring chlorophyll variable fluorescence (P* quenching), pH-sensitive dye changes, and oximetry. Br-substitution slows and destabilizes cellular growth, resulting from lower light-saturated O₂ evolution rate (−20 %) and proton release (−36 % ΔpH gradient). The latter implies less ATP production. In Br- cultures, protonogenic S-state transitions (S₂ → S₃ → S₀’) slow with increasing light intensity and during O₂/water exchange (S₀’ → S₀ → S₁), while the non-protonogenic S₁ → S₂ transition is kinetically unaffected. As flash rate increases in Cl⁻ cultures, both rate and extent of acidification of the lumen increase, while charge recombination is suppressed relative to Br⁻. The Cl⁻ advantage in rapid proton escape from the WOC to lumen is attributed to correlated ion-pair movement of H₃O⁺Cl⁻ in dry water channels vs. separated Br⁻ and H⁺ ion movement through different regions (>200-fold difference in Bronsted acidities). By contrast, at low flash rates a previously unreported reversal occurs that favors Br⁻ cultures for both proton evolution and less PSII charge recombination. In Br⁻ cultures, slower proton transfer rate is attributed to stronger ion-pairing of Br⁻ with AA residues lining the water channels. Both anions charge-neutralize protons and shepherd them to the lumen using dry aqueous channels.     

In Situ Active Site Refreshing of Electro-Catalytic Materials for Ultra-Durable Hydrogen Evolution at Elevated Current Density

Enhancing the durability of catalysts is of critical significance to industrialize green hydrogen production. Herein, a novel active site in situ refreshing strategy is proposed and demonstrated to fabricate highly active and ultra-durable hydrogen evolution reaction (HER) electro-catalytic material by HER activation. Briefly, a composite catalytic material is synthesized, which features Ni(PO₃)₂ active sites being embedded inside the amorphous Mo compound matrix (named NiMoO-P). The Mo compound matrix undergoes gradual dissolution during HER followed by a dynamic equilibrium between the dissolution and deposition of the amorphous matrix. This process promotes the continuous exposure of insoluble Ni(PO₃)₂ and Ni₂P partially converted from Ni (PO₃) ₂ in situ on the surface during HER activation. Thus, activated catalyst exhibits excellent HER performance featuring an extremely high current density of 1500 mA cm⁻² at a rather low overpotential of 340 mV, and more attractively, an ultra-long durability for hydrogen evolution for at least 1000 h at an industrial-applicable current density of 900 mA cm⁻². The mechanisms for the especially high HER performance are attributed to the exposure and continuous refreshing of Ni(PO₃)₂ and the in situ formed Ni₂P during the HER process based on the DFT calculations and quasi-in situ Raman spectroscopic monitoring.     

In-Situ Constructuring of Copper-Doped Bismuth Catalyst for Highly Efficient CO2 Electrolysis to Formate in Ampere-Level

CO₂ electrochemical reduction (CO₂RR) can mitigate environmental issues while providing valuable products, yet challenging in activity, selectivity, and stability. Here, a CuS-Bi₂S₃ heterojunction precursor is reported that can in situ reconstruct to Cu-doped Bismuth (CDB) electrocatalyst during CO₂RR. The CDB exhibits an industrial-compatible current density of −1.1 A cm⁻² and a record-high formate formation rate of 21.0 mmol h⁻¹ cm⁻² at −0.86 V versus the reversible hydrogen electrode toward CO₂RR to formate, dramatically outperforming currently reported catalysts. Importantly, the ultrawide potential region of 1050 mV with high formate Faradaic efficiency of over 90% and superior long-term stability for more than 100 h at −400 mA cm⁻² can also be realized. Experimental and theoretical studies reveal that the remarkable CO₂RR performance of CDB results from the doping effect of Cu which optimizes adsorption of the *OCHO and boosts the structural stability of metallic bismuth catalyst. This study provides valuable inspiration for the design of element-doping electrocatalysts to enhance catalytic activity and durability.     

Single-Atom Immobilization Boosting Oxygen Redox Kinetics of High-Entropy Perovskite Oxide Toward High-Performance Lithium-Oxygen Batteries

Understanding and modulating the unique electronic interaction between single-metal atoms and high entropy compounds are of great significance to enable their high-efficiency oxygen electrocatalysis for aprotic lithium-oxygen (Li-O₂) batteries. Herein, a novel bi-functional electrocatalyst is for the first time created by immobilizing single-atom ruthenium (Ru) on lanthanum-based high entropy perovskite oxide La(Mn_0.2Co_0.2Fe_0.2Ni_0.2Cr_0.2)O₃ (Ru@HEPO), which demonstrates high activity and stability in Li-O₂ batteries. The heteronuclear coordination between single-atom Ru and HEPO facilitates fast electron transfer from Ru to HEPO by establishing Ru-O-M (M stands for Mn, Co, Fe, Ni) bridges, which well redistributes electrons within the Ru@HEPO hence significantly improving its interfacial charge transfer kinetics and electrocatalytic activity. Additionally, the strong electron coupling between Ru and Mn atoms enhances the hybridization between Mn 3d and O 2p orbitals, which promotes the inherent affinity of Ru@HEPO toward the LiO₂ intermediate, thereby reducing the reaction energy barrier of the oxygen electrode. As a result, the Ru@HEPO-based Li-O₂ batteries deliver remarkable electrochemical performances, such as high energy efficiency (87.3% at 100 mA g⁻¹), excellent rate capability (low overpotential of 0.52 V at 100 mA g⁻¹) and durable cyclability (345 cycles at 300 mA g⁻¹). This work opens up a promising avenue for the development of high entropy-based electrocatalysts for Li-O₂ batteries by precisely tailoring the electronic distributions at an atomic scale.     

Construction of Stable Li2O-Rich Solid Electrolyte Interphase for Practical PEO-Based Li-Metal Batteries

Polyethylene oxide (PEO)-based solid polymer electrolytes (SPE) have garnered recognition as highly promising candidates for advanced lithium-metal batteries. However, the practical application of PEO-based SPE is hindered by its low critical current density (CCD) resulting from undesired dendrite growth. In this study, a PEO-based SPE that exhibits an ultra-high CCD (4 mA cm⁻²) is presented and enhanced lithium ionic conductivity through the incorporation of small amounts of P₂S₅ (PS). The crystalline Li₂O-rich and P/S-containing solid electrolyte interphase (SEI) is revealed by cryo-electron microscope (cryo-EM) and Time of flight secondary ion mass spectrometry (TOF-SIMS), which inhibits dendrite growth and adverse reactions between SPE and reductive lithium, thus offering a spherical growth behavior for dendrite-free lithium metal anode. Consequently, utilizing the PS-integrated SPE, a Li-Li symmetric cell demonstrates reduced resistance during operation, enabling stable cycles exceeding 200 hours at 0.5 mA cm⁻² and 0.5 mAh cm⁻², a stringent test condition for PEO-based electrolytes. Moreover, a Li/SPE/LiFePO₄ (LFP) pouch cell exhibits 80% capacity retention after 100 cycles with 50 µm Li and 30 µm PEO electrolyte, showcasing its potential for practical applications.     

Controllable Sulfurization of MXenes to In-Plane Multi-Heterostructures for Efficient Sulfur Redox Kinetics

Although in-plane heterostructure with high ion transport pathway and unique interfacial atomic structure offers endless possibilities in the catalysis field, it is still challenging to directly synthesize MXene-based in-plane heterostructure due to the differences in crystal structures and growth conditions. Here, Mo₂C–MoS₂ in-plane multi-heterostructures are synthesized by topological conversion of sandwich-like mesoporous Mo₂C–SiO₂ layers in sulfur vapor and subsequent removal of SiO₂. During the conversion process, the exposed Mo₂C will efficiently converted to 2H phase MoS₂, meanwhile, the covered Mo₂C remained stable, affording metallic Mo₂C MXene and semiconducting MoS₂ in-plane multi-heterostructures compatible in one layer. The resultant Mo₂C–MoS₂ layer has multiple heterointerfaces, build-in electric fields as well as abundant defects. Such structural features enable to improve of the electrochemical active surface area (16.4 mF cm⁻²), which not only facilitates the bidirectional sulfur electrochemistry between solid Li₂S and soluble lithium polysulfides, but also enhances the transfer kinetics of electrons and ions, giving rise to a high-rate performance (642 mAh g⁻¹ at 5 C) and a long-term cycle life (1000 cycles at 5 C) in lithium–sulfur batteries.     

On the Role of Bimetal-Doped BaCoO3−𝛿 Perovskites as Highly Active Oxygen Electrodes of Protonic Ceramic Electrochemical Cells

Protonic ceramic electrochemical cells (PCECs) hold great promise as an energy conversion and storage technology at lower temperatures (400–650 °C). However, the sluggish reaction kinetics at the oxygen electrode hinder the electrochemical activity of PCECs. Herein, a series of bifunctional oxygen electrodes based on bimetal-doped BaCoO_3-𝛿 (BCO) are reported. Doping hampers hexagonal perovskite formation and transforms BCO into cubic perovskite, improving water uptake and hydration abilities. Density functional theory calculations highlight the effects of phase transformation on the proton transport properties of oxygen electrodes. Notably, PCECs incorporating the bimetal-doped electrodes exhibit maximum power densities of 3.15 W cm⁻² (650 °C) and 2.25 W cm⁻² (600 °C) in fuel cell mode, as well as a current density of 4.21 A cm⁻² at 1.3 V (650 °C) in electrolysis cell mode, setting record-high values. The findings provide insights into the rational design of bifunctional oxygen electrodes for high-performance PCECs.