A new review of single-ion conducting polymer electrolytes in the light of ion transport mechanisms

With the depletion of fossil fuels and the demand for high-performance energy storage devices,solidstate lithium metal batteries have received widespread attention due to their high energy density and safety advantages.Among them,the earliest developed organic solid-state polymer electrolyte has a promising future due to its advantages such as good mechanical flexibility,but its poor ion transport performance dramatically limits its performance improvement.Therefore,single-ion conducting polymer electrolytes(SICPEs)with high lithium-ion transport number,capable of improving the concentration polarization and inhibiting the growth of lithium dendrites,have been proposed,which provide a new direction for the further development of high-performance organic polymer electrolytes.In view of this,lithium ions transport mechanisms and design principles in SICPEs are summarized and discussed in this paper.The modification principles currently used can be categorized into the following three types:enhancement of lithium salt anion-polymer interactions,weakening of lithium salt anion-cation interactions,and modulation of lithium ion-polymer interactions.In addition,the advances in single-ion conductors of conventional and novel polymer electrolytes are summarized,and several typical highperformance single-ion conductors are enumerated and analyzed in what way they improve ionic conductivity,lithium ions mobility,and the ability to inhibit lithium dendrites.Finally,the advantages and design methodology of SICPEs are summarized again and the future directions are outlined.

Stepwise optimization of single-ion conducting polymer electrolytes for high-performance lithium-metal batteries

Single-ion conducting polymer electrolytes(SIPEs)are promising candidates for high-energy and highsafety lithium-metal batteries(LMBs).However,their insufficient ionic conductivity and electrochemical stability hinder their practical application.Herein,three new SIPEs,i.e.,poly(1,4-phenylene ether ether sulfone)-Li(PEES-Li),polysulfone-Li(PSF-Li),and hexafluoropolysulfone-Li(6FPSF-Li),all containing covalently tethered perfluorinated ionic side chains,have been designed,synthesized,and compared to investigate the influence of the backbone chemistry and the concentration of the ionic group on their electrochemical properties and cell performance.Especially,the trifluoromethyl group in the backbone and the concentration of the ionic function appear to play an essential role for the charge transport and stability towards oxidation,and the combination of both yields the best-performing SIPE with high ionic conductivity of ca.2.5×10^(-4)S cm^(-1),anodic stability of more than 4.8 V,and the by far highest capacity retention in Li‖LiNi0.6Co0.2Mn0.2O2cells.

Electronegativity-Induced Single-Ion Conducting Polymer Electrolyte for Solid-State Lithium Batteries

The application of solid polymer electrolytes(SPEs)is severely impeded by the insufficient ionic conductivity and low Li^(+)transference numbers(t_(Li)^(+)).Here,we report an iodine-driven strategy to address both the two longstanding issues of SPEs simultaneously.Electronegative lodine-containing groups introduced on polymer chains effectively attract Li^(+)ions,facilitate Li^(+)transport,and promote the dissociation of Li salts.Meanwhile,iodine is also favorable to alleviate the strong O-Li^(+)coordination through a Lewis acidbase interaction,further improving the ionic conductivity and t_(Li)^(+).As a proof of concept,an iodinated single-ion conducting polymer electrolyte(IPE)demonstrates a high ionic conductivity of 0.93 mS cm^(-1)and a high t_(Li)^(+)of 0.86 at 25℃,which is among the best results ever reported for SPEs.Moreover,symmetric Li/Li cells with IPE achieve a long-term stability over 2600 h through the in-situ formed LiF-rich interphase.As a result,Li-S battery with IPE maintains a high capacity of 623.7 mAh g^(-1)over 300 cycles with an average Coulombic efficiency of 99%.When matched with intercalation cathode chemistries,Li/IPE/LiFePO_(4)and Li/IPE/LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)solid-state batteries also deliver high-capacity retentions of 95%and 97%at 0.2 C after 120 cycles,respectively.

Dyson–Maleev theory of an X X Z ferrimagnetic spin chain with single-ion anisotropy

We use the mean-field approximation of Dyson–Maleev representation to study an XXZ Heisenberg ferrimagnetic spin chain with single-ion anisotropy. By solving the self-consistent equations with different anisotropies, λ and D respectively,the energy spectrums, internal energy, static susceptibility and specific heat are calculated. Especially, the quantum phase transition of the magnetization plateau induced by single-ion anisotropy D is obtained in the model of the ferrimagnetic spin chain by using Dyson–Maleev mean-field theory.

SINGLE-ION CONDUCTIVITY IN POLY (LITHIUM PROPIONATE METHYL SILOXANE)

Poly(lithium propionate methyl siloxane )as a single-ion carrier source was synthesized. The crosslinked film showed lower lithium ionic conductivity at room temperature (about 10^(-10) S/cm). However,the lithium ionic conductivity was obviously increased by blending with high polar polymers such as polyethylene oxide, poly (methylsiloxane - co- ethylene oxide) and poly (methylsiloxane- g- ethylene oxide). In the blend system a high conductivity of 10^(-7)-10^(-5) Scm^(-1) at room temperature was obtained and the single-ion conductivity was deeply influenced by the content of the poly (lithium propionate methyl siioxane). The dc ionic conductivity of the flexible crosslinked films is more stable over time.

Design of the CAS-LIBB Single-Ion Microbeam Endstation Ⅱ

Cellular micro-irradiation is now recognized as a powerful technique to unveil the mechanisms of interaction between ionizing radiation and living cells or tissues. The single-ion microbeam （SIM） is uniquely capable of delivering precisely the predefined number of charged particles （precise doses of radiation） to specific individual cells or sub-cellular targets in situ. No active research in the field concerning the original process of the interaction between low-energy ions and complicated organisms has been reported yet. To address this challenge, the aim of the present design is to further wrestle with multi-dimensional quantitative information from living cells traversed by an exact number of ions real-time rather than endpoints, in the time scale from milliseconds to days.

Single-Ion Microbeam for Applications in Radiobiology:State of the Art

Single-Ion Microbeam (SIM) is uniquely capable of precisely delivering a predefined number of charged particles (precise doses of radiation) to individual cells or sub-cellular targets in situ. Since the early 1990's, there has been an ever-increasing interest in developing and applying the SIM technique to problems in radiobiology for studies of cell and tissue damaged by ionizing radiations. Potential applications for SIM in radiobiology continues to grow and have been diversified. There are currently more than 14 SIM facilities worldwide, and they have been in a constant state of evolution. This paper reviews the current state of SIM research worldwide and the related pivotal technological developments in the fields of both biophysics and radiobiology. Representative applications and the perspective of SIM are also introduced and discussed.

Highly sensitive Fe^(3+)luminescence detection via single-ion adsorption

To achieve a lower detection limit has always been a goal of analytical chemists.Herein,we demonstrate the first picomolar level detection capability for Fe3+ion via luminescence detection technology.The results of structural analysis and theoretical calculation show that Fe3+ions are adsorbed on the central node of Eu-DBM(DBM=dibenzoylmethane)sensor in the form of single ion at ultralow concentration.Subsequently,the pathways of photo-induced charge and energy transfer of the obtained Eu-DBM@Fe^(3+)material have been changed,from the initial DBM-to-Eu^(3+)before Fe^(3+)adsorption to the ultimate DBM-to-Fe^(3+)after adsorption process,which quenches the luminescence of Eu3+ion.This work not only obtains the highly sensitive luminescence detection ability,but also innovatively proposes the single-ion adsorption mechanism,both of which have important scientific and application values for the development of more efficient detection agents in the future.

Lithiated Nafion-garnet ceramic composite electrolyte membrane for solid-state lithium metal battery

Single-ion conducting solid polymer electrolytes are expected to play a vital role in the realization of solid-state Li metal batteries.In this work,a lithiated Nafion(Li-Nafion)-garnet ceramic Li6.25La3 Zr2 Al0.25O12(LLZAO)composite solid electrolyte(CSE)membrane with 30μm thickness was prepared for the first time.By employing X-ray photoelectron spectroscopy and transmission electron microscope,the interaction between LLZAO and Li-Nafion was investigated.It is found that the LLZAO interacts with the Li-Nafion to form a space charge layer at the interface between LLZAO and Li-Nafion.The space charge layer reduces the migration barrier of Li-ions and improves the ionic conductivity of the CSE membrane.The CSE membrane containing 10 wt%LLZAO exhibits the highest ionic conductivity of2.26×10-4 S cm-1 at 30℃among the pristine Li-Nafion membrane,the membrane containing 5 wt%,20 wt%,and 30 wt%LLZAO,respectively.It also exhibits a high Li-ion transference number of 0.92,and a broader electrochemical window of 0-+4.8 V vs.Li+/Li than that of 0-+4.0 V vs.Li+/Li for the pristine Li-Nafion membrane.It is observed that the CSE membrane not only inhibits the growth of Li dendrites but also keeps excellent electrochemical stability with the Li electrode.Benefitting from the above merits,the solid-state LiFePO4/Li cell fabricated with the CSE membrane was practically charged and discharged at 30℃.The cell exhibits an initial reversible discharge specific capacity of 160 mAh g-1 with 97%capacity retention after 100 cycles at 0.2 C,and maintains discharge specific capacity of 126 mAh g-1 after500 cycles at 1 C.The CSE membrane prepared with Li-Nafion and LLZAO is proved to be a promising solid electrolyte for advanced solid-state Li metal batteries.

CATIONIC CONDUCTIVITY FOR THE CROSSLINKED P [OLIGO (OXYETHYLENE) METHACRYLATE-COoMETHACRYLOYL ALKYLSULFONIC ACID LITHIUM]

Crosslinked copolymers with single Li^+-ionic conductivity were prepared from oligo (oxyethylene) methacrylate (MEO_n), methacryloyl alkylsulfonic acid lithium (SAMLi), and oligo (oxyethylene) dimethacrylate (DMEO_n). Li^+-ionic conductivity of the copolymer is improved by crosslinking and presented as a function of polymerization degree (n) in MEO_n, comonomeric salt concentration (O/Li), and crosslinking degree. The crosslinked copolymer P (0.7 MEO_(14)-0.3DMEO_(14)-SHMLi) without other small molecular additives exhibits an optimum Li^+-ionic conductivity of 1.2×10^(-6) S/cm at 25℃. Dc polarization test in the cell composed of Li/copolymer/Li shows a constant dc ionic conductivity which closes gradually to the ac one with decreasing dc polarization potential.

Novel single-ion conducting polymer electrolytes with high toughness and high resistance against lithium dendrites

Solid-state polymer electrolytes are considered as an alternative to classic liquid electrolytes,particularly for application in highenergy lithium metal batteries.With respect to common dual-ion conductors,single-ion conducting polymer electrolytes(SICPEs)are less affected by lithium dendrites growth and thus are particularly interesting for application in lithium metal batteries.In this work,novel SIC-PEs are developed,based on an ionomer having poly(ethylene-alt-maleimide)backbone and lithium phenylsulfonyl(trifluoromethanesulfonyl)imide pendant moieties,further blended with poly(ethylene oxide)(PEO)and poly(ethylene glycol)dimethyl ether(PEGDME).These SIC-PEs exhibit ionic conductivity around~7×10^(−6)S·cm^(−1) at 70℃,lithium transference number close to unity,and excellent mechanical properties,with fracture toughness over 30 J·cm^(−3).Additionally,the electrolytes show very high resistance against lithium dendrites growth,by cycling for more than 1200 h in Li°symmetric cells at a current density of 0.1 mA·cm^(−2).LiFePO4||Li°cells with these SIC-PEs were cycled at 70℃ and C/10,showing initial capacity of almost 160 mAh·g^(−1)and residual capacity of 45%after 100 cycles.This work shows that single-ion conducting polymer electrolytes based on poly(ethylene-alt-maleimide)backbone are promising materials for application as electrolytes or catholytes in lithium metal polymer batteries.

Observation of high ionic conductivity of polyelectrolyte microgels in salt-free solutions

Here, we report an observation that illustrate the potential of polyelectrolyte microgels in salt-free solutions to display a high ionic conductivity. Laser light scattering and ionic conductivity tests on very dilute aqueous dispersions of the microgels indicate that both small size and swollen state of gel particles play vital roles, which should favor the counterions to freely penetrate and leave gel particles, and thus can contribute to the ion-conducting property. Upon discovering this on microgels that are composed of imidazolium-based poly(ionic liquid), we also illustrate the generality of the finding to single lithium-ion polyelectrolyte microgels that are of more technically relevant features for applications, for instance, as injectable liquid “microgel-in-solution” electrolytes of high conductivity(ca. 8.2 × 10^(-2)S/m at 25.0 ℃ for1.0 × 10^(-2)g/m L of microgels in a LiNO_(3)-free 1:1 v/v mixture of 1,2-dioxolane and dimethoxymethane) and high lithium-ion transference number(0.87) for use in the rechargeable lithium-sulfur battery.

A hybrid lithium sulfonated polyoxadiazole derived single-ion conducting gel polymer electrolyte enabled effective suppression of dendritic lithium growth

Lithium metal is deemed as an ideal anode material in lithium-ion batteries because of its ultrahigh theoretical specific capacity and the lowest redox potential.However,the rapid capacity attenuation and inferior security resulting from the dendritic lithium growth severely limit its commercialization.Herein a novel hybrid gel polymer electrolyte (GPE) based on electrospun lithium sulfonated polyoxadiazole (LiSPOD) nanofibrous membrane swelled by lithium bis(trifluoromethanesulfonyl)imide (Li TFSI) ether liquid electrolyte is proposed to address the issue of lithium dendrites.The Li-SPOD membrane synthesized by a simple one-pot method exhibits excellent mechanical strength and thermal resistance due to its high molecular weight and rigid backbone.The electron-withdrawing oxadiazole ring and oxadiazole ring-Li;complex,and N,O heteroatoms with lone pairs of electrons in Li-SPOD macromolecular chains facilitate the dissociation of-SO_(3)Li group and Li^(+)transference.The hybrid Li-SPOD GPE exhibits both a high lithium-ion transference number (0.64) and high ionic conductivity (2.03 m S/cm) as well as superior interfacial compacity with lithium anodes.The Li Fe PO_(4)-Li cell using this novel GPE can operate steadily at 2C for 300 cycles,remaining a high discharge capacity of 125 m Ah/g and dendrite-free anode.Remarkable performance improvements for the Li-Li and Cu-Li cells are also presented.

Detection of DC electric forces with zeptonewton sensitivity by single-ion phonon laser

Detecting extremely small forces helps exploring new physics quantitatively.Here we demonstrate that the phonon laser made of a single trapped ^(40)Ca^(+) ion behaves as an exquisite sensor for small force measurement.We report our successful detection of small electric forces regarding the DC trapping potential with sensitivity of(2.41±0.49)zN/√Hz,with the ion only under Doppler cooling,based on the injection-locking of the oscillation phase of the phonon laser in addition to the classical squeezing applied to suppress the measurement uncertainty.We anticipate that such a single-ion sensor would reach a much better force detection sensitivity in the future once the trapping system is further improved and the fluorescence collection efficiency is further enhanced.

Magnetic molecular materials with paramagnetic lanthanide ions

The diverse magnetic properties of lanthanide-based magnetic molecular materials are introduced in the following organization.First,the general aspects of magnetic molecular materials and electronic states of lanthanide ions are introduced.Then the structures and magnetic properties are described and analyzed for molecules with one lanthanide ion,4f-4f,4f-3d and 4f-p magnetic coupling interactions.In each section,magnetic coupling,magnetic ordering and magnetic relaxation phenomenon are briefly reviewed using some examples.Finally,some possibilities of developing magnetic molecular materials containing lanthanide ions are discussed in the outlook part.

Simultaneous assembly of mononuclear and dinuclear dysprosium(Ⅲ) complexes behaving as single-molecule magnets in a one-pot hydrothermal synthesis

Two dysprosium(Ⅲ) complexes derived from 2,2'-bipyridine-6,6'-dicarboxylic acid(H_2bpdc),[Dy(bpdc)(Hbpdc)]-3H_2O(1) and[Dy_2(bpdc)_3(H_2O)_3]·2.125H_2O(2),were isolated from the same hydrothermal reaction container as different phases.Compound1 is a mononuclear complex with a DyN_4O_4 coordination polyhedron;whereas compound 2 is a dinuclear complex with two types of eight coordinated dy sprosium(Ⅲ) ions,showing DyN_4O_4 and DyN_2O_6 coordination polyhedra,respectively.Remarkably,a new type of(H_2O)_6 supramolecular aggregate exists in the crystal structure of 2.Magnetic investigations revealed that 1 is a field-induced single-ion magnet with an effective energy barrier of 45.6 K,exhibiting two-step magnetic relaxation;while an intramolecular ferromagnetic interaction exists in 2,which is a field-induced single-molecule magnet,displaying two-step magnetic relaxation too,with effective energy barriers of 53.4 and 92.1 K,respectively.

Polyacrylonitrile Nanofber‑Reinforced Flexible Single‑Ion Conducting Polymer Electrolyte for High‑Performance,Room‑Temperature All‑Solid‑State Li‑Metal Batteries

Single-ion conducting polymer electrolytes(SIPEs)can be formed by anchoring charge delocalized anions on the side chains of a crosslinked polymer matrix,thereby eliminating the severe concentration polarization efect in conventional dual-ion polymer electrolytes.Addition of a plasticizer into the polymer matrix confers advantages of both liquid and solid electrolytes.However,plasticized SIPEs usually face a trade-of between conductivity and mechanical strength.With insufcient strength,potentially there is short-circuiting failure during cycling.To address this challenge,a simple and mechanicallyrobust SIPE was developed by crosslinking monomer lithium(4-styrenesulfonyl)(trifuoromethylsulfonyl)imide(LiSTFSI)and crosslinker poly(ethylene glycol)diacrylate(PEGDA),with plasticizer propylene carbonate(PC),on electrospun polyacrylonitrile nanofbers(PAN-NFs).The well-fabricated polymer matrix provided fast and efective Li^(+) conductive pathways with a remarkable ionic conductivity of 8.09×10^(-4) S cm^(−1) and a superior lithium-ion transference number close to unity(t_(Li+)=0.92).The introduction of PAN-NFs not only improved the mechanical strength and fexibility but also endowed the plasticized SIPE with a wide electrochemical stability window(4.9 V vs.Li^(+)/Li)and better cycling stability.Superior longterm lithium cycling stability and dynamic interfacial compatibility were demonstrated by lithium symmetric cell testing.Most importantly,the assembled all-solid-state Li metal batteries showed stable cycling performance and remarkable rate capability both in low and high current densities.Therefore,this straightforward and mechanically reinforced SIPE exhibits great potential in the development of advanced all-solid-state Li-metal batteries.

CONDUCTIVITY AND DIELECTRIC BEHAVIOR OF PLiAMPS-BASED SEMI-IPN SINGLE ION CONDUCTOR PLASTICIZED WITH POLY(SILOXANE-G-ETHYLENE OXIDE)

Comb poly(siloxane-g-ethylene oxide)(PSi-PE)with high chain segmental mobility,as a plasticizer,was introduced into poly(lithium 2-acrylamido-2-methyl-1-propanesulfonate)(PLiAMPS)-based semi-interpenetrating polymer network single-ion conductors.The structures of PSi-PE and PLiAMPS were characterized by FTIR spectroscopy.The distribution of PSi-PE in polyelectrolyte matrix was investigated through observing the residual surface morphology of conductor membrane after being etched by toluene.AC impedance and dielectric behavior measurements were used to investigate the impact of PSi-PE on the ionic conductivity and to analyze the mechanism of conductivity variation.Compared with the unplasticized membranes,the ionic conductivity of the membrane with the addition of 35 wt.%PSi-PE was improved by 20 times.Meanwhile,the dielectric constant(ε)of the membrane was increased to 1330 and the relaxation time was decreased to 0.012 s.The changes of dielectric properties reflect directly the effect of PSi-PE on the dissociation ability of Liþand the chain segmental mobility,which well explains the reasons of ionic conductivity variation.

Helical Covalent Polymers with Unidirectional Ion Channels as Single Lithium-Ion Conducting Electrolytes

Single-ion conducting polymer electrolytes have attracted great attention as safe alternatives to liquid electrolytes in high energy density lithium-ion batteries.Herein,we report the first example of a crystalline anionic helical polymer as a single lithium-ion conducting solid polymer electrolyte(SPE).Single-crystal X-ray analysis shows that the polymer folds into densely packed double helices,with bundles of unidirectional negatively charged channels formed that can facilitate lithium-ion transportation.