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Ion-exchange reactions are commonly used to develop novel metastable electrode materials for alkali-ion batteries that cannot be synthesized using direct chemical reactions. In this study, the electrochemical K to Na ion-exchange reaction mechanisms in a layered KxCoO2 cathode as a model system were investigated using operando and ex situ structure characterization techniques. Some level of K ions was observed to remain in the layered structure during the electrochemical ion-exchange reactions. Interestingly, the K ions are well separated from the Na-rich phases in the discharged state, and they form an intermediate phase in which K and Na ions are mixed at the top of charge. We discovered that such residual K ions prevent the collapse of the layered structure in the high-voltage regime, thereby improving the cycling stability in a Na-battery system.

Our combined computations and experiments suggest the Mg-Ti-O chemical spaces for novel ternary oxide compounds that can offer high conductivity and corrosion stability to be used in fuel cell applications.

Summary Conventional Li-ion cathode materials are dominated by well-ordered structures, in which Li and transition metals occupy distinct crystallographic sites. We show in this paper that profoundly new degrees of freedom for the optimization of electrochemical properties may be accessed if controllable cation disorder is introduced. In a class of high-capacity spinel-type cathode materials, we identify cation to anion ratio in synthesis as a key parameter for tuning the structure continuously from a well-ordered spinel, through a partially ordered spinel, to rocksalt. We find that the varying degree of cation disorder modifies the voltage profile, rate capability, and charge-compensation mechanism in a rational and predictable way. Our results indicate that spinel-type order is most beneficial for achieving high-rate performance as long as the cooperative 8a to 16c phase transition is suppressed, while more rocksalt-like disorder facilitates O redox, which can increase capacity. Our findings reveal an important tuning handle for achieving high energy and power in the vast space of partially ordered cathode materials.

Advances in solid-state batteries have primarily been driven by the discovery of superionic conducting structural frameworks that function as solid electrolytes. We demonstrate the ability of high-entropy metal cation mixes to improve ionic conductivity in a compound, which leads to less reliance on specific chemistries and enhanced synthesizability. The local distortions introduced into high-entropy materials give rise to an overlapping distribution of site energies for the alkali ions so that they can percolate with low activation energy. Experiments verify that high entropy leads to orders-of-magnitude higher ionic conductivities in lithium (Li)–sodium (Na) superionic conductor (Li-NASICON), sodium NASICON (Na-NASICON), and Li-garnet structures, even at fixed alkali content. We provide insight into selecting the optimal distortion and designing high-entropy superionic conductors across the vast compositional space.

Technological, safety-related and volatile properties were analyzed in coagulase-negative staphylococci (CNS) isolates from Chinese spontaneously fermented meat products. A total of 107 CNS isolates were identified via 16 S rRNA sequencing, and the most recovered species were S. saprophyticus (53.3 %), S. edaphicus (12.1 %), and S. epidermidis (10.3 %). Among them, 58 CNS isolates belonging to 9 species were selected with higher activities of catalase, nitrate reductase, proteolysis, and lipolysis, as well as higher tolerance to stressful environmental conditions. Then, 7 CNS isolates belonging to 4 species were further selected based upon excellent technological characteristics, lack of hemolysis and antibiotic resistance, and a low production of biogenic amines. The volatile profiles of these 7 strains cultivated in pork broth was determined. S. casei No. 1 produced significant amounts of phenethyl alcohol, geraniol, and 3-methyl-butanol. S. xylosus No. 120 produced the highest amount of methyl ketones with the potential to provide dry-cured odor of fermented meats. The volatile profile was highly strain dependent. Several CNS identified in this study have the potential to be used as the starter cultures for fermented meat products.

Author(s): Zhong, P; Cai, Z; Zhang, Y; Giovine, R; Ouyang, B; Zeng, G; Chen, Y; Clement, R; Lun, Z; Ceder, G | Abstract: Using both computations and experiments, we demonstrate that the performance of Li-excess cation-disordered rocksalt cathodes can be improved by Mg substitution. Mg reduces the amount of Li in the compound that is strongly bound to F and thereby increases the capacity. This enables the use of fluorination as a tool to improve stability of the compounds without significant loss of capacity. Mg emerged as the most optimal substitution element from a systematic computational study aimed at identifying inactive doping elements with a strong enough bonding strength to fluorine to displace Li from the F environments. Our results also show that capacity can be traded for cycle life depending on whether Mg is substituted for Li or for the redox metal. This design strategy should be considered in fluorinated cathodes, which will facilitate the design of optimized disordered rocksalt oxyfluoride cathodes.

High-entropy (HE) ceramics, by analogy with HE metallic alloys, are an emerging class of solid solutions composed of a large number of species. These materials offer the benefit of large compositional flexibility and can be used in a wide variety of applications, including thermoelectrics, catalysts, superionic conductors and battery electrodes. We show here that the HE concept can lead to very substantial improvements in performance in battery cathodes. Among lithium-ion cathodes, cation-disordered rocksalt (DRX)-type materials are an ideal platform within which to design HE materials because of their demonstrated chemical flexibility. By comparing a group of DRX cathodes containing two, four or six transition metal (TM) species, we show that short-range order systematically decreases, whereas energy density and rate capability systematically increase, as more TM cation species are mixed together, despite the total metal content remaining fixed. A DRX cathode with six TM species achieves 307 mAh g−1 (955 Wh kg−1) at a low rate (20 mA g−1), and retains more than 170 mAh g−1 when cycling at a high rate of 2,000 mA g−1. To facilitate further design in this HE DRX space, we also present a compatibility analysis of 23 different TM ions, and successfully synthesize a phase-pure HE DRX compound containing 12 TM species as a proof of concept. High-entropy ceramics are solid solutions offering compositional flexibility and wide variety of applicability. High-entropy concepts are shown to lead to substantial performance improvement in cation-disordered rocksalt-type cathodes for Li-ion batteries.

The rapid market growth of rechargeable batteries requires electrode materials that combine high power and energy and are made from earth-abundant elements. Here we show that combining a partial spinel-like cation order and substantial lithium excess enables both dense and fast energy storage. Cation overstoichiometry and the resulting partial order is used to eliminate the phase transitions typical of ordered spinels and enable a larger practical capacity, while lithium excess is synergistically used with fluorine substitution to create a high lithium mobility. With this strategy, we achieved specific energies greater than 1,100 Wh kg–1 and discharge rates up to 20 A g–1. Remarkably, the cathode materials thus obtained from inexpensive manganese present a rare case wherein an excellent rate capability coexists with a reversible oxygen redox activity. Our work shows the potential for designing cathode materials in the vast space between fully ordered and disordered compounds. There is an intensive search for high-performance cathode materials for rechargeable batteries. Here the authors report that oxyfluorides with partial spinel-like cation order, made from earth-abundant elements, display both exceptionally high energy and power.

Circ-BPTF (hsa_circ_0000799) is a novel circular RNA derived from BPTF exons. Although BPTF is a well-studied predecessor gene, the characteristics and functions of circ-BPTF have not yet been reported. Here, we show that expression of circ-BPTF is increased in bladder cancer (BCa) tissues and cell lines compared with noncancerous tissues and cell lines. Consistently, BCa patients with higher expression levels of circ-BPTF were found to have higher tumor grades and poorer prognosis. Functionally, knockdown of circ-BPTF inhibited tumor progression in vitro and in vivo. Mechanistically, a target microRNA of circ-BPTF was confirmed to be miR-31-5p, and miR-31-5p mimics partially reversed the effect of circ-BPTF. Furthermore, RAB27A was predicted and shown to be a target of miR-31-5p, and circ-BPTF attenuated the anti-oncogenic effect of miR-31-5p and consequently enhanced RAB27A expression. In summary, our findings reveal that circ-BPTF promotes BCa progression through the miR-31-5p/RAB27A axis, suggesting that circ-BPTF may be a potential target for BCa treatment.

Summary Mn-based Li-excess cation-disordered rocksalt (DRX) oxyfluorides are promising candidates for next-generation rechargeable battery cathodes owing to their large energy densities, the earth abundance, and low cost of Mn. In this work, we synthesized and electrochemically tested four representative compositions in the Li-Mn-O-F DRX chemical space with various Li and F content. While all compositions achieve higher than 200 mAh g−1 initial capacity and good cyclability, we show that the Li-site distribution plays a more important role than the metal-redox capacity in determining the initial capacity, whereas the metal-redox capacity is more closely related to the cyclability of the materials. We apply these insights and generate a capacity map of the Li-Mn-O-F chemical space, LixMn2-xO2-yFy (1.167 ≤ x ≤ 1.333, 0 ≤ y ≤ 0.667), which predicts both accessible Li capacity and Mn-redox capacity. This map allows the design of compounds that balance high capacity with good cyclability.

Iron fluoride is widely used in energy and heterogeneous catalytic reactions due to its advantages such as high specific capacity and low cost. However, most of the current research is to modify the material size of iron fluoride, and there are few reports on the adjustment of its crystal plane and morphology. This work reports a method for synthesizing highly dispersed three-dimensional flower-like FeF3·0.33H2O particles with a simple one-step solvothermal method using inorganic anions. Furthermore, the influence of the presence of inorganic anions on the crystal morphology and crystal plane orientation is described and quantified through the calculation of atomic density and the characterization of the morphology and specific surface area of the material. Among them, a micro–nano flower-like material constructed of tens of nanometers of primary particles has a larger (002) plane area and specific surface area than traditional materials. Generally, the (002) plane has a one-dimensional tunnel composed of multiple hexagonal cavities, which is helpful for the ion intercalation and deintercalation. Therefore, FeF3·0.33H2O crystals with specific morphology can be obtained by adjusting the type of inorganic anions, reaction time and water content in the solvent.

In cation-disordered rocksalt Li-ion cathode materials, an excess of Li with respect to the transition metal content is necessary for the creation of percolating pathways for Li transport. Because of the lower amount of redox-active transition metal, a substantial part of the charge transfer must occur via less reversible oxygen redox. Fluorination can be used to minimize this dependence on oxygen redox by increasing the amount of low-valent transition metal in the compound, but it adds complexity to materials design. Here, we investigate the feasibility of using computationally constructed phase diagrams to facilitate the search for optimal oxyfluorides. We use the phase diagram of LiF–Li3NbO4–NiO to identify Li1.13Ni0.57Nb0.3O1.75F0.25 and Li1.19Ni0.59Nb0.22O1.46F0.54 as two promising compositions and demonstrate that they can be successfully synthesized. These compounds exhibit significantly reduced hysteresis and higher energy density than the previously reported Li1.3Ni0.27Nb0.43O2 compound in this s...

Searching for a material that simultaneously satisfies highly conductive and corrosion-stable properties is crucial for various energy conversion applications, particularly for catalyst-supporting materials in polymer electrolyte membrane fuel cells (PEMFC). Here, we suggest the Mg-Ti-O chemical space as promising ternary compounds with high electrical conductivity and corrosion stability in acidic conditions to be potentially used in such applications. A high electrical conductivity (6.09 × 10-1 S/cm) and a good corrosion stability (1.2 × 10-4 mA cm-2 at pH = 1) are achieved at room temperature, by tuning the chemical compositions of Mg1-x Ti2+x O5 (MTO). We found that the corrosion stability of suggested MTO is two orders of magnitude higher than that of conventional carbon supporters used for PEMFC while providing high electrical conductivity. Furthermore, our combined computational and experimental works elucidate that the reducing gas environment during the solid-state synthesis ensures the higher Ti solubility in MTO, i.e., a reduced valence state of Ti, thus promoted the electrical conduction.

The Fiber Bragg grating sensor (FBG) is a kind of optical fiber sensor, compared with the electric sensor, it has many irreplaceable advantages for aerospace applications. The challenge of FBG for cryogenic application is how to increase the sensitivity of bare FBG and reduce nonlinear error. Two different thermosetting epoxy materials were studied to recoat bare FBG and presented a specific packaging method for thermosetting coatings. The verification of the accuracy of the model that is used to describe the FBG coated with thermosetting polymers by comparing the calculated results with the warming-up experiment conducted in the temperature range of 120K-328K using epoxy coated FBGs and bare FBG has been conducted. The results show a great improvement of sensitivity and good linearity, and the model can also be used to predict the characteristics of FBG coated with epoxy resins at cryogenic temperature and determine the stability of the epoxy.