Identifying the Role of the Cationic Geometric Configuration in Spinel Catalysts for Polysulfide Conversion in Sodium-Sulfur Batteries

Activating Transition-Metal Oxides through In Situ Regulation of Lower Hubbard Band for Catalytic Conversion of Lithium Polysulfides

Catalytic conversion of lithium polysulfides (LiPSs) is regarded as an effective avenue to tackle the shuttle effect of lithium-sulfur (Li-S) batteries, especially based upon transition-metal oxides (TMOs). However, the activity origin and corresponding mechanistic insights into such catalytic systems remain elusive. Herein, an activated state associated with the lower Hubbard band (LHB) transition is proposed to elucidate the origin of activity of TMOs by taking Mn3O4 as a model electrocatalyst. Specifically, the broadening of LHB width, the upshift of LHB position, and the orbital rearrangement of LHB, triggered by the in situ substitution of the O atoms in Mn3O4 with the S atoms of LiPSs under working conditions, synergistically enable fast electron transfer and modulate the adsorption capability to a moderate level. Benefiting from these advantages, the Mn3O4 electrocatalyst is converted from the torpid state to the activated state for expediting LiPS conversion. Eventually, the Li-S batteries assembled with Mn3O4 deliver excellent rate performance over 6 C and outstanding cycling stability over 1000 cycles. Moreover, an Ah-scale pouch cell is constructed and delivers a notable energy density of 388.1 W h kg-1. Our work offers a promising pathway based on the regulation of LHB for designing high-performance electrocatalysts for Li-S systems and beyond.

Niobium Phosphide-Induced Sulfur Cathode Interface with Fast Lithium-Ion Flux Enables Highly Stable Lithium-Sulfur Catalytic Conversion

Research on the Li-S catalytic chemistry primarily focus on the development of high-performance catalysts and the exploration of their reaction mechanisms, with limited attention given to the impact on the interface at the cathode. Moreover, regulating the Li+ flux at the cathode interface can enhance Li2S conversion kinetics without compromising the intrinsic catalytic activity of catalyst. This work presents a paradigm that employs interface regulation to enhance Li-S battery (LSB) cycling stability. A novel phosphorus doped carbon supported niobium phosphide nanocrystals (NbP/PC) catalyst is developed and demonstrates exceptional intrinsic activity for lithium polysulfide conversion while it facilitates lithium salt dissociation through intermolecular hybridization. The NbP-induced functional interface layer with abundant LiF and Li3N provides efficient Li+ transport channel for Li2S decomposition, which further mitigates the passivation of active sites. In consequence, the assembled LSB exhibits a capacity retention rate of 0.04 % per cycle after 1100 cycles at a 1 C. Furthermore, the pouch battery with an energy density of 451 Wh kg-1 maintains stable performance over 20 cycles. This strategy addresses the limitations of traditional catalytic material design in the chemical regulation of the cathodic interface for promising future of LSBs.

Phase and Orbital Engineering Effectuating Efficient Adsorption and Catalysis toward High-Energy Lithium-Sulfur Batteries

The delicate construction of electrocatalysts with high catalytic activity is a strategic method to enhance the kinetics of lithium-sulfur batteries (LSBs). Adjusting the local structure of the catalyst is always crucial for understanding the structure-activity relationship between atomic structure and catalyst performance. Here, in situ induction of electron-deficient B enables phase engineering Mo2C, realizing the transition from hexagonal (h-Mo2C) to cubic phase (c-B-Mo2C). Meanwhile, the empty sp3 orbital of B favors the effective bonding with electron-rich sulfur, creates a more valid orbital engineering available. Relying on the binary engineering via B doping, the adsorption and conversion of polysulfides are promoted. Hence, the c-B-Mo2C based cell achieves a low-capacity degradation of 0.04% with the coulombic efficiency exceeding 99.8% in 1000 cycles. Uniform Li+ transport is consistently achieved at 2 mA cm-2 for over 600 h. A 6.67Ah-c-B-Mo2C based pouch cell has a high energy density of up to 502.1 Wh kg-1 (E/S ratio of 2.4 µL mg S -1), while the pouch cell of 2 Ah exhibits an energy density of 372 Wh kg-1 more than 100 cycles. This study takes advantage of the combined engineering method to provide a guiding approach for elevating the activity of the electrocatalysts rationally.

Optimizing Adsorption-Catalysis Synergy to Accelerate Sulfur Conversion Kinetics in Room-Temperature Na-S Batteries

Room-temperature sodium-sulfur (RT Na-S) batteries are expected to become the next-generation energy storage system due to their ultrahigh theoretically energy density of 1274 Wh kg-1, abundant sulfur resource, and low cost. However, practical application is hindered by challenges of severe shuttle effect and sluggish S conversion kinetics. In this study, a series of nano-sized nickel-based chalcogenides are designed and fabricated as electrocatalysts for S cathode. The p orbitals originated from different anions show great effect on the partial-filled d orbital of the metal Ni site, which further regulates the electronic states of the catalytic site. Theoretical and experimental results confirm the excellent electrocatalytic performance of NiSe electrocatalyst with low reaction energy barriers, moderate adsorption capability, and strong catalytic conversion ability, consistent with Sabatier's principle. The optimized NiSe catalyst presents a high reversible capacity of 720.4 mAh g-1 with excellent durability over 200 cycles at 0.2 A g-1 retained a capacity of 401.4 mAh g-1 after 1000 cycles at 2 A g-1 in RT Na-S batteries. This work presents the balancing of adsorption and catalytic conversion toward polysulfides via the modulation of d/p orbitals of active sites.

Superstoichiometric reversible and manipulable copper-ion intercalation in niobium selenide

Few-layer stacked niobium selenide (NbSe2) has evoked great interest owing to its intrinsically exotic properties and accessible manipulation by controlled ion intercalation for superconductivity physics and advanced device applications. However, attempts to extend the range of reversible intercalation stoichiometries are often hindered by overexpanded bond rupture and intrinsic-limit transition metal redox centres in selenides when proceeding towards deep intercalation. Here, we report that reversible unconventional superstoichiometric controlled intercalation in NbSe2 with up to two copper-ions per unit cell can be realized by triggering anionic redox, a fivefold improvement over previous report. Synergistic charge transfer of the transition metal and selenium framework inhibited the disorder of bonds and lattice structures to avoid falling into conversion, which is essential for obtaining superstoichiometric intercalation products, enabling tunable copper-ion de/intercalation repeatable for 11,000 cycles. Moreover, deep copper-ion intercalation and its derived intercalation compound family demonstrate milestone performance in capacity and cycling stability for extended electrochemical energy storage applications such as copper batteries, hybrid-ion zinc batteries, and nonaqueous potassium batteries. Our findings broaden the realm of intercalation compounds and offers appealing possibilities for tailoring on-demand physicochemical properties of materials towards the envisioned functional applications.

Metal Doping Activation of Anion-Mediated Electron Transfer in Catalytic Reactions

Heteroatom-doping has emerged as a transformative approach to producing high-performance catalysts, yet the current trial-and-error approach to optimize these materials remains ineffective. To enable the rational design of more efficient catalysts, models grounded in a deeper understanding of catalytic mechanisms are essential. Existing models, such as d-band center theory, fall short in explaining the role of dopants, particularly when these dopants do not directly interact with reactants. In this study, we synthesize various heteroatom-doped catalysts to explore the correlation between the electronic effects of the dopants and catalyst activity. Using Co-MoS2 as a model catalyst and the Li-S redox reaction within the cathode of Li-S batteries as a test system, we show the interaction between cobalt sites and adjacent lattice sulfur atoms disrupts the intrinsic structural and electronic symmetry of MoS2. This disruption enhances the transfer of spin-polarized electrons from metal centers to lattice sulfur and promotes the adsorption of reactant intermediates. Furthermore, by analyzing 20 different dopant elements, we establish a linear relationship between the electron density in the lattice sulfur and catalyst activity toward the reduction of sulfur species, a relationship that extends to other catalytic systems, such as the hydrogen evolution reaction.

Carbon-doped bimetallic oxide nanoflakes for simultaneous electrochemical analysis of ascorbic acid, uric acid, and acetaminophen in sweat

Non-invasive continuous detection using tears or sweat as substitutes for blood samples has become an emerging method for real-time monitoring of human health. However, its development is limited by the low sample volume and low level of analytes. The simultaneous determination of multi-analytes with highly sensitive electrochemical sensing platforms has undoubtedly resulted in breakthrough innovations. Furthermore, the determination mode of multi-analyte combinations can accurately characterize the course of certain diseases. In particular, the simultaneous determination of ascorbic acid (AA), uric acid (UA), and acetaminophen (AC) in sweat will provide a one-stop detection system for cardiovascular and degenerative diseases for the entire course analysis. A sacrificial template strategy was adopted in this work using graphene oxide (GO) to guide the growth of two-dimensional Fe-Co composite nanoflakes with large specific surface areas. Defects were introduced via doping carbon through the incomplete pyrolysis of GO. The synthesized C-Fe1.33Co1.67O4 exhibited massive redox sites and was highly reactive, which met the requirements for multi-substance analysis. The electrochemical sensor based on C-Fe1.33Co1.67O4 accurately and sensitively demonstrated simultaneous detection of AA, UA, and AC in sweat, with a wide detection range for AA (4.0-11500 μM) and high sensitivity for UA and AC (304.5 μA mM-1 and 404.1 μA mM-1, respectively), along with low detection limit (1.69 μM for AA, 0.23 μM for UA, and 0.07 μM for AC). The sensor also possessed adequate mechanical flexibility, making it suitable for body surface detection, and its performance was maintained above 80% after high-intensity bending 350 times.

Valence Electron: A Descriptor of Spinel Sulfides for Sulfur Reduction Catalysis

Catalysts are essential for achieving high-performance lithium-sulfur batteries. The precise design and regulation of catalytic sites to strengthen their efficiency and robustness remains challenging. In this study, spinel sulfides and catalyst design principles through element doping are investigated. This research highlights the distinct role of lattice sulfur sites in lithium polysulfide conversion and emphasizes the differences in catalytic activity between metal and anion sites. The valence electron model as a descriptor can characterize catalytic performance, guiding the design of a (FeCo)3(PS)4 catalyst co-doped with cation and anion. The (FeCo)3(PS)4 exhibits the highest catalytic performance among spinel catalysts to data, particularly under high sulfur loading conditions. It achieves an initial specific capacity of 1205.9 mAh g-1 (6.1 mAh cm-2) at a sulfur loading of 5 mg cm-2 and 1192.7 mAh g-1 (11.9 mAh cm-2) at 10 mg cm-2, demonstrating excellent electrocatalytic performance.

Spin effects in regulating the adsorption characteristics of metal ions

Understanding the adsorption behavior of intermediates at interfaces is crucial for various heterogeneous systems, but less attention has been paid to metal species. This study investigates the manipulation of Co3+ spin states in ZnCo2O4 spinel oxides and establishes their impact on metal ion adsorption. Using electrochemical sensing as a metric, we reveal a quasi-linear relationship between the adsorption affinity of metal ions and the high-spin state fraction of Co3+ sites. Increasing the high-spin state of Co3+ shifts its d-band center downward relative to the Fermi level, thereby weakening metal ion adsorption and enhancing sensing performance. These findings demonstrate a spin-state-dependent mechanism for optimizing interactions with various metal species, including Cu2+, Cd2+, and Pb2+. This work provides new insights into the physicochemical determinants of metal ion adsorption, paving the way for advanced sensing technologies and beyond.

Critical Role of Tetrahedral Coordination in Determining the Polysulfide Conversion Efficiency on Spinel Oxides

Understanding the structure-property relationship and the way in which catalysts facilitate polysulfide conversion is crucial for the rational design of lithium-sulfur (Li-S) battery catalysts. Herein, a series of NiAl2O4, CoAl2O4, and CuAl2O4 spinel oxides with varying Ni2+, Co2+, or Cu2+ tetrahedral and octahedral site occupancy are studied as Li-S battery catalysts. Combined with experimental and theoretical analysis, the tetrahedral site is identified as the most active site for enhancing polysulfide adsorption and charge transfer. This work demonstrates the geometric configuration dependence of spinel oxides for polysulfide conversion and highlights the role of the molecular orbital in determining the activity of cations in different geometries, thereby providing new insights into the rational design of Li-S battery catalysts.

Stable Na/K-S Batteries with Conductive Organosulfur Polymer Microcages as Cathodes

Na-S and K-S batteries, with high-energy density, using naturally more abundant and affordable metals compared with rare resources like Li, Co, and Ni elements, have inspired intense research interest. However, the sulfur cathodes for Na/K storage are plagued by soluble polysulfide shuttling, larger volumetric deformation, and sluggish redox kinetics. Here, we report that a conductive organosulfur polymer microcage, fabricated facilely with the microbe and elemental sulfur as precursors, can effectively address these issues for stable high-capacity Na-S and K-S batteries. The covalently bonded short-chain sulfur species enable superior reaction kinetics and avoid soluble polysulfide formation. The microcage architecture with built-in cavities buffers the volume deformation to ensure a resilient electrode. The resultant conductive organosulfur polymer can promise a combination of high capacity and extraordinary cyclability with a promising rate and Coulombic efficiency. Especially, as a K-S battery cathode, it could deliver a high capacity of 1206.5 mAh g-1 together with an extraordinary cyclability (>99% capacity retention over 1100 cycles), which is much better than that of state-of-the-art sulfur cathodes. This work envisions new perspectives on building conductive organosulfur cathode materials with high performance via a simple and feasible protocol.

Da Silva L, Luo Y, Lu Y, Huang C, Härk E, Fleming J, Chenevier P, Cabot A, Bai Y, Botifoll M, Black AP, An Q, Amietszajew T, Arbiol J. Mechanistic Insights and Technical Challenges in Sulfur-Based Batteries: A Comprehensive In Situ/Operando Monitoring Toolbox

Batteries based on sulfur cathodes offer a promising energy storage solution due to their potential for high performance, cost-effectiveness, and sustainability. However, commercial viability is challenged by issues such as polysulfide migration, volume changes, uneven phase nucleation, limited ion transport, and sluggish sulfur redox kinetics. Addressing these challenges requires insights into the structural, morphological, and chemical evolution of phases, the associated volume changes and internal stresses, and ion and polysulfide diffusion within the battery. Such insights can only be obtained through real-time reaction monitoring within the battery's operational environment, supported by molecular dynamics simulations and advanced artificial intelligence-driven data analysis. This review provides an overview of in situ/operando techniques for real-time tracking of these processes in sulfur-based batteries and explores the integration of simulations with experimental data to provide a holistic understanding of the critical challenges, enabling advancements in their development and commercial adoption.

Mn─O Covalency as a Lever for Na⁺ Intercalation Kinetics: The Role of Oxygen Edge-Sharing Co Octahedral Sites in MnO₂

The strategic enhancement of manganese-oxygen (Mn─O) covalency is a promising approach to improve the intercalation kinetics of sodium ions (Na⁺) in manganese dioxide (MnO2). In this study, an augmenting Mn─O covalency in MnO2 by strategically incorporating cobalt at oxygen edge-sharing Co octahedral sites is focused on. Both experimental results and density functional theory (DFT) calculations reveal an increased electron polarization from oxygen to manganese, surpassing that directed toward cobalt, thereby facilitating enhanced electron transfer and strengthening covalency. The synthesized Co-MnO2 material exhibits outstanding electrochemical performance, demonstrating a superior specific capacitance of 388 F g-1 at 1 A g-1 and maintaining 97.21% capacity retention after 12000 cycles. Additionally, an asymmetric supercapacitor constructed using Co-MnO2 achieved a high energy density of 35 Wh kg-1 at a power density of 1000 W kg-1, underscoring the efficacy of this material in practical applications. This work highlights the critical role of transition metal-oxygen interactions in optimizing electrode materials and introduces a robust approach to enhance the functional properties of manganese oxides, thereby advancing high-performance energy storage technologies.

P-doped RuSe2 on Porous N-Doped Carbon Matrix as Catalysts for Accelerated Sulfur Redox Reactions

Monocomponent catalysts exhibit the limited catalytic conversion of polysulfides due to their intrinsic electronic structure, but their catalytic activity can be improved by introducing heteroatoms to regulate its electronic structure. However, the rational selection principles of doping elements remain unclear. Here, we are guided by theoretical calculations to select the suitable doping elements based on the balanced relationship between the adsorption strength of lithium polysulfides (LiPSs) and catalytic activity of lithium sulfide. We apply the screening method to develop a new catalyst of phosphorus doped RuSe2, manifesting the further enhanced conductivity compared with original RuSe2, facilitating charge transfer and further modulating the d-band center of RuSe2, thereby augmenting its effectiveness in interacting with LiPSs. Consequently, the assembled cell exhibits an areal capacity of 7.7 mAh cm-2, even under high sulfur loading of 8.0 mg cm-2 and a lean electrolyte condition (5.0 μL mg-1). This rational screening strategy offers a robust solution for the design of advanced catalysts in the field of lithium-sulfur batteries and potentially other domains as well.

A Click Chemistry Strategy Toward Spin-Polarized Transition-Metal Single Site Catalysts for Dynamic Probing of Sulfur Redox Electrocatalysis

Catalytic conversion of lithium polysulfides (LiPSs) is a crucial approach to enhance the redox kinetics and suppress the shuttle effect in lithium-sulfur (Li-S) batteries. However, the roles of a typical heterogenous catalyst cannot be easily identified due to its structural complexity. Compared with the distinct sites of single atom catalysts (SACs), each active site of single site catalysts (SSCs) is identical and uniform in their spatial energy, binding mode, and coordination sphere, etc. Benefiting from the well-defined structure, iron phthalocyanine (FePc) is covalently clicked onto CuO nanosheet to prepare low spin-state Fe SSCs as the model catalyst for Li-S electrochemistry. The periodic polarizability evolution of Fe-N bonding is probed during sulfur redox reaction by in situ Raman spectra. Theoretical analysis shows the decreased d-band center gap of Fe (Δd) and delocalization of dxz/dyz after the axial click confinement. Consequently, Li-S batteries with Fe SSCs exhibit a capacity decay rate of 0.029% per cycle at 2 C. The universality of this methodological approach is demonstrated by a series of M SSCs (M = Mn, Co, and Ni) with similar variation of electronic configuration. This work provides guidance for the design of efficient electrocatalysis in Li-S batteries.

Cobalt Ditelluride Meets Tellurium Vacancy: An Efficient Catalyst as a Multifunctional Polysulfide Mediator toward Robust Lithium-Sulfur Batteries

The commercialization of lithium-sulfur batteries (LSBs) faces significant challenges due to persistent issues, such as the shuttle effect of lithium polysulfides (LiPSs) and the slow kinetics of cathodic reactions. To address these limitations, this study proposes a vacancy-engineered cobalt ditelluride catalyst (v-CoTe2) supported on nitrogen-doped carbon as a sulfur host at the cathode. Density functional theory calculations and experimental results indicate that the electron configuration modulation of v-CoTe2 enhances the chemical affinity and catalytic activity toward LiPS. Specifically, v-CoTe2 can strongly interact with PSs through multisite coordination, effectively facilitating the kinetics of the LiPS redox reaction. Furthermore, the introduction of Te vacancies generates a large number of spin-polarized electrons, further enhancing the reaction kinetics of LiPS. As a result, the v-CoTe2@S cathode demonstrates high initial capacity and excellent cyclic stability, maintaining 80.4% capacity after 500 cycles at a high current rate of 3 C. Even under a high sulfur load of 6.7 mg cm-2, a high areal capacity of 6.1 mA h cm-2 is retained after 50 cycles. These findings highlight the significant potential of Te vacancies in CoTe2 as a sulfur host material for LSBs.

Regulating the mobility of lattice oxygen on hollow cobalt-manganese sub-nanospheres for enhanced catalytic oxidation of toluene and o-xylene

Promoting lattice oxygen mobility of Co-based catalysts is crucial to making progress in catalytic oxidation technology. The addition of manganese, a transition metal with similar ionic radius to cobalt and variable valence, was supposed to enhance the mobility of lattice oxygen species of Co-based oxide. A range of hollow CoMnaOx sub-nanosphere catalysts with different Mn/Co ratios was synthesized via a template-sacrificed method, and the effects of different Mn/Co ratios on the structural properties of the catalysts and their catalytic performance for benzene series volatile organic compounds (VOCs) oxidation were investigated. Hollow CoMn2Ox sub-nanosphere exhibited good catalytic activity for oxidation of toluene (T90 = 265 °C) and o-xylene (T90 = 297 °C), as well as excellent recycling ability and water resistance. By adjusting the Mn/Co ratio, metal ions enter into the different tetrahedral or octahedral active sites. Compared with Co3O4, the desorption temperature of surface lattice oxygen on CoMn2Ox decreased by 110 °C. These results demonstrate that the addition of manganese can encourage the electron transfer on CoMnaOx, indicating that the introduction of the appropriate amount of manganese accelerates the activation of gas O2 and mobility of surface lattice oxygen species, thereby expediting the oxidation of benzene series VOCs.

Accelerated Conversion of Polysulfides for Ultra Long-Cycle of Li-S Battery at High-Rate over Cooperative Cathode Electrocatalyst of Ni0.261Co0.739S2/N-Doped CNTs

Despite the very high theoretical energy density, Li-S batteries still need to fundamentally overcome the sluggish redox kinetics of lithium polysulfides (LiPSs) and low sulfur utilization that limit the practical applications. Here, highly active and stable cathode, nitrogen-doped porous carbon nanotubes (NPCTs) decorated with NixCo1-xS2 nanocrystals are systematically synthesized as multi-functional electrocatalytic materials. The nitrogen-doped carbon matrix can contribute to the adsorption of LiPSs on heteroatom active sites with buffering space. Also, both experimental and computation-based theoretical analyses validate the electrocatalytic principles of co-operational facilitated redox reaction dominated by covalent-site-dependent mechanism; the favorable adsorption-interaction and electrocatalytic conversion of LiPSs take place subsequently by weakening sulfur-bond strength on the catalytic NiOh 2+-S-CoOh 2+ backbones via octahedral TM-S (TM = Ni, Co) covalency-relationship, demonstrating that fine tuning of CoOh 2+ sites by NiOh 2+ substitution effectively modulates the binding energies of LiPSs on the NixCo1-xS2@NPCTs surface. Noteworthy, the Ni0.261Co0.739S2@NPCTs catalyst shows great cyclic stability with a capacity of up to 511 mAh g-1 and only 0.055% decay per cycle at 5.0 C during 1000 cycles together with a high areal capacity of 2.20 mAh cm-2 under 4.61 mg cm-2 sulfur loading even after 200 cycles at 0.2 C. This strategy highlights a new perspective for achieving high-energy-density Li-S batteries.

Promoting Polysulfide Redox Reactions through Electronic Spin Manipulation

Catalytic additives able to accelerate the lithium-sulfur redox reaction are a key component of sulfur cathodes in lithium-sulfur batteries (LSBs). Their design focuses on optimizing the charge distribution within the energy spectra, which involves refinement of the distribution and occupancy of the electronic density of states. Herein, beyond charge distribution, we explore the role of the electronic spin configuration on the polysulfide adsorption properties and catalytic activity of the additive. We showcase the importance of this electronic parameter by generating spin polarization through a defect engineering approach based on the introduction of Co vacancies on the surface of CoSe nanosheets. We show vacancies change the electron spin state distribution, increasing the number of unpaired electrons with aligned spins. This local electronic rearrangement enhances the polysulfide adsorption, reducing the activation energy of the Li-S redox reactions. As a result, more uniform nucleation and growth of Li2S and an accelerated liquid-solid conversion in LSB cathodes are obtained. These translate into LSB cathodes exhibiting capacities up to 1089 mA h g-1 at 1 C with 0.017% average capacity loss after 1500 cycles, and up to 5.2 mA h cm-2, with 0.16% decay per cycle after 200 cycles in high sulfur loading cells.

A Critical Review on Room-Temperature Sodium-Sulfur Batteries: From Research Advances to Practical Perspectives

Room-temperature sodium-sulfur (RT-Na/S) batteries are promising alternatives for next-generation energy storage systems with high energy density and high power density. However, some notorious issues are hampering the practical application of RT-Na/S batteries. Besides, the working mechanism of RT-Na/S batteries under practical conditions such as high sulfur loading, lean electrolyte, and low capacity ratio between the negative and positive electrode (N/P ratio), is of essential importance for practical applications, yet the significance of these parameters has long been disregarded. Herein, it is comprehensively reviewed recent advances on Na metal anode, S cathode, electrolyte, and separator engineering for RT-Na/S batteries. The discrepancies between laboratory research and practical conditions are elaborately discussed, endeavors toward practical applications are highlighted, and suggestions for the practical values of the crucial parameters are rationally proposed. Furthermore, an empirical equation to estimate the actual energy density of RT-Na/S pouch cells under practical conditions is rationally proposed for the first time, making it possible to evaluate the gravimetric energy density of the cells under practical conditions. This review aims to reemphasize the vital importance of the crucial parameters for RT-Na/S batteries to bridge the gaps between laboratory research and practical applications.

Electronic Spin Alignment within Homologous NiS2/NiSe2 Heterostructures to Promote Sulfur Redox Kinetics in Lithium-Sulfur Batteries

The catalytic activation of the Li-S reaction is fundamental to maximize the capacity and stability of Li-S batteries (LSBs). Current research on Li-S catalysts mainly focuses on optimizing the energy levels to promote adsorption and catalytic conversion, while frequently overlooking the electronic spin state influence on charge transfer and orbital interactions. Here, hollow NiS2/NiSe2 heterostructures encapsulated in a nitrogen-doped carbon matrix (NiS2/NiSe2@NC) are synthesized and used as a catalytic additive in sulfur cathodes. The NiS2/NiSe2 heterostructure promotes the spin splitting of the 3d orbital, driving the Ni3+ transformation from low to high spin. This high spin configuration raises the electronic energy level and activates the electronic state. This accelerates the charge transfer and optimizes the adsorption energy, lowering the reaction energy barrier of the polysulfides conversion. Benefiting from these characteristics, LSBs based on NiS2/NiSe2@NC/S cathodes exhibit high initial capacity (1458 mAh·g⁻1 at 0.1C), excellent rate capability (572 mAh·g⁻1 at 5C), and stable cycling with an average capacity decay rate of only 0.025% per cycle at 1C during 500 cycles. Even at high sulfur loadings (6.2 mg·cm⁻2), high initial capacities of 1173 mAh·g⁻1 (7.27 mAh·cm⁻2) are measured at 0.1C, and 1058 mAh·g⁻1 is retained after 300 cycles.

Controllable Regulation of the Oxygen Redox Process in Lithium-Oxygen Batteries by High-Configuration-Entropy Spinel with an Asymmetric Octahedral Structure

Designing bifunctional electrocatalysts to boost oxygen redox reactions is critical for high-performance lithium-oxygen batteries (LOBs). In this work, high-entropy spinel (Co0.2Mn0.2Ni0.2Fe0.2Cr0.2)3O4 (HEOS) is fabricated by modulating the internal configuration entropy of spinel and studied as the oxygen electrode catalyst in LOBs. Under the high-entropy atomic environment, the Co-O octahedron in spinel undergoes asymmetric deformation, and the reconfiguration of the electron structure around the Co sites leads to the upward shift of the d-orbital centers of the Co sites toward the Fermi level, which is conducive to the strong adsorption of redox intermediate LiO2 on the surface of the HEOS, ultimately forming a layer of a highly dispersed Li2O2 thin film. Thin-film Li2O2 is beneficial for ion diffusion and electron transfer at the electrode-electrolyte interface, which makes the product easy to decompose during the charge process, ultimately accelerating the kinetics of oxygen redox reactions in LOBs. Based on the above advantages, HEOS-based LOBs deliver high discharge/charge capacity (12.61/11.72 mAh cm-2) and excellent cyclability (424 cycles). This work broadens the way for the design of cathode catalysts to improve oxygen redox kinetics in LOBs.

Blocking Metal Nanocluster Growth through Ligand Coordination and Subsequent Polymerization: The Case of Ruthenium Nanoclusters as Robust Hydrogen Evolution Electrocatalysts

Metal nanoclusters providing maximized atomic surface exposure offer outstanding hydrogen evolution activities but their stability is compromised as they are prone to grow and agglomerate. Herein, a possibility of blocking metal ion diffusion at the core of cluster growth and aggregation to produce highly active Ru nanoclusters supported on an N, S co-doped carbon matrix (Ru/NSC) is demonstrated. To stabilize the nanocluster dispersion, Ru species are initially coordinated through multiple Ru─N bonds with N-rich 4'-(4-aminophenyl)-2,2:6',2''-terpyridine (TPY-NH2) ligands that are subsequently polymerized using a Schiff base. After the pyrolysis of the hybrid composite, highly dispersed ultrafine Ru nanoclusters with an average size of 1.55 nm are obtained. The optimized Ru/NSC displays minimal overpotentials and high turnover frequencies, as well as robust durability both in alkaline and acidic electrolytes. Besides, outstanding mass activities of 3.85 A mg-1 Ru at 50 mV, i.e., 16 fold higher than 20 wt.% Pt/C are reached. Density functional theory calculations rationalize the outstanding performance by revealing that the low d-band center of Ru/NSC allows the desorption of *H intermediates, thereby enhancing the alkaline HER activity. Overall, this work provides a feasible approach to engineering cost-effective and robust electrocatalysts based on carbon-supported transition metal nanoclusters for future energy technologies.

Origin of Phase Engineering CoTe2 Alloy Toward Kinetics-Reinforced and Dendrite-Free Lithium-Sulfur Batteries

Slow electrochemistry kinetics and dendrite growth are major obstacles for lithium-sulfur (Li-S) batteries. The investigations over the polymorph effect require more endeavors to further access the related catalyst design principles. Herein, the systematic evaluation of CoTe2 alloy with two polymorphs regarding sulfur reduction reaction (SRR) and lithium plating/stripping is reported. As disclosed by theoretical calculations and electrochemical measurements, the orthorhombic (o-) and hexagonal (h-) CoTe2 make a substantial difference. The reactivity origin of the CoTe2 polymorphs is explored. The higher position of d-band centers for the Co atoms on the o-CoTe2 leads to a higher displacement of the antibonding state; the lower antibonding state occupancy, the more effective the interaction with the sulfide moieties and lithium. Hence, o-CoTe2 annihilates h-CoTe2 and exhibits better catalysis and more uniform lithium deposition, consolidated by excellent performance of full cell made of o-CoTe2 . It keeps stable charging/discharging for 800 cycles at 0.5 C with only 0.055% capacity decay per cycle and even achieves an areal capacity of 6.5 mAh cm-2 at lean electrolyte and high sulfur loading of 6.4 mg cm-2 . This work establishes the mechanistic perspective about the catalysts in Li-S batteries and provides new insight into the unified solution.

Expediting Ethylbenzene Oxidation via a Bimetallic Cobalt-Manganese Spinel Structure with a Modulated Electronic Environment

The catalytic oxidation of ethylbenzene (EB) into acetophenone (AP) is a vibrant area, with a growing number of researchers paying attention to this thematic investigation. Herein, we demonstrate that spinel-type (Co,Mn)(Co,Mn)2O4 can function as an efficient catalyst for the solvent-free oxidation of EB with molecular oxygen. The incorporation of Mn into the Co3O4 network can break the local structural symmetry of Co-O-Co linkages due to the bond competition, inducing the formation of an asymmetrical Co-O-Mn configuration with an electron local exchange interaction. The Co-O-Mn sites can facilitate the perturbation of nonpolar O2 and thus contribute to the generation of abundant •O2- species for initiating the oxidation of EB. We envision that this study not only provides a promising catalyst for EB oxidation but also affords a new insight into the design of advanced spinel oxides for selective oxidation reactions.