Boosting of Redox-Active Polyimide Porous Organic Polymers with Multi-Walled Carbon Nanotubes towards Pseudocapacitive Energy Storage.

Redox-active porous organic polymers (POPs) demonstrate significant potential in supercapacitors. However, their intrinsic low electrical conductivity and stacking tendencies often lead to low utilization rates of redox-active sites within their structural units. Herein, polyimide POPs (donated as PMTA) are synthesized in situ on multi-walled carbon nanotubes (MWCNTs) from tetramino-benzoquinone (TABQ) and 1,4,5,8-naphthalene tetracarboxylic dianhydride (PMDA) monomers. The strong π-π stacking interactions drive the PMTA POPs and the MWCNTs together to form a PMTA/MWCNT composite. With the assistance of MWCNTs, the stacking issue and low conductivity of PMTA POPs are well addressed, leading to the obvious activation and enhanced utilization of the redox-active groups in the PMTA POPs. PMTA/MWCNT then achieves a high capacitance of 375.2 F g-1 at 1 A g-1 as compared to the pristine PMTA POPs (5.7 F g-1) and excellent cycling stability of 89.7% after 8000 cycles at 5 A g-1. Cyclic voltammetry (CV) and in situ Fourier-Transform Infrared (FT-IR) results reveal that the electrode reactions involve the reversible structural evolution of carbonyl groups, which are activated to provide rich pseudocapacitance. Asymmetric supercapacitors (ASCs) assembled with PMTA/MWCNTs and activated carbon (AC) offer a high energy density of 15.4 Wh kg-1 at 980.4 W kg-1 and maintain a capacitance retention of 125% after 10,000 cycles at 5 A g-1, indicating their good potential for practical applications.

Zincophilic Sites Enriched Hydrogen-bonded Organic Framework as Multifunctional Regulating Interfacial Layers for Stable Zinc Metal Batteries.

To construct an efficient regulating layer for Zn anodes that can simultaneously address the issues of dendritic growth and side reactions is highly demanded for stable zinc metal batteries (ZMBs). Herein, we fabricate a hydrogen-bonded organic framework (HOF) enriched with zincophilic sites as a multifunctional layer to regulate Zn anodes with controlled spatial ion flux and stable interfacial chemistry (MA-BTA@Zn). The framework with abundant H-bonds helps capture H2O and remove the solvated shells on [Zn(H2O)6]2+, leading to suppressed side reactions. The HOF layer also helps form electrolyte-philic surfaces and expose Zn (002) crystal planes which benefit for rapid conduction and uniform deposition of Zn2+, and weakened sides reactions. Additionally, the electrochemically active zincophilic sites (C=O, -NH2 and triazine groups) favor the targeted guidance and penetration of Zn2+ and provide advantageous sites for uniform Zn deposition. High Young's modulus of the HOF layer further contributes to a high interfacial flexibility and stability against Zn plating-associated stress. The MA-BTA@Zn symmetric cells thereby obtain a substantially extended battery life over 1000 h at 4 mA cm-2. The MA-BTA@Zn||Cu half-cell demonstrates a highly reversible Zn stripping/plating process over 1500 cycles with impressive average Coulombic efficiency (CE) of 99.5% at 10 mA cm-2.

A promising strategy to improve the stability and immunogenicity of killed but metabolically active vaccines: low-temperature preparation and coating of nanoparticles.

Bacteria are becoming an increasingly serious threat to human health. The emergence of super bacteria makes clinical treatment more difficult. Vaccines are one of the most effective means of preventing and treating bacterial infections. As a new class of vaccines, killed but metabolically active (KBMA) vaccines provide the immunogenicity of live vaccines and the safety of inactivated vaccines. Herein, a promising strategy is proposed to improve the stability and immunogenicity of KBMA vaccines. KBMA vaccines were produced at low temperature (4 °C), and the bacterial surface was engineered using mesoporous silica nanoparticle (MSN) coating. Compared to vaccines prepared at room temperature, the metabolic activity of KBMA vaccines prepared at 4 °C remarkably improved. Benefiting from the induction of MSNs, the stability of KBMA vaccines was increased and the preservation time was prolonged at 4 °C. Meanwhile, metabolomics analysis showed that the metabolite spectrum of live bacteria changed after photochemical treatment and MSN coating, which interfered with organic acid metabolism pathways, lipid metabolism and biosynthesis of secondary metabolites. Furthermore, the immune response in the mice treated with KBMA/MSN vaccines was similar to that in those treated with live vaccines and stronger than that in those treated with inactivated vaccines. In comparison with the control group, bacteria tissue burdens of KBMA/MSN group were significantly reduced. CD4+ T cells dominated immune responses for the protection of mice. Thus, the current work promotes the application of KBMA vaccines, providing an alternative choice for treating bacterial infections.

Cobalt exposure and pulmonary function reduction in chronic obstructive pulmonary disease patients: the mediating role of club cell secretory protein.

BACKGROUND: Cobalt (Co) is a metal which is widely used in the industrial production. The previous studies found the toxic effects of environmental Co exposure on multiple organs. However, the correlation of blood Co concentration with lung function was inconsistent in patients with chronic obstructive pulmonary disease (COPD). METHODS: All 771 stable COPD patients were recruited. Peripheral blood and clinical information were collected. The levels of blood Co and serum CC16 were measured. RESULTS: Cross-sectional study suggested that the level of blood Co was inversely and dose-dependently related to lung function parameters. Each 1 ppm elevation of blood Co was related to 0.598 L decline in FVC, 0.465 L decline in FEV1, 6.540% decline in FEV1/FVC%, and 14.013% decline in FEV1%, respectively. Moreover, higher age, enrolled in winter, current-smoking, higher smoking amount, and inhaled corticosteroids prominently exacerbated the negative correlation between blood Co and lung function. Besides, serum CC16 content was gradually reduced with blood Co elevation in COPD patients. Besides, serum CC16 was positively correlated with lung function, and inversely related to blood Co. Additionally, decreased CC16 substantially mediated 11.45% and 6.37% Co-triggered downregulations in FEV1 and FEV1%, respectively. CONCLUSION: Blood Co elevation is closely related to the reductions of pulmonary function and serum CC16. CC16 exerts a significantly mediating role of Co-related to pulmonary function decrease among COPD patients.

Longitudinal associations between serum IL-34 with severity and prognosis in community-acquired pneumonia patients.

BACKGROUND: Interleukin-34 (IL-34) is a hematopoietic cytokine and a ligand of colony-stimulating factor 1 receptor (CSF-1R). Numerous studies have demonstrated that IL-34 is involved in several inflammatory diseases. Nevertheless, the role of IL-34 is obscure in community-acquired pneumonia (CAP) patients. This research aimed to assess the associations of serum IL-34 with severity and prognosis in CAP patients through a longitudinal study. METHODS: CAP patients and healthy volunteers were recruited. Peripheral blood samples were collected. Serum IL-34 and inflammatory cytokines were tested by enzyme linked immunosorbent assay (ELISA). Demographic characteristics and clinical information were acquired through electronic medical records. RESULTS: Serum IL-34 was elevated in CAP patients compared with healthy volunteers. The content of serum IL-34 was gradually upregulated with increased CAP severity scores. Mixed logistic and linear regression models suggested that serum IL-34 elevation was associated with increased PSI and SMART-COP scores. Correlative analysis found that serum IL-34 was positively correlated with inflammatory cytokines among CAP patients. A longitudinal study indicated that higher serum IL-34 at admission elevated the risks of mechanical ventilation and death during hospitalization. Serum IL-34 had a higher predictive capacity for death than CAP severity scores. CONCLUSION: There are prominently positive dose-response associations between serum IL-34 at admission with the severity and poor prognosis, suggesting that IL-34 is implicated in the occurrence and development of CAP. Serum IL-34 may serve as a biomarker to forecast disease progression and poor prognosis in CAP patients.

Densely populated tiny RuO2 crystallites supported by hierarchically porous carbon for full acidic water splitting.

The exploitation of highly active bifunctional electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic media has been a subject receiving immense interest. However, the existing catalysts usually suffer from low catalytic efficiency and poor corrosion resistance under acidic conditions. Herein, we report a facile molten salt method to fabricate ruthenium dioxide nanoparticles supported by hierarchically porous carbon (RuO2/PC) as a bifunctional electrocatalyst for full water splitting under strong acidic conditions. The formation of a densely populated nanocrystalline RuO2/carbon heterostructure helps expose catalytic sites, accelerates the mass transfer rate, and further enhances the acid resistance of RuO2 nanoparticles. The as-synthesized RuO2/PC consequently exhibits superior catalytic performance for the OER with an overpotential of 181 mV upon 10 mA cm-2 compared to that of the commercial RuO2 (343 mV) and a comparable performance to Pt/C for the HER (47.5 mV upon 10 mA cm-2) in 0.5 M H2SO4. The RuO2/PC shows promising stability with little degradation over ∼24 h. Impressively, the water electrolyzer based on RuO2/PC shows an overpotential of 326 mV at 10 mA cm-2, much lower than that of the electrolyzer based on the combination of Pt/C and RuO2 (400 mV), indicating its great potential towards practical application.

Microwave-Assisted Metal-Organic Frameworks Derived Synthesis of Zn2GeO4 Nanowire Bundles for Lithium-Ion Batteries.

Germanium-based multi-metallic-oxide materials have advantages of low activation energy, tunable output voltage, and high theoretical capacity. However, they also exhibit unsatisfactory electronic conductivity, sluggish cation kinetics, and severe volume change, resulting in inferior long-cycle stability and rate performance in lithium-ion batteries (LIBs). To solve these problems, we synthesize metal-organic frameworks derived from rice-like Zn2GeO4 nanowire bundles as the anode of LIBs via a microwave-assisted hydrothermal method, minimizing the particle size and enlarging the cation's transmission channels, as well as, enhancing the electronic conductivity of the materials. The obtained Zn2GeO4 anode exhibits superior electrochemical performance. A high initial charge capacity of 730 mAhg-1 is obtained and maintained at 661 mAhg-1 after 500 cycles at 100 mA g-1 with a small capacity degradation ratio of ~0.02% for each cycle. Moreover, Zn2GeO4 exhibits a good rate performance, delivering a high capacity of 503 mA h g-1 at 5000 mA g-1. The good electrochemical performance of the rice-like Zn2GeO4 electrode can be attributed to its unique wire-bundle structure, the buffering effect of the bimetallic reaction at different potentials, good electrical conductivity, and fast kinetic rate.

A novel exposure mode based on UVA-LEDs for bacterial inactivation.

As an emerging UV source, ultraviolet light-emitting diodes (UV-LEDs) are increasingly being used for disinfection purposes. UVA-LEDs have a higher output power, lower cost, and stronger penetration and cause less harm than UVC-LEDs. In this study, a novel exposure mode based on UVA was proposed and well demonstrated by various experiments using S. aureus as an indicator. Compared with single-dose exposure, fractionated exposure with a 15 min interval between treatments resulted in increased S. aureus inactivation. A longer interval or lower first irradiation dose was unfavorable for inactivation. Fractionated exposure changed the inactivation rate constant and eliminated the shoulder in the fluence-response curves. This resulted in changing the sensitivity of bacteria to UVA and improving bacterial inactivation. Moreover, the fractioned exposure mode has universality for various bacteria (including gram-positive and gram-negative bacteria). S. aureus was not reactivated by photoreactivation or dark repair after UVA treatment. As expected, the cells were damaged more seriously after fractionated exposure, further suggesting the advantages of this new exposure mode. In addition, the mechanism by which bacteria were inactivated after fractionated exposure was investigated, and it was found that •OH played an important role. A longer interval between treatments showed an adverse effect on inactivation, mainly due to the reduction of •OH and recovery of intracellular GSH. In summary, the current work provides novel ideas for the application of UVA-LEDs, which will give more choices for disinfection treatment.

Integrated analysis of multiple microarray studies to establish differential diagnostic models of Crohn's disease and ulcerative colitis based on a metalloproteinase-associated module.

Background: The ulcerative colitis (UC) and Crohn's disease (CD) subtypes of inflammatory bowel disease (IBD) are autoimmune diseases influenced by multiple complex factors. The clinical treatment strategies for UC and CD often differ, indicating the importance of improving their discrimination. Methods: Two methods, robust rank aggregation (RRA) analysis and merging and intersection, were applied to integrate data from multiple IBD cohorts, and the identified differentially expressed genes (DEGs) were used to establish a protein-protein interaction (PPI) network. Molecular complex detection (MCODE) was used to identify important gene sets. Two differential diagnostic models to distinguish CD and UC were established via a least absolute shrinkage and selection operator (LASSO) logistic regression, and model evaluation was performed in both the training and testing groups, including receiver operating characteristic (ROC) curves, calibration plots and decision curve analysis (DCA). The potential value of MMP-associated genes was further verified using different IBD cohorts and clinical samples. Results: Four datasets (GSE75214, GSE10616, GSE36807, and GSE9686) were included in the analysis. Both data integration methods indicated that the activation of the MMP-associated module was significantly elevated in UC. Two LASSO models based on continuous variable (Model_1) and binary variable (Model_2) MMP-associated genes were established to discriminate CD and UC. The results showed that Model_1 exhibited good discrimination in the training and testing groups. The calibration analysis and DCA showed that Model_1 exhibited good performance in the training group but failed in the testing group. Model_2 exhibited good discrimination, calibration and DCA results in the training and testing groups and exhibited greater diagnostic value. The effects of Model_1 and Model_2 were further verified in a new IBD cohort of GSE179285. The MMP genes exhibited high value as biomarkers for the discrimination of IBD patients using published cohort and immunohistochemistry (IHC) staining data. The MMP-associated gene levels were statistically significantly positively correlated with the levels of the differentially expressed cell types, indicating their potential value in differential diagnosis. The single-cell analysis confirmed that the expression of ANXA1 in UC was higher than that in CD. Conclusion: MMP-associated modules are the main differential gene sets between CD and UC. The established Model_2 overcomes batch differences and has good clinical applicability. Subsequent in-depth research investigating how MMPs are involved in the development of different IBD subtypes is necessary.

Tin-nitrogen coordination boosted lithium-storage sites and electrochemical properties in covalent-organic framework with layer-assembled hollow structure.

Covalent-organic frameworks (COFs) and related composites show an enormous potential in next-generation high energy-density lithium-ion batteries. However, the strategy to design functional covalent organic framework materials with nanoscale structure and controllable morphology faces serious challenges. In this work, a layer-assembled hollow microspherical structure (Sn@COF-hollow) based on the tin-nitrogen (Sn-N) coordination interaction is designed. Such carefully-crafted hollow structure with large exposed surface area and metal center decoration endows the Sn@COF-hollow electrode with more activated lithium-reaction sites, including Sn ions, carbon-nitrogen double bond (CN) groups and carbon-carbon double bond (CC) units from aromatic benzene rings. Besides, the layer-assembled hollow structure of the Sn@COF-hollow electrode can also alleviate the volume expansion of electrode during repeated cycling, and achieve fast electrons/ions transmission and capacitance-dominated lithium-reaction kinetics, further leading to enhanced cycling performance and rate properties. In addition, the effective combination of the inorganic metal and organic framework components in the Sn@COF-hollow electrode can promote its improved conductivity and further enhance lithium-storage properties. Benefited from these merits, the Sn@COF-hollow electrode delivers highly reversible large capacities of 1080 mAh g-1 after 100 cycles at 100 mA g-1 and 685 mAh g-1 after 300 cycles at 1000 mA g-1. This work provides an interesting and effective way to design COF-based anodes of lithium-ion battery with improved electrochemical performances.

Functionalized Graphene Quantum Dots Modified Dioxin-Linked Covalent Organic Frameworks for Superior Lithium Storage.

Covalent organic framework, as an emerging porous nano-frame structure with pre-designed structure and custom properties, has been demonstrated as a prospective electrode for rechargeable Li-ion batteries. For improving the reversible capacity and long-term cycle stability of COF materials, we propose a GQDs modified COF material (COF-GQDs) and apply it as the anode for LIBs for the first time. This COF-GQDs electrode delivers enhanced long-term cycling performance with a large capacity of ∼820 mAh g-1 after 300 cycles at 100 mA g-1 and an improved rate performance. The enhanced lithium-storage performance, in terms of obvious-shortened activation process and high reversible capacities, can be attributed to the modification of carboxyl GQDs, which would activate more active sites (activated C=C groups from benzene rings) for lithium-storage, and provide fast lithium-ion transportation kinetic. Besides, the decreased interphase resistance, enhanced electronic conductivity, and prevented aggregation of needle-flake COF structure, originated from the addition of GQDs, which lead to the enhanced improved cycling stability of the COF-GQDs electrode. This manuscript can promote the further exploration on the design of COF-related materials with modification of functionalized carbonaceous materials to achieve enhanced lithium-storage properties for next-generation energy storage.

Cobalt Coordinated Cyano Covalent-Organic Framework for High-Performance Potassium-Organic Batteries.

Potassium ion batteries (PIBs) are expected to become the next large-scale energy storage candidates due to its low cost and abundant resources. And the covalent organic framework (COF), with designable periodic organic structure and ability to organize redox active groups predictably, has been considering as the promising organic electrode candidate for PIB. Herein, we report the facile synthesis of the cyano-COF with Co coordination via a facile microwave digestion reaction and its application in the high-energy potassium ion batteries for the first time. The obtained COF-Co material exhibits the enhanced π-π accumulation and abundant defects originated from the Co interaction with the two-dimensional layered sheet structure of COF, which are beneficial for its energy-storage application. Adopted as the inorganic-metal boosted organic electrode for PIBs, the COF-Co with Co coordination can promote the formation of the π-K+ interaction, which could lead to the activation of aromatic rings for potassium-ion storage. Besides, the porous two-dimensional layered structure of COF-Co with abundant defects can also promote the shortened diffusion distance of ion/electron with promoted K+ insertion/extraction ability. Enhanced cycling stability with large reversible capacity (371 mAh g-1 after 400 cycles at 100 mA g-1) and good rate properties (105 mAh g-1 at 2000 mA g-1) have been achieved for the COF-Co electrode.

Imine-Induced Metal-Organic and Covalent Organic Coexisting Framework with Superior Li-Storage Properties and Activation Mechanism.

Due to the adjustable structure and the broad application prospects in energy and other fields, the exploration of porous organic materials [metal-organic polymers (MOPs), covalent organic frameworks (COFs), etc.] has attracted extensive attention. In this work, an imine-induced metal-organic and covalent organic coexisting framework (Co-MOP@COF) hybrid was designed based on the combination between the amino units from the organic ligands of Co-MOP and the aldehyde groups from COF. The obtained Co-MOP@COF hybrid with layer-decorated microsphere morphology exhibited good electrochemical cycling performance (a large reversible capacity of 1020 mAh g-1 after 150 cycles at 100 mA g-1 and a reversible capacity of 396 mAh g-1 at 500 mA g-1 ) as the anode for Li-ion batteries. The coexisting framework structure endowed the Co-MOP@COF hybrid with more surface area exposed in the exfoliated COF structure, which provided rapid Li-ion diffusion, better electrolyte infiltration, and effective activation of functional groups. Therefore, the Co-MOP@COF hybrid material achieved an enhanced Li storage mechanism involving multi-electron redox reactions, related to the CoII center and organic groups (C=C groups of benzene rings and C=N groups), and furthermore improved electrochemical performance.

Ultra-small Fe3O4 nanodots encapsulated in layered carbon nanosheets with fast kinetics for lithium/potassium-ion battery anodes.

Iron oxides are regarded as promising anodes for both lithium-ion batteries (LIBs) and potassium-ion batteries (KIBs) due to their high theoretical capacity, abundant reserves, and low cost, but they are also facing great challenges due to the sluggish reaction kinetics, low electronic conductivity, huge volume change, and unstable electrode interphases. Moreover, iron oxides are normally prepared at high temperature, forming large particles because of Ostwald ripening, and exhibiting low electronic/ionic conductivity and unfavorable mechanical stability. To address those issues, herein, we have synthesized ultra-small Fe3O4 nanodots encapsulated in layered carbon nanosheets (Fe3O4@LCS), using the coordination interaction between catechol and Fe3+, demonstrating fast reaction kinetics, high capacity, and typical capacitive-controlled electrochemical behaviors. Such Fe3O4@LCS nanocomposites were derived from coordination compounds with layered structures via van der Waals's force. Fe3O4@LCS-500 (annealed at 500 °C) nanocomposites have displayed attractive features of ultra-small particle size (∼5 nm), high surface area, mesoporous and layered feature. When used as anodes, Fe3O4@LCS-500 nanocomposites delivered exceptional electrochemical performances of high reversible capacity, excellent cycle stability and rate performance for both LIBs and KIBs. Such exceptional performances are highly associated with features of Fe3O4@LCS-500 nanocomposites in shortening Li/K ion diffusion length, fast reaction kinetics, high electronic/ionic conductivity, and robust electrode interphase stability.

The Progress and Prospect of Tunable Organic Molecules for Organic Lithium-Ion Batteries.

Compared to inorganic electrodes, organic materials are regarded as promising electrodes for lithium-ion batteries (LIBs) due to the attractive advantages of light elements, molecular-level structural design, fast electron/ion transferring, favorable environmental impacts, and flexible feature, etc. Not only specific capacities but also working potentials of organic electrodes are reasonably tuned by polymerization, electron-donating/withdrawing groups, and multifunctional groups as well as conductive additives, which have attracted intensive attention. However, organic LIBs (OLIBs) are also facing challenges on capacity loss, side reactions, electrode dissolution, low electronic conductivity, and short cycle life, etc. Many strategies have been applied to tackle those challenges, and many inspiring results have been achieved in the last few decades. In this review, we have introduced the basic concepts of LIBs and OLIBs, followed by the typical cathode and anode materials with various physicochemical properties, redox reaction mechanisms, and evolutions of functional groups. Typical charge-discharge behaviors and molecular structures of organic electrodes are displayed. Moreover, effective strategies on addressing problems of organic electrodes are summarized to give some guidance on the synthesis of optimized organic electrodes for practical applications of OLIBs.

Hierarchical "tube-on-fiber" carbon/mixed-metal selenide nanostructures for high-performance hybrid supercapacitors.

This work reports hierarchical "tube-on-fiber" nanostructures, composed of carbon nanotubes (CNTs) on carbon nanofibers (CNFs), impregnated with mixed-metal selenide nanoparticles (Co-Zn-Se@CNTs-CNFs), as high performance supercapacitors. Co-Zn hybrid zeolitic imidazolate framework-67 (Co-Zn ZIF-67) was electrospun with polyacrylonitrile (PAN) to form nanofibers that were sequentially thermally treated and subjected to selenylation. The "tube-on-fiber" structure is designed to confine the Co-Zn mixed-metal selenide nanoparticles and prevents their agglomeration. Extruded CNTs rooting in carbon nanofibers further improve the electronic conductivity. The mixed-metal selenide allows more accommodation space and faradic reactions compared to single metal selenide. Based on these merits, the hierarchical Co-Zn-Se@CNTs-CNFs exhibit a high specific capacity of 1040.1 C g-1 (1891 F g-1) at 1 A g-1 with impressive rate performance in supercapacitors. Furthermore, a hybrid supercapacitor with Co-Zn-Se@CNTs-CNFs as the cathode and porous carbon nanofibers as the anode (denoted as Co-Zn-Se@CNTs-CNFs//PCNFs) is fabricated. It delivers a superior energy and power density of 61.4 W h kg-1 and 754.4 W kg-1, respectively, and meanwhile retains 31.7 W h kg-1 of the energy density with 15 421.6 W kg-1 of the working power. In addition, the assembled supercapacitor device displays an excellent capacity retention of 88.6% after 8000 cycles at 5 A g-1.

Strong Surface-Bound Sulfur in Carbon Nanotube Bridged Hierarchical Mo2 C-Based MXene Nanosheets for Lithium-Sulfur Batteries.

In this work, hydroxyl-functionalized Mo2 C-based MXene nanosheets are synthesized by facilely removing the Sn layer of Mo2 SnC. The hydroxyl-functionalized surface of Mo2 C suppresses the shuttle effect of lithium polysulfides (LiPSs) through strong interaction between Mo atoms on the MXenes surface and LiPSs. Carbon nanotubes (CNTs) are further introduced into Mo2 C phase to enlarge the specific surface area of the composite, improve its electronic conductivity, and alleviate the volume change during discharging/charging. The strong surface-bound sulfur in the hierarchical Mo2 C-CNTs host can lead to a superior electrochemical performance in lithium-sulfur batteries. A large reversible capacity of ≈925 mAh g-1 is observed after 250 cycles at a current density of 0.1 C (1 C = 1675 mAh g-1 ) with good rate capability. Notably, the electrodes with high loading amounts of sulfur can also deliver good electrochemical performances, i.e., initial reversible capacities of ≈1314 mAh g-1 (2.4 mAh cm-2 ), ≈1068 mAh g-1 (3.7 mAh cm-2 ), and ≈959 mAh g-1 (5.3 mAh cm-2 ) at various areal loading amounts of sulfur (1.8, 3.5, and 5.6 mg cm-2 ) are also observed, respectively.

Functionalized Graphene Quantum Dot Modification of Yolk-Shell NiO Microspheres for Superior Lithium Storage.

Yolk-shell NiO microspheres are modified by two types of functionalized graphene quantum dots (denoted as NiO/GQDs) via a facile solvothermal treatment. The modification of GQDs on the surface of NiO greatly boosts the stability of the NiO/GQD electrode during long-term cycling. Specifically, the NiO with carboxyl-functionalized GQDs (NiO/GQDsCOOH) exhibits better performances than NiO with amino-functionalized GQDs (NiO/GQDsNH2 ). It delivers a capacity of ≈1081 mAh g-1 (NiO contribution: ≈1182 mAh g-1 ) after 250 cycles at 0.1 A g-1 . In comparison, NiO/GQDsNH2 electrode holds ≈834 mAh g-1 of capacity, while the bald NiO exhibits an obvious decline in capacity with ≈396 mAh g-1 retained after cycling. Except for the yolk-shell and mesoporous merits, the superior performances of the NiO/GQD electrode are mainly ascribed to the assistance of GQDs. The GQD modification can support as a buffer alleviating the volume change, improve the electronic conductivity, and act as a reservoir for electrolytes to facilitate the transportation of Li+ . Moreover, the enrichment of carboxyl/amino groups on GQDs can further donate more active sites for the diffusion of Li+ and facilitate the electrochemical redox kinetics of the electrode, thus together leading to the superior lithium storage performance.

Boosting lithium storage in covalent organic framework via activation of 14-electron redox chemistry.

Conjugated polymeric molecules have been heralded as promising electrode materials for the next-generation energy-storage technologies owing to their chemical flexibility at the molecular level, environmental benefit, and cost advantage. However, before any practical implementation takes place, the low capacity, poor structural stability, and sluggish ion/electron diffusion kinetics remain the obstacles that have to be overcome. Here, we report the synthesis of a few-layered two-dimensional covalent organic framework trapped by carbon nanotubes as the anode of lithium-ion batteries. Remarkably, upon activation, this organic electrode delivers a large reversible capacity of 1536 mAh g-1 and can sustain 500 cycles at 100 mA g-1. Aided by theoretical calculations and electrochemical probing of the electrochemical behavior at different stages of cycling, the storage mechanism is revealed to be governed by 14-electron redox chemistry for a covalent organic framework monomer with one lithium ion per C=N group and six lithium ions per benzene ring. This work may pave the way to the development of high-capacity electrodes for organic rechargeable batteries.