Mechanism of high Li-ion conductivity in poly(vinylene carbonate)-poly(ethylene oxide)cross-linked network based electrolyte revealed by solid-state NMR

Solid polymer electrolytes(SPEs)have become increasingly important in advanced lithium-ion batteries(LIBs)due to their improved safety and mechanical properties compared to organic liquid electrolytes.Cross-linked polymers have the potential to further improve the mechanical property without trading off Li-ion conductivity.In this study,focusing on a recently developed cross-linked SPE,i.e.,the one based on poly(vinylene carbonate)-poly(ethylene oxide)cross-linked network(PVCN),we used solid-state nuclear magnetic resonance(NMR)techniques to investigate the fundamental interaction between the chain segments and Li ions,as well as the lithium-ion motion.By utilizing homonuclear/heteronuclear correlation,CP(cross-polarization)kinetics,and spin-lattice relaxation experiments,etc.,we revealed the structural characteristics and their relations to lithium-ion mobilities.It is found that the network formation prevents poly(ethylene oxide)chains from crystallization,which could create sufficient space for segmental tumbling and Li-ion co nductio n.As such,the mechanical property is greatly improved with even higher Li-ion mobilities compared to the poly(vinylene carbonate)or poly(ethylene oxide)based SPE analogues.

An Endotenon Sheath-Inspired Double-Network Binder Enables Superior Cycling Performance of Silicon Electrodes

Silicon(Si)has been regarded as an alternative anode material to traditional graphite owing to its higher theoretical capacity(4200 vs.372 m Ah g;).However,Si anodes suffer from the inherent volume expansion and unstable solid electrolyte interphase,thus experiencing fast capacity decay,which hinders their commercial application.To address this,herein,an endotenon sheathinspired water-soluble double-network binder(DNB)is presented for resolving the bottleneck of Si anodes.The as-developed binder shows excellent adhesion,high mechanical properties,and a considerable self-healing capability mainly benefited by its supramolecular hybrid network.Apart from these advantages,this binder also induces a Li;N/Li F-rich solid electrolyte interface layer,contributing to a superior cycle stability of Si electrodes.As expected,the DNB can achieve mechanically more stable Si electrodes than traditional polyacrylic acid and pectin binders.As a result,DNB delivers superior electrochemical performance ofSi/Li half cells and Li Ni;Co;Mn;O;/Si full cells,even with a high loading of Si electrode,to traditional polyacrylic acid and pectin binders.The bioinspired binder design provides a promising route to achieve long-life Si anode-assembled lithium batteries.

Polymer electrolytes for Li-S batteries:Polymeric fundamentals and performance optimization

Lithium-sulfur(Li-S) batteries have been considered as one of the most promising candidates to traditional lithium ion batteries due to its low cost,high theoretical specific capacity(1675 mAh g^(-1)) and energy density(2600 Wh kg^(-1)) of sulfur.Compared with traditional liquid electrolytes,polymer electrolytes(PEs) are ever-increasingly preferred due to their higher safety,superior compatibility,long cycling stability and so on.Despite some progresses on PEs,however,there remain lots of hurdles to be addressed prior to commercial applications.This review begins with native advantages for PEs to replace LEs,and then proposes the ideal requirements for PEs.Furthermore,a brief development history of typical PEs for Li-S batteries is presented to systematically summarize the recent achievements in Li-S batteries with PEs.Noted that the structure-performance relationships of polymer matrixes for PEs are highlighted.Finally,the challenges and opportunities on the future development of PEs are presented.We hold the view that composite polymer electrolytes in virtue of the high ionic conductivity and the compatible interfacial property will be promising solution for high performance Li-S batteries.

Correction to:An endotenon sheath‑inspired double‑network binder enables superior cycling performance of silicon electrodes

The original version of this article unfortunately contained some mistakes.1.The authors found that the data unit in Fig.3a–f is wrong.The corrected version of Fig.3 is given below:2.The authors found that explanation of the data lines in Fig.2e is wrong.The corrected version of the explanation of Fig.2e is given below:The DNB can endure approximately 300%stretching and withstand stress up to about 1.5 MPa,as shown in Fig.2e.

Flame-retardant quasi-solid polymer electrolyte enabling sodium metal batteries with highly safe characteristic and superior cycling stability

Con ventio nal liquid electrolytes based sodium metal batteries suffer from severe safety hazards owing to electrolyte leakage,in flammability and dendritic sodium deposit!on.Herein,we report a flame-retardant quasi-solid polymer electrolyte with poly(methyl vinyl ether-alt-maleic an hydride)(P(MVE-alt-MA))as host,bacterial cellulose(BC)as reinforceme nt,and triethyl phosphate/vinyle ne carb on ate/sodium perchlorate(TEP/VC/NaClO4)as plasticizer for highly safe sodium metal batteries.The as-obtained quasi-solid polymer electrolyte exhibits superior flame retardancy(self-extinguish within 1 s),complete non-leakage property and wide electrochemical windows(4.4 V).More importantly,Na3V2(PO4)3/Na metal batteries using such polymer electrolyte delivers superior I on g-term cycli ng stability(84.4%capacity rete ntion after 1000 cycles)which is significantly better than that(only 2%after 240 cycles)of liquid electrolyte.In addition,this flame-retardant quasi-solid polymer electrolyte provides favorable cycle performance(80.2%capacity retention after 70 cycles at 50°C and 84.8%capacity retention after 50 cycles at-10°C)for Na3V2(PO4)3/Na metal batteries.And this battery also displayed a normal charge/discharge property even at-15°C.These fascinating cycle properties are mainly ascribed to the effective pro怕ctive layers formed on Na3V2(PC>4)3 cathode and sodium metal ano de.More thorough in vestigati on elucidates that such flame-retardant quasi-solid polymer electrolyte plays a multif unctional role in the adva need sodium metal batteries:(1)being in volved in the formatio n of a favorable cathode electrolyte in terface(CEI)to inhibit the dissolutio n of van adium and maintai n the structure integrity of the Na3V2(PO4)3;(2)participati ng in building a stable solid electrolyte in terface(SEI)to suppress the growth of Na dendrites;(3)integrating flame-retardanee into polymer sodium batteries to enhance flame-resistanee,eliminate electrolyte leakage,and thus improve safety of sodium batteries.Based on these results,we further assembled Na3V2(PO4)3/MoS2 pouch cell which can withsta nd harsh conditions(be nded or cut off a corn er),confirming the obtai ned polymer electrolyte with superior non-leakage property.In all,these outstanding characteristics would endow this flame-retardant quasi-solid polymer electrolyte a very promising can didate for highly-safe sodium metal batteries.

How Do Polymer Binders Assist Transition Metal Oxide Cathodes to Address the Challenge of High‑Voltage Lithium Battery Applications?

Research on the chemistry of high-energy-density transition metal oxide cathodes(TMOCs)is at the forefront in the pursuit of lithium-ion batteries with increased energy density.As a critical component of these cathodes,binders not only glue cathode active material particles and conducting carbons together and to current collectors but also play pivotal roles in building multiscale compatible interphases between electrolytes and cathodes.In this review,we outline several vital design considerations of high-voltage binders,several of which are already present in traditional binder design that need to be highlighted,and systematically reveal the chemistry and mechanisms underpinning such binders for in-depth understanding.Further optimization of the design of polymer binders to improve battery performance is also discussed.Finally,perspec-tives regarding the future rational design and promising research opportunities of state-of-the-art binders for high-voltage TMOCs are presented.

(C_(16)H_(28)N)_(2)SbCl_(5):一种具有亮橙色发射的新型无铅零维金属卤化物杂化物

零维金属卤化物因其迷人的光电特性而处于蓬勃发展的状态.本文报道了一种(C_(16)H_(28)N)_(2)SbCl_(5)(C_(16)H_(28)N+=苄基三丙基铵阳离子)的锑基金属卤化物,其中孤立的[SbCl_(5)]2−团簇被C_(16)H_(28)N+包围,形成零维方形金字塔结构.(C_(16)H_(28)N)_(2)SbCl_(5)在低能辐照(400 nm)时在633 nm处呈现宽带橙色发射,具有97.8%的近单位光致发光量子效率.有趣的是,(C_(16)H_(28)N)_(2)SbCl_(5)在高能辐照(300 nm)时在477 nm处显示出一个额外的发射峰,这是由自旋-轨道耦合的二重态转变为两个独立的自束缚激子形成的.变温拉曼光谱显示了多声子耦合的特征,这证明(C_(16)H_(28)N)_(2)-SbCl_(5)中存在强烈的非谐性电子-声子相互作用.变温发射光谱和密度泛函理论计算表明,所观察到的双峰发射源于[SbCl_(5)]2−单元中的单重态和三重态自束缚激子.结合(C_(16)H_(28)N)_(2)SbCl_(5)的高效发光和优异的稳定性,我们还制备了超高显色指数为96.6的稳定白光发光二极管.

An in-situ generated composite solid-state electrolyte towards high-voltage lithium metal batteries

The solid-state electrolyte(SSE) has promising applications in next-generation lithium(Li) metal batteries(LMBs) because of its significantly enhanced safety and more compatible interface characteristics than flammable traditional liquid electrolytes.However,only a few attempts have achieved high-performance high-voltage LMBs,which is attributed to the fact that both high ionic conductivity and good compatibility with electrodes can hardly be achieved simultaneously.Herein,a composite solid-state electrolyte(CSE) based on star-shaped siloxane-based polymer electrolyte coupled with Li_(6.75)La_(3)Zr_(1.75)Ta_(0.25)O_(12)(LLZTO)ceramic fillers is designed and prepared through a facile in-situ polymerization method.The obtained CSE exhibits high ionic conductivity(i.e.,1.68 × 10^(-4) S cm^(-1) at a temperature of 60 ℃),superior anodic stability,and high Li-ion transference number(i.e.,0.53) because of the multifunctional synergistic effect of the polymer electrolyte with LLZTO ceramic fillers.Moreover,the as-developed CSE shows excellent compatibility with Li anodes.As a result,the as-developed CSE enables the development of long-life 4.4-V-class solid-state LMBs with a Li CoO_(2) cathode,with 79.7% capacity retention and 99.74% average Coulombic efficiency after 500 cycles at a 0.5 C rate.Postmortem analysis of cycled batteries confirms that such superior battery performance can be mainly ascribed to the formation of a compatible electrode/electrolyte interface.Furthermore,excellent safety features can be observed in LiCoO_(2)/Li pouch batteries.This work provides an important guide for the rational design of SSEs for high-voltage LMBs.

基于文献分析的《劳动合同法》立法思路争论的研究

《劳动合同法》对于保护劳动者的合法权益、构建和谐稳定的劳动关系发挥着重要的作用,然而自2008年颁布实施以来,关于《劳动合同法》本身的争论不断,经过2012年的修订,争论反而有增无减。通过研究发现,争论的焦点在于《劳动合同法》是否过度保护或过度倾斜于劳动者,损害了企业的利益。为了深入剖析《劳动合同法》的利弊以及导致争论的深层原因,本研究对近十年来公开发表的209篇相关文献进行分析,发现劳动者和用人单位面对同一部法律受到的影响并不对等,二者的利益未能很好地兼顾平衡。进一步研究发现其根本原因在于《劳动合同法》对劳动者提供倾斜性保护或单边保护的立法思路上。文章重点围绕《劳动合同法》的立法思路、劳动者与用人单位之间的权益不均衡等问题进行了深入的分析和讨论,最后针对性地就《劳动合同法》存在的问题提出了修法思路的建议。