Single‐Ion Conducting Electrolyte Based on Electrospun Nanofibers for High‐Performance Lithium Batteries

Herein, a novel electrospun single‐ion conducting polymer electrolyte (SIPE) composed of nanoscale mixed poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) and lithium poly(4,4′‐diaminodiphenylsulfone, bis(4‐carbonyl benzene sulfonyl)imide) (LiPSI) is reported, which simultaneously overcomes the drawbacks of the polyolefin‐based separator (low porosity and poor electrolyte wettability and thermal dimensional stability) and the LiPF₆ salt (poor thermal stability and moisture sensitivity). The electrospun nanofiber membrane (es‐PVPSI) has high porosity and appropriate mechanical strength. The fully aromatic polyamide backbone enables high thermal dimensional stability of es‐PVPSI membrane even at 300 °C, while the high polarity and high porosity ensures fast electrolyte wetting. Impregnation of the membrane with the ethylene carbonate (EC)/dimethyl carbonate (DMC) (v:v = 1:1) solvent mixture yields a SIPE offering wide electrochemical stability, good ionic conductivity, and high lithium‐ion transference number. Based on the above‐mentioned merits, Li/LiFePO₄ cells using such a SIPE exhibit excellent rate capacity and outstanding electrochemical stability for 1000 cycles at least, indicating that such an electrolyte can replace the conventional liquid electrolyte–polyolefin combination in lithium ion batteries (LIBs). In addition, the long‐term stripping–plating cycling test coupled with scanning electron microscope (SEM) images of lithium foil clearly confirms that the es‐PVPSI membrane is capable of suppressing lithium dendrite growth, which is fundamental for its use in high‐energy Li metal batteries.     

Conductive and Catalytic Triple‐Phase Interfaces Enabling Uniform Nucleation in High‐Rate Lithium–Sulfur Batteries

Rechargeable lithium–sulfur batteries have attracted tremendous scientific attention owing to their superior energy density. However, the sulfur electrochemistry involves multielectron redox reactions and complicated phase transformations, while the final morphology of solid‐phase Li₂S precipitates largely dominate the battery's performance. Herein, a triple‐phase interface among electrolyte/CoSe₂/G is proposed to afford strong chemisorption, high electrical conductivity, and superb electrocatalysis of polysulfide redox reactions in a working lithium–sulfur battery. The triple‐phase interface effectively enhances the kinetic behaviors of soluble lithium polysulfides and regulates the uniform nucleation and controllable growth of solid Li₂S precipitates at large current density. Therefore, the cell with the CoSe₂/G functional separator delivers an ultrahigh rate cycle at 6.0 C with an initial capacity of 916 mAh g^?1 and a capacity retention of 459 mAh g^?1 after 500 cycles, and a stable operation of high sulfur loading electrode (2.69–4.35 mg cm^?2). This work opens up a new insight into the energy chemistry at interfaces to rationally regulate the electrochemical redox reactions, and also inspires the exploration of related energy storage and conversion systems based on multielectron redox reactions.     

Atomic Sn4+ Decorated into Vanadium Carbide MXene Interlayers for Superior Lithium Storage

Ion intercalation is an important way to improve the energy storage performance of 2D materials. The dynamic energy storage process in such layered intercalations is important but still a challenge mainly due to the lack of effective operando methods. Herein, a unique atomic Sn⁴⁺–decorated vanadium carbide (V₂C) MXene not only exhibiting highly enhanced lithium‐ion battery (LIB) performance, but also possessing outstanding rate and cyclic stability because of the expanded interlayer space and the formation of V? O? Sn bonding is demonstrated. In combination with ex situ tests, an operando X‐ray absorption fine structure measurement is developed to explore the dynamic mechanism of V₂C@Sn MXene electrodes in LIBs. The results clearly reveal the valence changes of vanadium (V), tin (Sn), and positive contribution of oxygen (O) atoms during the charging/discharging process, confirming their contribution for lithium storage capacity. The stability of intercalated MXene electrode is further in situ studied to prove the key role of V? O? Sn bonding.     

我国少数民族孕产妇孕期保健及其健康现状综述

孕产妇孕期保健及孕产妇健康对促进安全分娩和优生优育起着十分重要的作用,随着我国孕产妇保健工作的进一步完善及国家二胎政策的实施,现代临床医学所倡导的优生优育的观念已逐渐被社会广泛认可。然而,我国少数民族地区多有经济落后、地理位置偏僻、思想观念陈旧等问题,导致我国少数民族孕产妇孕期保健水平还比较低下,孕产妇健康状况有待改善。为预防少数民族地区出生缺陷,降低出生缺陷率,提高优生率,提高少数民族地区出生人口素质,通过完善医疗制度,改善医疗环境,合理营养干预及加强家庭访视等相关健康教育促进孕期保健,提高孕前检查的依从性,实现优生,孕产期健康教育可以降低整个孕期出现的危险因素,本文对我国少数民族的孕产妇孕期保健及健康做一综述。     

Solvent‐Mediated Li2S Electrodeposition: A Critical Manipulator in Lithium–Sulfur Batteries

Controlling electrochemical deposition of lithium sulfide (Li₂S) is a major challenge in lithium–sulfur batteries as premature Li₂S passivation leads to low sulfur utilization and low rate capability. In this work, the solvent's roles in controlling solid Li₂S deposition are revealed, and quantitative solvent‐mediated Li₂S growth models as guides to solvent selection are developed. It is shown that Li₂S electrodeposition is controlled by electrode kinetics, Li₂S solubility, and the diffusion of polysulfide/Li₂S, which is dictated by solvent's donicity, polarity, and viscosity, respectively. These solvent‐controlled properties are essential factors pertaining to the sulfur utilization, energy efficiency and reversibility of lithium–sulfur batteries. It is further demonstrated that the solvent selection criteria developed in this study are effective in guiding the search for new and more effective electrolytes, providing effective screening and design criteria for computational and experimental electrolyte development for lithium–sulfur batteries.     

Correlation between Li Plating Behavior and Surface Characteristics of Carbon Matrix toward Stable Li Metal Anodes

Carbonaceous materials are widely employed to host Li for stable and safe Li metal batteries while relatively little effort is devoted to tailoring the surface properties of carbon to facilitate uniform Li plating. Herein, the correlation between Li plating behavior and the surface characteristics of electrospun porous carbon nanofibers (PCNFs) is systemically elucidated through experiments and theoretical calculations. It is revealed that the neat carbon surface suffers from severe lattice mismatch with Li metal, hindering uniform Li plating. In contrast, open pores created on the PCNF surface serve as active sites for controlled initial nucleation of Li. The introduction of oxygenated functional groups further facilitates the nucleation of Li on PCNFs through the largely reduced nucleation energy barrier. The Li film uniformly deposited on PCNFs enables efficient use of the whole carbon surface, giving rise to enhanced cyclic stability of the electrode. When used as an anode in lithium–sulfur batteries, the modified electrode delivers an excellent energy density of 385 Wh kg^?1 after 100 cycles. The fundamental correlation established in this study is universal to all types of carbonaceous materials and sheds new light on the rational design of high‐performance Li metal anodes by controlling the initial Li nucleation.     

Rational Design of Hierarchical “Ceramic‐in‐Polymer” and “Polymer‐in‐Ceramic” Electrolytes for Dendrite‐Free Solid‐State Batteries

Solid polymer electrolytes as one of the promising solid‐state electrolytes have received extensive attention due to their excellent flexibility. However, the issues of lithium (Li) dendrite growth still hinder their practical applications in solid‐state batteries (SSBs). Herein, composite electrolytes from “ceramic‐in‐polymer” (CIP) to “polymer‐in‐ceramic” (PIC) with different sizes of garnet particles are investigated for their effectiveness in dendrite suppression. While the CIP electrolyte with 20 vol% 200 nm Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) particles (CIP‐200 nm) exhibits the highest ionic conductivity of 1.6 × 10^?4 S cm^?1 at 30 °C and excellent flexibility, the PIC electrolyte with 80 vol% 5 µm LLZTO (PIC‐5 µm) shows the highest tensile strength of 12.7 MPa. A sandwich‐type composite electrolyte (SCE) with hierarchical garnet particles (a PIC‐5 µm interlayer sandwiched between two CIP‐200 nm thin layers) is constructed to simultaneously achieve dendrite suppression and excellent interfacial contact with Li metal. The SCE enables highly stable Li plating/stripping cycling for over 400 h at 0.2 mA cm^?2 at 30 °C. The LiFePO₄/SCE/Li cells also demonstrate excellent cycle performance at room temperature. Fabricating sandwich‐type composite electrolytes with hierarchical filler designs can be an effective strategy to achieve dendrite‐free SSBs with high performance and high safety at room temperature.