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The thermodynamic condition for phase formation in the Al–Si–Ti system is crucial for understanding the reason behind deteriorations of grain refinement and castability of Al–Si–Ti alloys. Seven Al–Si–Ti alloys annealed between 550 and 650 °C were used to clarify the inconsistencies of phase equilibria in the Al–Si rich region. The existences of τ 1 (Zr 3 Al 4 Si 5 -type tetragonal), τ 2 (ZrSi 2 -type orthogonal) and the three-phase equilibrium of τ 1 + α-Al + Si were confirmed. Combined with a critical review of literature data, a CALPHAD-type thermodynamic description was developed for the phase equilibria in the Al–Si rich region of the Al–Si–Ti system between 550 and 900 °C. Meanwhile, edge-to-edge matching analysis according to the crystal structures of τ 1 and τ 2 shows that their nucleation efficacies for α-Al are both weaker than that of Ti(Al,Si) 3 . From the calculated phase equilibrium of L + τ 2 + Ti(Al,Si) 3 at 727 °C and the local equilibrium principle, τ 2 would form on the surface of TiAl 3 particle and deteriorate its grain refinement efficiency for α-Al. From the calculated liquidus projection, Ti(Al,Si) 3 is the primary phase within 0–10.3 wt.% Si and 0.08–0.30 wt.% Ti. To avoid the formation of τ 1 and τ 2 for retaining good grain refinement efficiency and castability, a Ti/Si threshold was determined by thermodynamic calculations. [ABSTRACT FROM AUTHOR]

The development of potassium‐ion batteries (KIBs) relies on the exploration of stable layer‐structured oxide cathode materials and a comprehensive understanding of ion storage and diffusion behaviors. A multiphase riveting‐structured O3/P2/P3‐Na0.9[Ni0.3Mn0.55Cu0.1Ti0.05]O2 (Tri‐NMCT) is employed as cathode material for KIBs. It demonstrates an initial discharge specific capacity of 108 mA g−1 at current density of 15 mA g−1 in the voltage range of 1.5–4 V. Excellent cyclic stability is exhibited as well with a high 83% capacity retention after 600 cycles at a higher current density of 300 mA g−1. Based on the in‐situ XRD, it reveals that the P2 phase offers a more stable triangular prism site compared to the O3 phase. This stability inhibits the undesired phase transition from P3 to O3 during discharge, thereby ensuring the long‐term cyclic performance. Furthermore, Density of state (DOS) calculations and migration barrier analyses indicate a preferential migration of K+ ions to the P2 phase due to the lower Fermi level. This observation elucidates the structural preservation of the P3 phase during K+ embedding. Overall, this work sheds light on Tri‐NMCT as a promising cathode material for advanced KIBs. [ABSTRACT FROM AUTHOR]

Potassium metal batteries (PMBs) are regarded as viable candidates for future electrochemical energy storage devices with potential high energy density and low cost. However, uncontrollable potassium dendrite growth and huge volume expansion severely inhibit the practical application of PMBs. Herein, inspired by the structure and functionalities of tree bark, an antimony (Sb) nano‐clusters decorated N‐doped interconnected carbon nanospheres/potassium composite electrode with biomimetic fast ionic channels is developed to realize the dendrite‐free potassium metal batteries. The composite electrode provides abundant nucleation sites and interconnected ion transport channels, facilitating rapid ion transport kinetics and highly reversible potassium plating/stripping behaviors. Consequently, the assembled symmetric cell exhibits an ultra‐long cycle life (1100 h at 1.0 mA cm−2/1.0 mAh cm−2) in carbonate electrolyte. Moreover, the K full cells demonstrate enhanced cycling stability (1500 cycles at 8 C) and rate capacity (117.27 mAh g−1 at 20 C). This novel biomimetic design of composite anode presents an effective and rational approach for achieving stable PMBs. [ABSTRACT FROM AUTHOR]

Ammonia, a vital component in the synthesis of fertilizers, plastics, and explosives, is traditionally produced via the energy‐intensive and environmentally detrimental Haber–Bosch process. Given its considerable energy consumption and significant greenhouse gas emissions, there is a growing shift toward electrocatalytic ammonia synthesis as an eco‐friendly alternative. However, developing efficient electrocatalysts capable of achieving high selectivity, Faraday efficiency, and yield under ambient conditions remains a significant challenge. This review delves into the decades‐long research into electrocatalytic ammonia synthesis, highlighting the evolution of fundamental principles, theoretical descriptors, and reaction mechanisms. An in‐depth analysis of the nitrogen reduction reaction (NRR) and nitrate reduction reaction (NitRR) is provided, with a focus on their electrocatalysts. Additionally, the theories behind electrocatalyst design for ammonia synthesis are examined, including the Gibbs free energy approach, Sabatier principle, d‐band center theory, and orbital spin states. The review culminates in a comprehensive overview of the current challenges and prospective future directions in electrocatalyst development for NRR and NitRR, paving the way for more sustainable methods of ammonia production. [ABSTRACT FROM AUTHOR]

Electrocatalyst plays animportant role in electrochemical ammonia synthesis by determining the nitrogen reduction reaction pathway. Featuring the inherent half‐filled 3d orbitals, ion‐based alloy electrocatalysts have been attracting much more attention owing to the controllable driving force to adsorb and activate N≡N bonds. Besides supplying unoccupied d‐orbital to accommodate lone‐pair electrons to facilitate nitrogen adsorption, donating d‐orbital electrons to nitrogen antibonding orbitals to dissociate N≡N bond is demandedas well. By palladium (Pd) to synthesize PdFe3 nano‐alloy, numerous Fe 3d orbitals can be reconstructed via charge polarization between Fe and Pd, simultaneously lowering corresponding work functions. Meanwhile, the positively charged Fesites in PdFe3 can strengthen suppress the proton adsorption by electrostatic repulsion. A considerably optimized ammonia production rate of 29.07 µg h−1 mgcat.−1 and Faradic efficiency of 22.8% are accomplished at a low overpotential of −0.2 V vs. RHE. Density functional theory combined with in‐situ ATR‐FTIR results confirmthe electrocatalytic nitrogen reduction follows the associative distalmechanism and the electron‐deficient Fe induced through Pd facilitates significantly lowering the first‐step‐protonation energy barrier of only 0.07 eV (*N2 + *H →*NNH). [ABSTRACT FROM AUTHOR]

K‐metal batteries have become one of the promising candidates for the large‐scale energy storage owing to the virtually inexhaustible and widely potassium resources. The uneven K+ deposition and dendrite growth on the anode causes the batteries prematurely failure to limit the further application. An integrated K‐metal anode is constructed by cold‐rolling K metal with a potassiphilic porous interconnected mediator. Based on the experimental results and theoretical calculations, it demonstrates that the potassiphilic porous interconnected mediator boosts the mass transportation of K‐metal anode by the K affinity enhancement, which decreases the concentration polarization and makes a dendrite‐free K‐metal anode interface. The interconnected porous structure mitigates the internal stress generated during repetitive deposition/stripping, enabling minimized the generation of electrode collapse. As a result, a durable K‐metal anode with excellent cycling ability of exceed 1, 000 h at 1 mA cm−2/1 mAh cm−2 and lower polarization voltage in carbonate electrolyte is obtained. This proposed integrated anode with fast K+ kinetics fabricated by a repeated cold rolling and folding process provides a new avenue for constructing a high‐performance dendrites‐free anode for K‐metal batteries. [ABSTRACT FROM AUTHOR]

Prussian blue analogs (PBAs) are promising cathode materials for sodium‐ion batteries (SIBs) due to their low‐cost, similar energy density comparable with that of LiFePO4 in lithium‐ion batteries, and long cycle life. Nevertheless, crystal water (≈10 wt%) in PBAs from aqueous synthesis environments can bring significant side effects in real SIBs, especially for calendar life and high temperature storage performance. Therefore, it is of great importance to eliminate crystal water in PBAs for future commercial applications. Herein, a facile heat‐treatment method is reported in order to remove water from Fe‐based PBAs. Although the heat‐treated sample can be easily rehydrated in air, it still exhibits a stable cycling performance over 2000 times under controlled charge cut‐off voltage. In situ synchrotron high‐temperature powder X‐ray diffraction demonstrates that the as‐prepared sample is maintained at a new trigonal phase after dehydration. Moreover, the redox reaction of low‐spin Fe2+/Fe3+ is activated and the high‐temperature storage performance of as‐prepared sample is significantly improved after removal of water. [ABSTRACT FROM AUTHOR]

A series of Li 2 Fe 1-3 x /2 V x P 2 O 7 ( x = 0, 0.025, 0.05, 0.075, and 0.1) cathode materials for LIBs were prepared by the sol-gel method. Structural characterization of Li 2 Fe 1-3 x /2 V x P 2 O 7 ( x = 0, 0.025, 0.05, 0.075, and 0.1) samples was conducted by synchrotron X-ray diffraction. The morphology and oxidation states of Fe 2+ and V 3+ in the Li 2 Fe 1-3 x /2 V x P 2 O 7 samples were confirmed by scanning electron microscopy and magnetic susceptibility measurements, respectively. The electrochemical measurements indicated that Li 2 Fe 1-3 x /2 V x P 2 O 7 ( x = 0.025) delivered the higher reversible capacity of 79.9 mAh g −1 at 1 C in the voltage range of 2.0 - 4.5 V with higher 77.9% capacity retention after 300 cycles than those of Li 2 FeP 2 O 7 (48.9 mAh g −1 and 72.6%). Moreover, the rate capability of Li 2 Fe 1-3 x /2 V x P 2 O 7 ( x = 0.025) were also significantly enhanced through vanadium substitution to iron of Li 2 Fe 1-3 x /2 V x P 2 O 7 . The vanadium substituted to Fe2 site of Li 2 FeP 2 O 7 decreases Li occupying the Li5 position in the FeO 5 unit, leading to a low degree exchange between Li and Fe in the MO 5 (M = Li and Fe). The low degree cation disorder was beneficial to lithium-ion extraction/insertion during the charge-discharge process and hence enhances the capacity and rate capability. [ABSTRACT FROM AUTHOR]

Abstract: LiNi1/3Mn1/3Co1/3O2 (NMC) as a cathode material for lithium ion batteries has been synthesized by the sol–gel method. The X-ray diffraction Rietveld refinement results indicated that single-phase NMC with hexagonal layered structure was obtained. Scanning electron microscope images revealed well crystallized NMC with uniform particle size in the range of 100–200 nm. The performance of the NMC electrodes with sodium carboxylmethyl cellulose (CMC), poly(vinylidene fluoride) (PVDF), and alginate from brown algae as binders was compared. Constant current charge–discharge test results demonstrated that the NMC electrode using CMC as binder had the highest rate capability, followed by those using alginate and PVDF binders, respectively. Electrochemical impedance spectroscopy test results showed that the electrode using CMC as the binder had lower charge transfer resistance and lower apparent activation energy than the electrodes using alginate and PVDF as the binders. The apparent activation energies of NMC electrodes using CMC, alginate, and PVDF as binders were calculated to be 27.4 kJ mol−1, 33.7 kJ mol−1, and 36 kJ mol−1, respectively. [Copyright &y& Elsevier]

Room‐temperature sodium–sulfur (RT Na–S) batteries have attracted extensive attention because of their low cost and high specific energy. RT Na–S batteries, however, usually suffer from sluggish reaction kinetics, low reversible capacity, and short lifespans. Herein, it is shown that chain‐mail catalysts, consisting of porous nitrogen doped carbon nanofibers (PCNFs) encapsulating Co nanoparticles (Co@PCNFs), can activate sulfur via electron engineering. The chain‐mail catalysts Co@PCNFs with a micrograde hierarchical structure as a freestanding sulfur cathode (Co@PCNFs/S) can provide space for high mass loading of sulfur and polysulfides. The electrons can rapidly transfer from chain‐mail catalysts to sulfur and polysulfides during discharge–charge processes, therefore boosting its conversion kinetics. As a result, this freestanding Co@PCNFs/S cathode achieves a high sulfur loading of 2.1 ± 0.2 mg cm−2, delivering a high reversible capacity of 398 mA h g−1 at 0.5 C (1 C = 1675 mA g−1) over 600 cycles and superior rate capability of an average capacity of 240 mA h g−1 at 5 C. Experimental results, combined with density functional theory calculations, demonstrate that the Co@PCNFs/S can efficiently improve the conversion kinetics between the polysulfides and Na2S via transferring electrons from Co to them, thereby realizing efficient sulfur redox reactions. [ABSTRACT FROM AUTHOR]

An effective regulation of the magnetism and interface of ferromagnetic materials is not only of great scientific significance, but also has an urgent need in modern industry. In this work, by using the first-principles calculations, we demonstrate an effective approach to achieve non-volatile electrical control of ferromagnets, which proves this idea in multiferroic heterostructures of ferromagnetic LaTiO3 and ferroelectric BiFeO3. The results show that the magnetic properties and two-dimensional electron gas concentrations of LaTiO3 films can be controlled by changing the polarization directions of BiFeO3. The destroyed symmetry being introduced by ferroelectric polarization of the system leads to the transfer and reconstruction of the Ti-3d electrons, which is the fundamental reason for the changing of magnetic properties. This multiferroic heterostructures will pave the way for non-volatile electrical control of ferromagnets and have potential applications. [ABSTRACT FROM AUTHOR]

The strategy of inducing interlayer anionic ligands in 2D MoS1.5Se0.5 nanosheets is employed to consolidate the interlayer band gap and optimize the electronic structure for the potassium ion battery. It combines complementary advantages from two kinds of anionic ligands with high conductivity and good affinity with potassium ions. The potassium ion diffusion rate is accelerated as well by an optimized lower energy barrier for ion diffusion pathways, with the formation of highly reversible KMo3Se3 crystal other than K0.4MoS2/K2MoS4, which encounters a much slower electro/ion diffusion rate upon discharging. These advances deliver enhanced potassium storage properties with excellent cycling stability, with retained specific capacity of 531.6 mAh g−1 at a current density of 200 mA g−1 even after 1000 cycles, and high rate capability with specific capacity of 270.1 mAh g−1 at 5 A g−1. The insertion and conversion mechanism are also elucidated by a combination of density functional theory computations and in situ synchrotron measurements. [ABSTRACT FROM AUTHOR]

Despite the high theoretical capacity of the sodium–sulfur battery, its application is seriously restrained by the challenges due to its low sulfur electroactivity and accelerated shuttle effect, which lead to low accessible capacity and fast decay. Herein, an elaborate carbon framework, interconnected mesoporous hollow carbon nanospheres, is reported as an effective sulfur host to achieve excellent electrochemical performance. Based onin situsynchrotron X-ray diffraction, the mechanism of the room temperature Na/S battery is proposed to be reversible reactions between S8and Na2S4, corresponding to a theoretical capacity of 418 mAh g–1. The cell is capable of achieving high capacity retention of ∼88.8% over 200 cycles, and superior rate capability with reversible capacity of ∼390 and 127 mAh g–1at 0.1 and 5 A g–1, respectively. [ABSTRACT FROM AUTHOR]

The isothermal section of Ce–Mg–Ni ternary system at 673 K was constructed through thermodynamic calculation coupled with experimental verification. Under guidance of the phase diagram in Mg-rich corner, Ce 2.92 Mg 91.84 Ni 5.24 was designed to investigate its hydrogen storage properties. Moreover, the mechanism of α-to-β (α: diluted phase and β: hydride) phase transformation in the Ce 2.92 Mg 91.84 Ni 5.24 –H 2 system was elucidated by in situ synchrotron powder X-ray diffraction (SR-PXRD). The alloy showed a good activated ability and displayed two plateaus in the pressure–composition–temperature curves. The kinetic mechanisms of hydriding and dehydriding reactions were analyzed by Chou model. The rate-controlling steps were the diffusion for the initial stage in hydriding reaction and the surface penetration for dehydriding reaction. SR-PXRD patterns indicated that the activated Ce 2.92 Mg 91.84 Ni 5.24 gradually transformed into CeH 2.51 , (Mg) (with solid solution of H atoms) and Mg 2 NiH 0.3 , finally transformed into CeH 2.51 , MgH 2 and Mg 2 NiH 4 during the first hydriding process. [ABSTRACT FROM AUTHOR]

Abstract: A high performance Li3V2(PO4)3 cathode material for lithium ion batteries was synthesized by the microwave-assisted hydrothermal method followed by a post annealing process. The synchrotron X-ray diffraction analysis results confirmed that single-phase Li3V2(PO4)3 with monoclinic structure was obtained. Scanning electron microscope and transmission electron microscope images revealed that the as-prepared Li3V2(PO4)3 was composed of nanowires and microsized particles. Electrochemical results demonstrated that the Li3V2(PO4)3 electrode measured at 10 C after 500 cycles can deliver discharge capacities of 85.4 mAh g−1 and 103.4 mAh g−1, with a capacity retention of 99.3% and 95.9%, in the voltage ranges of 3.0–4.3 V and 3.0–4.8 V, respectively, indicating good cycling stability. Furthermore, the electrochemical performance of Li3V2(PO4)3 in ionic liquid electrolytes between 3.0 V and 4.8 V was also measured. [Copyright &y& Elsevier]

Abstract: Ti is usually added into aluminum–zinc alloys to refine the grains and improve plasticity and strength. However, the precipitated phases and the mechanism of grain refinement were not fully understood. In this study, a new ternary phase τ–Ti26Al55Zn19 was found, which formed by the diffusion of Zn atoms into TiAl3 phase. Its crystal structure has been investigated by high resolution X-ray diffraction (HRXRD) and high resolution transmission electron microscopy (HRTEM). The Rietveld refinement results show that the structure of τ–Ti26Al55Zn19 phase is an ordered face centered cubic with Ti atoms occupying 1a (0, 0, 0) positions and Al/Zn atoms occupying 3c (0, 0.5, 0.5) positions. The crystal structure is interpreted well with the selected area electron diffraction patterns and high resolution electron microscopy images. The microhardness value of Ti26Al55Zn19 was less than that of TiAl3 owing to the structure transformation. The curves observed from simultaneous thermogravimetric (TG) – differential scanning calorimetric (DSC) analyzer indicated that the τ–Ti26Al55Zn19 phase was stable up to 810.9°C, but above this temperature TiAl3 phase appeared from the liquid with the volatilization of Zn. [Copyright &y& Elsevier]