Composite Cathode Research Articles

CuCo2O4/CF cathode with bifunctional and dual reaction centers exhibits high RhB degradation in electro-Fenton systems

Cobalt-based oxide CuCo2O4-loaded CuCo2O4/carbon felt (CF) composite cathodes were synthesized by hydrothermal deposition of a precursor of Cu/Fe oxides on CF followed by roasting in air. The material serves both catalytic and cathodic dual functions in the heterogeneous electro-Fenton (EF) process. Through XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron spectroscopy), SEM (scanning electron microscope), and catalytic experiments, it was concluded that CuCo2O4 loading was successful and the highest hydrophilic 180-CuCo2O4/CF was obtained by varying the hydrothermal temperature without destroying the original structure. 180-CuCo2O4/CF accomplished 98.03 % degradation in 60 min, and it was found to maintain high degradation capacity in the pH 3 ∼ 9 range in experiments where the experimental parameters were varied. Compared to monometallic oxides, Cu and Co dual active centers are integrated in CuCo2O4, giving it diverse redox properties and oxidation states. As a result, the CuCo2O4/CF material can realize the dual function of catalytic and cathodic, which provides a new development direction in practical wastewater treatment.

Advances in Aqueous Zinc Ion Batteries based on Conversion Mechanism: Challenges, Strategies, and Prospects.

Recently, aqueous zinc-ion batteries with conversion mechanisms have received wide attention in energy storage systems on account of excellent specific capacity, high power density, and energy density. Unfortunately, some characteristics of cathode material, zinc anode, and electrolyte still limit the development of aqueous zinc-ion batteries possessing conversion mechanism. Consequently, this paper provides a detailed summary of the development for numerous aqueous zinc-based batteries: zinc-sulfur (Zn-S) batteries, zinc-selenium (Zn-Se) batteries, zinc-tellurium (Zn-Te) batteries, zinc-iodine (Zn-I2) batteries, and zinc-bromine (Zn-Br2) batteries. Meanwhile, the reaction conversion mechanism of zinc-based batteries with conversion mechanism and the research progress in the investigation of composite cathode, zinc anode materials, and selection of electrolytes are systematically introduced. Finally, this review comprehensively describes the prospects and outlook of aqueous zinc-ion batteries with conversion mechanism, aiming to promote the rapid development of aqueous zinc-based batteries.

Highly efficient electrocatalytic treatment of high-concentration 4-chlorophenol wastewater on Pd-Cu/PPy/NF composite cathode

Exploring highly active cathode materials for electrocatalytic hydrodechlorination (ECH) of chlorinated organic pollutants is of significant significance in terms of remediating environmental pollution and keeping ecological balance. In this work, polypyrrole (PPy) modified Ni foam (NF) was utilized as an efficient porous skeleton to fabricate Pd-Cu/PPy/NF composite cathode through electro-polymerization and subsequent chemical replacement method. The introduction of PPy interlayer on NF greatly improved the interfacial affinity of the substrate, facilitating to the uniform deposition of Pd-Cu particles. This enabled the formation of a compact and uniform microstructure with intimate contact Pd-Cu interface in the target Pd-Cu/PPy/NF composite electrode. Such structure feature vastly decreased charge transfer resistance and provided an abundance of close-contact Pd-Cu entities for yielding of activated hydrogen, thereby effectively enhancing the electrocatalytic performance of Pd-Cu/PPy/NF electrode for ECH of 4-chlorophenol with a high-concentration (>200 mg·L−1). Noticeably, a high ECH efficiency of approximately 96.9 % was obtained over Pd-Cu/PPy/NF cathode within 60 min. This study provides a simple, facile, and effective pathway to prepare high-performance composite cathode for electroreductive remediation of chlorophenol pollutants with high concentration.

Hydrothermal synthesis of LiMn0.79Fe0.2Mg0.01PO4/C composite cathode materials using different Li3PO4 precursors

Doping and particle size controlling are two important approaches to improve the electrochemical performance of LiMnxFe1−xPO4 cathode materials. By employing a straightforward hydrothermal method and utilizing cost-effective lithium phosphate (Li3PO4) as the precursor, we successfully synthesized high Mn-content LiMn0.79Fe0.2Mg0.01PO4/C composites. The results reveal that the minute amount of Mg substantially enhances the electrochemical performance. In the subsequent mechanism study using Li3PO4 precursors with different particle size, we found that the nucleation process, dependent on specific surface area and diffusion rate, is likely to play a critical role for the size and morphology of formed LiMn0.79Fe0.2Mg0.01PO4. LiMn0.79Fe0.2Mg0.01PO4/C (LMFP-1), synthesized from initially smaller-sized and less agglomerated Li3PO4 (LPO-1), exhibited the most diminutive average particle size coupled with the highest specific surface area, which further facilitated electrolyte interfacial interaction and promoted Li+ diffusion kinetics. At 1C, LMFP-1 displayed a specific capacity of 110.7 mAh g−1, with 97.07% capacity retention after 200 cycles. This study provides pivotal insights for the synthesis of high-performance LiMnxFe1−xPO4 materials.

Hybrid Organosulfur Network/MWCNT Composite Cathodes for Li-S Batteries.

Lithium-sulfur (Li-S) batteries hold a promising position as candidates for next-generation high-energy storage systems. Here, we combine inverse vulcanization of sulfur with multiwalled carbon nanotubes (MWCNTs) to increase the conductivity of cathode materials for Li-S batteries. The mixing process of inversely vulcanized sulfur copolymer networks with MWCNTs is aided by shear in a two-roll mill to take advantage of the soft nature of the copolymer. The high-throughput mixing method demands a source of conductive carbon that can be intimately mixed with the S copolymer, rendering MWCNTs an excellent choice for this purpose. The resulting sulfur copolymer network-MWCNTs composites were thoroughly characterized in terms of structure, chemical composition, thermal, and electronic transport properties, and finally evaluated by electrochemical benchmarking. These promising hybrids yielded electrodes with high sulfur content and demonstrate stable electrochemical performance exhibiting a specific capacity of ca. 550 mAh·gsulfur-1 (380 mAh·gelectrode-1) even after 500 charge-discharge cycles at specific current of 167 mA·g-1 (corresponds to 0.1C discharge rate), and thus are superior to melt-infiltrated reference samples.

Li‐Rich Organosulfur Cathode with Boosted Kinetics for High‐Energy Lithium‐Sulfur Batteries

Organosulfur materials containing sulfur–sulfur bonds are an emerging class of high‐capacity cathodes for lithium storage. However, it remains a great challenge to achieve rapid conversion reaction kinetics at practical testing conditions of high cathode mass loading and low electrolyte utilization. In this study, a Li‐rich pyrolyzed polyacrylonitrile/selenium disulfide (pPAN/Se2S3) composite cathode is synthesized by deep lithiation to address the above challenges. The Li‐rich molecular structure significantly boosts the lithium storage kinetics by accelerating lithium diffusivity and improving electronic conductivity. Even under practical test conditions requiring a lean electrolyte (Electrolyte/sulfur ratio of 4.1 μL mg−1) and high loading (7 mg cm−2 of pPAN/Se2S3), DL‐pPAN/Se2S3 exhibits a specific capacity of 558 mAh g−1, maintaining 484 mAh g−1 at the 100th cycle with an average Coulombic efficiency of near 100%. Moreover, it provides (electro)chemically stable Li resources to offset Li consumption over charge–discharge cycles. As a result the as‐fabricated anode‐free cell shows a superior cycling stability with 90% retention of the initial capacity over 45 cycles. This study provides a novel approach for fabricating high‐energy and stable Li–SPAN cells.

Constructing Resilient Cross‐Linked Network Toward Stable All‐Solid‐State Lithium‐Sulfur Batteries

AbstractLithium‐sulfur batteries utilizing sulfide solid electrolytes hold considerable potential for achieving both high energy density and enhanced safety. However, the substantial volume changes experienced by sulfur during cycling result in mechanical stress accumulation, leading to mechanical degradation and thereby degrading overall electrochemical performance. In this study, a stress‐buffer strategy is proposed to address this challenge by engineering a mechanically resilient crosslinked structure for the composite sulfur cathode. This structure is accomplished through the integration of a highly flexible thermoplastic elastomer (ethylene vinyl acetate, EVA), which enables stress release during sulfur volume variations by the repeated stretching and shrinking of EVA, thereby maintaining stable ionic/electronic diffusion channels within the electrode. By virtue of the mechanically stable architecture, the stress evolution experienced by the entire sulfur electrode is substantially reduced, witnessing a remarkable decrease of ≈33.7%. Consequently, the S‐EVA composite cathode demonstrates exceptional electrochemical performance, especially cycling stability. Notably, the S‐EVA composite cathode, with a high loading of 7.5 mg cm−2, exhibits stable cycling performance close to 3.0 mAh cm−2 within 50 cycles. This work not only offers novel insights into mitigating the mechanical stress within the electrode but also paves the way for developing durable high‐performance all‐solid‐state batteries.

The application of ferrous and graphitic N modified graphene-based composite cathode material in the bio-electro-Fenton system driven by sediment microbial fuel cells to degrade methyl orange

In this work, the ferrous (Fe2+) and graphitic N modified graphene-based composite cathode materials (N-rGO/Fe3O4) were developed through an in-situ reduction method, aiming to facilitate the two-electron pathway in the oxidation-reduction process. This approach generated a specific concentration of H2O2, enabling the construction of a sediment bio-electro-Fenton system using Fe2+ released from the cathode materials. Notably, this system operates without the need for proton exchange membranes. During the cathode material preparation, the utilization of Fe2+ as a reduction agent for graphene oxide (GO), triggered ammonia water to form graphitic N in graphene sheets. This addition enhanced the two-electron pathway, resulting in increased H2O2 production. Specifically, when the Fe2+ concentration was maintained at 0.1 mol/L, precise preparation of N-rGO/Fe3O4 occurred, leading to a maximum output voltage of 0.528 V and a maximum power density of 178.17 mW/m2. The degradation of methyl orange (MO) reached 68.91% within a 25-h period, a phenomenon contributed to the presence of graphitic N in the graphene sheets. H2O2, a byproduct of the two-electron pathway in cathode oxidation reduction reaction, played a crucial role in constructing the bio-electro-Fenton system. This system, in conjunction with Fe2+ released from N-rGO/Fe3O4, facilitated the complete degradation process of MO.

Boosting the capacity and life span of Zn-supply cathode in “rocking-chair” aqueous Zn-ion batteries by vanadium–manganese coupling strategy

Owing to the scarcity of eminent Zn-supply cathodes, traditional aqueous Zn-ion batteries still pin the hope on Zn-metal anode to supply charge carriers, which induces the formidable issues of dendrite growth and side reactions. Herein, we deploy a zinc vanadium–manganese composite cathode material, Zn2.5Mn0.5V3O8, in which the V–Mn coupling in the spinel matrix supplies the Zn2+ ions and eliminates the common usage of Zn metal anode. In the half-cell test, this cathode delivers a specific capacity of 355 mA·h/g at 200 mA/g and capacity retention of 75.7% after 4500 cycles at 5 A/g. The energy storage mechanism can be summarized as a two-step phase transformation in the first charge process, and the co-intercalation of Zn2+/H+ into host accomplished with a conversion reaction in the subsequent cycles. A Zn-metal free “rocking-chair” aqueous Zn-ion battery is fabricated by using Zn2.5Mn0.5V3O8 as the cathode and anthraquinone as the anode. This full cell exhibits stable cycling performance up to 1000 cycles (80.8% at 200 mA/g and 96.4% at 2.0 A/g). This “rocking-chair” strategy provides a new route to expediate the development of aqueous zinc batteries.

A high-efficient stable surface-prelithiated Li1.2Ni0.13Co0.13Mn0.54O2 cathode enabled by sacrificial lithium nitrides for high-energy-density lithium-ion batteries

Lithium-rich cathode materials with superior practical specific capacity over 250 mAh g−1 are considered as one of the resolutions for high-energy-density lithium-ion batteries, while the intrinsic capacity loss caused by solid electrolyte interface (SEI) formation on the anode impedes the increase of energy density. To address this issue, we propose a composite cathode prelithiation strategy including a carbon-incorporated lithium phosphorus oxynitride (LiCPON) layer and a sacrificial Li3N (Sac. Li3N) layer, which can not only compensate for the capacity loss effectively and controllably with a high lithium utilization rate over 85% but also provide outstanding atmosphere stability with an 80.2% lithium utilization rate after exposed in dry air for 8 hours. The energy densities achieve 489.5 Wh kg−1 and 497.3 Wh kg−1 initially after cathode prelithiation in full cells paired with Si/C and SiOx/C anodes, corresponding to a 11.9% and 11.6% increase, respectively. The energy densities still remain 318.7 Wh kg−1 and 319.7 Wh kg−1 after 50 cycles with an increase of 13.7% and 11.7%, respectively. The cathode electrolyte interface (CEI) and SEI layers are mutually optimized and the electrolyte adsorption and degradation are suppressed after cathode prelithiation. Our work has demonstrated that such a composite cathode prelithiation strategy provides the possibility for large-scale industrial production, transportation, and conservation of prelithiated lithium-rich cathodes to achieve high-energy-density lithium-ion batteries.

Enhanced heterogeneous electro-Fenton process for degradation of rhodamine B: FeOCl/CF@AB composite cathode with superior efficiency and sustainability

With the growing environmental concerns and increasing demand for clean energy, the synthesis of Stable and efficient heterogeneous Electro-Fenton catalysts gains significant attention in the market. We present a novel FeOCl/CF@AB composite cathode designed for efficient heterogeneous electro-Fenton degradation of rhodamine B. The composite cathode exhibits remarkable catalytic performance, outperforming the raw carbon felt electrode, and achieving significantly higher rhodamine B degradation rates. The incorporation of acetylene black encapsulation provides excellent stability, preserving the FeOCl active sites from corrosion and ensuring sustained catalytic activity even after multiple reuse cycles. The electron penetration mechanism on the FeOCl/CF@AB cathode is elucidated through density functional theory calculations, revealing spontaneous O2 activation and H2O2 generation. Electron transfer between Fe(II) species and the acetylene black shell facilitates these processes. The presence of •OH species supports the degradation of rhodamine B to intermediates and mineralization to CO2 and H2O. Furthermore, LC-MS analysis unveils the detoxification effect of the electro-Fenton process with FeOCl/CF@AB, presenting reduced developmental toxicity of degradation intermediates. Economic cost analysis demonstrates the feasibility and cost-effectiveness of the FeOCl/CF@AB cathode for large-scale wastewater treatment applications. In conclusion, the FeOCl/CF@AB composite cathode showcases stability and efficiency, offering a promising and sustainable electro-Fenton technology for dye wastewater treatment.

Computational modeling of coupled mechanical damage and electrochemistry in ternary oxide composite electrodes

Performance degradation of ternary layered oxide cathodes largely originates from their loss of structural integrity in cyclic usage. Mechanical damage, such as intergranular fracture of the active particles, is not only a mechanical cleavage process but also interferes with electrochemical kinetics such as infiltration of liquid electrolyte, surface corrosion of the constituent primary particles, and may eventually isolate the primary grains from the electron conducting network. Here we develop a computational framework that integrates electrochemistry of a LiNixMnyCo1−x−yO2 (NMC) composite cathode with mechanical damage of the active particles. To fully examine the intricate chemomechanical behavior of the electrode, we evaluate the effects of the anisotropic material properties, the influence of mechanical potential on Li transport, and the concurrent intergranular fracture and electrolyte penetration along the grain boundaries upon multiple cycles. Electrolyte infiltration benefits capacity retention but aggravates further mechanical damage by corrosion. Structural failure mostly occurs in the first charging due to the anisotropic mechanical strain between the primary grains, while the resulting damage remains stable in the later few cycles. The results are consistent with experimental observations and the integration of electrochemistry and mechanical failure enables a step further understanding of the complex mechanism of battery degradation.

Tailoring Ba0.5Sr0.5FeO3-δ cobalt-free perovskites with zinc as triple-conducting cathodes for protonic ceramic fuel cells

Developing triple-conducting cathode is an available way to enhancing the electrochemical performance of protonic ceramic fuel cells (PCFCs). Here we report a systematical investigation on the performance of cobalt-free perovskites Ba0.5Sr0.5Fe1-xZnxO3-δ (x = 0, 0.1, and 0.2; BSF, BSFZ0.1, and BSFZ0.2) as triple-conducting cathodes for PCFCs. Zn doping improves the hydration capacity, oxygen vacancy concentration, surface exchange coefficient, and bulk diffusion coefficient of BSFZx (x = 0.1 and 0.2) as compared to the bare BSF. Theory calculations show that Zn doping benefits the oxygen vacancy formation, which is conducive to the promotion of cathodic oxygen reduction reaction (ORR). Among materials investigated, the BSFZ0.2 perovskite possesses an abundance of oxygen vacancies, strong hydration capacity and exceptional triple conductivity (H+/O2−/e−), and thus showing the lowest polarization resistance (Rp) of 0.328 Ω cm2 at 700 °C under wet air. At 700 °C, the cell reaches a maximum power density of 497 mW cm−2 in H2 using BSFZ0.2-30 wt% BaZr0.4Ce0.4Y0.15Zn0.05O3-δ (BZCYZ) composite cathode based on 25-μm-thick BZCYZ electrolyte, and there is no obvious deterioration in performance after operation for 100 h. The rate-limiting steps of ORR on BSFZ0.2-BZCYZ composite cathode are determined to be the surface oxygen incorporated into lattice reaction processes. These findings demonstrate that the proposed BSFZ0.2 holds great potential as a cobalt-free triple-conducting cathode for PCFCs.

A Dual Active Site Organic–Inorganic Poly(O‐Phenylenediamine)/NH4V3O8 Composite Cathode Material for Aqueous Zinc‐Ion Batteries

AbstractAqueous zinc‐ion batteries, considered one of the important candidate technologies for green and environmentally friendly large‐scale energy storage, hinge upon the performance of cathode materials as the key factor driving their development. Vanadate oxide is a promising cathode material due to its high theoretical capacity; furthermore, in order to accelerate the reaction kinetics, ion or molecular intercalation is often utilized. However, non‐electrochemically active intercalants tend to cause capacity degradation. In this study, a one‐step hydrothermal method is employed to intercalate electrochemically active poly‐o‐phenylenediamine (PoPDA) into the interlayers of NH4V3O8 (NVO), with graphene oxide (GO) being used to further improve the conductivity of the composite material (NVO/PoPDA@GO). The insertion of PoPDA expands the interlayer spacing of the NVO, alters the charge distribution, and enhances the migration rate of Zn2+ among the hybrid materials. Additionally, PoPDA serves as a support within the interlayers, improving the material stability. Moreover, the reversible transformation and rearrangement of chemical bonds (C═N/C─N) in PoPDA allows for coordination with Zn2+, providing additional capacity. As a result, NVO/PoPDA@GO exhibits excellent electrochemical performance, releasing a specific capacity of 433 mAh g−1 at 0.5 A g−1, even with a capacity of 224 mAh g−1 at 5 A g−1. This work provides a promising direction for the preparation of organic–inorganic composite cathode materials with dual active components.

Efficacy and mechanism of Microcystis aeruginosa removal by activated carbon fiber/nanoscale zero-valent iron/nickel foam cathodic electrochemical system

ABSTRACT Cyanobacterial outbreaks seriously affect drinking water safety. Therefore, developing effective algal removal technologies is urgently needed. The study aims to investigate the effects of pH, electrode distance, current density, and initial algal concentration on electrochemical algae collection. Consequently, we loaded nanoscale zero-valent iron (nZVI) on activated carbon fiber/nickel foam (ACF/Ni) to form an ACF/nZVI/Ni composite cathode using the liquid phase reduction method and used titanium-based platinum plating (Pt/Ti) as the anode to construct a novel Pt/Ti- ACF/nZVI/Ni electrochemical system. The results showed that on pH of 6.0, the electrode distance was 10 mm, the current density was 75 mA/cm2, and the initial algal concentration was OD680 = 0.100; the algal cell removal rate was 94.20% after electrolysis for 30 min. This paper provides an efficient and environmentally friendly electrochemical algal removal technology for protecting the safety of drinking water and dealing with cyanobacterial outbreaks.

Investigating the production of all-solid-state battery composite cathodes by numerical simulation of the stressing conditions in a high-intensity mixer

All-solid-state batteries (ASSB) are considered as attractive further development of conventional lithium-ion batteries, since they are expected to deliver higher energy and power densities. So far, ASSB with inorganic solid electrolytes have not been applied in large-scale due to difficulties in processing, insufficient overall ionic conductivities, and high interfacial resistances between active material and solid electrolyte. In this publication, the influence of stressing conditions on the scalable production of ASSB composite cathodes via a high-intensity mixer is investigated. The high-intensity mixer is supposed to circumvent the challenge of high interfacial resistances within an ASSB cathode consisting of submicron-sized active material LiFePO4, carbon black and solid electrolyte Li3InCl6. The mixing process is simulated employing the discrete-element-method, from which the stressing conditions acting on the particles are extracted and linked with microstructural observations and electrochemical data. These investigations show that the capacity of the ASSB increases with increasing specific energy input, which is, however, limited by a certain stress intensity determined by the rotational speed of the mixer. This examination of the influence of stressing conditions on the production and electrochemical performance of ASSB cathodes lays the foundation for further simulations and experimental investigations in the field of up-scaled ASSB cathode production.

State of Charge-Dependent Impedance Spectroscopy as a Helpful Tool to Identify Reasons for Fast Capacity Fading in All-Solid-State Batteries.

Thiophosphate-based all-solid-state batteries (ASSBs) are considered the most promising candidate for the next generation of energy storage systems. However, thiophosphate-based ASSBs suffer from fast capacity fading with nickel-rich cathode materials. In many reports, this capacity fading is attributed to an increase of the charge transfer resistance of the composite cathode caused by interface degradation and/or chemo-mechanical failure. The change in the charge transfer resistance is typically determined using impedance spectroscopy after charging the cells. In this work, we demonstrate that large differences in the long-term cycling performance also arise in cells, which exhibit a comparable charge transfer resistance at the cathode side. Our results confirm that the charge transfer resistance of the cathode is not necessarily responsible for capacity fading. Other processes, such as resistive processes on the anode side, can also play a major role. Since these processes usually depend on the state of charge, they may not appear in the impedance spectra of fully charged cells; i.e., analyzing the impedance spectra of charged cells alone is insufficient for the identification of major resistive processes. Thus, we recommend measuring the impedance at different potentials to get a complete understanding of the reasons for capacity fading in ASSBs.

A high-performance composite cathode based on thermal expansion complementation for SOFC

The discrepancy in thermal expansion coefficients (TECs) between the cobalt-based cathode and the electrolyte presents a notable obstacle in attaining optimal performance levels for solid oxide fuel cells (SOFCs). Here we propose to introduce negative thermal expansion (NTE) component Sm0.85Zn0.15MnO3 (SZM) to SrNb0.1Co0.9O3−δ (SNC) cathode to prepare SNC-xSZM (x = 0, 10, 20 and 30 %) composite cathode materials. The impact of incorporating negative thermal expansion material on the composition and properties of the matrix materials were examined by X-ray diffraction, thermal dilatometer, high-resolution transmission electron microscopy, and electrochemical workstation. The results show that SNC-xSZM can achieve more ideal thermal matching with Ce0.8Gd0.2O1.9 (GDC), and the thermal expansion coefficient decreases observably from 25.47 × 10−6 K−1 for x = 0 to 13.74 × 10−6 K−1 for x = 30 %. The optimal comprehensive electrochemical performance is obtained for SNC-20SZM, which possesses the minimum polarization resistance (Rp) of 0.012 Ω cm2 at 700 °C. The SNC-20SZM-based cell shows a maximum peak power density (PPD) of 1.22 W cm−2 while exhibiting stable operation for a continuous duration of 120 h at a constant current of 0.8 A cm−2, with performance remaining optimal. Moreover, SNC-20SZM demonstrates exceptional durability and stability over prolonged durations even in high CO2 atmospheres. An innovative approach for enhancing the development of intermediate-temperature solid oxide fuel cells (IT-SOFCs) involves incorporating SZM in the SNC cathode, thereby augmenting electrochemical performance and narrowing the gap in the thermal expansion coefficient among SOFC modules.

Metal-organic-framework derived NiS2/C hollow structures for enhanced polysulfide redox kinetics in lithium-sulfur batteries.

To cope with the shuttling of soluble lithium polysulfides in lithium-sulfur batteries, confinement tactics, such as trapping of sulfur within porous carbon structures, have been extensively studied. Although performance has improved a bit, the slow polysulfide conversion inducing fast capacity decay remains a big challenge. Herein, a NiS2/carbon (NiS2/C) composite with NiS2 nanoparticles embedded in a thin layer of carbon over the surface of micro-sized hollow structures has been prepared from Ni-metal-organic frameworks. These unique structures can physically entrap sulfur species and also influence their redox conversion kinetics. By improving the reaction kinetics of polysulfides, the NiS2/carbon@sulfur (NiS2/C@S) composite cathode with a suppressed shuttle effect shows a high columbic efficiency and decent rate performance. An initial capacity of 900 mAh g-1 at the rate of 1 C (1 C = 1675 mA g-1) and a low-capacity decline rate of 0.132% per cycle after 500 cycles are obtained, suggesting that this work provides a rational design of a sulfur cathode.

Unraveling the Spatial Asynchronous Activation Mechanism of Oxygen Redox‐Involved Cathode for High‐Voltage Solid‐State Batteries

AbstractLi‐rich layered oxides (LRLO) exhibit significant potential for use in all‐solid‐state lithium batteries (ASSLBs) owing to their high capacities and wide range of operating voltages. However, the practical application of LRLO in ASSLBs is hindered by the severe failure of carrier transport at the solid–solid interface, which subsequently limits the electrochemical activity of these batteries. Here, the spatially asynchronous activation mechanism of the LRLO in ASSLBs is presented. A spectroscopic study extending from the surface into the bulk interior of LRLO indicates that the activation kinetics of anionic oxygen prefers hysteretic delivery over uniform delivery and fast transition metals (TMs) activation. This spatial hetero activation is dominated by the failure of carrier transport at the interface, which is induced by microstructural defects in the composite cathode. This study is expected to facilitate the microstructural design of high‐performance LRLO‐based ASSLBs.