Designing Rational Interfacial Bonds for Hierarchical Mineral-Type Trogtalite with Double Carbon towards Ultra-Fast Sodium-Ions Storage Properties

Engineering advanced sodium-ion storage materials with considerable kinetic behaviors have triggered a series of active explorations. However they still suffer from interfacial gaps and uncompleted redox reactions, bringing about poor rate abilities. Herein, through the strategy of salt-fixed and thermochemical manners, the CoSe₂/O C with interfacial chemical Co O C bonds are successfully prepared, displaying the reduced particles and optimized structural features. Meanwhile, from the analysis of long-term phase changing curves and ex-situ technologies, the CoSe₂ would be decomposed into CoSe and Se phases but captured by the synergistic effect of their physical-chemical evolutions, while the structure and new-type are stabilized after cycling. Profiting from the “bridge” roles of bonds, the electrons are effectively accelerated with the deepening redox reactions. As expected, based on these advantages, the ultra-fast abilities are reached about 346 mAh g⁻¹ at 15.0 A g⁻¹ after 3500 cycles, and their capacity of full-cells are also kept at about 326 mAh g⁻¹ (cathodes Na₃V₂(PO₄)₃@C vs anodes CoSe₂/O C). The detailed analysis of kinetic behaviors strongly demonstrated that the increased interfacial charge storage and conductivities are crucial for promoting the ions-storage abilities. Given this, the rational work is anticipated to provide significant strategies for advanced energy-storage materials.     

Fe?N?C Electrocatalysts with Densely Accessible Fe?N4 Sites for Efficient Oxygen Reduction Reaction

The development of iron and nitrogen co-doped carbon (Fe N C) electrocatalysts for the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells (PEMFCs) is a grand challenge due to the low density of accessible Fe N₄ sites. Here, an in situ trapping strategy using nitrogen-rich molecules (e.g., melamine, MA) is demonstrated to enhance the amount of accessible Fe N₄ sites in Fe N C electrocatalysts. The melamine molecules can participate in the coordination of Fe ions in zeolitic imidazolate frameworks to form Fe N₆ sites within precursors. These Fe N₆ sites are then converted into atomically dispersed Fe N₄ sites during a pyrolytic process. Remarkably, the Fe N C/MA exhibits a high single-atom Fe content (3.5 wt.%), a large surface area (1160 m² g⁻¹), and a high density of accessible FeN₄ sites (45.7 × 10¹⁹ sites g⁻¹). As a result, Fe N C/MA shows a much enhanced ORR activity with a half-wave potential of 0.83 V (vs the reversible hydrogen electrode) in a 0.5 m H₂SO₄ electrolyte solution and a good performance in a PEMFC system with an activity of 80 mA cm⁻² at 0.8 V under 1.0 bar H₂/air. This work offers a promising approach toward high-performance carbon-based ORR electrocatalysts.     

Discriminating Active B?N Sites in Coralloidal B,N Dual-Doped Carbon Nano-Bundles for Boosted Zn-Ion Storage Capability

Dual doping of boron (B) and nitrogen (N) provides an effective strategy to tailor chemical properties and electron distributions in the carbon plane, as well as customize the energy storage performance. Herein, a systematic theoretical and experimental study on rationally constructing coralloidal B, N dual-doped carbon (BNC) nano-bundles with abundant B N bonds for efficient Zn-ion storage is presented. Compared with the single B or N doped sample and other dual-doped B and N sites, the B N bond sites are found to boost the adsorption of Zn ions and enhance the electronic conductivity, which efficiently contribute to Zn-ion storage. As expected, the optimized BNC nano-bundles display greatly improved electrochemical performance, manifested by the high specific capacity of 204 mAh g⁻¹ at 0.2 A g⁻¹ and ultralong cycling stability for 40 000 cycles, outperforming most of the state-of-the-art carbon cathodes. Moreover, a distinguished energy density of 178.7 Wh kg⁻¹ and a high-power density of 17.5 kW kg⁻¹ are achieved with a constructed BNC//Zn device. This work not only provides critical insight for designing advanced carbon materials but also deepens the fundamental understanding of the governing mechanisms in dual-doped carbon electrodes.     

Hierarchical Ni?Mo?S and Ni?Fe?S Nanosheets with Ultrahigh Energy Density for Flexible All Solid‐State Supercapacitors

Highly flexible supercapacitors (SCs) have great potential in modern electronics such as wearable and portable devices. However, ultralow specific capacity and low operating potential window limit their practical applications. Herein, a new strategy for the fabrication of free‐standing Ni? Mo? S and Ni? Fe? S nanosheets (NSs) for high‐performance flexible asymmetric SC (ASC) through hydrothermal and subsequent sulfurization technique is reported. The effect of Ni²⁺ is optimized to attain hierarchical Ni? Mo? S and Ni? Fe? S NS architectures with high electrical conductivity, large surface area, and exclusive porous networks. Electrochemical properties of Ni? Mo? S and Ni? Fe? S NS electrodes exhibit that both have ultrahigh specific capacities (≈312 and 246 mAh g^?1 at 1 mA cm^?2), exceptional rate capabilities (78.85% and 78.46% capacity retention even at 50 mA cm^?2, respectively), and superior cycling stabilities. Most importantly, a flexible Ni? Mo? S NS//Ni? Fe? S NS ASC delivers a high volumetric capacity of ≈1.9 mAh cm^?3, excellent energy density of ≈82.13 Wh kg^?1 at 0.561 kW kg^?1, exceptional power density (≈13.103 kW kg^?1 at 61.51 Wh kg^?1) and an outstanding cycling stability, retaining ≈95.86% of initial capacity after 10 000 cycles. This study emphasizes the potential importance of compositional tunability of the NS architecture as a novel strategy for enhancing the charge storage properties of active electrodes.     

Hierarchical Cross-Linked Carbon Aerogels with Transition Metal-Nitrogen Sites for Highly Efficient Industrial-Level CO2 Electroreduction

Developing highly efficient carbon aerogels (CA) electrocatalysts based on transition metal-nitrogen sites is critical for the CO₂ electroreduction reaction (CO₂RR). However, simultaneously achieving a high current density and high Faradaic efficiency (FE) still remains a big challenge. Herein, a series of unique 3D hierarchical cross-linked nanostructured CA with metal-nitrogen sites (M N, M = Ni, Fe, Co, Mn, Cu) is developed for efficient CO₂RR. An optimal CA/N-Ni aerogel, featured with unique hierarchical porous structure and highly exposed M-N sites, exhibits an unusual CO₂RR activity with a CO FE of 98% at −0.8 V. Notably, an industrial current density of 300 mA cm⁻² with a high FE of 91% is achieved on CA/N-Ni aerogel in a flow-cell reactor, which outperforms almost all previously reported M-N/carbon based catalysts. The CO₂RR activity of different CA/N-M aerogels can be arranged as Ni, Fe, Co, Mn, and Cu from high to low. In situ spectroelectrochemistry analyses validate that the rate-determining step in the CO₂RR is the formation of *COOH intermediate. A Zn CO₂ battery is further assembled with CA/N-Ni as the cathode, which shows a maximum power density of 0.5 mW cm⁻² and a superior rechargeable stability.     

Semi-Solid CNT@NaK Anode for Potassium Metal Battery

The C K bond plays a significant role in stabilizing the Na-K (NaK) alloy electrodes due to the enhancive interfacial affinity. In this study, a method for constructing semi-solid K metal electrodes with rich C K bonds by in situ replacement of N-doped carbon nanotubes (CNT) and liquid NaK alloy is proposed. Based on the in situ infrared thermal imaging technique combined with heat calculation, X-ray photoelectron spectroscopy elemental analysis, and reaction thermodynamic calculation, graphite-N, which is widely distributed on the wall of CNT, offers plenty of replacement sites for forming C K bonds. Due to the rich bonds, the amount of CNT sharply reduces in dendrite-free semi-solid CNT@NaK electrodes and the activity of NaK alloy raises to ≈90%. This discovery provides a new idea for establishing dendrite-free anodes for K metal batteries.     

Fe?N4O?C Nanoplates Covalently Bonding on Graphene for Efficient CO2 Electroreduction and Zn?CO2 Batteries (Adv. Funct. Mater. 27/2023)

Electrochemical carbon dioxide (CO₂) reduction into value-added products holds great promise in moving toward carbon neutrality but remains a grand challenge due to lack of efficient electrocatalysts. Herein, the nucleophilic substitution reaction is elaborately harnessed to synthesize carbon nanoplates with a Fe N₄O configuration anchored onto graphene substrate (Fe N₄O C/Gr) through covalent linkages. Density functional theory calculations demonstrate the unique configuration of Fe N₄O with one oxygen (O) atom in the axial direction not only suppresses the competing hydrogen evolution reaction, but also facilitates the desorption of *CO intermediate compared with the commonly planar single-atomic Fe sites. The Fe N₄O C/Gr shows excellent performance in the electroreduction of CO₂ into carbon monoxide (CO) with an impressive Faradaic efficiency of 98.3% at −0.7 V versus reversible hydrogen electrode (RHE) and a high turnover frequency of 3511 h⁻¹. Furthermore, as a cathode catalyst in an aqueous zinc (Zn)-CO₂ battery, the Fe N₄O C/Gr achieves a high CO Faradaic efficiency (≈91%) at a discharge current density of 3 mA cm⁻² and long-term stability over 74 h. This work opens up a new route to simultaneously modulate the geometric and electronic structure of single-atomic catalysts toward efficient CO₂ conversion.     

High-Performance Quasi-Solid-State Na-Air Battery via Gel Cathode by Confining Moisture

Rechargeable Na-air batteries are the subject of great interest because of their high theoretical specific energy density, lower cost, and lower charge potential compared with Li-air batteries. However, high purity O₂ as a working environment is required to achieve high-performance Na-air batteries, which obstructs their application as a high-energy-density battery. Although aqueous Na-air batteries can operate in ambient air, long cycle and high safety remain challenges for aqueous Na-air batteries because the aqueous electrolyte is volatile. Here, a quasi-solid-state Na-air battery is reported by utilizing a gel cathode, which is composed of single-walled carbon nanotubes and room-temperature ionic liquids, achieving high safety and long cycling life of 125 cycles (528 h) at a current density of 0.1 mA cm⁻², which is surprisingly better than that of quasi-solid-state Na O₂ batteries. In situ XRD characterizations reveal that water in ambient air is gradually deposited on the surface of the gel cathode to form a water layer, which facilitates the generation of soluble discharge product of NaOH thermodynamically with high conductivity. This work shall be critical to develop and promote the practical application of Na-air batteries, opening a new way to the design of solid-state metal-air batteries.     

Universal Source-Template Route to Metal Selenides Implanting on 3D Carbon Nanoarchitecture: Cu2−xSe@3D-CN with Se?C Bonding for Advanced Na Storage

The development of high-performance sodium ion batteries (SIBs) is heavily relied on the exploration of the appropriate electrode material for Na⁺ storage, which ought to feature merits of high capacity, easy-to-handle synthesis, high conductivity, expedite mass transportation, and stable structure upon charging–discharging cycle. Herein, a universal source-template method is reported to synthesize a variety of transition metal (e.g., V, Sb, W, Zn, Fe, Co, Ni, and Cu) selenides implanting on N doped 3D carbon nanoarchitecture hybrids (M_mSe_n@3D-CN) with powerful Se C bonding rivet. Benefiting from the superior architecture and potent Se C bonding between Cu_2−xSe and N-doped 3D carbon (3D-CN), the Cu_2−xSe@3D-CN nanohybrids, as anode of SIBs, show high capacity, high-rate capability, and long-cycle durability, which can deliver a reversible capacity of as high as 386 mAh g⁻¹, retain 219 mAh g⁻¹ even at 10 A g⁻¹, and run durably over thousands of charging–discharging cycles. The Cu_2−xSe@3D-CN as anode is also evaluated by developing a full SIB by coupling with the Na₃V₂(PO₄)₃ cathode, which can deliver high energy density and show excellent stability, shedding light on its potential in practical application.     

Creating an Air‐Stable Sulfur‐Doped Black Phosphorus‐TiO2 Composite as High‐Performance Anode Material for Sodium‐Ion Storage

With the increasing demand for low cost, long lifetime, high energy density storage systems, an extensive amount of effort has recently been focused on the development of sodium‐ion batteries (SIBs), and a variety of cathode materials have been discovered. However, looking for the most suitable anode material for practical application is a major challenge for SIBs. Herein, a high capacity sulfur‐doped black phosphorus‐TiO₂ (TiO₂‐BP‐S) anode material for SIBs is first synthesized by a feasible and large‐scale high‐energy ball‐milling approach, and its stability in air exposure is investigated through X‐ray photoelectron spectroscopy. The morphology of TiO₂‐BP‐S is characterized using transmission electron microscopy, indicating that the TiO₂ nanoparticles produce P? Ti bonds with BP. The TiO₂‐BP‐S composite with P? S and P? Ti bonds exhibits excellent stability in air and the superior electrochemical performance. For example, the discharge specific capacity is up to 490 mA h g^?1 after 100 cycles at 50 mA g^?1, and it remains at 290 mA h g^?1 after 600 cycles at 500 mA g^?1. Meanwhile, the scientific insight that the formation of stable P? S and P? Ti bonds can provide a guide for the practical large‐scale application of SIBs in other titanium base and black phosphorus materials is looked forward.     

Rechargeable Li?CO2 Batteries with Graphdiyne as Efficient Metal-Free Cathode Catalysts

A rechargeable Li CO₂ battery is one of the promising power sources for utilizing the greenhouse gas CO₂ in a sustainable approach. However, highly efficient catalysts for reversible formation/decomposition of insulating discharge product, Li₂CO₃, are the main challenge, which can boost the cycle stability. Herein, 2D single-atom-thick graphdiyne (GDY) with abundant acetylenic bond sites is prepared by a bottom-up cross-coupling reaction strategy and used as metal-free catalysts for reversible Li CO₂ batteries. The prepared GDY has a rich diacetylenic unit and atomic-level in-plane pores in the network, which can chemically adsorb the CO₂ molecules and easily promote the Li⁺ diffusion and thereby resulting in uniform nucleation and reversible formation/decomposition of the discharge product. The GDY hybrid cathodes show a small overpotential gap of 1.4 V at a current density of 50 mA · g⁻¹, a high full discharge capacity of 18 416 mAh · g⁻¹ at 100 mA · g⁻¹, and outstanding long-term stability of 158 cycles at 400 mA · g⁻¹ with a curtailing capacity of 1000 mAh · g⁻¹. Furthermore, a flexible belt-shaped Li CO₂ battery is fabricated as a proof of concept with a high gravimetric energy density of 165.5 Wh · kg⁻¹ (based on the mass of the whole device) as well as excellent mechanical flexibility.     

High-Capacity and Stable Sodium-Sulfur Battery Enabled by Confined Electrocatalytic Polysulfides Full Conversion

The efficient polysulfide capture and reversible sulfur recovery during reverse charging process are critical to exploiting the full potential of room temperature Na S batteries. Here, based on a core-shell design strategy, the structural and chemical synergistic manipulation of sodium polysulfides quasi-solid-state reversible conversion is proposed. The sulfur is encapsulated in the multi-pores of 3D interconnected carbon fiber as the core structure. The Fe(CN)₆⁴⁻-doped polypyrrole film serves as a redox-active polar shell to lock up polysulfides and promote complete polysulfide conversion. Importantly, the short-chain Na₂S₄ polysulfides are reduced to Na₂S directly leaving with a small fraction of soluble intermediates as the cation-transfer medium at the core/shell interface, and freeing up formation of solid Na₂S₂ incomplete product. Further, the redox mediator with open Fe species electrocatalytically lowers the Na₂S oxidation energy barrier and renders the high reversibility of electrodeposited Na₂S. The tunable quasi-solid-state reversible sulfur conversion under versatile polymer sheath greatly enhances sulfur utilization, affording a remarkable capacity of 1071 mAh g⁻¹ and a stable high capacity of 700 mAh g⁻¹ at 200 mA g⁻¹ after 200 cycles. The confined electrocatalytic effect provides a strategy for tuning electrochemical pathway of sulfur species and guarantees high-efficiency sulfur electrochemistry.     

Highly Boosted Reaction Kinetics in Carbon Dioxide Electroreduction by Surface-Introduced Electronegative Dopants

Effectively improving the selectivity while reducing the overpotential over the electroreduction of CO₂ (CO₂ER) has been challenging. Herein, electronegative N atoms and coordinatively unsaturated Ni N₃ moieties co-anchored carbon nanofiber (Ni N₃ NCNFs) catalyst via an integrated electrospinning and carbonization strategy are reported. The catalyst exhibits a maximum CO Faradaic efficiency (F.E.) of 96.6%, an onset potential of −0.3 V, and a low Tafel slope of 71 mV dec⁻¹ along with high stability over 100 h. Aberration corrected scanning transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy identify the atomically dispersed Ni N₃ sites with Ni atom bonded by three pyridinic N atoms. The existence of abundant electronegative N dopants adjoin the Ni N₃ centers in Ni N₃ NCNFs. Theoretical calculations reveal that both, the undercoordinated Ni N₃ centers and their first neighboring C atoms modified by extra N dopants, display the positive effect on boosting CO₂ adsorption and water dissociation processes, thus accelerating the CO₂ER kinetics process. Furthermore, a designed Zn CO₂ battery with the cathode of Ni N₃ NCNFs delivers a maximum power density of 1.05 mW cm⁻² and CO F.E. of 96% during the discharge process, thus providing a promising approach to electric energy output and chemical conversion.     

Interfacial Chemical Bond and Oxygen Vacancy-Enhanced In2O3/CdSe-DETA S-scheme Heterojunction for Photocatalytic CO2 Conversion

The S-scheme heterojunctions have great potential for photocatalytic carbon dioxide reduction due to their unique carrier migration pathways, superior carrier separation efficiencies, and high redox capacities. However, the precise process of the oriented powerful electron transport remains a great challenge. Herein, an In O Cd bond-modulated S-scheme heterojunction of In₂O₃/CdSe-DETA is synthesized by a simple microwave-assisted hydrothermal method for the accelerated photogenerated electron transfer. Meanwhile, the oxygen vacancies (Vo) of In₂O₃ have an electron capture effect. Consequently, thanks to the synergistic effect of this In-Vo-In-O-Cd structural units at the interface, electrons are extracted and rapidly transferred to the surface-active sites, which improves the electronic coupling of CO₂. This finding precisely adjusts the electron transfer pathway and shortens the electron transfer distance. The synergistic effect of this chemical bond established in the S-scheme heterostructure with oxygen vacancies in In₂O₃ (Vo-In₂O₃) provides new insights into photocatalytic CO₂ reduction.     

Evaluation of Zn?Sn?O buffer layers for CuIn0.5Ga0.5Se2 solar cells

Thin Zn Sn O films are evaluated as new buffer layer material for Cu(In,Ga)Se₂‐based solar cell devices. A maximum conversion efficiency of 13.8% (V_oc = 691 mV, J_sc(QE) = 27.9 mA/cm², and FF = 71.6%) is reached for a solar cell using the Zn Sn O buffer layer which is comparable to the efficiency of 13.5% (V_oc = 706 mV, J_sc(QE) = 26.3 mA/cm², and FF = 72.9%) for a cell using the standard reference CdS buffer layer. The open circuit voltage (V_oc) and the fill factor (FF) are found to increase with increasing tin content until an optimum in both parameters is reached for Sn/(Zn + Sn) values around 0.3–0.4. Copyright © 2010 John Wiley & Sons, Ltd.     

Optimized Ti?O Subcompounds and Elastic Expanded MXene Interlayers Boost Quick Sodium Storage Performance

To develop quick-charge sodium-ion battery, it is significant to optimize insertion-type anode to afford fast Na⁺ diffusion rate and excellent electron conductivity. First-principles calculations reveal the Ti O subcompound superiority for Na⁺ diffusion following Ti(II) O > Ti(III) O > Ti(IV) O. Hence, in situ growth of amorphous Ti O subcompounds with rich oxygen defects based on Ti₃C₂T_x-MXene is developed. Meanwhile, the composite presents expanded MXene interlayer spacing and much enhanced conductivity. The synergistic effect of enhanced electron/ion conduction gives a high capacity of 107 mAh g⁻¹ at 50 A g⁻¹, which gives 50% and 150% increasements compared with one counterpart without valence adjustment and another one without MXene expansion. It only needs 20 s (at 30 A g⁻¹) to complete the discharge/charge process and obtains a capacity of 144.5 mAh g⁻¹, which also shows a long-term cycling stability at quick-charge mode (121 mAh g⁻¹ after 10000 cycles at 10 A g⁻¹). The enhanced performance comes from fast electron transfer among Ti O subcompounds contributed by rich-defect amorphous TiO_2–x, and a reversible change of elastic MXene with interlayer spacing between 1.4 and 1.9 nm during Na⁺ insertion/extraction process. This study provides a feasible route to boost the kinetics and develop quick-charge sodium-ion battery.     

Design of Hierarchical Ni?Co@Ni?Co Layered Double Hydroxide Core–Shell Structured Nanotube Array for High‐Performance Flexible All‐Solid‐State Battery‐Type Supercapacitors

A novel hierarchical nanotube array (NTA) with a massive layered top and discretely separated nanotubes in a core–shell structure, that is, nickel–cobalt metallic core and nickel–cobalt layered double hydroxide shell (Ni? Co@Ni? Co LDH), is grown on carbon fiber cloth (CFC) by template‐assisted electrodeposition for high‐performance supercapacitor application. The synthesized Ni? Co@Ni? Co LDH NTAs/CFC shows high capacitance of 2200 F g^?1 at a current density of 5 A g^?1, while 98.8% of its initial capacitance is retained after 5000 cycles. When the current density is increased from 1 to 20 A g^?1, the capacitance loss is less than 20%, demonstrating excellent rate capability. A highly flexible all‐solid‐state battery‐type supercapacitor is successfully fabricated with Ni? Co LDH NTAs/CFC as the positive electrode and electrospun carbon fibers/CFC as the negative electrode, showing a maximum specific capacitance of 319 F g^?1, a high energy density of 100 W h kg^?1 at 1.5 kW kg^?1, and good cycling stability (98.6% after 3000 cycles). These fascinating electrochemical properties are resulted from the novel structure of electrode materials and synergistic contributions from the two electrodes, showing great potential for energy storage applications.     

One-Step Sintering Synthesis Achieving Multiple Structure Modulations for High-Voltage LiCoO2

The structure instability issues of the highly delithiated LiCoO₂ have significantly hindered its high-voltage applications (≥4.55 V vs Li/Li⁺). Herein, for the first time, multiple modifications of Li_0.9Mg_0.05CoO₂ (L_0.9M_0.05CO) via a simple one-step sintering synthesis are reported. A combination of the bulk Li/Co antisites, a Mg-pillar enriched surface, and a thin Mg O coating layer is achieved to maintain both the bulk and surface structural stability of L_0.9M_0.05CO upon cycling at an upper cut-off voltage of 4.6 V. The bulk Li/Co antisites are discovered to enhance the H1-3 phase evolution reversibility, the Mg pillars that substitute the Li sites effectively reinforces the surface structure, and the thin Mg O coating layer can effectively prevent the cathode from severe side reactions. Benefiting from the reduced but reversible H1-3 phase transition and the reinforced surface structure, L_0.9M_0.05CO shows an excellent cycle stability. This work provides a new structure modulation route for developing high-voltage LiCoO₂ cathodes.     

A Robust Ternary Heterostructured Electrocatalyst with Conformal Graphene Chainmail for Expediting Bi-Directional Sulfur Redox in Li–S Batteries

Designing high-performance electrocatalysts for boosting aprotic electrochemistry is of vital importance to drive longevous Li–S batteries. Nevertheless, investigations on probing the electrocatalytic endurance and protecting the catalyst activity yet remain elusive. Here, a ternary graphene-TiO₂/TiN (G-TiO₂/TiN) heterostructure affording conformal graphene chainmail is presented as an efficient and robust electrocatalyst for expediting sulfur redox kinetics. The G-TiO₂/TiN heterostructure synergizes adsorptive TiO₂, catalytic TiN, and conductive graphene armor, thus enabling abundant anchoring points for polysulfides and sustained active sites to allow smooth bi-directional electrocatalysis. Encouragingly, in situ crafted graphene chainmail ensures favorable protection of inner TiO₂/TiN to retain their catalytic robustness towards durable sulfur chemistry. As expected, sulfur cathodes mediated by ternary G-TiO₂/TiN harvest an impressive rate capability (698.8 mAh g⁻¹ at 5.0 C), favorable cycling stability (a low decay of 0.054% per cycle within 1000 cycles), and satisfactory areal capacity under elevated loading (delivering 8.63 mAh cm⁻² at a sulfur loading of 10.4 mg cm⁻²). The ternary heterostructure design offers an in-depth insight into the electrocatalyst manipulation and protection toward long lifespan Li–S batteries.     

NiMoO4 Nanosheets Anchored on N?S Doped Carbon Clothes with Hierarchical Structure as a Bidirectional Catalyst toward Accelerating Polysulfides Conversion for Li?S Battery

The serious shuttle effect, sluggish reduction kinetics of polysulfides and the difficult oxidation reaction of Li₂S have hindered Li S battery practical application. Herein, a 3D hierarchical structure composed of NiMoO₄ nanosheets in situ anchored on N S doped carbon clothes (NiMoO₄@NSCC) as the free-standing host is creatively designed and constructed for Li S battery. Dual transitional metal oxide (NiMoO₄) increases the electrons density near the Fermi level due to the contribution of the incorporating molybdenum (Mo), leading to the smaller bandgap, and thus stronger metallic properties compared with NiO. Furthermore, as a bidirectional catalyst, NiMoO₄ is proposed to facilitate reductions of polysulfides through lengthening the S S bond distance of Li₂S₄ and reducing the free energy of polysulfides conversion, meanwhile promote critical oxidation of insulative discharge product (Li₂S) via lengthening Li S bond distance of Li₂S and decreasing Li₂S decomposition barrier. Therefore, after loading sulfur (2 mg cm⁻²), NiMoO₄@NSCC/S as the self-supporting cathode for the Li S battery exhibits impressive long cycle stability. This study proposes a concept of a bidirectional catalyst with dual metal oxides, which would supply a novel vision to construct the high-performance Li S battery.