Stable Operation Induced by Plastic Crystal Electrolyte Used in Ni-Rich NMC811 Cathodes for Li-Ion Batteries

The LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode material has been of significant consideration owing to its high energy density for Li-ion batteries. However, the poor cycling stability in a carbonate electrolyte limits its further development. In this work, we report the excellent electrochemical performance of the NMC811 cathode using a rational electrolyte based on organic ionic plastic crystal N-ethyl-N-methyl pyrrolidinium bis(fluorosulfonyl)imide C2mpyr[FSI], with the addition of (1:1 mol) LiFSI salt. This plastic crystal electrolyte (PC) is a thick viscous liquid with an ionic conductivity of 2.3 × 10-3 S cm-1 and a high Li+ transference number of 0.4 at ambient temperature. The NMC811@PC cathode delivers a discharge capacity of 188 mA h g-1 at a rate of 0.2 C with a capacity retention of 94.5% after 200 cycles, much higher than that of using a carbonate electrolyte (54.3%). Moreover, the NMC811@PC cathode also exhibits a superior high-rate capability with a discharge capacity of 111.0 mA h g-1 at the 10 C rate. The significantly improved cycle performance of the NMC811@PC cathode can be attributed to the high Li+ conductivity of the PC electrolyte, the stable Li+ conductive CEI film, and the maintaining of particle integrity during long-term cycling. The admirable electrochemical performance of the NMC811|C2mpyr[FSI]:[LiFSI] system exhibits a promising application of the plastic crystal electrolyte for high voltage layered oxide cathode materials in advanced lithium-ion batteries.

[Epidemiological trend of early-onset gastric cancer and late-onset gastric cancer in China from 2000 to 2019]

Objective: In order to understand the changing trends of gastric cancer incidence and mortality in early-onset and late-onset in China from 2000 to 2019. Methods: The Global Burden of Disease research data was collected, and Excel and R 4.2.1 softwares were used to examine the incidence rate, mortality rate, and disability-adjusted life years (DALY) of Chinese people from 2000 to 2019, with a focus on gender, age, and year. Results: In 2019, the crude incidence rates were 7.06/100 000 (95%UI: 6.63/100 000-7.59/100 000) and 114.52/100 000 (95%UI: 108.79/100 000-121.63/100 000) for early- and late-onset gastric cancer, respectively. The crude mortality rate for early-onset gastric cancer was 3.29/100 000 (95%UI: 3.11/100 000- 3.50/100 000), while the crude mortality rate for late-onset gastric cancer was 81.88/100 000 (95%UI: 78.15/100 000-86.04/100 000). Additionally, the crude DALY rates for these two types of gastric cancer were 156.48/100 000 (95%UI: 148.82/100 000-165.84/100 000) and 1 750.13/100 000 (95%UI: 1 661.21/100 000-1 852.99/100 000). The standardized incidence of early-onset gastric cancer decreased from 5.49/100 000 in 2000 to 4.76/100 000 in 2019, and that of late-onset gastric cancer decreased from 143.45/100 000 in 2000 to 123.02/100 000 in 2019.The standardized mortality rate of early-onset gastric cancer decreased from 4.16/100 000 in 2000 to 2.18/100 000 in 2019, and that of late-onset gastric cancer decreased from 140.82/100 000 in 2000 to 91.49/100 000 in 2019. The standardized DALY rate for early-onset gastric cancer in 2019 was 105.87/100 000 (95%UI: 87.98/100 000 -125.60/100 000), lower than 198.84/100 000 (95%UI: 179.47/100 000- 219.83/100 000) in 2000. The standardized DALY rate for late onset gastric cancer in 2019 was 1 821.11/100 000 (95%UI: 1 509.42/100 000-2 158.53/100 000), lower than 2 932.52/100 000 (95%UI: 2 665.92/100 000-3 252.60/100 000) in 2000. Conclusions: The standardized mortality rate of early-onset gastric cancer in China showed a decreasing trend from 2000 to 2019. The standardized mortality rate of late onset gastric cancer showed a trend of first increasing and then decreasing. Notably, the incidence, mortality, and DALY of late-onset gastric cancer were significantly higher than those of early-onset gastric cancer during this period. Additionally, male incidence, mortality, and crude DALY rates were higher than female.

Ultrafast Charge-Discharge Capable and Long-Life Na3.9 Mn0.95 Zr0.05 V(PO4 )3 /C Cathode Material for Advanced Sodium-Ion Batteries

Na₄ MnV(PO₄ )₃ /C (NMVP) has been considered an attractive cathode for sodium-ion batteries with higher working voltage and lower cost than Na₃ V₂ (PO₄ )₃ /C. However, the poor intrinsic electronic conductivity and Jahn-Teller distortion caused by Mn³⁺ inhibit its practical application. In this work, the remarkable effects of Zr-substitution on prompting electronic and Na-ion conductivity and also structural stabilization are reported. The optimized Na_3.9 Mn_0.95 Zr_0.05 V(PO₄ )₃ /C sample shows ultrafast charge-discharge capability with discharge capacities of 108.8, 103.1, 99.1, and 88.0 mAh g^-1 at 0.2, 1, 20, and 50 C, respectively, which is the best result for cation substituted NMVP samples reported so far. This sample also shows excellent cycling stability with a capacity retention of 81.2% at 1 C after 500 cycles. XRD analyses confirm the introduction of Zr into the lattice structure which expands the lattice volume and facilitates the Na⁺ diffusion. First-principle calculation indicates that Zr modification reduces the band gap energy and leads to increased electronic conductivity. In situ XRD analyses confirm the same structure evolution mechanism of the Zr-modified sample as pristine NMVP, however the strong ZrO bond obviously stabilizes the structure framework that ensures long-term cycling stability.

Establishment of a simplified score for predicting risk during intrahospital transport of critical patients: A prospective cohort study

AIMS AND OBJECTIVES

To establish a simple score that enables nurses to quickly, conveniently and accurately identify patients whose condition may change during intrahospital transport.

BACKGROUND

Critically ill patients may experience various complications during intrahospital transport; therefore, it is important to predict their risk before they leave the emergency department. The existing scoring systems were not developed for this population.

DESIGN

A prospective cohort study.

METHODS

This study used convenience sampling and continuous enrolment from 1 January, 2019, to 30 June, 2021, and 584 critically ill patients were included. The collected data included vital signs and any condition change during transfer. The STROBE checklist was used.

RESULTS

The median age of the modelling group was 74 (62, 83) years; 93 (19.7%) patients were included in the changed group, and 379 (80.3%) were included in the stable group. The five independent model variables (respiration, pulse, oxygen saturation, systolic pressure and consciousness) were statistically significant (p < .05). The above model was simplified based on beta coefficient values, and each variable was assigned 1 point, for a total score of 0-5 points. The AUC of the simplified score in the modelling group was 0.724 (95% CI: 0.682-0.764); the AUC of the simplified score in the validation group (112 patients) was 0.657 (95% CI: 0.566-0.741).

CONCLUSIONS

This study preliminarily established a simplified scoring system for the prediction of risk during intrahospital transport from the emergency department to the intensive care unit. It provides emergency nursing staff with a simple assessment tool to quickly, conveniently and accurately identify a patient's transport risk.

RELEVANCE TO CLINICAL PRACTICE

This study suggested the importance of strengthening the evaluation of the status of critical patients before intrahospital transport, and a simple score was formed to guide emergency department nurses in evaluating patients.

Toward High-Performance Mg-S Batteries via a Copper Phosphide Modified Separator

Magnesium-sulfur (Mg-S) batteries are emerging as a promising alternative to lithium-ion batteries, due to their high energy density and low cost. Unfortunately, current Mg-S batteries typically suffer from the shuttle effect that originates from the dissolution of magnesium polysulfide intermediates, leading to several issues such as rapid capacity fading, large overcharge, severe self-discharge, and potential safety concern. To address these issues, here we harness a copper phosphide (Cu3P) modified separator to realize the adsorption of magnesium polysulfides and catalyzation of the conversion reaction of S and Mg2+ toward stable cycling of Mg-S cells. The bifunctional layer with Cu3P confined in a carbon matrix is coated on a commercial polypropylene membrane to form a porous membrane with high electrolyte wettability and good thermal stability. Density functional theory (DFT) calculations, polysulfide permeability tests, and post-mortem analysis reveal that the catalytic layer can adsorb polysulfides, effectively restraining the shuttle effect and facilitating the reversibility of the Mg-S cells. As a result, the Mg-S cells can achieve a high specific capacity, fast rates (449 mAh g-1 at 0.1 C and 249 mAh g-1 at 1.0 C), and a long cycle life (up to 500 cycles at 0.5 C) and operate even at elevated temperatures.

A High-Rate, Durable Cathode for Sodium-Ion Batteries: Sb-Doped O3-Type Ni/Mn-Based Layered Oxides

O3-Type layered oxides are widely studied as cathodes for sodium-ion batteries (SIBs) due to their high theoretical capacities. However, their rate capability and durability are limited by tortuous Na⁺ diffusion channels and complicated phase evolution during Na⁺ extraction/insertion. Here we report our findings in unravelling the mechanism for dramatically enhancing the stability and rate capability of O3-NaNi_0.5Mn_0.5-xSb_xO₂ (NaNMS) by substitutional Sb doping, which can alter the coordination environment and chemical bonds of the transition metal (TM) ions in the structure, resulting in a more stable structure with wider Na⁺ transport channels. Furthermore, NaNMS nanoparticles are obtained by surface energy regulation during grain growth. The synergistic effect of Sb doping and nanostructuring greatly reduces the ionic migration energy barrier while increasing the reversibility of the structural evolution during repeated Na⁺ extraction/insertion. An optimized NaNMS-1 electrode delivers a reversible capacity of 212.3 mAh g^-1 at 0.2 C and 74.5 mAh g^-1 at 50 C with minimal capacity loss after 100 cycles at a low temperature of -20 °C. Such electrochemical performance is superior to most of the reported layered oxide cathodes used in rechargeable SIBs.

Mg2+-Doping Constructed a Continuous and Homogeneous Cathode-Electrolyte Interphase Film on Na3.12Fe2.44(P2O7)2 with Superior and Stable High-Temperature Performance for Sodium-Ion Storage

Sodium-ion batteries (SIBs) are on the verge of achieving practical applications, and the key is to find suitable electrode materials. The polyanionic iron-based material Na_3.12Fe_2.44(P₂O₇)₂ (NFPO) possesses an open three-dimensional framework structure with good thermal stability and is regarded as an outstanding cathode material for SIBs. Nevertheless, its poor electrical conductivity, problems with erosion of electrolytes, and structural deterioration during cycling still need to be urgently addressed. Here, we first design a Mg²⁺-doped NFPO (NFPO-Mg) material with a dual-action effect. On the one hand, Mg²⁺ improves the intrinsic conductivity of the NFPO material, and on the other hand, Mg²⁺ promotes the formation of a homogeneous and stable cathode-electrolyte interphase film during the cycling process, which results in a superior rate performance and cycling stability. A capacity of 68.6 mAh g^-1 was achieved at 50C (1C = 117.4 mAh g^-1), and a capacity retention of 79.1% was maintained after 3000 cycles at 20C. More impressively, NFPO-Mg exhibits outstanding high-temperature electrochemical performance, with a capacity retention of 95.3% after 400 cycles at 10C at 60 °C (much higher than the 54.2% for the NFPO). This paper explores an effective method for improving the electrochemical performance of cathode materials, which may prove instrumental in guiding the design of more high-performance cathode materials in the future.

Retraction: Prussian blue without coordinated water as a superior cathode for sodium-ion batteries

Retraction of ‘Prussian blue without coordinated water as a superior cathode for sodium-ion batteries’ by Dezhi Yang et al., Chem. Commun., 2015, 51, 8181–8184, https://doi.org/10.1039/C5CC01180A.

Prussian Blue/RGO with Less Coordinated Water as Superior Cathode Material for Sodium-Ion Batteries

A micro-cubic Prussian blue (PB) with less coordinated water is first developed by electron exchange between graphene oxide and PB. The obtained reduced graphene oxide-PB composite exhibited increased redox reactions...

Multifunctional Catalyst CuS for Nonaqueous Rechargeable Lithium-Oxygen Batteries

Copper sulfide with flower-like (f-CuS) and carambola-like (c-CuS) morphologies was successfully synthesized by a facile one-step solvothermal route with different surfactants. When employed as cathode catalysts for lithium-oxygen batteries (LOBs), f-CuS outperforms c-CuS in terms of oxygen electrochemistry, judging from the faster kinetics and the higher reversibility of oxygen reduction/oxidation reactions, as well as the better LOB performance. Moreover, an abnormal high-potential discharge plateau was observed in the discharge profile of the LOB. To understand the different performances of f-CuS and c-CuS and the abnormal high-potential plateau, theoretical calculations were conducted, based on which a mechanism was proposed and verified with experiments. On the whole, CuS can work as a multifunctional catalyst for promoting LOB performance, which means that the dissolved CuS in LiTFSI/TEGDME electrolyte can serve as a liquid catalyst by the redox couples of Cu(TFSI)₂/Cu(TFSI)₂^-/Cu(TFSI)₂^2-, in addition to the function as a traditional solid catalyst in the cathode.

Structural and chemical evolution in layered oxide cathodes of lithium-ion batteries revealed by synchrotron techniques

Rechargeable battery technologies have revolutionized electronics, transportation and grid energy storage. Many materials are being researched for battery applications, with layered transition metal oxides (LTMO) the dominating cathode candidate with remarkable electrochemical performance. Yet, daunting challenges persist in the quest for further battery developments targeting lower cost, longer lifespan, improved energy density and enhanced safety. This is, in part, because of the intrinsic complexity of real-world batteries, featuring sophisticated interplay among microstructural, compositional and chemical heterogeneities, which has motivated tremendous research efforts using state-of-the-art analytical techniques. In this research field, synchrotron techniques have been identified as a suite of effective methods for advanced battery characterization in a non-destructive manner with sensitivities to the lattice, electronic and morphological structures. This article provides a holistic overview of cutting-edge developments in synchrotron-based research on LTMO battery cathode materials. We discuss the complexity and evolution of LTMO’s material properties upon battery operation and review recent synchrotron-based research works that address the frontier challenges and provide novel insights in this field. Finally, we formulate a perspective on future directions of synchrotron-based battery research, involving next-generation X-ray facilities and advanced computational developments.

Iron Phosphide Confined in Carbon Nanofibers as a Free-Standing Flexible Anode for High-Performance Lithium-Ion Batteries

Iron phosphide with high specific capacity has emerged as an appealing candidate for next-generation lithium-ion battery anodes. However, iron phosphide could undergo conversion reactions and generally suffer from a rapid capacity degradation upon cycling due to its structure pulverization. Chemomechanical breakdown of iron phosphide due to its rigidity has been a challenge to fully realizing its electrochemical performance. To address this challenge, we report here on an enticing opportunity: a flexible, free-standing iron phosphide anode with Fe₂P nanoparticles confined in carbon nanofibers may overcome existing challenges. For the synthesis, we introduce a facile electrospinning strategy that enables in situ formation of Fe₂P within a carbon matrix. Such a carbon matrix can effectively minimize the structure change of Fe₂P particles and protect them from pulverization, allowing the electrodes to retain a free-standing structure after long-term cycling. The produced electrodes showed excellent electrochemical performance in lithium-ion half and full cells, as well as in flexible pouch cells. These results demonstrate the successful development of iron phosphide materials toward high capacity, light weight, and flexible energy storage.

Structural Tuning of a Flexible and Porous Polypyrrole Film by a Template-Assisted Method for Enhanced Capacitance for Supercapacitor Applications

Constructing a rational electrode structure for supercapacitors is critical to accelerate the electrochemical kinetics process and thus promote the capacitance. Focusing on the flexible supercapacitor electrode, we synthesized a three-dimensional (3D) porous polypyrrole (PPy) film using a modified vapor phase polymerization method with the use of a porous template (CaCO₃). The porous design provided the PPy film with an improved surface area and pore volume. The porous PPy film electrode was studied as a binder-free electrode for supercapacitors. It was found that the abundant interpenetrated pores created by the CaCO₃ templates within the 3D framework are beneficial to overcoming the diffusion-controlled limit in the overall electrochemical process. It was revealed by electrochemical investigation that a more pseudocapacitive contribution than diffusion-controlled process contribution was observed in the total charge in the redox reaction. The galvanostatic charge/discharge (GCD) measurements showed that the optimized 3D porous PPy film electrode delivered a high capacitance of 313.6 F g^-1 and an areal capacitance of 98.0 mF cm^-2 at 1.0 A g^-1 in a three-electrode configuration, which is nearly three times that of the dense counterpart electrode synthesized in the absence of the CaCO₃ template. A specific capacitance of 62.5 F g^-1 at 0.5 A g^-1 and 31.1 F g^-1 at 10 A g^-1 was obtained in a symmetric capacitor device. In addition, the porous structure provided the PPy film with the attractive capability of accommodating the volume change during the doping/dedoping process. This is essential for the PPy film to maintain a long cycling life in a practical operation for a supercapacitor. It turned out that a high capacitance retention up to 81.3% after 10,000 GCD cycles was obtained for the symmetric supercapacitor device with the 3D porous PPy electrode (57.1% capacitive retention was observed for the dense PPy electrode). The strategy and the insight analysis are expected to provide valuable guidance for the design and the synthesis of flexible and wearable film electrodes with high performance.

Spray-dried assembly of 3D N,P-Co-doped graphene microspheres embedded with core-shell CoP/MoP@C nanoparticles for enhanced lithium-ion storage

The advancement of novel synthetic approaches for micro/nanostructural manipulation of transition metal phosphide (TMP) materials with precisely controlled engineering is crucial to realize their practical use in batteries. Here, we develop a novel spray-drying strategy to construct three-dimensional (3D) N,P co-doped graphene (G-NP) microspheres embedded with core-shell CoP@C and MoP@C nanoparticles (CoP@C⊂G-NP, MoP@⊂G-NP). This intentional design shows a close correlation between the microstructural G-NP and chemistry of the core-shell CoP@C/MoP@C nanoparticle system that contributes towards their anode performance in lithium-ion batteries (LIBs). The obtained structure features a conformal porous G-NP framework prepared via the co-doping of heteroatoms (N,P) that features a 3D conductive highway that allows rapid ion and electron passage and maintains the overall structural integrity of the material. The interior carbon shell can efficiently restrain volume evolution and prevent CoP/MoP nanoparticle aggregation, providing excellent mechanical stability. As a result, the CoP@C⊂G-NP and MoP@⊂G-NP composites deliver high specific capacities of 823.6 and 602.9 mA h g^-1 at a current density of 0.1 A g^-1 and exhibit excellent cycling stabilities of 438 and 301 mA h g^-1 after 500 and 800 cycles at 1 A g^-1. The present work details a novel approach to fabricate core-shell TMPs@C⊂G-NP-based electrode materials for use in next-generation LIBs and can be expanded to other potential energy storage applications.

Risk prediction using the National Early Warning Score and the Worthing Physiological Scoring System in patients who were transported to the Intensive Care Unit from the Emergency Department: A cohort study

OBJECTIVES

The aim of this study was to assess the value of the National Early Warning Score and Worthing Physiological Scoring System for predicting changes in the condition of critical cases during transfer from the emergency department to the intensive care unit.

METHODS

This prospective single-centre study was conducted at a 1759-bed hospital in Beijing. We recorded the vital signs in the cases before leaving the emergency department and their changes in condition during transit.

RESULTS

A total of 258 critically ill cases were included. Forty-four cases (17.05%) exhibited changes in their condition during transit. Compared with cases with NEWS ≤ 5, cases with NEWS > 5 were more likely to experience changes with an OR of 5.744 (95% CI 2.888-11.426). Compared with cases with WPS ≤ 2, cases with WPS > 2 were more likely to experience changes with an OR of 7.217 (95% CI 3.575-14.569). The difference between the areas under the curve of the NEWS (0.751 ± 0.045) and the WPS (0.736 ± 0.045) was not statistically significant (P = 0.4518).

CONCLUSION

In our study, the Worthing Physiological Scoring System and National Early Warning Score both exhibited good discriminatory power, but the Worthing Physiological Scoring System is simpler to use and more suitable for use in a busy emergency department.

Improved Cycling Performance of P2-Na0.67Ni0.33Mn0.67O2 Based on Sn Substitution Combined with Polypyrrole Coating

P2-Na_0.67Ni_0.33Mn_0.67O₂ presents high working voltage with a theoretical capacity of 173 mAh g^-1. However, the lattice oxygen on the particle surface participates in the redox reactions when the material is charged over 4.22 V. The resulting oxidized oxygen aggravates the electrolyte decomposition and transition metal dissolution, which cause severe capacity decay. The commonly reported cation substitution methods enhance the cycle stability by suppressing the high voltage plateau but lead to lower average working voltage and reduced capacity. Herein, we stabilized the lattice oxygen by a small amount of Sn substitution based on the strong Sn-O bond without sacrificing the high voltage performance and further protected the particle surface by polypyrrole (PPy) coating. The obtained Na_0.67Ni_0.33Mn_0.63Sn_0.04O₂@PPy (3.3 wt %) composite showed excellent cycling stability with a reversible capacity of 137.6 (10) and 120.0 mAh g^-1 (100 mA g^-1) with a capacity retention of 95% (10 mA g^-1, 50 cycles) and 82.5% (100 mA g^-1, 100 cycles), respectively. The present work indicates that slight Sn substitution combined with PPy coating could be an effective approach to achieving superior cycling stability for high-voltage layered transition metal oxides.

Surface Tuning to Promote the Electrocatalysis for Oxygen Evolution Reaction: From Metal-Free to Cobalt-Based Carbon Electrocatalysts

Heterogeneous electrocatalytic reactions only occur at the interface between the electrocatalyst and reactant. Therefore, the active sites are only necessary to be distributed on the surface of the electrocatalyst. Based on this motivation, here, we demonstrate a systematic study on surface tuning for a carbon-based electrocatalyst from metal-free (with the heteroatoms N and S, NS/C) to metal-containing surfaces (with Co, N, and S, CoNS/C). The CoNS/C electrocatalyst was obtained by pyrolyzing the Co precoordinated and p-toluenesulfonate-doped polypyrrole (PPy). It was found that the coordination of Co on the PPy ring tuned the final carbon electrocatalyst into a catalyst with a CoN_x moiety-rich surface. In addition, the as-synthesized CoNS/C was determined to have a very high loading of cobalt up to 2.02 wt %. The pyrolysis of the cobalt-containing precursor tends to proceed toward a characteristic of a higher sp² carbon content, a higher surface area, and more nitrogen as well as active nitrogen sites than its metal-free counterpart. The most distinguished feature for such a catalyst is that the truly most active component is only distributed on the surface, in contrast with that of the conventional metal-N-based catalyst present throughout the bulky structure. Especially, the electrocatalytic activity toward oxygen evolution reaction (OER) has been investigated experimentally and theoretically. The results showed that the OER performance of the carbon-based electrocatalyst was remarkably boosted after the introduction of Co with an overpotential decrease from 678 to 345 mV at 10 mA cm^-2. Furthermore, CoNS/C displayed an excellent durability upon a long-term measurement. The apparent activation energy measurements revealed that the metal-rich surface contributed to overcome the energy barrier for OER. In addition, density functional theory calculations have been conducted to explain the correlated OER mechanism. This study is expected to provide an effective strategy for the design and the synthesis of highly active metal-nitrogen-type electrocatalysts with a high metal loading for various electrocatalytic reactions.

Structural and chemical interplay between nano-active and encapsulation materials in a core–shell SnO2@MXene lithium ion anode system

Structural and chemical interplay between nano-active and encapsulation materials in a core–shell SnO₂@MXene lithium ion anode system was investigated in detail.

High temperature proton exchange membrane fuel cells: progress in advanced materials and key technologies

High temperature proton exchange membrane fuel cells (HT-PEMFCs) are one type of promising energy device with the advantages of fast reaction kinetics (high energy efficiency), high tolerance to fuel/air impurities, simple plate design, and better heat and water management. They have been expected to be the next generation of PEMFCs specifically for application in hydrogen-fueled automobile vehicles and combined heat and power (CHP) systems. However, their high-cost and low durability interposed by the insufficient performance of key materials such as electrocatalysts and membranes at high temperature operation are still the challenges hindering the technology's practical applications. To develop high performance HT-PEMFCs, worldwide researchers have been focusing on exploring new materials and the related technologies by developing novel synthesis methods and innovative assembly techniques, understanding degradation mechanisms, and creating mitigation strategies with special emphasis on catalysts for oxygen reduction reaction, proton exchange membranes and bipolar plates. In this paper, the state-of-the-art development of HT-PEMFC key materials, components and device assembly along with degradation mechanisms, mitigation strategies, and HT-PEMFC based CHP systems is comprehensively reviewed. In order to facilitate further research and development of HT-PEMFCs toward practical applications, the existing challenges are also discussed and several future research directions are proposed in this paper.

Construction of Multifunctional Nanoarchitectures in One Step on a Composite Fuel Catalyst through In Situ Exsolution of La0.5Sr0.5Fe0.8Ni0.1Nb0.1O3-δ

Multifunctional nanoarchitecture (MNA) on catalysts has attracted great attention because of its capability to improve the performance, durability, and resistance to unwanted side reactions. Such structures, however, are conventionally prepared by deposition methods, which inherently suffer from costly and time-consuming drawbacks. Here, we report a simple one-step process to successfully construct a novel MNA with core-shell nanoparticles anchored at the heterointerface of dual-phase oxide substrates through a phase transition and in situ exsolution of perovskite La_0.5Sr_0.5Fe_0.8Ni_0.1Nb_0.1O_3-δ (LSFNNb0.1) in wet H₂ (3% H₂O) at 800 °C. The core-shell nanoparticles are composed of a Ni-Fe alloy core and a SrLaFeO₄-type layered perovskite oxide shell (RP-Ruddlesden-Popper-layered perovskites), which synergistically improves the electrochemical activity and effectively suppresses aggregation and coarsening of the metallic core. The RP phase also covers the surface of perovskite bulk (SP-single perovskite), forming the heterointerface and preventing further decomposition of the SP phase. The RP/SP heterointerface may improve the kinetics of surface exchange of oxygen species, resulting in the enhancement of performance and durability of the reduced LSFNNb0.1 as an anode for solid oxide fuel cells (SOFCs). A doped zirconia electrolyte-supported single cell with the anode achieves the maximum power density (MPD) of 0.83 W cm^-2 at 800 °C in wet H₂, and the corresponding polarization resistance is as low as 0.15 Ω cm². This work reveals the formation mechanism of the MNA by investigating the evolution of the crystal structure, composition and morphology of LSFNNb0.1, when changing reducing temperature and time in wet H₂ and 5% H₂-Ar. The oxygen vacancies and phase transitions are found to play important roles in the formation of the MNA. The construction of MNAs in one step opens a new opportunity to design and prepare high-performance and stable catalysts for applications in energy conversion and storage.

Three-Dimensional Magnesiophilic Scaffolds for Reduced Passivation toward High-Rate Mg Metal Anodes in a Noncorrosive Electrolyte

Magnesium ion batteries are a promising alternative of the lithium counterpart; however, the poorly ion-conductive passivation layer on Mg metal makes plating/stripping difficult. In addition to the generally recognized chemical passivation, the interphase is dynamically degraded by electrochemical side reactions. Especially under high current densities, the interphase thickens, exacerbating the electrode degradation. Herein, we adopt 3D Mg₃Bi₂ scaffolds for Mg metal, of which the high surface area reduces the effective current density to avoid continuous electrolyte decomposition and the good Mg affinity homogenizes nucleation. The greatly alleviated passivation layer could serve as a stable solid/electrolyte interface instead. The symmetric cell delivers a low overpotential of 0.21 and 0.50 V at a current density of 0.1 and 4 mA cm^-2, respectively, and a superior cycling performance over 300 cycles at 0.5 mA cm^-2 in a noncorrosive conventional electrolyte. This work proves that the control of dynamic passivation can enable high-power density Mg metal anodes.

Poly(vinylene carbonate)-Based Composite Polymer Electrolyte with Enhanced Interfacial Stability To Realize High-Performance Room-Temperature Solid-State Sodium Batteries

Solid-state rechargeable batteries using polymer electrolytes have been considered, which can avoid safety issues and enhance energy density. However, commercial application of the polymer electrolyte solid-state battery is still significantly limited by the low room-temperature ionic conductivity, poor mechanical properties, and weak interfacial compatibility between the electrolyte and electrode, especially for the room-temperature solid-state rechargeable battery. In this work, a poly(vinylene carbonate)-based composite polymer electrolyte (PVC-CPE) is reported for the first time to realize room-temperature solid-state sodium batteries with high performances. This in situ solidified PVC-CPE possesses superior ionic conductivity (0.12 mS cm^-1 at 25 °C), high Na⁺ transference number (t_Na⁺ = 0.60), as well as enhanced electrode/electrolyte interfacial stability. Notably, the composite cathode NaNi_1/3Fe_1/3Mn_1/3O₂ (c-NFM) is designed through the in situ growth of the polymer electrolyte inside the electrode to decrease interfacial resistance and facilitate effective ion transport in electrode/electrolyte interfaces. It is demonstrated that the solid-state c-NFM/PVC-CPE/Na battery assembled by a one-step in situ solidification method exhibits remarkably enhanced cell performances at room temperature compared with a reference NFM/PVC-CPE/Na assembled through a conventional ex situ method. The battery presents a high initial specific capacity of 104.2 mA h g^-1 at 0.2 C with a capacity retention of 86.8% over 250 cycles and ∼80.2 mA h g^-1 at 1 C. This study suggests that PVC-CPE is a very promising electrolyte for solid-state sodium batteries. This study also suggests a new method to design high-performance polymer electrolytes for other solid-state rechargeable batteries to realize high safety and considerable electrochemical performance at room temperature.

Enhanced Electrochemical Performance of Sodium Manganese Ferrocyanide by Na3(VOPO4)2F Coating for Sodium-Ion Batteries

Sodium manganese ferrocyanide Na_xMn[Fe(CN)₆]_y is an attractive cathode material for sodium-ion batteries. However, Na_xMn[Fe(CN)₆]_y prepared by simple coprecipitation of Mn²⁺ and [Fe(CN)₆]^4- usually shows poor cycling performance, which hinders its practical application. In this work, electrochemical performance of a Na_1.6Mn[Fe(CN)₆]_0.9 (PBM) sample prepared by the simple precipitation method was greatly improved by coating with Na₃(VOPO₄)₂F (NVOPF) via a solution precipitation method. The as-prepared PBM@NVOPF with a coating quantity of 2.0% molar ratio showed enhanced rate capability and superior cyclic stability. The discharge capacities of PBM@NVOPF were 101.5 mA h g^-1 (1 C) and 91.4 mA h g^-1 (10 C), with a capacity retention of 84.3% after 500 cycles at 1 C, 20 °C. It also exhibited excellent cyclic stability at elevated temperature with an initial capacity of 109.5 mA h g^-1 and a capacity retention of 78.8% after 200 cycles at 1 C, 55 °C. In comparison, uncoated PBM showed a discharge capacity of 105.7 mA h g^-1 (1 C) and 76.7 mA h g^-1 (10 C), with a capacity retention of only 42.0% after 500 cycles at 1 C, 20 °C. The high-temperature performance of bare PBM was very poor, and the capacity retention was only 35.7% after 40 cycles because of serious Mn/Fe dissolution which caused structural deterioration of PBM. NVOPF coating protected the PBM from suffering corrosion in the electrolyte, thus ensured the framework stability of PBM during long-term cycling and contributed to the excellent electrochemical performance.

Rational Design of the Robust Janus Shell on Silicon Anodes for High-Performance Lithium-Ion Batteries

The high-capacity silicon anode is regarded as a promising electrode material for next-generation lithium-ion batteries. Unfortunately, its practical application is still severely hindered by electrode fracture and unstable solid electrolyte interphase during cycling. Herein, we design a structure of encapsulating silicon in a robust "janus shell", in which an internal graphene shell with sufficient void space is used to absorb the mechanical stress induced by volume expansion, and the conformal carbon outer shell is introduced to strongly bond the loosely stacked graphene shell and simultaneously seal the nanopores on the surface. With the ultrastable janus carbon shell, the excellent structural integrity of the electrode and stable solid electrolyte interphase layer could be effectively preserved, resulting in an impressive cycling behavior. Indeed, the as-synthesized anodes demonstrate superior cycle stability and excellent rate performance, delivering a high reversible capacity of 1416 mA h g^-1 at a current density of 0.2 A g^-1 and 852 mA h g^-1 at a high current density of 5 A g^-1. Remarkably, the superior capacity retention of 88.5% could be achieved even after 400 cycles at a high current density of 2 A g^-1. More importantly, this work opens up a novel avenue to address high-capacity anodes with a large volume change.

Identifying Active Sites for Parasitic Reactions at the Cathode-Electrolyte Interface

Nickel-rich transition metal oxides are the most promising high-voltage and high-capacity cathode materials for high-energy-density lithium batteries. Improving the chemical/electrochemical stability of the cathode-electrolyte interface has been the major technical focus to enable this class of cathode materials. In this work, LiCoO₂ is adopted as the model cathode material to investigate the active sites for parasitic reactions between the delithiated cathode and the nonaqueous electrolyte. Both ab initio calculations and experimental results clearly show that the partially coordinated transition metal atoms at the surface are responsible for the parasitic reactions at the cathode-electrolyte interface. This finding lays out fundamental support for rational interfacial engineering to further improve the life and safety characteristics of nickel-rich cathode materials.

Coaxial Carbon Nanotube Supported TiO2@MoO2@Carbon Core-Shell Anode for Ultrafast and High-Capacity Sodium Ion Storage

The sluggish kinetic in electrode materials is one of the critical challenges in achieving high-power sodium ion storage. We report a coaxial core-shell nanostructure composed of carbon nanotube (CNT) as the core and TiO₂@MoO₂@C as shells for a hierarchically nanoarchitectured anode for improved electrode kinetics. The 1D tubular nanostructure can effectively reduce ion diffusion path, increase electrical conductivity, accommodate the stress due to volume change upon cycling, and provide additional interfacial active sites for enhanced charge storage and transport properties. Significantly, a synergistic effect between TiO₂ and MoO₂ nanostructures is investigated through ex situ solid-state nuclear magnetic resonance. The electrode exhibits a good rate capability (150 mAh g^-1 at 20 A g^-1) and superior cycling stability with a reversibly capacity of 175 mAh g^-1 at 10 A g^-1 for over 8000 cycles.

High-sulfur coal-derived nitrogen, sulfur dual-doped carbon as an economical metal-free electrocatalyst for oxygen reduction reaction

The search for an economical electrocatalyst for oxygen reduction reaction (ORR) is a worldwide issue for fuel cells and metal–air batteries. Herein, we used cheap and available high-sulfur inferior coal as the single precursor to synthesize an N, S dual-doped carbon (NSC) metal-free electrocatalyst for the ORR. The N, S dual-doped carbon (NSC), prepared at 800 °C (NSC800), possessed a large specific surface area of 942 m² g⁻¹, with an amorphous carbon structure and more defects than the others. Furthermore, it contains 1.06 at% N and 2.24 at% S, where N is resolved into pyridinic-N, pyrrolic-N, and graphitic-N. For the electrochemical behavior, NSC800 displayed a good ORR electrocatalytic activity, with the ORR peak potential at −0.245 V (vs. SCE) and half-wave potential (E_1/2) at −0.28 V (vs. SCE) in an alkaline solution. This study not only gives an original and facile method to prepare an economical ORR electrocatalyst but also provides a novel clean-use of high-sulfur inferior coal.

The search for an economical electrocatalyst for oxygen reduction reaction (ORR) is a worldwide issue for fuel cells and metal–air batteries.

Cobalt phosphide embedded in a graphene nanosheet network as a high-performance anode for Li-ion batteries

Cobalt phosphide embedded in a graphene nanosheet network can be developed by a versatile strategy for advanced Li-ion battery anodes.

Bifidobacterium infantis M-63 improves mental health in victims with irritable bowel syndrome developed after a major flood disaster

Individuals in a community who developed irritable bowel syndrome (IBS) after major floods have significant mental health impairment. We aimed to determine if Bifidobacterium infantis M-63 was effective in improving symptoms, psychology and quality of life measures in flood-affected individuals with IBS and if the improvement was mediated by gut microbiota changes. Design was non-randomised, open-label, controlled before-and-after. Of 53 participants, 20 with IBS were given B. infantis M-63 (1×10⁹ cfu/sachet/day) for three months and 33 were controls. IBS symptom severity scale, hospital anxiety and depression scale, SF-36 Questionnaire, hydrogen breath testing for small intestinal bacterial overgrowth and stools for 16S rRNA metagenomic analysis were performed before and after intervention. 11 of 20 who were given probiotics (M-63) and 20 of 33 controls completed study as per-protocol. Mental well-being was improved with M-63 vs controls for full analysis (P=0.03) and per-protocol (P=0.01) populations. Within-group differences were observed for anxiety and bodily pain (both P=0.04) in the M-63 per-protocol population. Lower ratio of Firmicutes/Bacteroidetes was observed with M-63 vs controls (P=0.01) and the lower ratio was correlated with higher post-intervention mental score (P=0.04). B. infantis M-63 is probably effective in improving mental health of victims who developed IBS after floods and this is maybe due to restoration of microbial balance and the gut-brain axis. However, our conclusion must be interpreted within the context of limited sample size. The study was retrospectively registered on 12 October 2017 and the Trial Registration Number (TRN) was NCT03318614.

Nitrogen and Phosphorus Codoped Porous Carbon Framework as Anode Material for High Rate Lithium-Ion Batteries

Slow kinetics and low specific capacity of graphite anode significantly limit its applications in the rapidly developing lithium-ion battery (LIB) markets. Herein, we report a carbon framework anode with ultrafast rate and cycling stability for LIBs by nitrogen and phosphorus doping. The electrode structure is constructed of a 3D framework built from 2D heteroatom-doped graphene layers via pyrolysis of self-assembled supramolecular aggregates. The synergistic effect from the nanostructured 3D framework and chemical doping (i.e., N- and P-doping) enables fast kinetics in charge storage and transport. A high reversible capacity of 946 mAh g^-1 is delivered at a current rate of 0.5 A g^-1, and excellent rate capability (e.g., a capacity of 595 mAh g^-1 at 10 A g^-1) of the electrode is shown. Moreover, a moderate surface area from the 3D porous structure contributes to a relatively high initial Coulombic efficiency of 74%, compared to other graphene-based anode materials. The electrode also demonstrates excellent cycling stability at a current rate of 2 A g^-1 for 2000 cycles. The synthetic strategy proposed here is highly efficient and green, which can provide guidance for large-scale controllable fabrication of carbon-based anode materials.

Insight into Ca-Substitution Effects on O3-Type NaNi1/3 Fe1/3 Mn1/3 O2 Cathode Materials for Sodium-Ion Batteries Application

O3-type NaNi_1/3 Fe_1/3 Mn_1/3 O₂ (NaNFM) is well investigated as a promising cathode material for sodium-ion batteries (SIBs), but the cycling stability of NaNFM still needs to be improved by using novel electrolytes or optimizing their structure with the substitution of different elements sites. To enlarge the alkali-layer distance inside the layer structure of NaNFM may benefit Na⁺ diffusion. Herein, the effect of Ca-substitution is reported in Na sites on the structural and electrochemical properties of Na_1-x Ca_x/2 NFM (x = 0, 0.05, 0.1). X-ray diffraction (XRD) patterns of the prepared Na_1-x Ca_x/2 NFM samples show single α-NaFeO₂ type phase with slightly increased alkali-layer distance as Ca content increases. The cycling stabilities of Ca-substituted samples are remarkably improved. The Na_0.9 Ca_0.05 Ni_1/3 Fe_1/3 Mn_1/3 O₂ (Na_0.9 Ca_0.05 NFM) cathode delivers a capacity of 116.3 mAh g^-1 with capacity retention of 92% after 200 cycles at 1C rate. In operando XRD indicates a reversible structural evolution through an O3-P3-P3-O3 sequence of Na_0.9 Ca_0.05 NFM cathode during cycling. Compared to NaNMF, the Na_0.9 Ca_0.05 NFM cathode shows a wider voltage range in pure P3 phase state during the charge/discharge process and exhibits better structure recoverability after cycling. The superior cycling stability of Na_0.9 Ca_0.05 NFM makes it a promising material for practical applications in sodium-ion batteries.

A self-assembled dual-phase composite as a precursor of high-performance anodes for intermediate temperature solid oxide fuel cells

A durable high-performance anode composed of Fe–Cu nano-fibers, a Ruddlesden–Popper layered perovskite and a single perovskite is prepared from a dual-phase precursor.

Carbon-coated FeP nanoparticles anchored on carbon nanotube networks as an anode for long-life sodium-ion storage

Carbon-coated FeP nanoparticles anchored on carbon nanotube networks with enhanced cycling stability for sodium-ion storage.

Red Phosphorus-Embedded Cross-Link-Structural Carbon Films as Flexible Anodes for Highly Reversible Li-Ion Storage

Red phosphorus (P) is considered to be one of the most attractive anodic materials for lithium-ion batteries (LIBs) due to its high theoretical capacity of 2596 mAh g^-1. However, intrinsic characteristics such as the poor electronic conductivity and large volume expansion at lithiation impede the development of red P. Here, we design a new strategy to embed red P particles into a cross-link-structural carbon film (P-C film), in order to improve the electronic conductivity and accommodate the volume expansion. The red P/carbon film is synthesized via vapor phase polymerization (VPP) followed by the pyrolysis process, working as a flexible binder-free anode for LIBs. High cycle stability and good rate capability are achieved by the P-C film anode. With 21% P content in the film, it displays a capacity of 903 mAh g^-1 after 640 cycles at a current density of 100 mA g^-1 and a capacity of 460 mAh g^-1 after 1000 cycles at 2.0 A g^-1. Additionally, the Coulombic efficiency reaches almost 100% for each cycle. The superior properties of the P-C films together with their facile fabrication make this material attractive for further flexible and high energy density LIB applications.