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The current emphasis of research on PEM fuel cells is the exploration of novel, resilient, and very efficient electrocatalysts that do not rely on platinum, while also ensuring long-term stability. This study aimed to enhance the catalytic activity as cathode electrocatalysts by synthesizing Palladium-cobalt alloy nanoparticles using the ultrasonic spraying (US) technique and then dispersing them over a carbon black substrate. The ultrasonic spray method produces crystalline catalysts in the liquid-vapor interface reaction without requiring additional energy. Analyses were performed using XRD, SEM, EDS, XPS and TEM to determine the structural and morphological properties of the nanocatalysts. XRD analysis determined the average particle size of USCo–Pd/C and US-CoPd/C nanocatalysts to 1.37 nm and 1.09 nm, respectively. CV measurements identified ECSA values for USCo–Pd/C and US-CoPd/C as 7.1 m2/g Pd and 8.9 m2/g Pd. The relative performance ranking of cathode electrocatalysts for PEM fuel cells was evaluated at a cell temperature of 70 °C. The order of reactivity for the catalysts is as follows: US-CoPd/C > USCo–Pd/C > PdCo/C > Pd/C. The better electrochemical performance of USCo–Pd/C and US-CoPd/C nanocatalysts as cathode catalysts in PEM fuel cell applications, in comparison to Pd/C and PdCo/C catalysts, can be attributed to the modification of the electronic structure of palladium. This modification depends on the synthesis of cobalt and palladium metals together using the US method and the synergistic effect of the catalysts. [Display omitted] • CoPd nanocatalysts were synthesized via ultrasonic spray at gas-liquid interfaces. • US-CoPd/C showed 3–3.5x higher activity than PdCoC synthesized by reduction. • PEM fuel cell performance improved with increasing cell temperature. • Ultrasonic spray synthesis maintained activity, unlike conventional methods. [ABSTRACT FROM AUTHOR]

In this investigation, we successfully synthesized a series of Swedenborgite-type Y 1-x Pr x BaCo 3 ZnO 7+δ (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5, abbreviated as YP x BCZ) oxides by a solid-state reaction method. The results show that YP x BCZ (x = 0.0, 0.1, 0.2, and 0.3) are single-phase structures, but YP 0.4 BCZ and YP 0.5 BCZ show interesting self-assembled composite phases. After long-term phase stability testing, YP 0.3 BCZ showed the best thermal stability. All samples show good chemical and thermal compatibility with La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-δ electrolyte. The thermal expansion coefficients in the temperature range from 30 °C to 1000 °C are equal to 9.8-13.1 × 10−6 K−1, close to that of the LSGM electrolyte. It is also found that Pr doping improves high temperature conductivity of YP x BCZ. The conductivity of YP 0.3 BCZ, YP 0.4 BCZ, and YP 0.5 BCZ reach 15.1, 18.5, and 22.5 S cm−1 at 800 °C. In addition, the area specific resistance (ASR) value decreases as the Pr content increases (0.038, 0.033, and 0.027 Ω cm2 at 800 °C for YP 0.3 BCZ, YP 0.4 BCZ, and YP 0.5 BCZ), improving the catalytic activity of the material. Another interesting finding was that the ASR of samples subjected to high temperature thermal decomposition was not adversely affected by the presence of decomposition products. The maximum power densities of YP 0.3 BCZ, YP 0.4 BCZ, and YP 0.5 BCZ in the single cells at 800 °C were 845, 930, and 1044 mW cm2, respectively. These results indicate that YP 0.3 BCZ, YP 0.4 BCZ, and YP 0.5 BCZ are promising cathode materials for intermediate-temperature solid oxide fuel cell. [Display omitted] [ABSTRACT FROM AUTHOR]

Sm 0.5 Sr 0.5 CoO 3-δ (SSC) fiber-electrode materials were prepared via electrospinning in this work. The characteristics of SSC fibers are influenced by the parameters of electrospinning, specifically the nitrate concentration of the spinning solution, applied voltage, and the gap between the spinneret and collector. The as-prepared SSC fibers exhibited average diameters ranging from 240 nm to 6.49 μm, which contracted to 50 nm–2.53 μm after calcination at 800 °C. Symmetric cells with SSC fiber-electrodes demonstrated an area-specific resistance (ASR) ranging from 0.212 to 0.508 Ω cm2 at 700 °C in air. In addition to the morphology of SSC fibers, the average grain size of the SSC fibers also exhibited potential influence on their ASR performance. [ABSTRACT FROM AUTHOR]

Activating anionic redox reaction (ARR) has attracted a great interest in Li/Na‐ion batteries owing to the fascinating extra‐capacity at high operating voltages. However, ARR has rarely been reported in aqueous zinc‐ion batteries (AZIBs) and its possibility in the popular MnO2‐based cathodes has not been explored. Herein, the novel manganese deficient MnO2 micro‐nano spheres with interlayer "Ca2+‐pillars" (CaMnO‐140) are prepared via a low‐temperature (140 °C) hydrothermal method, where the Mn vacancies can trigger ARR by creating non‐bonding O 2p states, the pre‐intercalated Ca2+ can reinforce the layered structure and suppress the lattice oxygen release by forming Ca−O configurations. The tailored CaMnO‐140 cathode demonstrates an unprecedentedly high rate capability (485.4 mAh g−1 at 0.1 A g−1 with 154.5 mAh g−1 at 10 A g−1) and a marvelous long‐term cycling durability (90.6 % capacity retention over 5000 cycles) in AZIBs. The reversible oxygen redox chemistry accompanied by CF3SO3− (from the electrolyte) uptake/release, and the manganese redox accompanied by H+/Zn2+ co‐insertion/extraction, are elucidated by advanced synchrotron characterizations and theoretical computations. Finally, pouch‐type CaMnO‐140//Zn batteries manifest bright application prospects with high energy, long life, wide‐temperature adaptability, and high operating safety. This study provides new perspectives for developing high‐energy cathodes for AZIBs by initiating anionic redox chemistry. [ABSTRACT FROM AUTHOR]

Protonic ceramic fuel cells (PCFCs), which are based on proton conducting electrolytes, are a class of power generation devices that can efficiently operate at the intermediate (500–700 °C), even low (450 °C) temperatures, but their development is hindered by sluggish cathodic kinetics at reduced temperatures. At the PCFC cathode, the absorbed oxygen molecules react with oxygen vacancies, protons and electrons to generate water and release electrical energy. Thus, the PCFC cathode materials require percolation network for proton, oxide-ion, and electron carriers simultaneously. In this work, we developed a triple ionic-electronic conductor BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ as a new cathode material for the PCFCs using BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ as the electrolyte. Anode supported cells were fabricated and the performances were investigated. Compared with the parent oxide, tungsten doping can significantly improve the electrochemical reduction kinetic of oxygen. The BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ based PCFC obtained the peak power density of 688 mW ⋅ cm−2 at 600 °C, which is 1.29 time higher than that of BaCo 0.4 Fe 0.4 Zr 0.2 O 3-δ based PCFC (the peak power density of 534 mW ⋅ cm−2 at 600 °C). Moreover, BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ has a better thermal expansion matching with the electrolyte material BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ. [Display omitted] [ABSTRACT FROM AUTHOR]

Oxygen redox in layered oxide cathodes for Na‐ion batteries is considered a promising approach for improving the energy density. However, oxygen‐redox‐based cathodes suffer from sluggish kinetics and undesirable structural change during charge/discharge, leading to poor electrochemical performances. Herein, introducing vacancies (□) in the transition metal layers enables the enhanced oxygen redox‐based electrochemical performances in the P3‐type Mn‐based layered oxide cathode is demonstrated. The vacancies can play a role of the local distortion buffers, resulting in the enhanced oxygen redox kinetics and the suppressed structural deformation such as P3‐O3(II) phase transition. The oxygen‐redox‐based P3‐type Na0.56[Ni0.1Mn0.81□0.09]O2 exhibits the large discharge capacity of ≈140.95 mAh g−1 at 26 mA g−1 with a high average discharge voltage of ≈3.54 V (vs Na+/Na). Even at 650 mA g−1, its discharge capacity and average operation voltages delivered ≈122.06 mAh g−1 and ≈3.22 V, respectively. Especially, the small gap of average discharge voltage indicates both improves power‐capability and enhanced kinetics of oxygen redox in P3‐type Na0.56[Ni0.1Mn0.81□0.09]O2. Moreover, the vacancy buffer in the transition metal layers results in the stable cycle‐performance of P3‐type Na0.56[Ni0.1Mn0.81□0.09]O2 with the capacity retention of ≈80.80% for 100 cycles, due to the suppressed P3‐O3(II) phase transition. [ABSTRACT FROM AUTHOR]

Rechargeable lithium batteries (LBs) are considered the most promising electrochemical energy storage systems for utilizing renewable energies like solar and wind, ushering society into an electric era. However, the development of LBs faces challenges due to interfacial issues caused by side reactions between existing electrode and electrolyte materials. Magnetron sputtering (MS), a type of physical vapor deposition technology, offers solutions with its wide material selection, gentle deposition process, high uniformity of nano/micro‐scale thin films, and strong thin‐film adhesion. This review outlines the main operating principles of MS technology and explores its advanced applications in interfacial modification of various cathodes, anodes, separators, solid‐state electrolytes, and thin‐film LBs integrated with other microelectronic devices. Furthermore, the review discusses the potential of MS technology to accelerate scientific research and industrial progress toward higher‐performance LBs, advancing human society. [ABSTRACT FROM AUTHOR]

Solid oxide electrolysis cell (SOEC) is a promising solid-state electrochemical device that can convert CO 2 into CO with high efficiency. However, the poor catalytic activity and Sr segregation of the cathode diminish the electrode reaction, hindering the large-scale application. Herein, a medium-entropy strategy is proposed to suppress the Sr enrichment while enhancing the catalytic activity for CO 2. The surface Sr content on Sr 2 Fe 1.2 Ni 0.1 Cu 0.1 Co 0.1 Mo 0.5 O 6-δ (SFNCCM) is significantly reduced after the Ni, Cu, and Co co-doping at Fe-site. Moreover, the oxygen surface exchange and bulk diffusion coefficient at 800 °C for SFNCCM oxide reach 2.42 × 10−4 cm2 s−1 and 2.28 × 10−5 cm2 s−1, which are 1.35 and 1.39 times higher than parent Sr 2 Fe 1.5 Mo 0.5 O 6-δ (SFM) oxide. At 850 °C and 1.5 V, single with SFNCCM-Sm 0.2 Ce 0.8 O 6-δ (SDC) composite exhibits a current density of 2.22 A cm−2 with good stability for up to 100 h. The results suggest that the medium-entropy strategy is a promising method to inhibit Sr segregation and enhance the performance of CO 2 direct electrolysis. • The stability of SFM in CO 2 is significantly improved by medium-entropy strategy. • Surface Sr segregation is dramatically suppressed on SFNCCM oxide. • The catalytic activity for CO 2 RR is enhanced by the low-valent elements co-doping. • The current density of the SFNCCM electrode reaches 2.2 A cm−2 at 850 °C, 1.5 V. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries (Li-S batteries) have attracted wide attention due to their high theoretical energy density and the low cost of sulfur cathode material. However, the poor conductivity of the sulfur cathode, the polysulfide shuttle effect, and the slow redox kinetics severely affect their cycling performance and Coulombic efficiencies, especially under low-temperature conditions, where these effects are more exacerbated. To address these issues, this study designs and synthesizes a microspherical cobalt molybdate@reduced graphene oxide (CoMoO4@rGO) composite material as the cathode material for Li-S batteries. By growing CoMoO4 nanoparticles on the rGO surface, the composite material not only provides a good conductive network but also significantly enhances the adsorption capacity to polysulfides, effectively suppressing the shuttle effect. After 100 cycles at room temperature with a current density of 1 C, the reversible specific capacity of the battery stabilizes at 805 mAh g−1. Notably, at −20 °C, the S/CoMoO4@rGO composite achieves a reversible specific capacity of 840 mAh g−1. This study demonstrates that the CoMoO4@rGO composite has significant advantages in suppressing polysulfide diffusion and expanding the working temperature range of Li-S batteries, showing great potential for applications in next-generation high-performance Li-S batteries. [ABSTRACT FROM AUTHOR]

Despite concerns regarding safety, economics, and the environment, lithium-ion batteries (LIBs) are considerably utilized on account of their low energy density and capacity. Li–sulfur (Li–S) batteries have become a promising substitute for LIBs. Here, we first compared both systems in their cons and pros and analyzed the leading countries and companies in Li–S research are assessed through the utilization of an academic database. The scope of our research includes performance-enhancing design elements, cathode components, and binder materials. Synthetic and natural binders are trialed in an effort to enhance Li–S performance. Understanding the fundamental mechanisms enables the development of durable cathodes and binders. To overcome obstacles such as polysulfide adsorption, shuttle effect, and ion transport limitations, conducting polymers, metal/metal oxides, carbon-based compounds, MOFs, and Mxenes are investigated as potential cathode materials. In addition to pore characteristics and active polar sites, the efficacy of a battery is influenced by the anode surface geometry and heteroatom doping. Our review indicates that binders and sulfur/host composites must be meticulously chosen for Li–S battery cathode materials. This research advances energy storage technology by establishing the foundation for economically viable lithium–sulfur batteries with superior performance. [ABSTRACT FROM AUTHOR]

LiNi1/3Mn1/3Co1/3O2 (NMC 111) materials show promise as cathodes for lithium‐ion batteries (LIBs). However, their widespread use is hampered by various technical challenges, including rapid capacity fading and voltage instability. The cathode materials synthesized using the combustion method were annealed at various temperatures ranging from 650 to 900 °C for 24 h. In this study, we identified an optimal annealing temperature of 750 °C for LiNi0.3Mn0.3Co0.3Ti0.1O2 (NMCT) materials. NMCT‐750 exhibits an initial discharge capacity of about 140.1 mAh g−1 and retains the capacity of 91 % after 30th cycles. The good performance of NMCT‐750 is directly attributed to reduced cation mixing and the establishment of a stable structure with small particle sizes. In contrast, higher annealing temperatures (850 °C) lead to a rapid increase in primary particle size and result in poor cycling stability. Therefore, NMCT‐750, annealed at 750 °C, holds great potential as a cathode material for the next generation of LIBs. [ABSTRACT FROM AUTHOR]

All‐solid‐state batteries (ASSBs), configured with solid electrolytes, have received considerable attention as a future energy solution across diverse sectors of modern society. Unlike conventional liquid electrolytes in particular, sulfide solid electrolytes have various advantages, such as high ionic conductivity (>10−3 S cm−1), good ductile properties, and thermal stability. Despite these advantages, the practical application of sulfide solid electrolytes in ASSBs is still limited due to their interfacial instability with commercial cathode materials. Unfortunately, the spontaneous formation of a space charge layer (SCL) at the interface between the cathode material and the solid electrolyte leads to heightened interfacial resistance, obstructing Li+ transport. To address this issue, proper interfacial engineering is still required to facilitate smooth Li+ migration across the interfaces. In this respect, various functional materials have been under exploration as buffer layers, which are intended to suppress the formation of the SCL at these interfaces. Herein, focus is given on the critical significance of these buffer layers between cathode materials and sulfide solid electrolytes in the development of ASSBs. Considering the present limitations, future research directions for next‐generation ASSBs are discussed. These insights are poised to offer valuable guidance for the strategic design and development of highly reliable ASSBs. [ABSTRACT FROM AUTHOR]

KFeSO4F (KFSF) is considered a potential cathode due to the large capacity and low cost. However, the inferior electronic conductivity leads to poor electrochemical performance. Defect engineering can facilitate the electron/ion transfer by tuning electronic structure, thus providing favorable electrochemical performance. Herein, through the regulation of surface defect engineering in reduced graphene oxide (rGO), the Fe-C bonds were formed between KFSF and rGO. The Fe-C bonds formed work in regulating the Fe-3d orbital as well as promoting the migration ability of K ions and increasing the electronic conductivity of KFSF. Thus, the KFSF@rGO delivers a high capacity of 119.6 mAh g-1. When matched with a graphite@pitch-derived S-doped carbon anode, the full cell delivers an energy density of 250.5 Wh kg-1 and a capacity retention of 81.5% after 400 cycles. This work offers a simple and valid method to develop high-performance cathodes by tuning defect sites. [ABSTRACT FROM AUTHOR]

In this work, sodium cobalt phosphate (NaCoPO4) was successfully prepared by a cost-effective ionothermal method using a deep eutectic solvent (DES) for the first time. The synthesized NaCoPO4 was used to fabricate a cathode material for aqueous rechargeable sodium-ion batteries. The surface morphology of the prepared materials and its compositional analysis were done by using field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray (EDX) analysis, respectively. The X-ray diffraction (XRD), SEM, and EDX studies revealed that the material has orthorhombic-shaped particle morphology with uniform distribution and is in nanoscale (approximately 50 nm). The nature of the cation inserted (Na+ ion insertion) was confirmed by recording CV profiles at different concentrations of the Na2SO4 electrolyte. The reversibility of the electrode redox reaction was studied by varying the scan rate in CV studies, and it was found that the electrode exhibits a reversible behavior with a resistive behavior. In GCPL studies, the cell TiO2/2MNa2SO4/NaCoPO4 showed significant reversibility with a prominent discharge capacity of 85 mAh g−1 at 0.1°C and 88% of capacity retention after 100 cycles. Thus, the prepared materials could be used as an effective futuristic alternative battery material for rechargeable batteries. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries are thought to be a new generation of secondary batteries that will replace lithium‐ion batteries due to their great safety and inexpensive cost. In the cathode materials of aqueous zinc ion batteries with long life and high capacity, abundant active sites and crystal structure stability play an important role. In the present work, the strategy of Na+ intercalation of Fe2VO4 (FVO) is proposed, aiming at the insertion of Na+, which not only enriches the active sites, but also sodium and iron ions act as guest species with the negatively charged VOx lattice to provide strong electrostatic attraction to stabilize the lamellar structure. In terms of electrochemical performance, the discharge specific capacity is 370 mAh g−1 at a current density of 0.1 A g−1, and when the current density is arising 5 A g−1, the specific capacity also reaches 200 mAh g−1 after cycling 2000 with a capacity retention of 99 %, which is better than the electrochemical performance of Fe2VO4 (FVO) alone at 50 mAh g−1. The superior electrochemical performance proves that FVO−Na is an ideal cathode material for zinc ion batteries. [ABSTRACT FROM AUTHOR]

Flexible zinc‐air batteries (FZABs) have emerged as a promising alternative to lithium‐ion batteries in flexible electronic devices due to the advantages of excellent mechanical properties, high energy density, and notable safety. However, the unclear causes of performance degradation and failure mechanisms of FZABs significantly impede their commercialization. Therefore, extensive research is needed to fully reveal the factors and mechanisms responsible for the performance decline of FZABs. In this review, the failure mechanisms of FZABs' key components, including the Zn anode, solid electrolyte, catalyst air cathode, and electrolyte/electrode interface are analyzed and discussed. To promote further research and development of FZABs, a series of challenges and corresponding strategies are summarized and analyzed. Finally, the future development of FZABs is envisioned. This paper aims to comprehensively elucidate the failure mechanisms of FZABs, guide the development of high‐performance FZABs, and thus promote their commercialization. [ABSTRACT FROM AUTHOR]

One of the primary challenges encountered in durability of polymer electrolyte membrane fuel cells (PEMFCs) is the carbon support corrosion of the conventional Pt/C catalyst. To address this challenge, the carbon support is replaced with titanium-based ones in the present study. Pt/TiO 2 , Pt/TiO 2-x (Pt/Black TiO 2), and Pt/TiC catalysts are synthesized and their structural characteristics, electrochemical activity for the oxygen reduction reaction (ORR), and stability are investigated and evaluated in comparison with the conventional Pt/C catalyst. Based on structural analyses, it is observed that the Pt/TiC catalyst exhibits a high specific surface area (1050 cm2 mg−1) and proper electrical conductivity of the support (4.5 × 10⁻1 S cm−1). According to the electrochemical evaluations, the Pt/TiC catalyst demonstrates superior ORR activity in acidic media, with a higher half-wave potential (0.84 V RHE) and a lower Tafel slope (69 mV.dec⁻1). Furthermore, stability evaluations indicate that both Pt/TiC and Pt/TiO 2-x catalysts exhibit higher stability compared to the Pt/C catalyst. Finally, based on the results obtained from the fuel cell tests, the Pt/TiC catalyst demonstrates competitive performance under optimal operating conditions (maximum power density of 573 mW cm−2 and current density of 694 mA cm−2 at 0.6 V) despite the low cathode loading of 0.1 mg Pt /cm2. [Display omitted] • Durability of Pt/TiO 2 Pt/TiO 2-x , and Pt/TiC is evaluated using 10000 aging cycles. • Among the synthesized catalysts, Pt/TiC shows superior ORR activity and stability. • Pt/TiC as the cathode catalyst shows a proper performance at low Pt loading. [ABSTRACT FROM AUTHOR]

Fe-doped cobaltite Ca 3 Co 4 O 9 (CCO) is modified to enhance the efficiency of CCO cathodes in protonic ceramic fuel cells (PCFCs). The Ca 3 Co 3.8 Fe 0.2 O 9 (CCFO) material enhances the creation of oxygen vacancies, hydration, and proton migrations, as demonstrated by first-principles calculations. Subsequent investigations show that doping Fe into CCO improves the charger diffusion abilities and maintains compatible thermal expansion. A PCFC with a CCFO cathode demonstrates superior fuel cell performance, reaching 1790 mW cm−2 at 700 °C. This performance surpasses that of a cell with a CCO cathode and sets a new record for layer cobaltite in PCFCs. The composite cathode design hinders the performance of CCFO and CCO cathodes in PCFCs, indicating proton conduction in these oxides. This aligns with first-principles simulations, making them promising cathode options for PCFCs. [ABSTRACT FROM AUTHOR]

Achieving high performance and stability in cathodes for the oxygen reduction reaction is crucial for the advancement of proton ceramic fuel cells (PCFCs). The introduction of non-metal doping method presents an opportunity to simultaneously optimize the perovskite structure and augment the activity and stability of the oxygen reduction reaction. Herein, we develop a phosphorus-doped SrCo 0·8 Fe 0·15 P 0·05 O 3-δ (SCFP) cathode for PCFCs. The SCFP cathode shows a low area specific resistance of 0.24 Ω cm2 at 650 °C in wet air (5% H 2 O), which is smaller than that of the phosphorus-free SrCo 0·8 Fe 0·2 O 3-δ (SCF) electrode (0.34 Ω cm2). The Ni–BaZr 0.1 Ce 0·7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) anode-supported single cell with BZCYYb electrolyte and SCFP cathode exhibits a superior performance of 865 mW cm−2 at 650 °C under H 2 atmosphere. This underscores the effectiveness of the phosphorus-doping strategy as a promising approach for advancing cathode development in PCFCs. [Display omitted] [ABSTRACT FROM AUTHOR]

Sc is used as a dopant to tailor the traditional Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) cathode for protonic ceramic fuel cells (PCFCs). Experiments and first-principles calculations are used in this study to explore the influence of Sc-doping on the performance of BSCF cathodes for PCFCs. Sc can only occupy the Co or Fe sites, and doping Sc at the Ba or Sr sites results in the formation of secondary phases. The use of Sc dopant reduces the high thermal expansion of traditional BSCF. More importantly, doping Sc into BSCF reduces the formation of oxygen vacancies while improving hydration and decreasing the proton migration barrier. Doping Sc at the Fe site outperforms doping at the Co site in terms of oxygen vacancy content, hydration capability, and proton migration ability. The new Ba 0.5 Sr 0.5 Co 0.8 Fe 0.1 Sc 0.1 O 3-δ (Sc doped at Fe site) has a high fuel cell performance of 1666 mW cm−2 at 700 °C and a low polarization resistance of 0.033 Ω cm2. The fuel cell performance is superior to that of most BSCF-based PCFCs reported, indicating the efficacy of using the Sc-doping strategy to tailor BSCF and the importance of selecting the appropriate doping site. [ABSTRACT FROM AUTHOR]

A novel cathode material, denoted as BaZr 0.26 Fe 0.64 Ni 0.1 O 3-δ (BZFN010), has been suggested for application in proton-conducting solid oxide fuel cells (H-SOFCs), aiming to enhance electrochemical performance. The introduction of Zr into the original BaFeO 3-δ (BFO) results in improved chemical stability against CO 2. However, despite this enhancement, the electrochemical performance remains unsatisfactory. Hence, we leveraged the outstanding stability of BZF and incorporated Ni, a well-known element renowned for its remarkable catalytic qualities, into the cell to augment its properties. This enhancement is substantiated by a combination of experimental and theoretical calculations. When employed as a cathode, the BZFN010 material exhibited markedly superior performance compared to the BaZr 0.36 Fe 0.54 O 3 (BZF36) cathode. It demonstrated a 57% increase in power density, rising from 998 mW cm-2 to 1570 mW cm-2 at 700 °C. This study employs a chained-style cathode exploration strategy, commencing with the conventional BFO cathode, progressing to the enhanced stability of BZF36, and culminating in the optimized catalytic activity of BZFN010. Our work represents an intriguing strategy for the design of H-SOFC cathodes. [ABSTRACT FROM AUTHOR]

We regulate the particle size and crystallographic facet of single-crystal (SC) Li(Ni,Mn) 2 O 4 (LNMO) cathode materials via flux-selective molten salt method. By simply adjusting Li 2 MoO 4 or LiI as sintering aids, we synthesized size controlled SC particles, both small and large, and comparatively investigated their electrochemical behavior focusing on the lithiation/delithiation reactivity in conjunction with the particle size and surface planes. Considering the growth mechanism of a SC particles with a specific crystal plane, such particle size control is not determined solely by the synthetic condition but must also consider the interfacial energy of the crystal planes in conjunction with the fluxes what we used. While the initial charge capacity is similar, the given cathode using a small SC LNMO (using LiI) with uniform particle sizes (≤5 μm) exhibits outstanding rate capability with stable capacity retention under changing current density, which indicates stable lithium transport during the repetitive electrochemical reactions. The dependency of the impedance response with change in the electrode resistances as well as the stability during the cycle reactions in conjunction with the post-mortem Li distribution by using laser-induced breakdown spectroscopy as a function of porosity change and cell degradation are thoroughly discussed from the standpoint of regulated particle property. [ABSTRACT FROM AUTHOR]

Sluggish reaction kinetics in oxygen reduction reaction (ORR) is one of the most important challenges to the development of protonic ceramic fuel cells (PCFCs). La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) exhibits high mixed ionic–electronic conductivity in traditional solid oxide fuel cells, but their slow proton transfer and ORR kinetics impedes practical applications. Herein, composite Pr2Ni0.5Co0.5O4−δ (PNC) particles composed of a perovskite PrNi0.5Co0.5O3−δ phase and a PrO2 phase are impregnated into a LSCF cathode to enhance the ORR activity and proton transfer. The polarization tested in a symmetric cell with PNC‐impregnated LSCF cathode is 0.06 Ω cm2 at 700 °C. The fuel cell with this impregnated cathode shows maximum power densities of 1857 mW cm−2 at 700 °C. Moreover, the impregnated cathode exhibits a low degradation rate in the durability test. This work not only provides a novel and practical approach to improving the performance of current cathode materials for PCFCs but also highlights the potential for enhancing the commercial viability of PCFC technology. [ABSTRACT FROM AUTHOR]

A facile preparation protocol for a porous carbon skeleton supported lithium iron phosphate nanocomposite material (LFP/C) is derived from a ferric gallate (Fe-GA) metal–organic framework (MOF) precursor. [Display omitted] Lithium iron phosphate (LiFePO 4 , LFP) has become one of the most widely used cathode materials for lithium-ion batteries. The inferior lithium-ion diffusion rate of LFP crystals always incurs poor rate capability and unsatisfactory low-temperature performances. To meet with the requirements from the ever-growing market, it is of great significance to synthesize carbon supported LFP nanocomposite (LFP/C) cathode materials using cost effective and environmentally friendly methods. In this work, an LFP/C cathode material is straightforwardly prepared from a metal–organic framework (MOF) precursor ferric gallate (Fe-GA) using its self-template effect. The Fe-GA precursor is firstly fabricated from the redox coprecipitation reaction between Fe foils and gallic acid (GA) molecules in mild aqueous phase. Then the Fe-GA is directly converted to the LFP/C sample after a following solid-state reaction. In half-cells, the LFP/C composite exhibits a reversible capacity of 109.7 mAh·g−1 after 500 cycles under the current rate of 100 mA·g−1 at 25 °C as well as good rate capabilities. In the LFP/C//graphite full-cells, the LFP/C composite can deliver a reversible capacity of 71.4 mAh·g−1 after 50 cycles in the same condition as the half-cells. The electrochemical performances of the LFP/C cathode in half-cells at lower temperature of −10 °C are also examined. Particularly, the evolution of samples has been explored and the lithium-ion storage mechanism of the LFP/C cathode has been unveiled. The sample synthesis protocol is straightforward, eco-friendly and atomic efficient, which can be considered to have good potential for scaling-up. [ABSTRACT FROM AUTHOR]

Fuel cell and lithium ion battery (LIB) technologies are increasingly recognized as cutting‐edge power sources that are gradually displacing various versions of older systems. High‐performance electrode materials must be developed for enhanced next‐generation LIBs. Because of their low cost, high theoretical specific capacity, and environmental friendliness, nanoparticles based on zinc oxide (ZnO) have been regarded as promising alternatives. However, significant problems including intrinsic poor conductivity and significant volume expansion have made ZnO‐based nanomaterials for less viable. In this review we discussed about the mechanism of lithium ion battery and how strategies to overcome intrinsic poor conductivity and significant volume expansion of ZnO‐based nanomaterials. Followed by the best methods for improving the lithium ion storage capacity of ZnO‐based materials as cathode and anode separately reviewed. And summarized the challenges and potential lines of inquiry for Zn‐based nanomaterials in the future. [ABSTRACT FROM AUTHOR]

In this work, sodium cobalt phosphate (NaCoPO4) was successfully prepared by a cost-effective ionothermal method using a deep eutectic solvent (DES) for the first time. The synthesized NaCoPO4 was used to fabricate a cathode material for aqueous rechargeable sodium-ion batteries. The surface morphology of the prepared materials and its compositional analysis were done by using field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray (EDX) analysis, respectively. The X-ray diffraction (XRD), SEM, and EDX studies revealed that the material has orthorhombic-shaped particle morphology with uniform distribution and is in nanoscale (approximately 50 nm). The nature of the cation inserted (Na+ ion insertion) was confirmed by recording CV profiles at different concentrations of the Na2SO4 electrolyte. The reversibility of the electrode redox reaction was studied by varying the scan rate in CV studies, and it was found that the electrode exhibits a reversible behavior with a resistive behavior. In GCPL studies, the cell TiO2/2MNa2SO4/NaCoPO4 showed significant reversibility with a prominent discharge capacity of 85 mAh g-1 at 0.1°C and 88% of capacity retention after 100 cycles. Thus, the prepared materials could be used as an effective futuristic alternative battery material for rechargeable batteries. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) have been regarded as promising candidates for large‐scale energy storage system, and their electrochemical performance is determined by the cathode materials. Recently, the polyanion‐type cathode Na4Fe3(PO4)2P2O7 (NFPP) demonstrates decent performance, while there exists promotion space with respect to its cycle stability and rate capability. Herein, an entropy‐enhanced Na4Fe2.95(NiCoMnMgZn)0.01(PO4)2P2O7 (HE‐NFPP) cathode is proposed with improved rate performance (67.1 mAh g−1 at 50 C) and cycle performance (retention of 92.0% after 1000 cycles at 1 C). The enhancement of configuration entropy improves the structural stability of NFPP thermodynamically. In‐situ XRD illustrates the sodium storage mechanism of HE‐NFPP as an imperfect solid solution reaction driven by Fe2+/Fe3+ redox with a low volume change of 4.0% (90.9% of NFPP). Through doping, the structure distortion and abrupt rearrangement are inhibited. Additionally, HE‐NFPP and hard carbon (HC) are utilized to fabricate pouch cell that demonstrates an average working voltage of 3.0 V and a maximum energy density of 165 Wh kg−1 (based on the total mass of active materials). These results highlight the potential for enhancing the high‐rate and long‐cycle performance of NFPP as a promising cathode for SIBs through an entropy‐enhanced multi‐doping strategy. [ABSTRACT FROM AUTHOR]

Iron‐based mixed polyanion phosphate Na4Fe3(PO4)2P2O7 (NFPP) is recognized as a promising cathode for Sodium‐ion Batteries (SIBs) due to its low cost and environmental friendliness. However, its inherent low conductivity and sluggish Na+ diffusion limit fast charge and low‐temperature sodium storage. This study pioneers a scalable synthesis of hollow core–shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with tiny‐void space (THoCS‐0.6Ni) via a one‐step spray‐drying combined with calcination process due to the different viscosity, coordination ability, molar ratios, and shrinkage rates between citric acid and polyvinylpyrrolidone. This unique structure with interconnected carbon networks ensures rapid electron transport and fast Na+ diffusion, as well as efficient space utilization for relieving volume expansion. Incorporating regulation of lattice structure by doping Ni heteroatom to effectively improve intrinsic electron conductivity and optimize Na+ diffusion path and energy barrier, which achieves fast charge and low‐temperature sodium storage. As a result, THoCS‐0.6Ni exhibits superior rate capability (86.4 mAh g−1 at 25 C). Notably, THoCS‐0.6Ni demonstrates exceptional cycling stability at −20 °C with a capacity of 43.6 mAh g−1 after 2500 cycles at 5 C. This work provides a universal strategy to design the hollow core–shelled structure with tiny‐void space cathode materials for reversible batteries with fast‐charge and low‐temperature Na‐storage features. [ABSTRACT FROM AUTHOR]

With the large‐scale application of lithium‐ion batteries (LIBs), a huge amount of spent LIBs will be generated each year and how to realize their recycling and reuse in a clean and effective way poses a challenge to the society. In this work, using the electrolyte of spent LIBs as solvent, we in situ fluorinate the conductive three‐dimensional porous copper foam by a facile solvent‐thermal method and then coating it with a cross‐linked sodium alginate (SA) layer. Benefiting from the solid‐electrolyte interphase (SEI) that accommodating the volume change of internal CuF2 core and SA layer that inhibiting the dissolution of CuF2, the synthesized CuF2@void@SEI@SA cathode with a pomegranate‐like structure (yolk‐shell) exhibits a large reversible capacity of ~535 mAh g−1 at 0.05 A g−1 and superb cycling stability. This work conforms to the development concept of green environmental protection and comprehensively realizes the unity of environmental, social and economic benefits. [ABSTRACT FROM AUTHOR]

This study reports that hot pressing a high loading (9.375 mg cm−2; > 5 mAh cm−2) all-solid-state FeS2 composite cathodes at 240 °C and 47 MPa improved initial cycle performance. At 25 °C, a cold-pressed cell delivered negligible capacity whereas a hot-pressed cell delivered 332 mAh g−1 (2.34 mAh cm−2). At 60 °C, a cold-pressed cell delivered 666 mAh g−1 (4.70 mAh cm−2) whereas a hot-pressed cell delivered 782 mAh g−1 (5.52 mAh cm−2). Hot-pressed cathode composites had a 20% porosity whereas cold-pressed cathode composites had a 30% porosity. Increased initial discharge capacity was attributed to better solid–solid interfacial contact between sulfide solid-state electrolyte (SSE) particles and between SSE and FeS2 active material particles. Cell failure occurred upon extended cycling due to the stresses generated by the expansion of lithiated FeS2. FIBSEM cross-sectional imaging of post mortem cathode composites revealed horizontal cracking indicative of electrode delamination due to electrode expansion. [ABSTRACT FROM AUTHOR]

This study outlines an effective method for improving the electrochemical properties of MoO 3 by tuning the electronic spin state of Mo via Ni doping, which can enhance its reactivity and weaken the diffusion energy barrier between Zn2+ and MoO 3. [Display omitted] • The electron spin states of Mo are modulated via Ni-ion doping. • The storage mechanism of this electron spin states tuning strategy is clarified. • The assembled Ni-MoO 3 //Zn can afford a high capacity of 258 mAh g −1 at 1 A/g. Aqueous zinc-ion batteries (AZIBs) have received considerable potential for their affordability and high reliability. Among potential cathodes, α-MoO 3 stands out due to its layered structure aligned with the (0 1 0) plane, offering extensive ionic insertion channels for enhanced charge storage. However, its limited electrochemical activity and poor Zn2+ transport kinetics present significant challenges for its deployment in energy storage devices. To overcome these limitations, we introduce a new strategy by doping α-MoO 3 with Ni (Ni-MoO 3), tuning the electron spin states of Mo. Thus modification can activate the reactivity of Ni-MoO 3 towards Zn2+ storage and weaken the interaction between Ni-MoO 3 and intercalated Zn2+, thereby accelerating the Zn2+ transport and storage. Consequently, the electrochemical properties of Ni-MoO 3 significantly surpass those of pure MoO 3 , demonstrating a specific capacity of 258 mAh g−1 at 1 A g−1 and outstanding rate performance (120 mAh g−1 at 10 A g−1). After 1000 cycles at 8 A g−1, it retains 76 % of the initial capacity, with an energy density of 154.4 Wh kg−1 and a power density of 11.2 kW kg−1. This work proves that the modulation of electron spin states in cathode materials via metal ion doping can effectively boost their capacity and cycling durability. [ABSTRACT FROM AUTHOR]

Fe-based double perovskites represent a significant category of cobalt-free materials and exhibit promise as cathodes for solid oxide fuel cells (SOFCs) because of their lower thermal expansivity and reduced cost. However, they often encounter challenges associated with poor oxygen reduction reactivity stemming from intrinsic low electronic and oxygen-ion conductivity. In this investigation, Ca was introduced as a dopant for the first time to improve the electrochemical properties of PrBaFe 2 O 5+ δ (PBFO). The findings unveiled effective adjustments in the formation of oxygen vacancy by introducing Ca into PBFO. Therefore, the oxygen adsorption, dissociation, and charge transfer processes were modulated considerably. At 800 °C, PrBa 0.9 Ca 0.1 Fe 2 O 5+ δ (PBCFO) exhibited a R p of 0.027 Ω cm2, representing a 78.1 % reduction in comparison with PBFO. Concurrently, the output power density of the PBCFO increased by 17.3 %. These results underscore the potential of Ca doping to elevate the ORR kinetics and CO 2 tolerance of PBFO. [ABSTRACT FROM AUTHOR]

The recent classification of lithium as a critical raw material surged the research and development (R&D) of post‐lithium batteries (PLBs). The larger cation charge carriers of these PLBs consequently entailed extensive materials R&D for battery components, especially cathode. Prussian Blue (PB) and its analogues (PBAs) have emerged as promising cathode materials for PLBs due to their desirable characteristics, including a three‐dimensional open framework structure that facilitates fast ion diffusion for both monovalent (Li+, Na+, K+) and multivalent (Mg2+, Ca2+, Zn2+, Al3+) ions, stable framework structures, electrochemical tunability, availability of widely used precursors, and ease of synthesis. Our comprehensive review reveals that several challenges are yet to be addressed in employing PBAs as cathode materials for PLBs, viz., vacancies, crystal water, side reactions, and conductivity issues. This review paper provides an exhaustive survey of material development, including the mitigation strategies of the challenges in employing PBAs as cathode materials for advancing PLBs (i. e., sodium‐ion batteries (SIBs), potassium‐ion batteries (KIBs), magnesium‐ion batteries (MIBs), calcium‐ion batteries (CIBs), zinc‐ion batteries (ZIBs), aluminum‐ion batteries (AIBs)) towards commercialization. [ABSTRACT FROM AUTHOR]

Sodium superionic conductor (NASICON)‐type cathode materials are considered promising candidates for high‐performance sodium‐ion batteries (SIBs) because of the abundance and low cost of raw materials. However, NASICON‐type cathodes suffer from low capacities. This limitation can be addressed through the activation of sodium‐excess phases, which can enhance capacities up to theoretical values. Thus, this paper proposes the use of transition metal (TM)‐substituted Na3V2(PO4)2F3 (NVPF) to induce sodium‐excess phases. To identify suitable doping elements, an inverse design approach is developed, combining machine learning prediction and density functional theory (DFT) calculations. Graph‐based neural networks are used to predict two crucial properties, i. e., the structural stability and voltage level. Results indicate that the use of TM‐substituted NVPF materials leads to about 150 % capacity enhancement with reduced time and resource requirements compared with the direct design approach. Furthermore, DFT calculations confirm improvements in cyclability, electronic conductivity, and chemical stability. The proposed approach is expected to accelerate the discovery of superior materials for battery electrodes. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) have been regarded as promising candidates for large‐scale energy storage system, and their electrochemical performance is determined by the cathode materials. Recently, the polyanion‐type cathode Na4Fe3(PO4)2P2O7 (NFPP) demonstrates decent performance, while there exists promotion space with respect to its cycle stability and rate capability. Herein, an entropy‐enhanced Na4Fe2.95(NiCoMnMgZn)0.01(PO4)2P2O7 (HE‐NFPP) cathode is proposed with improved rate performance (67.1 mAh g−1 at 50 C) and cycle performance (retention of 92.0% after 1000 cycles at 1 C). The enhancement of configuration entropy improves the structural stability of NFPP thermodynamically. In‐situ XRD illustrates the sodium storage mechanism of HE‐NFPP as an imperfect solid solution reaction driven by Fe2+/Fe3+ redox with a low volume change of 4.0% (90.9% of NFPP). Through doping, the structure distortion and abrupt rearrangement are inhibited. Additionally, HE‐NFPP and hard carbon (HC) are utilized to fabricate pouch cell that demonstrates an average working voltage of 3.0 V and a maximum energy density of 165 Wh kg−1 (based on the total mass of active materials). These results highlight the potential for enhancing the high‐rate and long‐cycle performance of NFPP as a promising cathode for SIBs through an entropy‐enhanced multi‐doping strategy. [ABSTRACT FROM AUTHOR]

Due to its abundant zinc resources, high safety and low cost, aqueous zinc-ion batteries (AZIBs) are considered one of the most interesting lithium-ion battery replacement technologies. Herein, a novel Zn-doped cathode material is achieved via pre-intercalation of Zn2+ into the prepared manganese tetroxide (Mn3O4)/graphene oxide (GO). The pre-intercalation of Zn2+ effectively increases the lattice spacing of Mn3O4 and reduces the barrier of insertion/extraction of Zn2+, thus improving the kinetic properties of the material. Meanwhile, the conductive carbon skeleton GO successfully combines with polyethyleneimine and Mn3O4, which can expand electron and ion conductivity and avoid chemical bulk change. This unique structure enables the Zn-doped cathode a reversible specific capacity with excellent performance (170 mAh g−1 at 200 mA g−1). Furthermore, the diffusion coefficient of the Zn-doped cathode is 10−9–10−10cm−2 s−1. Therefore, this study introduces a viable approach for the practical implementation of advanced electrode materials in AZIBs applications. Highlights: The Zn-doped Mn3O4/GO composite is prepared for a simple precipitation method. The Zn-doped Mn3O4/GO cells exhibit better electrochemical properties due to the interaction between the PEI-GO lattice framework and the zinc doping. The cathode of Zn-doped Mn3O4/GO provides a s a specific capacity of 140 mAh g−1 and a Coulomb efficacy of almost 100% at 0.5 A g−1 (after 1000 cycles). The results provide a new way to improve the electrochemical properties of Mn3O4. [ABSTRACT FROM AUTHOR]

LiFePO₄ (LFP) cathodes are popular due to their safety and cyclic performance, despite limitations in lithium-ion diffusion and conductivity. These can be improved with carbon coating, but further advancements are possible despite commercial success. In this study, we modified the carbon coating layer using sulfur to enhance the electronic conductivity and stabilize the carbon surface layer via two methods: 1-step and 2-step processes. In the 1-step process, sulfur powder was mixed with cellulose followed by heat treatment to form a coating layer; in the 2-step process, an additional coating layer was applied on top of the carbon coating layer. Electrochemical measurements demonstrated that the 1-step sulfur-modified LFP significantly improved the discharge capacity (~152 mAh·g−1 at 0.5 C rate) and rate capability compared to pristine LFP. Raman analyses indicated that sulfur mixed with a carbon source increases the graphitization of the carbon layer. Although the 2-step sulfur modification did not exceed the 1-step process in enhancing rate capability, it improved the storage characteristics of LFP at high temperatures. The residual sulfur elements apparently protected the surface. These findings confirm that sulfur modification of the carbon layer is effective for improving LFP cathode properties, offering a promising approach to enhance the performance and stability of LFP-based lithium-ion batteries. [ABSTRACT FROM AUTHOR]

This investigation focuses on nominally La‐doped Na0.67MnO2, exploring its structural, electrochemical, and battery characteristics for Na‐ion batteries. X‐ray diffraction analysis reveals formation of composite materials containing three distinct phases: P2‐Na0.67MnO2, NaMn8O16, and LaMnO3. The bond structures of the powders undergo scrutiny through Fourier‐transform infrared and Raman analyses, revealing dependencies on the NaO, MnO, and LaO structures. X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray dot mapping analyses show that the La ions are unevenly dispersed within the samples, exhibiting a valence state of 3+. Half‐cell tests unveil similarities in redox peaks between the cyclic voltammetry analysis of La‐doped samples and P2‐type Na0.67MnO2, with a reduction in peak intensities as La content increases. Electrochemical impedance spectroscopy model analysis indicates direct influences of La content on the half‐cell's resistive elements values. The synergistic effect of composite material with multiple phases yields promising battery performances for both half and full cells. The highest initial capacity value of 208.7 mAh g−1, with a 57% capacity fade, among others, is observed, and it diminishes with increasing La content. Full cells are constructed using an electrochemically presodiated hard carbon anode, yielding a promising capacity value of 184.5 mAh g−1 for sodium‐ion battery studies. [ABSTRACT FROM AUTHOR]

Li-CO2 batteries with unique reaction pathways and high theoretical capacity are powerful tools for addressing greenhouse issues. Thus, it is critical and urgent to develop highly active catalysts for the cathodes of Li-CO2 batteries to promote both CO2 reduction (CRR) and evolution reactions (CER). Herein, La0.8Sr0.2NixCu1–xO3 perovskite is in situ synthesized on multiwalled carbon nanotubes (LSNC/MWCNTs) paper as cathodes of Li-CO2 batteries. The morphology, structure, and electrochemical performance of the as-prepared cathodes are investigated systematically, as well as the reaction products and reversible reaction mechanism. As a result, the Li-CO2 batteries constructed with La0.8Sr0.2Ni0.7Cu0.3O3 (N7C3)/MWCNTs cathode exhibit remarkable electrochemical properties, showcasing a large specific capacity of 16.90 mAh cm–2 at a high specific current of 0.07 mA cm–2, a low overpotential of 0.76 V after 15 cycles rate test, and good cycling stability, maintaining a low overpotential throughout the 500 h of discharge–charging at 0.02 mA cm–2 with a cutoff capacity of 0.1 mAh cm–2 (50 cycles). The superior electrochemical performance of the N7C3/MWCNTs cathodes is attributed to the high Ni3+ content and a large amount of oxygen vacancies caused by the tuning of the atomic ratio on B-sites of perovskite crystals. The results of this work would provide an easy design option for the free-standing cathodes of Li-CO2 batteries and will inspire more original high-performance metal–air batteries. [ABSTRACT FROM AUTHOR]

P2‐type layered transition metal oxide Na0.67Ni0.33Mn0.67O2 is considered as a promising cathode for advanced sodium‐ion batteries due to its high theoretical specific capacity. However, the P2‐type cathode suffers severe P2‐O2 phase transition during cycling process, resulting unsatisfactory cyclic stability and rate capability. Herein, a Ca/Li co‐doped P2‐type Na0.62Ca0.05Ni0.33Mn0.57Li0.10O2 (NCNMLO) cathode material was synthesized through a simple sol‐gel method. With the synergistic effect of Ca‐doping at Na sites and Li substitution at transition metal (TM) sites, the cathode achieves an excellent electrochemical performance due to the inhibited P2‐O2 phase transition and improved ion diffusion with Na+/vacancy disordering arrangement. The NCNMLO cathode exhibits a good cyclic stability with 70.8 % of capacity retention at 1 C after 200 cycles and excellent rate capability with 40.1 mAh g−1 at 20 C. The dual sites doping strategy provides an effective and simple approach for designing high‐performance layered oxide cathode materials for sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) as highly effective energy conversation devices have gained substantial recognition and research interest. The electrochemical properties of the traditional SOFCs are restricted by the sluggish reaction kinetics for the cathode material when lowering the operation temperature to below 600°C. In addition, the stability of the cathode at reduced temperatures is also a big challenge for the widely popularization of SOFC technology. Achieving high activities and stable ORR in the cathode is crucial for the development of SOFCs. The doping active metal method has been demonstrated as an effective approach to optimize the phase structure and improve the ORR activity of the cathode. Herein, we successfully develop an Ir‐doped SrCoO3 − δ (SrCo0.98Ir0.02O3 − δ, SCI) cathode for SOFCs. SCI exhibits a low area‐specific resistance (ASR) of 0.057 Ω cm2 at 650°C, ~ 44% lower than 0.102 Ω cm2 of Ir‐free SrCoO3 − δ. The Ni–Sm0.2Ce0.8O1.90 (SDC) anode‐supported fuel cell with SDC electrolyte and SCI cathode obtains an excellent output performance (e.g., 1,128 mW cm−2 at 650°C). The desired results underscore the feasibility of the Ir‐doping strategy as an optimized method for the exploitation of advancing cathode in SOFCs. [ABSTRACT FROM AUTHOR]

This investigation is motivated by the surge of interest in materials, combining high spontaneous magnetization and pseudocapacitance at room temperature. Ferrimagnetic MnFe 2 O 4 offers benefits of high magnetization. However, the non-pseudocapacitive behavior, low capacitance and high resistance of MnFe 2 O 4 are limiting factors for its applications in magnetic pseudocapacitive devices. This investigation demonstrates that nearly ideal pseudocapacitive behavior can be achieved for MnFe 2 O 4 electrodes in Na 2 SO 4 electrolyte. High pseudocapacitance is observed in positive and negative potential ranges and two different charging mechanisms are proposed. High capacitance is achieved at a low impedance. The ability to achieve comparable and high areal capacitances in the positive and negative potential ranges facilitates the fabrication of a symmetric pseudocapacitive device, containing ferrimagnetic MnFe 2 O 4 as cathode and anode material for operation in enlarged voltage window of 1.6 V. The symmetric device shows capacitance of 0.92 F cm−2 at a current density of 3 mA cm−2. The individual electrodes and device show good cycling stability. The approach is based on the use of murexide and gallocyanine as redox-active dispersants and charge transfer mediators. The analysis of testing results provides an insight into the influence of chemical structure, charge and redox properties of the dispersants on the capacitive behavior. The ability to fabricate a pseudocapacitive device, containing two ferrimagnetic electrodes is promising for energy storage, water purification and novel applications based on magnetocapacitive effects. [ABSTRACT FROM AUTHOR]

The catalytic efficiency of the cathode is paramount in elevating the operational efficacy of low-temperature solid oxide fuel cells (LT-SOFCs) through expeditious facilitation of the oxygen reduction reaction (ORR). Cathode confronts formidable challenges due to oxygen reduction reaction (ORR) kinetics. This work aims to develop a high-performance cathode by doping strontium (Sr) into Nd 2- x Sr 2 x NiO 4. We synthesized a series of Nd 2- x Sr 2x NiO 4 (x : 0, 0.03, 0.06, 0.1) samples with varying Sr doping levels and evaluated their electrochemical performances. Nd2- x Sr 2 x NiO 4 with optimal ratio (x : 0.06) delivers the highest peak power density of 620–338 mw cm−2 at 550-470 °C among all four samples. The electrochemical impedance spectroscopy of the optimal composition revealed that Nd 2- x Sr 2 x NiO 4 exhibits low electrode polarization resistance of 0.34 Ω cm 2 , depicting its high catalytic performance and compatibility with the electrolyte and anode. Furthermore, XPS spectra also suggest higher surface oxygen vacancies than the other three samples, subsequently improving the conductivity and catalytic activity. Along with high power and OCVs, Nd 2- x Sr 2 x NiO 4 cathode-based SOFC is persistently stable for 40 h without significant degradation. These results conclusively point to demonstrating Nd 2- x Sr 2 x NiO 4 as a high-performing cathode for LT-SOFCs. [ABSTRACT FROM AUTHOR]

The lithium-sulfur battery (LSB) is a highly promising energy storage system with merits of exceptional theoretical specific capacity and energy density. However, challenges including insufficient sulfur conductivity, volume expansion, and the polysulfide shuttle effect result in rapid capacity decay and limited cycle life of the LSB, which significantly hinders its development. Inspired by the structure and forming process of paper, a fiber double network skeleton was constructed using flexible pulp fiber (PF) and highly conductive carbon fiber (CF). Following the principles of wet end chemistry in papermaking, MXene nanosheets with high adsorption and catalytic capacity for polysulfides were self-assembled on the surfaces of PF and CF to fabricate composite paper-based materials. The interwoven mesh of PF exhibited strong binding force and stable structure, providing support and protection for the CF interwoven mesh, resulting in a composite material with abundant porosity and excellent structural stability. Moreover, the CF interweaving network combined with an overlaid MXene interweaving network established an effective three-dimensional conductive pathway. When utilized as a self-supporting cathode in LSB, this composite paper-based material demonstrated outstanding cyclic stability. Under conditions of sulfur load at 2.3 mg·cm−2 and discharge at 0.2 C, the specific discharge capacity remained at 952 mAh·g−1 after 200 cycles with a capacity retention rate reaching 95.4%. The CF/PF@Mxene (CPCMX) also exhibited excellent tensile strength measured at 7.19 MPa while maintaining exceptional flexibility and electrolyte wettability. This research presents a highly promising solution for advancing the development of LSB with superior cycle stability. [ABSTRACT FROM AUTHOR]

Rechargeable lithium‐carbon dioxide (Li‐CO2) batteries present a compelling strategy for carbon capture and utilization techniques. Nevertheless, the formation of Li2CO3 as the main discharge product in the 4e−/3CO2 electrochemistry of Li‐CO2 batteries necessitates an elevated applied voltage to achieve full decomposition, which leads to severe performance issues in Li‐CO2 batteries. In this work, a stable lithium oxalate (Li2C2O4) electrochemistry involving a 2e−/2CO2 process triggered by Mo2N@Ti3C2O2 electrocatalyst is proposed, which facilitates highly reversible redox reactions in Li‐CO2 batteries. The presence of enriched ‐O terminations at the interface between Mo2N and Ti3C2O2 strengthens charge redistribution of Mo 3d orbital electron and enhances the coupling between Mo 3d orbitals and O 2p orbitals in Li2C2O4. The adsorption energy of Li2C2O4 on Mo2N@Ti3C2O2 surface and energy barrier for self‐disproportionation reaction of Li2C2O4 are further increased, enabling the stable Li2C2O4 electrochemistry. Therefore, the Mo2N@Ti3C2O2 based Li‐CO2 battery can produce Li2C2O4 discharge products even at a high discharge rate of 500 mA g−1 (ten times to previous studies) and during deep cycling processes. Due to the stable Li2C2O4 electrochemistry, Li‐CO2 batteries exhibit excellent electrochemical performance, including ultra‐low overpotential (0.55 V), ultra‐high energy efficiency (82.9%), and excellent cycling stability electrode (800 h). [ABSTRACT FROM AUTHOR]

Oxygen redox enhances the specific energy of sodium cathodes, but the other performance remains unsatisfactory. By introducing Cu into P2 lattice to replace Li cations, P3‐type Na0.75Li0.2Cu0.05Mn0.75O2 with high Na concentration is achieved. This modification induces notable alteration in the lattice structure, specifically increasing the interplanar spacing of NaO6 from 3.6 Å to 3.8 Å. The resultant P3‐type cathode delivers a remarkable capacity of 253 ± 1.3 mAh g−1 with energy density of 680 mWh g−1, setting a benchmark for P3‐type sodium cathodes. The high capacity can be attributed to the activation of Mn3+/ Mn4+ redox pair following Cu substitution. Further investigations confirm that Mn3+/ Mn4+, Cu2+/ Cu3+ and O2−/On− redox pairs all contribute to the high performance. The absence of O vacancy and the reduction in phase transitions enhance the cyclic performance with capacity retention of 86.3% at 0.5C. Additionally, the small diffusion energy barrier (34.6 KJ mol−1) results in a high Na diffusion coefficient (1.332 × 10−9 cm2 s−1), thereby promoting superior rate behavior with a capacity of 200.8± 2.1 mAh g−1 at 5C. These results demonstrate the advantages of the P3‐type Na0.75Li0.2Cu0.05Mn0.75O2 cathode over the other Na cathodes, suggesting high potential for application in high‐energy storage fields. [ABSTRACT FROM AUTHOR]

Li‐rich cathode materials (LRMs) are regarded as the key cathode candidates for next‐generation lithium‐ion batteries(LIBs) because of their high specific capacity and environmental friendliness. However, LRMs encounter poor cyclability and low initial coulombic efficiency (ICE) hindering their practical application. Herein, a general near‐surface in situ reconstruction strategy is proposed of constructing the Li/O dual vacancies and spinel‐carbon dual coating layers on the surface of LRMs concurrently to improve Li+ storage performance. The as‐prepared LRMs exhibit a greatly strengthened specific capacity of 283 mAh g−1 with an enhanced ICE of 94% and long‐term cyclability of 91% retention after 200 cycles compared with the pristine LRMs (212 mAh g−1 with an ICE of 65%, 76% retention after 200 cycles). Furthermore, it is theoretically revealed that O vacancies (Ov) prefer to occur at the interface of the C2/m and R3¯$\bar{3}$m phases to mitigate lattice stress, rather the O sites in individual C2/m or R3¯$\bar{3}$m phase with more coordinated atoms. Besides, Li ions exhibit lower migration energy from C2/m phase to R3¯$\bar{3}$m phase with the Ov located at the lattice interface. Therefore, this strategy opens a new avenue in the design perspective of the LRMs' near‐surface for high‐energy‐density LIBs. [ABSTRACT FROM AUTHOR]

A Sr-deficiency approach is utilized to adjust the composition of the standard Sr 2-x Fe 1.5 Mo 0.25 Sc 0.25 O 6 (SFMS) material, with the goal of improving the performance of the SFMS cathode in proton-conducting solid oxide fuel cells (H–SOFCs). The Sr-deficiency concentration is restricted to 10% at the Sr site, and an increase in Sr-deficiency leads to the formation of more oxygen vacancies. However, the presence of increased oxygen vacancies does not consistently enhance the diffusion capabilities of charge carriers. The excess of oxygen vacancies impedes the movement of oxygen and protons. The optimal oxygen and proton transport capabilities are achieved when the Sr-deficiency level is set at 5%. Specifically, this is observed in the compound Sr 1.9 Fe 1.5 Mo 0.25 Sc 0.25 O 6 (S1.9FMS). The enhanced oxygen and proton diffusion kinetics enable H–SOFCs to achieve exceptional performance when employing the S1.9FMS cathode, reaching a power density of 1709 mW cm−2 at 700 °C with a low polarization resistance of 0.023 Ω cm2. The fuel cell's output exceeds that of many previously reported H–SOFCs. Furthermore, the fuel cell utilizing the S1.9FMS cathode not only exhibits excellent fuel cell performance but also maintains reliable operational stability. This indicates that employing the Sr-deficiency technique with an appropriate level of deficiency is a successful approach to enhance the cathode performance for H–SOFCs. • A Sr-deficiency approach was used to tailor Sr 2-x Fe 1.5 Mo 0.25 Sc 0.25 O 6 (SFMS). • The Sr-deficient SFMS showed improved oxygen and proton diffusion kinetics. • A high fuel cell performance was obtained with the Sr 1.9 Fe 1.5 Mo 0.25 Sc 0.25 O 6 cathode. • Good stability was retained for the Sr 1.9 Fe 1.5 Mo 0.25 Sc 0.25 O 6 cathode. [ABSTRACT FROM AUTHOR]