Functionally Modified Polymer Electrolyte Based on Noncovalent Interaction for Stable Lithium Metal Batteries.

The charge transfer efficiency of the solid electrolyte depends on the number of lithium ions that can be effectively transported and participate in the electrode reaction. However, limited by the strong coupling relationship between Li+ and Lewis basic sites on the polymer chain, the Li+ transference number (tLi+) of the solid polymer electrolyte (SPE) based dual-ion conductor is typically low, resulting in excessive anion aggregation at the electrode side and inducing concentration polarization. In this study, we present a functionalized modified polymer electrolyte (FMPE) with selective cation transport, which was synthesized by embedding 4-(trifluoromethyl)styrene (TFS) functionalized groups onto the poly(diethylene glycol diacrylate) polymer chain. The TFS group formed noncovalent couplings with TFSI- anions through hydrogen bondings and dipole-dipole interactions, which effectively limited the migration of the anions and contributed to the elevated tLi+ of the FMPEs to 0.595 and 0.699 at 25 and 60 °C, respectively. Density functional theory (DFT) calculations were performed to verify the increased anion migration barriers for different noncovalent interactions and revealed that the conjugated system formed by the delocalized π electrons of the benzene ring and the C═O groups helped to disperse the electron distribution of the polymer chains. Consequently, the decrease in the degree of Li+ immobilization promotes the decoupling and migration of Li+ between the polymer chains. Benefiting from optimized Li+ transport behavior, the lithium metal batteries (LMBs) assembled by FMPEs and LiFePO4 exhibit excellent rate performance (discharge specific capacity of 88.8 mAh g-1 at 5 C) and stable long-term cycle performance (capacity decay rate of only 0.064% per cycle for 500 cycles at 25 °C and 0.5 C).

Electrochemically Dealloying Engineering toward Integrated Monolithic Electrodes with Superior Electrochemical Li-Storage Properties.

Integrated monolithic electrodes (IMEs) free of inactive components demonstrate great potential in boosting energy-power densities and cycling life of lithium-ion batteries. However, their practical applications are significantly limited by low active substance loading (< 4.0 mg cm-2 and 1.0 g cm-3), complicated manufacturing process, and high fabrication cost. Herein, employing industrial Cu-Mn alloy foil as a precursor, a simple neutral salt solution-mediated electrochemical dealloying strategy is proposed to address such problems. The resultant Cu-Mn IMEs achieve not only a significantly larger active material loading due to the in situ generated Cu2O and MnOx (ca. 16.0 mg cm-2 and 1.78 g cm-3), simultaneously fast transport of ions and electrons due to the well-formed nanoporous structure and built-in Cu current collector, but also high structural stability due to the interconnected ligaments and suitable free space to relieve the volume expansion upon lithiation. As a result, they demonstrate remarkable performances including large specific capacities (> 5.7 mAh cm-2), remarkable pseudocapacitive effect despite the battery-type constitutes, long cycling life, and good working condition in a lithium-ion full cell. This study sheds new light on the further development of IMEs, enriches the existing dealloying techniques, and builds a bridge between the two.

In Situ Polymerized Quasi-Solid Electrolytes Compounded with Ionic Liquid Empowering Long-Life Cycling of 4.45 V Lithium-Metal Battery.

High-voltage resistant quasi-solid-state polymer electrolytes (QSPEs) are promising for enhancing the energy density of lithium-metal batteries in practice. However, side reactions occurring at the interfaces between the anodes or cathodes and QSPEs considerably reduce the lifespan of high-voltage LMBs. In this study, a copolymer of vinyl ethylene carbonate (VEC) and poly(ethylene glycol) diacrylate (PEGDA) was used as the framework, with a cellulose membrane (CE) as the supporting layer. Based on density functional theory calculations, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI), an ionic liquid, was screened because of its lowest unoccupied molecular orbital energy level as a modifying agent for the in situ P(VECx-EGy)/Pyrz/LiTFSI@CE QSPEs synthesis. Pyr14+, with a lithiophobic alkyl chain, forms a dense positive ion shielding layer on the protruding tips of deposited lithium, facilitating uniform and smooth lithium deposition. Pyr14TFSI assists in constructing a stable solid electrolyte interphase (SEI) layer on the Li surface enriched with LiF, Li3N, and RCOOLi. The modulation of lithium deposition behavior on the anode by Pyr14TFSI ensures stable Li plating/stripping for >1500 h. A Li-Cu cell exhibits stable cycling for >200 cycles at a current density of 0.05 mA cm-2, with an average Coulombic efficiency of 92.7%. In situ polymerization ensures that P(VECx-EGy)/Pyrz/LiTFSI@CE QSPEs exhibit excellent interface compatibility with the anode and the cathode. The CR2032 button cell Li|P(VEC1-EG0.06)/Pyr0.4/LiTFSI@CE|LiCoO2 demonstrates stable cycling with a negligible capacity decay of 0.083% per cycle for >390 cycles at 25 °C and 0.2 C when using a high-voltage LiCoO2 (4.45 V) cathode. Furthermore, a 7.1 mAh pouch cell achieves stable charge-discharge cycles, confirming the pronounced stability of the as-fabricated QSPE at the interfaces of the high-voltage LiCoO2 cathode and Li anode.

[Effect of Intolerance of Uncertainty on Fear of Childbirth in Primiparas : A Moderated Mediating Model].

Objective: To explore the mediating effect of childbirth self-efficacy on the impact pathway of intolerance of uncertainty on the fear of childbirth in primiparas in the second and third trimesters and the potential moderating effect of perceived partner responsiveness. Methods: A total of 429 primiparas in their second and third trimesters completed the survey, which included general information questionnaire, Intolerance of Uncertainty Scale, Childbirth Self-Efficacy Inventory, Perceived Partner Responsiveness Scale, and Childbirth Attitudes Questionnaire. Rank sum test was used to compare the scores for the fear of childbirth among different groups and Spearman's correlation was used to analyze the scores for all the scales. In addition, the data were centrally processed by using PROCESS V3.4.1 Model 4 (a simple mediation model), Model 5 (the direct path of the mediation model was regulated), and non-parametric Bootstrap method to test the mediation effect and moderation effect. Results: The study showed that 54.31% of the participants experienced fear of childbirth. Their scores for intolerance of uncertainty, childbirth self-efficacy, and perceived partner responsiveness were 15.00 (8.00), 240.00 (75.00), and 72.00 (19.00), respectively. There were significant differences in the scores for the fear of childbirth scale among pregnant women of different age groups, gestational weeks, employment statuses, and average per capita monthly income of the family ( P<0.05). According to our findings, intolerance of uncertainty directly and positively impacted on fear of childbirth ( ß=0.76, P<0.001), with childbirth self-efficacy playing partial mediation role between them, its indirect effect being 0.05 and the contribution rate being 6.17%. In addition, after the scores of Perceived Partner Responsiveness Scale were added to the model, perceived partner responsiveness had no significant predictive effect for fear of childbirth, but the product term of the scores for Perceived Partner Responsiveness Scale and Intolerability Uncertainty Scale had significant predictive effect for fear of childbirth ( ß=0.01, P<0.05), which suggested that perceived partner responsiveness also played a moderating role between intolerance of uncertainty and fear of childbirth. Conclusion: Health care providers can help primiparas reduce fear of childbirth and improve their childbirth experience by reducing perceived intolerance of uncertainty, improving family support, and teaching coping strategies.

Quasi-Solid Polymer Electrolyte with Multiple Lithium-Ion Transport Pathways by In Situ Thermal-Initiating Polymerization.

Solid polymer electrolytes (SPEs) are considered to be attractive candidates for rechargeable batteries on account of their high safety and flexible processability. However, the restricted polymer segmental dynamics limit the Li+ conduction of SPEs. Herein, a composite electrolyte membrane was prepared via in situ thermal-initiating polymerization of diethylene glycol diacrylate (DEGDA) in a poly(vinylidene fluoride) frameworks (PVDF FMs) electrospun in advance. As a quasi-solid polymer electrolyte (QSPE), it provides multiple transport highways for Li+ built by the C═O or C-O or C═O/C-O groups in poly(diethylene glycol) diacrylate (PDEGDA), respectively, proved by density functional theory calculations together with the high-resolution 7Li solid-state nuclear magnetic resonance spectra. Since the interaction between Li+ and C═O is weaker than that between Li+ and C-O, Li+ tends to move along C═O dominating paths in PDEGDA/PVDF FMs QSPEs, even skipping back to C═O nodes from the original C-O dominating way. Multiple transport patterns facilitate Li+ migration within PDEGDA/PVDF FMs QSPEs, contributing to the ionic conductivity of 1.41 × 10-4 S cm-1 at 25 °C and the Li+ transference number of 0.454. Ascribing to the wetting capability of the monomer to the electrodes in use, compatible electrolyte/electrode interfaces with low interface resistance and compact cells were acquired by the in situ polymerization. Protective lithiated oligomers (RCOOLi) and LiF are enriched at the Li anode surface, promoting a lasting stable Li plating/stripping over 2000 h. By applying the QSPEs in LiFePO4 cell, a capacity of 157.7 mAh g-1 with almost 100% coulombic efficiency during 200 cycles is achieved at 25 °C.

Engineering CoP Alloy Foil to a Well-Designed Integrated Electrode Toward High-Performance Electrochemical Energy Storage.

Nanostructured integrated electrodes with binder-free design show great potential to solve the ever-growing problems faced by currently commercial lithium-ion batteries such as insufficient power and energy densities. However, there are still many challenging problems limiting practical application of this emerging technology, in particular complex manufacturing process, high fabrication cost, and low loading mass of active material. Different from existing fabrication strategies, here using a CoP alloy foil as a precursor  a simple neutral salt solution-mediated electrochemical dealloying method to well address the above issues is demonstrated. The resultant freestanding mesoporous np-Co(OH)x /Co2 P product possesses not only active compositions of high specific capacity and large electrode packing density (>3.0 g cm-3 ) to meet practical capacity requirements, high-conductivity and well-developed nanoporous framework to achieve simultaneously fast ion and electron transfer, but also interconnected ligaments and suitable free space to ensure strong structural stability. Its comprehensively excellent electrochemical energy storage (EES) performances in both lithium/sodium-ion batteries and lithium-ion capacitors can further illustrate the effectiveness of the integrated electrode preparation strategy, such as remarkable reversible specific capacities/capacitances, dominated pseudo-capacitive EES mechanism, and ultra-long cycling life. This study provides new insights into preparation and design of high-performance integrated electrodes for practical applications.

Bridging Li7La3Zr2O12 Nanofibers with Poly(ethylene oxide) by Coordination Bonds to Enhance the Cycling Stability of All-Solid-State Lithium Metal Batteries.

A solid-state composite polymer electrolyte comprising Li7La3Zr2O12 nanofibers (LLZO NFs) as fillers has the advantages of flexibility, ease of processing, and being low cost, thus being considered to be a promising electrolyte material for use in the next generation of highly safe lithium metal batteries. However, poor compatibility of organic parts and inorganic materials leads to quick capacity decay after long-term charge/discharging running because of inorganic/organic interface deterioration and thus, the related ineffective lithium-ion (Li+) conduction. Herein, a "Boston ivy-style" method is proposed to prepare a solid ceramic/polymer hybrid electrolyte that exhibits a dense interface structure. After grafting on Dynasylan IMEO (DI), the modified LLZO NFs are used as ligands to bond with coordinatively unsaturated metal centers of Ca2+. Furthermore, these Ca2+ bridge the modified LLZO NFs with poly(ethylene oxide) (PEO) via the ether oxygen atoms they possess. The bridges built between the two phases, PEO and LLZO NFs, are effective to interface strengthening and guarantee rapid Li+ conduction even after 900 cycles. The PEO/LLZO NFs-DI-Ca2+/LiTFSI electrolyte shows a high Li+ transference number of 0.72 (60 °C). The Li||LiFePO4 cell delivers excellent cycling stability (capacity retention of 70.8% after 900 cycles, 0.5 C) and rate performance. The bridge strategy is proved to be effective and probably a promotion to the application of ceramic polymer-based solid-state electrolytes.

High-efficiency 2D nanosheet exfoliation by a solid suspension-improving method.

Two-dimensional (2D) materials with mono or few layers have wide application prospects, including electronic, optoelectronic, and interface functional coatings in addition to energy conversion and storage applications. However, the exfoliation of such materials is still challenging due to their low yield, high cost, and poor ecological safety in preparation. Herein, a safe and efficient solid suspension-improving method was proposed to exfoliate hexagonal boron nitride nanosheets (hBNNSs) in a large yield. The method entails adding a permeation barrier layer in the solvothermal kettle, thus prolonging the contact time between the solvent and hexagonal boron nitride (hBN) nanosheet and improving the stripping efficiency without the need for mechanical agitation. In addition, the proposed method selectively utilizes a matching solvent that can reduce the stripping energy of the material and employs a high-temperature steam shearing process. Compared with other methods, the exfoliating yield ofhBNNSs is up to 42.3% at 150 °C for 12 h, and the strategy is applicable to other 2D materials. In application, the ionic conductivity of a PEO/hBNNSs composite electrolytes reached 2.18 × 10-4S cm-1at 60 °C. Overall, a versatile and effective method for stripping 2D materials in addition to a new safe energy management strategy were provided.

Lithium intercalation into bilayer graphene.

The real capacity of graphene and the lithium-storage process in graphite are two currently perplexing problems in the field of lithium ion batteries. Here we demonstrate a three-dimensional bilayer graphene foam with few defects and a predominant Bernal stacking configuration, and systematically investigate its lithium-storage capacity, process, kinetics, and resistances. We clarify that lithium atoms can be stored only in the graphene interlayer and propose the first ever planar lithium-intercalation model for graphenic carbons. Corroborated by theoretical calculations, various physiochemical characterizations of the staged lithium bilayer graphene products further reveal the regular lithium-intercalation phenomena and thus fully illustrate this elementary lithium storage pattern of two-dimension. These findings not only make the commercial graphite the first electrode with clear lithium-storage process, but also guide the development of graphene materials in lithium ion batteries.

Enhanced Catalytic Efficiency of Pt Nanoparticles Supported on 3D Ordered Macro-/Mesoporous Ce0.6 Zr0.3 Y0.1 O2 for Methane Combustion.

Highly dispersed Pt nanoparticles supported on high-surface-area 3D ordered macroporous (3DOM) Ce0.6 Zr0.3 Y0.1 O2 (CZY) are synthesized via a bubbling cetyltrimethyl ammonium bromide/P123-assisted reduction route. The 1.1 wt% Pt/3DOM CZY catalyst shows supercatalytic activity for methane combustion, which is attributed to a higher oxygen adspecies amount, larger surface area, better low-temperature reducibility, and unique nanovoid-walled 3DOM structure.

Manganese oxides with rod-, wire-, tube-, and flower-like morphologies: highly effective catalysts for the removal of toluene.

Nanosized rod-like, wire-like, and tubular α-MnO(2) and flower-like spherical Mn(2)O(3) have been prepared via the hydrothermal method and the CCl(4) solution method, respectively. The physicochemical properties of the materials were characterized using numerous analytical techniques. The catalytic activities of the catalysts were evaluated for toluene oxidation. It is shown that α-MnO(2) nanorods, nanowires, and nanotubes with a surface area of 45-83 m(2)/g were tetragonal in crystal structure, whereas flower-like spherical Mn(2)O(3) with a surface area of 162 m(2)/g was of cubic crystal structure. There were the presence of surface Mn ions in multiple oxidation states (e.g., Mn(3+), Mn(4+), or even Mn(2+)) and the formation of surface oxygen vacancies. The oxygen adspecies concentration and low-temperature reducibility decreased in the order of rod-like α-MnO(2) > tube-like α-MnO(2) > flower-like Mn(2)O(3) > wire-like α-MnO(2), in good agreement with the sequence of the catalytic performance of these samples. The best-performing rod-like α-MnO(2) catalyst could effectively catalyze the total oxidation of toluene at lower temperatures (T(50%) = 210 °C and T(90%) = 225 °C at space velocity = 20,000 mL/(g h)). It is concluded that the excellent catalytic performance of α-MnO(2) nanorods might be associated with the high oxygen adspecies concentration and good low-temperature reducibility. We are sure that such one-dimensional well-defined morphological manganese oxides are promising materials for the catalytic elimination of air pollutants.