O3 Type Research Articles

Advances in low-temperature solid oxide fuel cells: An explanatory review

This review article explores recent advancements and potential advantages of low-temperature solid oxide fuel cells (LT-SOFCs), offering a comprehensive overview of critical developments in the field. It highlights the significance of utilizing oxygen ion conducting electrolytes such as La0.8Sr0.2Ga0.8Mg0.2O3–type (LSGM) perovskties and yttria-stabilized zirconia (YSZ) in LT-SOFCs, emphasizing their role in facilitating efficient oxygen transport at lower temperatures. Furthermore, the review discusses the importance of electrode tailoring at the nanoscale using techniques like sol-gel and pulsed laser deposition (PLD), which have been shown to enhance the oxygen reduction reaction (ORR) at the cathode, thereby improving overall cell performance. One of the key focal points of the review is the exploration of perovskite structures and their imperative characteristics in LT-SOFCs. Specifically, it elucidates how oxygen defects within perovskites contribute to the migration of oxygen ions, consequently augmenting electrical conductivity within the cell. This discussion underscores the significance of understanding the fundamental principles governing ion transport mechanisms in electrolyte materials, which is crucial for the development of next-generation LT-SOFCs with improved efficiency and performance. Moreover, the review highlights recent advancements in the fabrication of nanoscale electrolyte films, which have shown promising results in reducing series resistance and enhancing cell performance at lower temperatures. Techniques such as atomic layer deposition (ALD), and spark plasma sintering (SPS) are discussed in the context of fabricating these nanoscale membranes, underscoring their potential for revolutionizing LT-SOFC technology. Overall, this review consolidates recent research findings and technological advancements in the field of LT-SOFCs, shedding light on the novel approaches and strategies employed to overcome existing challenges and propel the development of more efficient and practical fuel cell systems. By synthesizing key insights and highlighting future research directions, this review serves as a valuable resource for researchers and engineers working towards the advancement of LT-SOFC technology.

Rational design of an optimal Al-substituted layered oxide cathode for Na-ion batteries

Layered oxide cathodes, a promising avenue for Na-ion batteries, hold the highest potential for commercialization. Herein, we delve into the structural and electrochemical properties of Al-substituted layered oxides in our quest to pinpoint the optimal cathode composition in the Na3/4(Mn-Al-Ni)O2 pseudo-ternary system. The cathode materials investigated were synthesized in three distinct phase configurations, which include two monophasic configurations with P3 and P2-type structures and a third biphasic cathode with equal proportions of P3 and P2 phases. The fractions of the P3 and P2 type phases in the cathode materials were manipulated by adjusting the calcination temperature. The varying concentration of Mn3+ and Mn4+, confirmed by X-ray photoelectron spectroscopy, was found to impact the cyclic stability of these materials significantly. During electrochemical testing, the P3 cathodes showed impressive rate performance and exhibited an excellent specific capacity of 195 mAh g−1 at 0.1C. Regarding cyclic performance, the biphasic cathodes consistently outperformed their monophasic counterparts, with P3/P2-Na0.75Mn0.50Ni0.25Al0.25O2 exhibiting 82 % capacity retention after 300 cycles. Analysis of operando Synchrotron XRD data revealed an absence of P3 to O3 type phase transition in the cathodes even at low voltages where large structural variations to the unit cell structure were observed. The absence of P3 to O3 transformations and the superior electrochemical performance of Na0.75Mn0.50Ni0.25Al0.25O2 underlines the importance of Al substitution and P3/P2 biphasic structure in enhancing the electrochemical performance of layered oxides.

Accessing the O Vacancy with Anionic Redox Chemistry Toward Superior Electrochemical Performance in O3 type Na‐Ion Oxide Cathode

AbstractAnionic redox chemistry is now viewed as the effective paradigm of improving the capacity of layered oxide materials in Sodium‐ion battery. In this study, O3‐type layered oxide NaLi0.18Co0.23Ru0.59O2 (NLCR) with O redox ability is successfully synthesized via a facile solid‐state synthesis method. By manipulating the calcinate atmosphere with air and argon (sort by NLCR‐Air NLCR‐Ar respectively), a large amount of O vacancy is introduced in the NLCR‐Air cathode. NLCR‐Air with sufficient O vacancy exhibited superior rate performance which showed 87.7% capacity retention after 1000 cycles at 20 C. Both NLCR‐Air and NLCR‐Ar showed activation of O redox properties which is supported by the soft X‐ray absorption spectroscopy (sXAS). Nevertheless, the in‐situ X‐ray diffraction and sXAS studies disclosed the O vacancy can promote the reversible phase transition and effectively suppress the irreversible O redox upon cycling. These are further supported by theoretical study which suggested a fast kinetic of Na diffusion and less electron agglomeration around the O atom for NLCR‐Air with O vacancy.The research proposed a modification strategy with extraordinary reversible O redox property within O3‐type layered cathode and offered a novel insight into understanding the anionic redox mechanism thus provide guidance of material design advanced energy storage systems.

Negative Lattice Expansion in an O3‐Type Transition‐Metal Oxide Cathode for Highly Stable Sodium‐Ion Batteries

AbstractThe sodium extraction/insertion in layered transition‐metal oxide (TMO) cathode materials are typically accompanied by slab sliding and lattice changes, leading to microstructure destruction and capacity decay. Herein, negative lattice expansion is observed in an O3 type Ni‐based layered cathode of Na0.9Ni0.32Zn0.08Fe0.1Mn0.3Ti0.2O2 upon Na+ extraction. It is attributed to the weak Zn2+−O2− orbital hybridization and increased electron density of the surrounding oxygen for reinforced interlayer O−O repulsive force. This enables gliding of TMO slabs for the intergrowth phase transition of P3→OP2 to alleviate lattice strain with moderate lattice shrinkage, which exhibits general interslab spacings and volume changes as low as 2.4 % and 1.9 %, respectively. The strong Ti−O bonds accommodate the internal distortion of TMO6 octahedra due to the flexibility of TiO6 octahedra during cycling. These endow a high specific capacity of 144.9 mAh g−1 and excellent cycling performance of pouch‐type sodium‐ion batteries with 93 % capacity retention after 3600 cycles.

Negative Lattice Expansion in an O3-Type Transition-Metal Oxide Cathode for Highly Stable Sodium-Ion Batteries.

The sodium extraction/insertion in layered transition-metal oxide (TMO) cathode materials are typically accompanied by slab sliding and lattice changes, leading to microstructure destruction and capacity decay. Herein, negative lattice expansion is observed in an O3 type Ni-based layered cathode of Na0.9 Ni0.32 Zn0.08 Fe0.1 Mn0.3 Ti0.2 O2 upon Na+ extraction. It is attributed to the weak Zn2+ -O2- orbital hybridization and increased electron density of the surrounding oxygen for reinforced interlayer O-O repulsive force. This enables gliding of TMO slabs for the intergrowth phase transition of P3→OP2 to alleviate lattice strain with moderate lattice shrinkage, which exhibits general interslab spacings and volume changes as low as 2.4 % and 1.9 %, respectively. The strong Ti-O bonds accommodate the internal distortion of TMO6 octahedra due to the flexibility of TiO6 octahedra during cycling. These endow a high specific capacity of 144.9 mAh g-1 and excellent cycling performance of pouch-type sodium-ion batteries with 93 % capacity retention after 3600 cycles.

Realization High-Voltage Stabilization of O3-Type Layered Oxide Cathodes for Sodium-Ion Batteries by Sn Simultaneously Dual Modification

The total global production of lithium-ion batteries (LIBs) used in electric vehicles and stationary energy storage devices has increased sharply to reach the targeted Net Zero by 2050. This leads to concerns about the future and long-term availability and cost of critical raw materials (cobalt, nickel, lithium and copper) employed in LIBs. Therefore, alternative new-generation batteries with comparable performance but using less critical raw materials are needed.Sodium-ion Batteries (NIBs) offer a wealth of possibilities for inexpensive and sustainable energy storage devices. To maximize their potential, new cathode materials with high energy densities and stable structures are required. Cobalt-free sodium transition metal oxides of O3 type are a predominant cathode for NIBs due to their appreciable specific capacity, reduction in the use of critical elements, and the potential to rival LiFePO4 in terms of energy density. However, rapid capacity fading caused by serious structural and interfacial degradation hamper this process.Herein, we provide a novel Sn-modified O3-type NaNi1/3Fe1/3Mn1/3O2 cathode with improved high-voltage stability by bulk Sn doping and surface coating simultaneously. The bulk substitution of Sn4+ stabilizes the crystal structure by alleviating the irreversible high voltage phase transition and lattice structure degradation. In the meantime, the spontaneously formed tin rich surface layer effectively inhibits surface parasitic reactions and improves interfacial stability during cycling. As a result, the Sn-modified NaNi1/3Fe1/3Mn1/3O2 cathode exhibited excellent cycling performance by an almost doubled capacity retention increase after 200 cycles within 2.0-4.1V. The influence of Sn modification on the crystal structure and electrochemical properties has been investigated for the first time, and the mechanism was studied through an extensive analysis by in situ XRD, HRTEM, FIB-SEM, XPS and Mössbauer spectroscopy.This work offers an industrially feasible strategy to simultaneously stabilize the bulk structure and interface for O3-type layered cathodes for SIBs and raises the possibility of similar effective strategies to be employed for other energy storage materials Figure 1

DFT + U study of the structural, electronic and magnetic properties in the EuCoO3, EuFeO3, and EuCo0.5Fe0.5O3 type perovskite compounds

The study of the interactions between rare-earth elements and transition metals plays a crucial role in understanding the diverse magnetic states observed in systems with ABO3 perovskite structure. Exploring their behavior and the impact on their physical properties has such a significant interest, especially considering their potential applications across various technological sectors. In this research, we investigated the structural, electronic, and magnetic properties of three systems EuCoO3 (ECO), EuFeO3 (EFO), and EuCo0.5Fe0.5O3 (ECFO). We used the density functional theory based on the Hubbard model (DFT + U) approach to accomplish this. Our findings reveal that the ECO system has a bandgap of 1.052 eV for the spin down channel, while the spin up channel exhibits band gap of 1.066 eV, while the EFO system exhibits a slightly smaller bandgap of 0.958 eV. On the other hand, the ECFO system displays a bandgap value of approximately 0.961 eV for the spin-up channel and 1.6 eV for the spin-down channel. Furthermore, we observed an antiferromagnetic behavior in the EFO system, whereas the ECO and ECFO systems exhibit ferromagnetic behavior. These results provide insight into the distinct magnetic properties of these materials and contribute to our understanding of their potential applications as functional devices in various technological fields.

Computational and Experimental Study on the Combined Sulfur and Chromium Poisoning Mechanism of LSM, LSCF and LNO Cathodes

Prevovskite (La,Sr)MnO3 (LSM), (La,Sr)(Co,Fe)O3 (LSCF) and Ruddlesden-Popper (RP) type La2NiO4 (LNO) phase, as solid oxide fuel cell (SOFC) cathodes, has been used due to its high efficiency and low emissions. To further understand the long-term degradation mechanism of the LSM, LSCF, and LNO phase in SO2 and Cr vapor gas impurities, they were prepared, sintered, and heat-treated at 800, 900, and 1000 ℃ in the sulfur, chromium, and water vapor-containing atmospheres, respectively. Later, XRD, SEM and TEM techniques were applied to the samples and corresponding simulations were made by the CALPHAD approach based on the same experimental conditions to verify the formation of the detrimental secondary phases. Results showed good agreement among the predictions and experiments. More importantly, extensive simulations were also conducted under different conditions (temperature, the partial pressure of oxygen and impurities) to understand the long-term degradation mechanism and optimize the operating conditions.

Analysis of the Restructuring of the Active Layer of UAM-50 and UAM-100 Membranes during the Ultrafiltration Separation of Surfactant Solutions

It is established that the fractions of the characteristic intensities of OH group vibrations attributed to intramolecular H-bonds of O3–H···O5 and O2–H···O6 types and intermolecular H-bonds of O6–H···O3 type of air-dried samples are 0.12, 0.1, and 0.2 for UAM-100 membrane and 0.12, 0.1, and 0.19 for UAM-50 membrane. It is shown that the characteristic intensity of the ν(OH) absorption band grows from 9.55 to 10.3 in a working sample of the UAM-100 membrane and a drop in the symmetry index to 0.75 was explained by the oxidation of aldehyde groups at C1 pyranose ring to the carboxyl (–COOH). It is proved that the fractions of intermolecular bonds of О6–Н···О3 and intramolecular H-bonds of O3–H···O5 and O2–H···O6 are 0.15, 0.09, and 0.13 that indicates not only the structural rearrangement of the hydrogen bond system but also possibly the formation of weak hydrogen bonds between hydroxyl groups of pyranose rings and molecules of the sedimentary layer.

Biphasic high-entropy layered oxide as a stable and high-rate cathode for sodium-ion batteries

O3-phase layered oxides are promising cathode materials for sodium-ion batteries. However due to the strong Na+–O2- electrostatic attraction and the large size of Na ion, the O3 type cathodes suffer inferior rate capability and undesired phase transitions induced fast capacity fading. Herein, we propose a synergetic strategy of secondary phase (P2) and high-entropy to alleviate the aforementioned problems. Such a novel biphasic high-entropy (B-HE) layered cathode Na0.85Li0.05Ni0.25Cu0.025Mg0.025Fe0.05Al0.05Mn0.5Ti0.05O2 exhibits a specific capacity of 122 mAh g−1 at 0.2C, outstanding rate capacity of 81.8 mAh g−1 at 10C, and long-term cycling stability of ∼ 90% capacity retention after 1000 cycles at 10C. In situ XRD and electrochemical characterization demonstrate reversible phase transition of O3/P2 ↔ P3/P2 ↔ OP2/OP4, and the long-term existed P phase with fast Na ion migration paths. This biphasic high-entropy design strategy provides a promising road for advanced cathodes of Sodium-ion batteries.

Rational design of intergrowth P2/O3 biphasic layered structure with reversible anionic redox chemistry and structural evolution for Na-ions batteries

Layered oxides have attracted unprecedented attention for their outstanding performance in sodium-ion battery cathodes. Among them, the two typical candidates P2 and O3 type materials generally demonstrate large diversities in specific capacity and cycling endurance with their advantages. Thus, composite materials that contain both P2 and O3 have been widely designed and constructed. Nevertheless, the anionic/cationic ions’ behavior and structural evolution in such complex structures remain unclear. In this study, a deep analysis of an advanced Na0.732Ni0.273Mg0.096Mn0.63O2 material that contains 78.39 wt% P2 phase and 21.61 wt% O3 phase is performed based on two typical cathodes P2 Na0.67Ni0.33Mn0.67O2 and O3 NaNi0.5Mn0.5O2 that have the same elemental constitution but different crystal structures. Structural analysis and density functional theory (DFT) calculations suggest that the composite is preferred to form a symbiotic structure at the atomic level, and the complex lattice texture of the biphase structure can block unfavorable ion and oxygen migration in the electrode process. Consequently, the biphase structure has significantly improved the electrochemical performance and kept preferable anionic oxygen redox reversibility. Furthermore, the hetero-epitaxy-like structure of the intergrowth of P2 and O3 structures share multi-phase boundaries, where the inconsistency in electrochemical behavior between P2 and O3 phases leads to an interlocking effect to prevent severe structural collapse and relieves the lattice strain from Na+ de/intercalation. Hence, the symbiotic P2/O3 composite materials exhibited a preferable capacity and cyclability (∼130 mAh g−1 at 0.1 C, 73.1% capacity retention after 200 cycles at 1 C), as well as reversible structural evolution. These findings confirmed the advantages of using the bi/multi-phase cathode for high-energy Na-ion batteries.

Redox Evolution of Li-Rich Layered Cathode Materials

Li-rich layered oxides utilizing reversible oxygen redox are promising cathodes for high-energy-density lithium-ion batteries. However, they exhibit different electrochemical profiles before and after oxygen redox activation. Therefore, advanced characterization techniques have been developed to explore the fundamental understanding underlying their unusual phenomenon, such as the redox evolution of these materials. In this review, we present the general redox evolution of Li-rich layered cathodes upon activation of reversible oxygen redox. Various synchrotron X-ray spectroscopy methods which can identify charge compensation by cations and anions are summarized. The case-by-case redox evolution processes of Li-rich 3d/4d/5d transition metal O3 type layered cathodes are discussed. We highlight that not only the type of transition metals but also the composition of transition metals strongly affects redox behavior. We propose further studies on the fundamental understanding of cationic and anionic redox mixing and the effect of transition metals on redox behavior to excite the full energy potential of Li-rich layered cathodes.

Layered O6/O3 Multi-Phase Composite Derived from the P2/O3 Nanocrystalline Composite for High-Performance Li-Rich Manganese-Based Cathode Material

As a result of the redox reaction of lattice oxygen occurring at 4.5 V, the Li-rich manganese cathode material with an O3 configuration has a theoretically high discharge capacity (>250 mA h/g). However, it also suffers a structural transition from layered structure to spinel structure in the cycling process, leading to severe voltage decay and capacity fading. On contrary, the O6 type material obtained via ion exchange of P2 type material can effectively inhibit the phase transition and stabilize the layered structure. Hence, in this work, we design an O6/O3 multi-phase composite material after ion exchange of the P2/O3 nanocrystalline composite. Compared with the O3 type cathode, the as-obtained cathode composite exhibits a higher initial discharge capacity (≈265 mA h/g at 20 mA/g) and an excellent capacity retention (≈87% after 100 cycles). Moreover, the first cycle Coulombic efficiency increases by nearly 10%, and voltage attenuation is effectively inhibited. Our findings demonstrate that modulating the O6/O3 configuration is a practical and simple methodology to promote the electrochemical performance of lithium-rich layered materials.

Electrochemically induced cleavage cracking at twin boundary of sodium layered oxide cathodes

Twinning defects often present in crystalline materials when are subject to mechanical stimuli and are mostly affecting their physicochemical properties. The twinning formation and twin-assisted cracking upon cycling in sodium layered oxides (SLOs) are poorly understood. Combining atomic-resolution imaging, spectroscopy and first principles calculations, we reveal that growth twinning is unexpectedly common in the SLO materials and the twin boundaries show distinct structural and chemical characters from those identified in lithium layered oxides. A unique O-P-O twinning plane was identified in the O3 type SLO materials. We discover that twin-assisted Na diffusion cause large volume variations and trigger cleavage fracture during electrochemical cycling. The present findings not only establish a robust correlation between growth twinning and cleavage cracking in SLOs, but also offer general implications for the development of high-performing intercalation electrode materials by regulating crystallographic defects.

Co Substitution of Cationic and Transition Metal in O3-Type NaCrO2 Cathode for High Energy Density

The development of advanced cathode materials with high operating voltage and high reversible capacity is essential to promote the practical realization of sodium ion battery (SIB) technology. Here, O3 type Na0.9Ca0.035Cr0.97Ti0.03O2 is designed by Ca and Ti co-substitution in O3 type NaCrO2, and proposed as a new type of cathode material for high-energy density practical SIBs. On the basis of Chemical science, Alkalin ion successully incorporate NaO6 octahedron of Na0.9Ca0.035Cr0.97Ti0.03O2.1,2 In substitution process two Na+ per single Ca2+, while Cr3+ to Ti4+ ions.3,4 As a result Na+ vacancies are formed Na+ layer. Through co-substitution, structural stability of O3 – Na0.9Ca0.035Cr0.97Ti0.03O2 is increased, because stronger Ti – O bond and immobile Ca2+ ions in Na site synergistically make an effect the unit cell structures. This structural feature suppresses the irreversible phase transition and provide fast Na ion kinetics. In 1.5 – 3.8 voltage range, O3 – Na0.9Ca0.035Cr0.97Ti0.03O2 cathode to deliver the high initial Coulombic efficiency of 95%. Also at a 10 C rate, cathode retains the 90% of its initial capacity after 1000 cycles. In situ X-ray diffraction confirmed the reversible structure properties during charging and discharging process. Moreover, the cathode guarantees the practical applicability with good cycling in a pouch- type full cell using a hard carbon anode, as well as with excellent water durability. References J. J. Braconier, C. Delmas and P. Hagenmuller, Mat. Res. Bull., 1982, 17, 993–1000. J.-Y. Hwang, S.T. Myung and Y.K. Sun, Chem. Soc. Rev., 2017, 46, 3529–3614. L. Zheng, J.C. Bennett and M.N. Obrovac, J. Electrochem. Soc., 2019, 166, A2058–A2064.Y. Tsuchiya, K. Takanashi, T. Nishinobo, T. Ohta and N. Yabuuchi, Chem. Mater., 2016, 28, 7006–7016.

Enhanced electrochemical performance of O3-type Li0.6[Li0.2Mn0.8]O2 for lithium ion batteries via aluminum and boron dual-doping

An O3 type Li 0.6 [Li 0.2 Mn 0.8 ]O 2 lithium-rich material has a high reversible capacity due to the synergistic oxidation and reduction of anion and cation. However, the anion oxidation reaction that compensates the charge leads to a partial release of oxygen and the collapse of the structure inevitably. Here, we improve the structural stability of Li 0.6 [Li 0.2 Mn 0.8 ]O 2 by simultaneously introducing Al ions and B ions. Al ions and B ions randomly occupy octahedral and tetrahedral positions, hindering the migration of Mn ions and expanding the unit cell, resulting in a stable structure and promoting Li + migration. The co-doped sample has better electrochemical performance than the bare material, and the capacity retention increases from 62.48% to 82.48% after 80 cycles at 0.1C rate, and still provides a capacity of 226 mAh g −1 between 2 and 4.8 V.

Prompting structure stability of O3–NaNi0.5Mn0.5O2via effective surface regulation based on atomic layer deposition

Layered O3 type oxides exhibit promising prospects as high-performance cathodes for sodium-ion batteries (SIBs) due to their low cost and high theoretical capacities. Nevertheless, the intrinsic surface composition and bulk structure degradation upon cycling presents a huge obstacle to stable sodium-ion storage/transportation. Besides, the effective surface decoration on layered O3 oxides is still challenging through conventional wet chemical route owing to their extraordinarily high surface sensitivities. Herein, a typical O3 type layered oxide of NaNi0.5Mn0.5O2 (NNMO) was selected and successfully encapsulated by precisely controlled Al2O3 layers via atomic layer deposition (ALD) technology. With the optimally controlled Al2O3 thickness of 3 nm, the surface regulated NNMO delivers a highly reversible capacity of 73.6 mA h g-1, with a significantly improved capacity retention of 68.0% after 300 cycles at 0.5 C, and a superior rate capability of 65.8 mA h g-1 at 10 C. Further air sensitivity tests demonstrate that the protective layer could effectively mitigate the generation of sodium-based impurities on NNMO, and reduce the surface sensitivities. Both chemical and electrochemical aging tests confirm the contribution of Al2O3 coating layer in alleviating ion dissolution as well as stabilizing the structure and morphology of NNMO. Based on regulating the surface of O3 type layered oxides utilizing ALD technique, this work supplies an effective and facile strategy to overcome the challenges from fast structure degradation and electrochemical property decay, which not only highlights the significance and effectiveness of surface engineering in secondary batteries, but also sheds light on accurate interface construction and regulation for active electrode materials, particularly for those sensitive to ambient atmosphere.

NMR Study of LiCo0.96Al0.04O2 As a Positive Electrode Material for Li-Ion Batteries: Homogeneity and Role of Doping on Mechanisms

LiCoO2 (LCO) is one of the most widely used positive electrode materials in lithium-ion batteries due to its high volumetric energy density which can be further improved by charging at high voltages. However, working at high potential (above 4.3 V vs. Li+/Li) causes a deterioration in cycling performance induced by structural instabilities, electrolyte oxidation and Co dissolution. Extensive studies have been devoted to increasing energy density by increasing the cutoff voltage. The substitution of cobalt with various metals is one of the classic methods, the choice of aluminum as dopant for example is based on several criteria: low cost and non-toxicity, a similar radius for Al3+ compared to Co3+ (0.535 Å vs. 0.545 Å) facilitates the replacement of the latter and maintains the structure leading to the complete solid solution LiCo1-yAlyO2.We will focus here on LiCo0.96Al0.04O2, synthesized by the solid route and characterized by 7Li, 27Al and 59Co Nuclear Magnetic Resonance (NMR) and synchrotron X-Ray Diffraction (XRD). In addition to the characterization of the mean structure by XRD, the NMR allows us to study the local environments of the different nuclei. 27Al MAS NMR and synchrotron XRD studies revealed that the Al-doping in this material is homogeneous. 7Li MAS NMR indicates that its stoichiometry (Li/M=1.00) is ideal. The electrochemical study has shown that the phase transitions occurring during delithiation of LiCoO2, were partially eliminated by aluminum doping even with a low doping amount and the high potential mechanisms appear to be different. In order to better understand the role of Al-doping on the mechanisms involved during cycling, several phases LixCo0.96Al0.04O2 were prepared by electrochemical deintercalation and studied by 7Li, 59Co, and 27Al NMR and by XRD.During lithium deintercalation, Co3+ is oxidized to Co4+ then one unpaired electron is generated in the t2g band of Co atoms (t2g 5eg 0). For 0.8 ≤ x ˂ 1.00 the 7Li MAS NMR shows that the system behaves locally as two phase domain: domain with localized electrons and domain with delocalized ones on Con+ ions (Knight shift), even for very low amount of deintercalation (x=0.98), thus the XRD results confirm the existence of the biphasic domain. Whereas, a single phase domain is observed for the deintercalated materials with 0.4 ≤ x ≤ 0.8 and also at the NMR time of scale a single signal (Knight shift) is observed. This signal increases in intensity at the expense of 0 ppm and shifts to the higher isotropic displacement values up to x=0.5 then decreases, thus the evolution of the chex lattice parameter is correlated with the signal shift. For x = 0.3 and x = 0.2: a new broad signal appears probably due to formation of new Li environment in stacking faulted layers (O1 type). These different contributions will be more detailed on the presentation.

Synthesis and Electrochemical Investigation of O3-Type High-nickel NCM Cathodes for Sodium-ion Batteries

Sodium ion batteries(SIBs) are promising energy storage devices for smart grid applications due to their low cost and the high abundance of sodium, but few cathode materials of SIBs with high energy density are available for practical applications. Herein, a series of NaNCM ternary materials(NCM=nickel-cobalt-manganese) is obtained by solid- phase reaction with well-regulated temperature and other reaction conditions. XRD results show that impure NiO phase is more likely to occur under high nickel content. The cross-section SEM indicates that the primary particles in the electrode materials are radially distributed along the radial direction, and the internal porous structure is conducive to the infiltration of electrolyte. The initial specific capacities of Na[Ni0.68Co0.10Mn0.22]O2 (NaNCM712), Na[Ni0.6Co0.2Mn0.2]O2 (NaNCM622) and Na[Ni0.4Co0.3Mn0.3]O2(NaNCM433) at 0.2 C are 165.5, 153.1 and 146.8 mA·h/g, and the corresponding capacity retention rates are 63.2%, 78.5% and 71.7% after 100 cycles. NaNCM712 possesses the highest initial specific capacity, and NaNCM433 delivers the best rate capability. The rate capabilities of high-nickel and low-cobalt NaNCM cathodes need to be further improved. Moreover, ex-situ XRD pattern reveals the structure evolution (from O3 type to P2 type) during a long cycling charge and discharge process.

Morphologies and distributions of 5-HT containing enteroendocrine cells in the mouse large intestine.

Serotonin (5-HT)-containing gastrointestinal endocrine cells contribute to regulation of numerous bodily functions, but whether these functions are related to differences in cell shape is not known. The current study identified morphologies and localization of subtypes of 5-HT-containing enteroendocrine cells in the mouse large intestine. 5-HT cells were most frequent in the proximal colon compared with cecum and distal colon. The large intestine harbored both open (O) cells, with apical processes that reached the lumen, and closed (C) cells, not contacting the lumen, classified into O1, O2, and O3 and C1, C2, and C3 cells, by the lengths of their basal processes. O1 and C1 cells, with basal processes sometimes longer that 100µm, were most common in the distal colon. Their long basal processes ran against the inner surfaces of the mucosal epithelial cells and were strongly immunoreactive for 5-HT; these processes are ideally placed to communicate with the epithelium and to react to mechanical forces. O2 and C2 cells that had similar but shorter basal processes were also most common in the distal colon. O3 and C3 cells had no or very short basal processes. The O3 open type 5-HT cells were abundant in the proximal colon, particularly at the luminal surface, where they could release 5-HT into the lumen to act on luminal 5-HT receptors. Numerous O3 type 5-HT cells occurred in the lower (submucosal) region of the crypts in all segments and might release 5-HT to influence cell renewal in the crypt proliferative zones.