Interfacial built-in electric field and crosslinking pathways enabling WS_(2)/Ti_(3)C_(2)T_(x) heterojunction with robust sodium storage at low temperature

Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging.Besides,sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates.Herein,cross-linking nanoarchitectonics of WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,featuring built-in electric field(BIEF),have been developed,employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity.Particularly,the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti_(3)C_(2)T_(x) to layered WS_(2),spontaneously forming the BIEF and“ion reservoir”at the heterogeneous interface.Besides,the generation of cross-linking pathways further promotes the transportation of electrons/ions,which guarantees rapid diffusion kinetics and excellent structure coupling.Consequently,superior sodium storage performance is obtained for the WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,with only 0.2%decay per cycle at 5.0 A g^(-1)(25℃)up to 1000 cycles and a high capacity of 293.5 mA h g^(-1)(0.1A g^(-1)after 100 cycles)even at-20℃.Importantly,the spontaneously formed BIEF,accompanied by“ion reservoir”,in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.

Enhanced energy density and fast-charging ability via directional particle configuration

The limited energy density of lithium-ion capacitors poses a significant obstacle to their widespread application,primarily stemming from the inability of the electrodes to simultaneously fulfill both high energy density and rapid charging requirements.Experimental data demonstrate that a directional particle configuration can enhance charging speed while maintaining high-capacity density,but it is rarely discussed.Here,we have developed a particle-level electrochemical model capable of reconstructing an electrode with a directional particle configuration.By employing this method,an investigation was conducted to explore how the spatial morphology characteristics of particle configuration impact the energy storage characteristics of electrodes.Results demonstrate that rational particle configuration can effectively enhance the transport of lithium ions and create additional space for lithium-ion storage.With the same particle size distribution,the best electrode can increase the discharge capacity by up to132.4% and increase the charging SOC by 11.3% compared to the ordinary electrode under the condition of 6 C.These findings provide a further understanding of the energy storage mechanism inside the anisotropic particle distribution electrode,which is important for developing high-performance lithium-ion capacitors.

Interface Engineering of Fe_(7)S_(8)/FeS_(2) Heterostructure in situ Encapsulated into Nitrogen‑Doped Carbon Nanotubes for High Power Sodium‑Ion Batteries

Heterostructure engineering combined with carbonaceous materials shows great promise toward promoting sluggish kinetics,improving electronic conductivity,and mitigating the huge expansion of transition metal sulfide electrodes for high-performance sodium storage.Herein,the iron sulfide-based heterostructures in situ hybridized with nitrogen-doped carbon nanotubes(Fe_(7)S_(8)/FeS_(2)/NCNT)have been prepared through a successive pyrolysis and sulfidation approach.The Fe_(7)S_(8)/FeS_(2)/NCNT heterostructure delivered a high reversible capacity of 403.2 mAh g^(−1) up to 100 cycles at 1.0 A g^(−1) and superior rate capability(273.4 mAh g^(−1) at 20.0 A g^(−1))in ester-based electrolyte.Meanwhile,the electrodes also demonstrated long-term cycling stability(466.7 mAh g^(−1) after 1,000 cycles at 5.0 A g^(−1))and outstanding rate capability(536.5 mAh g^(−1) at 20.0 A g^(−1))in ether-based electrolyte.This outstanding performance could be mainly attributed to the fast sodium-ion diffusion kinetics,high capacitive contribution,and convenient interfacial dynamics in ether-based electrolyte.

In-situ electro-polymerization of L-tyrosine enables ultrafast,long cycle life for lithium metal battery

The growth of dendrites in the lithium(Li)metal anode hinders the commercialization of lithium metal batteries(LMBs).Electrolyte additives have proved to be an effective way to solve the problem of dendrites and improve the coulombic efficiency.Herein,we propose a strategy of using L-tyrosine(L-Tyr)as an additive to protect the lithium metal anode in situ,where L-Tyr can be electropolymerized in situ to form an ordered array of nanosheets on the surface of the lithium metal anode to uniformly deposit lithium ions.At the same time,the addition of L-Tyr changed the structure of the solvent in the electrolyte,because the carboxyl group on L-Tyr make DME form hydrogen bonds easily.Besides,the reduction of free DME makes more TFSI-involved in the formation of the SEI film on the electrode surface,which increases the proportion of LiF in the SEI film.With 2 wt%L-Tyr,Li||Li symmetric cells superior cycle stability in ether electrolytes,Li|Cu cells y improved stability up to 200 cycles with an average CE of 93.1%in ether electrolytes and Li||Li_(4)Ti_(5)O_(12)(LTO)demonstrated an excellent cycling capabilitie with 119 mAh/g capacity retention by the 5000^(th)cycle.

Three-dimensional crosslinked nanoarchitectonics of CoP@NC anchored on Ti_(3)C_(2)T_(x) with high ionic diffusion and enhanced sodium storage performance

Transition metal phosphides(CoP,etc.),featuring rich natural abundance and remarkable theoretical capacity,suffer from extremely poor rate capability and severe energy decay for sodium storage due to their huge volume change and low electronic conductivity.Herein,an elaborate hierarchical superstructure,nitrogen-doped carbon wrapped CoP in-situ anchored on Ti_(3)C_(2)Tx MXene(CoP@NC/Ti_(3)C_(2)Tx),was fabricated by crosslinking ZIF-67 on Ti_(3)C_(2)Tx flakes followed by successive carbonization and phosphorization.In principle,the dual modification for CoP nanoparticles through NC coating and Ti_(3)C_(2)T_(x) support can dramatically accelerate the ionic/electronic transportation and alleviate the structure change upon repeated sodiation/desodiation,thus leading to superior electrode integrity,modified ohmic polarization,and excellent electrochemical reversibility.Consequently,the elaborated hierarchical superstructure delivers impressive sodium storage performances with large capacity(396.06 mA·h/g at 0.1 A/g up to 100 cycles),robust rate performance(237.8 mA·h/g at 2.0 A/g),and satisfied cyclability(capacity retention of 81.3%at 1.0 A/g after 1,200 cycles).In principle,systematic electrochemical and characterizations measurements manifest that the high pseudocapacitive effect to charge storage,enhanced ionic diffusion kinetics,and remarkable electrochemical reversibility contribute to the impressive sodium storage performance of target CoP@NC/Ti_(3)C_(2)T_(x).Importantly,the unique modification strategy reported in this study paves a way to fabricate high-performance electrode for SIBs.

Self-healing ability of Prussian blue analogs for aqueous potassium-ion batteries

The slow reaction kinetics,combined with the relatively large radius of K-ion,makes it challenging to develop acceptable electrode materials for reversible insertion/deinsertion of potassium ions,thus reducing the cycle stability and reversible capacity of aqueous potassium-ion batteries(PIBs)[1].Given this,there is still a long way to go in developing high-performance electrode materials for PIBs with a stable cycle life and high energy density.According to a literature study on PIB electrode materials,the electrochemical performance of cathode materials can be easily achieved through various structural modifications[2–4].Nevertheless,the study of cathode material optimization and operating mechanisms is insufficient,hindering the energy density of PIBs from reaching a satisfactory level.In this context,the performance of cathode material becomes the decisive factor for the performance of PIBs.

Community assemblage of free-living diazotrophs along the elevational gradient of Mount Gongga

Mountain systems are unique for studying the responses of species distribution and diversity to environmental changes along elevational gradients.It is well known that free-living diazotrophic microorganisms are important to nitrogen cycling in mountain systems.However,the elevational patterns of free-living diazotrophs and the underlying ecological processes in controlling their turnover along broader gradients are less well documented.Here,we investigated the pattern of diazotrophic diversity along the elevational gradient(1800 m-4100 m)in Mount Gongga of China.The results showed that the α-diversity of diazotrophs did not change with the elevation from 1800 m to 2800 m,but decreased at elevations above 3000 m.Such diversity pattern was driven mainly by soil total carbon,nitrogen,and plant richness.Various diazotrophic taxa showed differential abundance-elevation relationships.Ecological processes determining diazotrophic community assemblage shift along the elevations.Deterministic processes were relatively stronger at both low and high elevations,whereas stochastic processes were stronger at the middle elevation.This study also suggested a strong relationship among aboveground plants and diazotrophs,highlighting their potential interactions,even for free-living diazotrophs.

Climate warming restructures seasonal dynamics of grassland soil microbial communities

Soil microbial community's responses to climate warming alter the global carbon cycle.In temperate ecosystems,soil microbial communities function along seasonal cycles.However,little is known about how the responses of soil microbial communities to warming vary when the season changes.In this study,we investigated the seasonal dynamics of soil bacterial community under experimental warming in a temperate tall‐grass prairie ecosystem.Our results showed that warming significantly(p=0.001)shifted community structure,such that the differences of microbial communities between warming and control plots increased nonlinearly(R^(2)=0.578,p=0.021)from spring to winter.Also,warming significantly(p<0.050)increased microbial network complexity and robustness,especially during the colder seasons,despite large variations in network size and complexity in different seasons.In addition,the relative importance of stochastic processes in shaping the microbial community decreased by warming in fall and winter but not in spring and summer.Our study indicates that climate warming restructures the seasonal dynamics of soil microbial community in a temperate ecosystem.Such seasonality of microbial responses to warming may enlarge over time and could have significant impacts on the terrestrial carbon cycle.

Flexible sodium-ion capacitors boosted by high electrochemicallyreactive and structurally-stable Sb_(2)S_(3)nanowire/Ti_(3)C_(2)Tx MXene film anodes

The rapid development of portable,foldable,and wearable electronic devices requires flexible energy storage systems.Sodiumion capacitors(SICs)combining the high energy of batteries and the high power of supercapacitors are promising solutions.However,the lack of flexible and durable electrode materials that allow fast and reversible Na+storage hinders the development of flexible SICs.Herein,we report a high-capacity,free-standing and flexible Sb2S3/Ti_(3)C_(2)Tx composite film for fast and stable sodium storage.In this hybrid nano-architecture,the Sb_(2)S_(3)nanowires uniformly anchored between Ti_(3)C_(2)Tx nanosheets not only act as sodium storage reservoirs but also pillar the two-dimensional(2D)Ti_(3)C_(2)Tx to form three-dimensional(3D)channels benefiting for electrolyte penetration.Meanwhile,the highly conductive Ti_(3)C_(2)Tx nanosheets provide rapid electron transport pathways,confine the volume expansion of Sb_(2)S_(3)during sodiation,and restrain the dissolution of discharged sodium polysulfides through physical constraint and chemical absorption.Owing to the synergistic effects of the one-dimensional(1D)Sb_(2)S_(3)nanowires and 2D MXenes,the resultant composite anodes exhibit outstanding rate performance(553 mAh·g−1 at 2 A·g−1)and cycle stability in sodium-ion batteries.Moreover,the flexible SICs using Sb2S3/Ti_(3)C_(2)Tx anodes and active carbon/reduced graphene oxide(AC/rGO)paper cathodes deliver a superior energy and power density in comparison with previously reported devices,as well as an excellent cycling performance with a high capacity retention of 82.78%after 5,000 cycles.This work sheds light on the design of next-generation low-cost,flexible and fast-charging energy storage devices.

Boosted electrochemical performance of Na_(3)V_(2)(PO_(4))_(3) at low temperature through synergistical F substitution and construction of interconnected nitrogen-doped carbonaceous network

Benefitting from its unique NASICON-type framework,the Na_(3)V_(2)(PO_(4))_(3)(NVP)cathodes have aroused extensive interest and have been deemed as the promising cathode candidate for sodium-ion batteries(SIBs).Unfortunately,the poor electronic conductivity,combined with the undesirable volume variations,seriously hinders the practical application of NVP cathode,especially at low temperatures.Herein,a dual-strategy,F substitution accompanied by V vacancies and the construction of three-dimensional(3D)nitrogen-doped carbonaceous frameworks(NC),were employed for the NVP cathode(F-NVP/C@3DNC).The former can remarkably decrease the particle size and enhance Na^(+)migration capability,increasing the ionic conductivity.Meanwhile,the electronic connection and effective buffering can be obtained from the latter,strengthening the electrode integrity.Consequently,up to 100 cycles at 0.1 A g^(-1),a reversible capacity of 113.8 mAh g^(-1),approaching the theoretical value(117 mAh g^(-1)),is demonstrated,accompa-nied by impressive capacity retentions at 1.0(93.75%after 4800 cycles)and 20.0 A g^(-1)(92.7%after 1000 cycles).More importantly,even at-20℃,a superior specific capacity(102.6 mAh g^(-1) after 100 cycles at 0.1 A g^(-1))and high capacity retention(86.6%at 20.0 A g^(-1) up to 1000 cycles)can still be obtained simul-taneously.Significantly,the design of F-NVP/C@3DNC provides insights for the fabrication of polyanion cathodes for applications at low temperatures with modified structure stability and reaction kinetics.

Overexpression of programmed cell death-1 (PD-1) affects circulatory Th1 and Th2 cells in patients with cardiac arrest in the early period after the return of spontaneous circulation

To the Editor:Cardiac arrest(CA)is the leading cause of morbidity and mortality among hospitalized patients globally and has low rates of overall survival.After the return of spontaneous circulation(ROSC),patients with CA and systemic ischemia/reperfusion injury can manifest as sepsis-like syndromes and immune disorders that increase the risk of infections.CD4^(+)T lymphocytes play an important role in organ ischemia-reperfusion injury.T-helper(Th)types 1 and 2 cells are classical subsets of CD4^(+)T cells.Extensive research on their functions in infectious and immune-related inflammatory diseases indicates that both subsets participate in host defense and direct immune responses.Data from CA/cardiopulmonary resuscitation porcine models and patients have revealed imbalances in Th1/Th2 cell ratio.[1]Therefore,Th1 and Th2 cells are important for understanding post-ROSC immune dysfunction in patients with CA.

Identification of unknown disinfection byproducts in drinking water produced from Taihu Lake source water

Although disinfection byproducts(DBPs) in drinking water have been suggested as a cancer causing factor, the causative compounds have not yet been clarified. In this study, we used liquid chromatography quadrupole-time-of-flight spectrometry(LC-QTOF MS) to identify the unknown disinfection byproducts(DBPs) in drinking water produced from Taihu Lake source water, which is known as a convergence point for the anthropogenic pollutants discharged from intensive industrial activities in the surrounding regions. In total, 91 formulas of DBPs were discovered through LC-QTOF MS nontarget screen, 81 of which have not yet been reported. Among the 91 molecules, 56 only contain bromine, 15 only contain chlorine and 20 DBPs have both bromine and chlorine atoms. Finally, five DBPs including 2,4,6-tribromophenol, 2,6-dibromo-4-chlorophenol, 2,6-dichloro-4-bromophenol, 4-bromo-2,6-di-tert-butylphenol and 3,6-dibromocarbazole were confirmed using standards. The former three compounds mainly formed in the predisinfection step(maximum concentration, 0.2-2.6 μg/L), while the latter two formed in the disinfection step(maximum concentration, 18.2-33.6 ng/L). In addition, 19 possible precursors of the discovered DBPs were detected, with the aromatic compounds being a major group. 2,6-di-tert-butylphenol as the precursor of 4-bromo-2,6-di-tert-butylphenol was confirmed with standard, with a concentration of 20.3 μg/L in raw water. The results of this study show that brominated DBPs which are possibly formed from industrial pollutants are relevant DBP species in drinking water produced form Taihu source water, suggesting protection of Taihu Lake source water is important to control the DBP risks.

Optimization of flow field in electrochemical trepanning of integral cascades(Ti6Al4V)

Ti6Al4V is widely applied in the integral cascades of aero engines.As an effective machining method,electrochemical trepanning(ECTr)has unique advantages in processing surface parts made of hard-to-cut materials.In ECTr,the state of the flow field has a significant effect on processing stability and machining quality.To improve the uniformity of the flow field when ECTr is applied to Ti6Al4V,two different flow modes are designed,namely full-profile electrolyte supply(FPES)and edges electrolyte supply(EES).Different from the traditional forward flow mode,the flow directions of the electrolyte in the proposed modes are controlled by inlet channels.Simulations show that the flow field under EES is more uniform than that under FPES.To further enhance the uniformity of the flow field,the structure of EES is optimized by modifying the insulating sleeve.In the optimized configuration,the longitudinal distance between the center of the inlet hole and the center of the blade is 6.0 mm,the lateral distance between the centers of the inlet holes on both sides is 16.5 mm,the length to which the electrolyte enters the machining area is 1.5 mm,and the height of the insulating sleeve is 13.5 mm.A series of ECTr experiments are performed under the two flow modes.Compared with EES,the blade machined by FPES is less accurate and has poorer surface quality,with a surface roughness(R_(a))of 3.346μm.Under the optimized EES,the machining quality is effectively enhanced,with the surface quality improved from R_(a)=2.621μm to R_(a)=1.815μm,thus confirming the efficacy of the proposed methods.