Lithium-ion transport in inorganic solid state electrolyte

An overview of ion transport in lithium-ion inorganic solid state electrolytes is presented, aimed at exploring and de signing better electrolyte materials. Ionic conductivity is one of the most important indices of the performance of inorganic solid state electrolytes. The general definition of solid state electrolytes is presented in terms of their role in a working cell （to convey ions while isolate electrons）, and the history of solid electrolyte development is briefly summarized. Ways of using the available theoretical models and experimental methods to characterize lithium-ion transport in solid state elec- trolytes are systematically introduced. Then the various factors that affect ionic conductivity are itemized, including mainly structural disorder, composite materials and interface effects between a solid electrolyte and an electrode. Finally, strategies for future material systems, for synthesis and characterization methods, and for theory and calculation are proposed, aiming to help accelerate the design and development of new solid electrolytes.

Incombustible solid polymer electrolytes:A critical review and perspective

Since the advent of the solid-state batteries,employing solid polymer electrolytes(SPEs)to replace routine flammable liquid electrolytes is regarded to be one of the most promising solutions in pursing highenergy-density battery systems.SPEs with superior thermal stability,good processability,and high mechanical modulus obtain increasing attentions.However,SPE-based batteries are not impenetrable due to their decomposition and combustibility under extreme conditions.Researchers believe incorporating appropriate flame-retardant additives/solvents/fragments into SPEs can intrinsically reduce their flammability to solve the battery safety issues.In this review,the recent research progress of incombustible SPEs,with special emphasis on flame-retardant structural design,is summarized.Specifically,a brief introduction of flame-retardant mechanism,evaluation index for safety of SPEs,and a detailed overview of the latest advances on diverse-types SPEs in various battery systems are highlighted.The deep insight into thermal ru naway process,the free-standing incombustible GPEs,and the ratio nal design of pouch cell structures may be the main directions to motivate revolutionary next-generation for safety batteries.

Poly(carbonate)-based ionic plastic crystal fast ion-conductor for solid-state rechargeable lithium batteries

Liquid plasticizers with a relatively higher dielectric coefficient like ethylene carbonate(EC),propylene carbonate(PC),and ethyl methyl carbonate(EMC) are the most commonly used electrolyte materials in commercial rechargeable lithium batteries(LIBs) due to their outstanding dissociation ability to lithium salts.However,volatility and fluidity result in their inevitable demerits like leakage and potential safety problem of the final LIBs.Here we for the first time device a subtle method to prepare a novel thermal-stable and non-fluid poly(carbonate) solid-state electrolyte to merge EC with lithium carriers.To this aim,a series of carbonate substituted imidazole ionic plastic crystals(G-NTOC) with different polymerization degrees have been synthesized.The resulting G-NTOC shows an excellent solid-state temperature window(R.T.-115℃).More importantly,the maximum ionic conductivity and lithium transference number of the prepared G-NTOC reach 0.36 × 10^(-3) S cm^(-1) and 0.523 at 30℃,respectively.Galvanostatic cycling test results reveal that the developed G-NTOC solid-state electrolytes are favorable to restraining the growth of lithium dendrite due to the excellent compatibility between the electrode and the produced plastic crystal electrolyte.The fabricated LiIG-NTOCILiFeP04 all-solid-state cell initially delivers a maximum discharge capacity of 152.1 mAh g^(-1) at the discharge rate of 0.1 C.After chargingdischarging the cell for 60 times,Coulombic efficiency of the solid-state cell still exceeds 97%.Notably,the LiIG-NTOCILiFeP04 cell can stably light a commercial LED with a rated power of 0.06 W for more than1 h at 30℃,and the output power nearly maintains unchanged with the charging-discharging cycling test,implying a sizeable potential application in the next generation of solid-state LIBs.

A low cost composite quasi-solid electrolyte of LATP, TEGDME,and LiTFSI for rechargeable lithium batteries

The composite quasi solid state electrolytes（CQSE） is firstly synthesized with quasi solid state electrolytes（QSE） and lithium-ion-conducting material Li1.4Al0.4Ti1.6（PO4）3（LATP）, and the QSE consists of [LiG4][TFSI] with fumed silica nanoparticles. Compared with LATP, CQSE greatly improves the interface conductance of solid electrolytes. In addition,it has lower liquid volume relative to QSE. Although the liquid volume fraction of CQSE is droped to 60%, its conductivity can also reach 1.39 × 10^-4S/cm at 20℃. Linear sweep voltammetry（LSV） is conducted on each composite electrolyte.The results show the possibility that CQSE has superior electrochemical stability up to 5.0 V versus Li/Li^＋1. TG curves also show that composite electrolytes have higher thermal stability. In addition, the performance of Li/QSE/Li Mn2O4 and Li/CQSE/Li Mn2O4 batteries is evaluated and shows good electrochemical characteristics at 60℃.

Forming solid electrolyte interphase in situ in an ionic conducting Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3-polypropylene(PP) based separator for Li-ion batteries

A new concept of forming solid electrolyte interphases（SEI） in situ in an ionic conducting Li（1.5）Al（0.5）Ge（1.5）（PO4）3-polypropylene（LAGP-PP） based separator during charging and discharging is proposed and demonstrated. This unique structure shows a high ionic conductivity, low interface resistance with electrode, and can suppress the growth of lithium dendrite. The features of forming the SEI in situ are investigated by scanning electron microscopy（SEM） and x-ray photoelectron spectroscopy（XPS）. The results confirm that SEI films mainly consist of lithium fluoride and carbonates with various alkyl contents. The cell assembled by using the LAGP-coated separator demonstrates a good cycling performance even at high charging rates, and the lithium dendrites were not observed on the lithium metal electrode. Therefore, the SEI-LAGP-PP separator can be used as a promising flexible solid electrolyte for solid state lithium batteries.

A composite PEO electrolyte with amide-based polymer matrix for suppressing lithium dendrite growth in all-solid-state lithium battery

The lithium dendrite growth is still a serious challenge and impeding the realistic applications of all-solid-state lithium batteries.In view of the amide containing sediment layer can be stable on lithium/cathodes,a composite polymer electrolyte with amide-based matrix is in-situ built on porous electrodes.With the introduction of amide,the polymer electrolyte presents excellent ability to inhibit lithium dendrite growth and makes the Li/Li symmetric battery stably work for 500 h with a good ionic conductivity of 4.25×10^(-5)S/cm at 40℃.The solid electrolyte also shows a wide electrochemical stable window and good interface contact with the porous cathode.Utilizing this composite polymer electrolyte,the all-solid-state Li/LiFePO_(4) battery shows an initial discharge capacity of 146.5 mA h/g at 0.1 C under 40℃ and remains 81.4%in 100 cycles.The polymer electrolyte also can present better properties after modification.These results demonstrate that the presented PA-based composite polymer electrolyte could be served as a good electrolyte candidate for all-solid-state lithium-ion batteries.

Synthesis and characterization of Li_(1.3)Al_(0.3)Ti_(1.7)(PO_4)_3-coated LiMn_2O_4 by wet chemical route

Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 was prepared by wet chemical route. The phase,surface morphology,and electrochemical properties of the prepared powders were characterized by X-ray diffraction,scanning electron micrograph,and galvanostatic charge-discharge experiments. Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 has similar X-ray diffraction patterns as LiMn2O4. The corner and border of Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 particles are not as clear as the uncoated one. The two powders show similar values of l...

Organic fast ion-conductor with ordered Li-ion conductive nano-pathways and high ionic conductivity for electrochemical energy storage

Solid electrolyte(SE)is the most crucial factor to fabricate safe and high-performance all-solid-state lithium-ion batteries.However,the most commonly reported SE,including solid polymer electrolyte(SPE)and inorganic oxides and sulfides,suffer problems of low ionic conductivity at room temperature for SPE and large interfacial impedance with electrodes for inorganic electrolytes.Here we for the first time demonstrate a novel ionic plastic crystal lithium salt solid electrolyte(OLiSSE)fast ion-conductor dilithium(1,3-diethyl-4,5-dicarboxylate)imidazole bromide with ordered Li-ion conductive nanopathways and an exceptional ionic conductivity of 4.4×10^(−3)Scm^(−1)at 30℃.The prepared OLiSSE exhibits apparent characters of typical ionic plastic crystals in the temperature range of−20 to 70℃,and shows remarkable thermal stability and electrochemical stability below 150℃ and 4.7 V,respectively.No lithium dendrite or short circuit behavior is detected for the Li|OLiSSE|Li cell after the galvanostatic charge-discharge test for 500 h.The fabricated Li|OLiSSE|LiFePO_(4) all-solid-state cell without using any separator and liquid plasticizer directly delivers an initial discharge capacity of 151.4 mAh g^(−1) at the discharge rate of 0.1 C,and shows excellent charge-discharge cycle stability,implying large potential application in the next generation of safe and flexible all-solid-state lithium batteries.

STUDY ON ION-POLYMER INTERACTION AND MORPHOLOGIC STRUCTURE OF POLYURETHANE/SALT SYSTEMS

A poly(ethylene oxide) urethane and a model compound of hard segment(HD) were prepared in this study. Solid polymer electrolytes were got from the blends of polyurethane, HD and NaClO 4. The samples were characterized by mean of FT IR and AFM. Effects of salt concentration on ion polymer interaction and further on morphologic structure of the composites were investigated and some interesting results were obtained. The results show that HD and concentration of NaClO 4 have an important effect on ion polymer interaction and morphologic structure of the complex. It is also found that in AFM pictures of the samples there is a transition point and ion polymer interaction of the polyurethane/salt systems play an extremely important role on morphologic structure.

A review on system and materials for aqueous flexible metal-air batteries

The exploration of aqueous flexible metal-air batteries with high energy density and durability has attracted many research efforts with the demand for portable and wearable electronic devices.Aqueous flexible metal-air batteries feature Earth-abundant materials,environmental friendliness,and operational safety.Each part of one metal-air battery can significantly affect the overall performance.This review starts with the fundamental working principles and the basic battery configurations and then highlights on the common issues and the recent advances in designing high-performance metal electrodes,solid-state electrolytes,and air electrodes.Bifunctional oxygen electrocatalysts with high activity and long-term stability for constructing efficient air electrodes in flexible metal-air batteries are summarized including metal-free carbon-based materials and nonprecious Co/Fe-based materials(alloys,metal oxides,metal sulfites,metal phosphates,metal nitrates,single-site metal-nitrogen-carbon materials,and composites).Finally,a perspective is provided on the existing challenges and possible future research directions in optimizing the performance and lifetime of the flexible aqueous solid-state metal-air batteries.

Advances in electrolyte safety and stability of ion batteries under extreme conditions

Electric vehicles have been promoted worldwide due to fast-charge technology of ion batteries.However,ion batteries’capacity and cycle life severely decay under extreme conditions,which is mostly related to electrolyte conductivity drop and side reactions.This review highlights the safety and stability of ion batteries in terms of thermal stability,non-flammability,low-temperature,and so on,outlining the disadvantages of organic liquid electrolyte,and summarizing effective solutions of polymer electrolytes,solid-state electrolytes,ionic liquid electrolytes,and aqueous electrolytes for the batteries.Moreover,the outlook on the electrolytes is put forward,which is available for research and development of the next generation batteries.

1,3-Dimethyl-2-imidazolidinone: an ideal electrolyte solvent for high-performance Li–O;battery with pretreated Li anode

Electrolytes are widely considered as a key component in Li–O;batteries (LOBs) because they greatly affect the discharge-charge reaction kinetics and reversibility.Herein,we report that 1,3-dimethyl-2-imidazolidinone (DMI) is an excellent electrolyte solvent for LOBs.Comparing with conventional ether and sulfone based electrolytes,it has higher Li_(2)O_(2)and Li_(2)CO_(3)solubility,which on the one hand depresses cathode passivation during discharge,and on the other hand promotes the liquid-phase redox shuttling during charge,and consequently lowers the overpotential and improves the cyclability of the battery.However,despite the many advantages at the cathode side,DMI is not stable with bare Li anode.Thus,we have developed a pretreatment method to grow a protective artificial solid-state electrolyte interface(SEI) to prevent the unfavorable side-reactions on Li.The SEI film was formed via the reaction between fluorine-rich organic reagents and Li metal.It is composed of highly Li^(+)-conducting Li_(x)BO_(y),LiF,Li_(x)NO_(y),Li_(3)N particles and some organic compounds,in which Li_(x)BO_(y)serves as a binder to enhance its mechanical strength.With the protective SEI,the coulombic efficiency of Li plating/stripping in DMI electrolyte increased from 20%to 98.5%and the fixed capacity cycle life of the assembled LOB was elongated to205 rounds,which was almost fivefold of the cycle life in dimethyl sulfoxide (DMSO) or tetraglyme(TEGDME) based electrolytes.Our work demonstrates that molecular polarity and ionic solvation structure are the primary issues to be considered when designing high performance Li–O;battery electrolytes,and cross-linked artificial SEI is effective in improving the anodic stability.

Enhancing ionic conductivity of garnet-type Nb-doped Li_(7)La_(3)Zr_(2)O_(12)by cerium doping

We investigated the effect of additional doping with Ce on the ionic conductivity of the Nb-doped Li_(7)La_(3)Zr_(2)O_(12)(LLZO)garnet ceramics using a combination of experimental and modeling approaches.Our results indicate that Ce doping can alter lattice parameters of the LLZNO,leading to the enhanced lithium ionic conductivity.The Ce,Nb co-doped LLZO(LLZNCO)structure with composition Li_(6.5)La_(3)Zr_(1.5-x)Nb_(0.5)Ce_(x)O_(12)(x=0.125)exhibits a lower activation energy(E_(a)=0.39 eV)than Li_(6.5)La_(3)Zr_(1.5)Nb_(0.5)O_(12)(LLZNO)(E_(a)=0.41 eV).Furthermore,Ce doping leads to an increase in Li~+conductivity from 6.4×10^(-4)to 7×10^(-4)S/cm at room temperature.In addition,we discuss the diffusivity and conductivity of our samples using ab initio molecular dynamics simulations and propose possible mechanisms to explain the enhanced Li-ion conductivity caused by co-doping with Ce and Nb.Our results demonstrate that the LLZNCO ceramics are promising candidates for potential solid-state electrolytes for Li-ion batteries.

Two-in-one tecton strategy to construct single crystalline hydrogen-bonded organic framework with high proton conductivity above 100℃

By tactically integrating two different kinds of proton donors and acceptors into one supramolecular tecton, a new crystalline hydrogen-bonded organic framework(HOF-SXU-1) has been developed. HOF-SXU-1 features a remarkable proton conductivity as high as 6.32 mS cm^(-1) and an extremely low activation energy of 0.16 eV at 160℃ under anhydrous N_(2) conditions.By contrast, under identical conditions, the organic precursors of HOF-SXU-1 only exhibit negligible proton conduction performance, demonstrating that the formation of HOF is crucial for excellent proton conduction performance.

Suppressing the liquid product crossover in electrochemical CO_(2)reduction

Coupling electrochemical CO_(2)reduction(CO_(2)R)with a renewable energy source to create high‐value fuels and chemicals is a promising strategy in moving toward a sustainable global energy economy.CO_(2)R liquid products,such as formate,acetate,ethanol,and propanol,offer high volumetric energy density and are more easily stored and transported than their gaseous coun-terparts.However,a significant amount(~30%)of liquid products from electrochemical CO_(2)R in a flow cell reactor cross the ion exchange membrane,leading to the substantial loss of system‐level Faradaic efficiency.This severe crossover of the liquid product has—until now—received limited attention.Here,we review promising methods to suppress liquid product crossover,including the use of bipolar membranes,solid‐state electrolytes,and cation‐exchange membranes‐based acidic CO_(2)R systems.We then outline the re-maining challenges and future prospects for the production of concentrated liquid products from CO_(2).