Highest Room Temperature Conductivity Research Articles

Ion-Dipole Interaction Regulation Enables High-Performance Single-Ion Polymer Conductors for Solid-State Batteries.

Solid polymer electrolytes with large ionic conductivity, high ionic transference number, and good interfacial compatibility with electrodes are highly desired for solid-state batteries. However, unwanted polarizations and side reactions occurring in traditional dual-ion polymer conductors hinder their practical applications. Here, single-ion polymer conductors (SIPCs) with exceptional selectivity for Li-ion conduction (Li-ion transference number up to 0.93), high room-temperature ionic conductivity of about 10-4 S cm-1 , and a wide electrochemical stability window (>4.5V, vs Li/Li+ ) are prepared by precisely regulating the ion-dipole interactions between Li+ and carbonyl/cyano groups. The resulting SIPCs show an excellent electrochemical stability with Li metal during long-term cycling at room temperature and 60°C. LiFePO4 -based solid-state cells containing the SIPCs exhibit good rate and cycling performance in a wide temperature range from -20 to 90°C. By the same way of ion-dipole interaction regulation, sodium- and potassium-based SIPCs with both high ionic conductivity and high cationic transference numbers are also prepared. The findings in this work provide guidance for the development of high-performance SIPCs and other metal-ion systems beyond Li+ .

(Digital Presentation) All-Solid-State Lithium Batteries: From Materials and Interface Design to Practical Pouch Cell Engineering

All-solid-state lithium batteries (ASSLBs) have gained substantial attention because of their intrinsic safety and high energy density.1 However, the commercialization of ASSLBs has been stymied by insufficient ionic conductivity of solid-state electrolytes, significant interfacial challenges, as well as the large gap between fundamental research and practical engineering. Over the past several years, we have been dedicated to developing ASSLBs from solid electrolyte synthesis to interface design to engineering practical solid-state pouch cells. First, a wet-chemistry method with a low cost was proposed to produce solid-state electrolytes at the kilogram level with a high room-temperature ionic conductivity (> 1 mS.cm-1).2 Second, the interfacial challenges of ASSLBs have been well addressed via increasing the ionic conductivity of interfacial buffer layers,3 manipulating interfacial nanostructures,4, 5 using single-crystal cathodes,6 deciphering interfacial reaction mechanisms,7 and constructing artificial solid electrolyte interphases (SEI),8 which successfully boosted interfacial ion and electron transport kinetics.9 Resultantly, ASSLBs demonstrated superior electrochemical performance. Third, practical solid-state pouch cells with high energy density have been engineered. Recently, a solvent-free process was proposed to fabricate freestanding and ultrathin inorganic solid electrolyte membranes.10 Furthermore, a feasible solid-liquid transformable interface was devised to improve the solid-solid ionic contact and accommodate the significant volume change of solid-state pouch cells.11, 12 The resultant solid-state pouch cells successfully demonstrated high energy density and unparalleled safety. In summary, our research not only provides an in-depth understanding of solid electrolyte synthesis and rational interface design but also offers feasible strategies to commercialize ASSLBs with high energy density, low cost, and excellent safety. References C. Wang, J. Liang, Y. Zhao, M. Zheng, X. Li and X. Sun, Energy Environ. Sci., 2021, 14, 2577-2619.C. Wang, J. Liang, J. Luo, J. Liu, X. Li, F. Zhao, R. Li, H. Huang, S. Zhao, L. Zhang, J. Wang and X. Sun, Sci. Adv., 2021, 7, eabh1896.C. Wang, J. Liang, S. Hwang, X. Li, Y. Zhao, K. Adair, C. Zhao, X. Li, S. Deng, X. Lin, X. Yang, R. Li, H. Huang, L. Zhang, S. Lu, D. Su and X. Sun, Nano Energy, 2020, 72, 104686.C. Wang, X. Li, Y. Zhao, M. N. Banis, J. Liang, X. Li, Y. Sun, K. R. Adair, Q. Sun, Y. Liu, F. Zhao, S. Deng, X. Lin, R. Li, Y. Hu, T.-K. Sham, H. Huang, L. Zhang, R. Yang, S. Lu and X. Sun, Small Methods, 2019, 3, 1900261.C. Wang, J. Liang, M. Jiang, X. Li, S. Mukherjee, K. Adair, M. Zheng, Y. Zhao, F. Zhao, S. Zhang, R. Li, H. Huang, S. Zhao, L. Zhang, S. Lu, C. V. Singh and X. Sun, Nano Energy, 2020, 76, 105015.C. Wang, R. Yu, S. Hwang, J. Liang, X. Li, C. Zhao, Y. Sun, J. Wang, N. Holmes, R. Li, H. Huang, S. Zhao, L. Zhang, S. Lu, D. Su and X. Sun, Energy Storage Mater., 2020, 30, 98-103.C. Wang, S. Hwang, M. Jiang, J. Liang, Y. Sun, K. Adair, M. Zheng, S. Mukherjee, X. Li, R. Li, H. Huang, S. Zhao, L. Zhang, S. Lu, J. Wang, C. V. Singh, D. Su and X. Sun, Adv. Energy Mater., 2021, 11, 2100210.C. Wang, Y. Zhao, Q. Sun, X. Li, Y. Liu, J. Liang, X. Li, X. Lin, R. Li, K. R. Adair, L. Zhang, R. Yang, S. Lu and X. Sun, Nano Energy, 2018, 53, 168-174.C. Wang, K. Adair and X. Sun, Acc. Mater. Res., 2022, 3, 21-32.C. Wang, R. Yu, H. Duan, Q. Lu, Q. Li, K. R. Adair, D. Bao, Y. Liu, R. Yang, J. Wang, S. Zhao, H. Huang and X. Sun, ACS Energy Lett., 2022, DOI: 10.1021/acsenergylett.1c02261, 410-416.C. Wang, Q. Sun, Y. Liu, Y. Zhao, X. Li, X. Lin, M. N. Banis, M. Li, W. Li, K. R. Adair, D. Wang, J. Liang, R. Li, L. Zhang, R. Yang, S. Lu and X. Sun, Nano Energy, 2018, 48, 35-43.C. Wang, K. R. Adair, J. Liang, X. Li, Y. Sun, X. Li, J. Wang, Q. Sun, F. Zhao, X. Lin, R. Li, H. Huang, L. Zhang, R. Yang, S. Lu and X. Sun, Adv. Funct. Mater., 2019, 29, 1900392.

A Polymerized‐Ionic‐Liquid‐Based Polymer Electrolyte with High Oxidative Stability for 4 and 5 V Class Solid‐State Lithium Metal Batteries (Adv. Energy Mater. 27/2022)

Polymer Electrolytes In article number 2200412, Chengyin Fu and co-workers develop a nonflammable polymer solid electrolyte, based on a low-cost polymerized ionic liquid, with a high room-temperature ionic conductivity of 0.8 mS cm−1 and a high oxidative stability > 5.0 V vs Li+/Li. The electrolyte enables high-performance solid-state lithium metal batteries with a high-energy uncoated LiNi0.8Mn0.1Co0.1O2 cathode and a high-voltage LiMn1.5Ni0.5O4 cathode at room temperature.

Room temperature deposition of freestanding BaTiO3 films: temperature-induced irreversible structural and chemical relaxation

The room temperature aerosol deposition method is especially promising for the rapid deposition of ceramic thick films, making it interesting for functional components in energy, mobility, and telecommunications applications. Despite this, a number of challenges remain, such as an enhanced electrical conductivity and internal residual stresses in as-deposited films. In this work, a novel technique that integrates a sacrificial water-soluble buffer layer was used to fabricate freestanding ceramic thick films, which allows for direct observation of the film without influence of the substrate or prior thermal treatment. Here, the temperature-dependent chemical and structural relaxation phenomena in freestanding BaTiO3 films were directly investigated by characterizing the thermal expansion properties and temperature-dependent crystal structure as a function of oxygen partial pressure, where a clear nonlinear, hysteretic contraction was observed during heating, which is understood to be influenced by lattice defects. As such, aliovalent doping and atmosphere-dependent annealing experiments were used to demonstrate the influence of local chemical redistribution and oxygen vacancies on the thermal expansion, leading to insight into the origin of the high room temperature conductivity of as-deposited films as well as greater insight into the influence of the induced chemical, structural, and microstructural changes in room temperature deposited functional ceramic thick films.Graphical abstract

Characterization of the structure and chemistry of the solid-electrolyte interface by cryo-EM leads to high-performance solid-state Li-metal batteries.

Solid-state lithium-metal (Li0) batteries are gaining traction for electric vehicle applications because they replace flammable liquid electrolytes with a safer, solid-form electrolyte that also offers higher energy density and better resistance against Li dendrite formation. Solid polymer electrolytes (SPEs) are highly promising candidates because of their tuneable mechanical properties and easy manufacturability; however, their electrochemical instability against lithium-metal (Li0), mediocre conductivity and poorly understood Li0/SPE interphases have prevented extensive application in real batteries. In particular, the origin of the low Coulombic efficiency (CE) associated with SPEs remains elusive, as the debate continues as to whether it originates from unfavoured interfacial reactions or lithium dendritic growth and dead lithium formation. In this work, we use state-of-the-art cryo-EM imaging and spectroscopic techniques to characterize the structure and chemistry of the interface between Li0 and a polyacrylate-based SPE. Contradicting the conventional knowledge, we find that no protective interphase forms, owing to the sustained reactions between deposited Li dendrites and polyacrylic backbones and succinonitrile plasticizer. Due to the reaction-induced volume change, large amounts of cracks form inside the Li dendrites with a stress-corrosion-cracking behaviour, indicating that Li0 cannot be passivated in this SPE system. On the basis of this observation, we then introduce additive engineering, leveraging from knowledge of liquid electrolytes, and demonstrate that the Li0 surface can be effectively protected against corrosion using fluoroethylene carbonate, leading to densely packed Li0 domes with conformal and stable solid-electrolyte interphase films. Owing to the high room-temperature ionic conductivity of 1.01 mS cm-1, the high transference number of 0.57 and the stabilized lithium-electrolyte interface, this improved SPE delivers an excellent lithium plating/stripping CE of 99% and 1,800 hours of stable cycling in Li||Li symmetric cells (0.2 mA cm-2, 1 mAh cm-2). This improved cathodic stability, along with the high anodic stability, enables a record high cycle life of >2,000 cycles for Li||LiFePO4 and >400 cycles for Li||LiCoO2 full cells.

Significantly Enhanced Thermoelectric Performance Achieved in CuGaTe2 through Dual-Element Permutations at Cation Sites.

CuGaTe2 has become a widely studied mid-temperature thermoelectric material due to the advantages of large element abundance, proper band gap, and intrinsically high Seebeck coefficient. However, the intrinsically high lattice thermal conductivity and low room-temperature electrical conductivity result in a merely moderate thermoelectric performance for pristine CuGaTe2. In this work, we found that Cu deficiency can significantly reduce the activation energy Ea of Cu vacancies from ∼0.17 eV for pristine CuGaTe2 to nearly zero for Cu0.97GaTe2, thus leading to dramatic improvements in hole concentration and power factor. More remarkably, element permutations (Ag/Cu and In/Ga) at both cation sites can effectively reduce the lattice thermal conductivity at the entire testing temperatures by producing intensive atomic-scale mass and strain fluctuations. Eventually, an ultrahigh peak ZTmax value of ∼1.5 at 873 K is achieved in the composition of Cu0.72Ag0.25Ga0.6In0.4Te2, while a large average ZTavg value of ∼0.7 (323-873 K) is obtained in the Cu0.67Ag0.3Ga0.6In0.4Te2 sample, both of which are significant improvements over pristine CuGaTe2.

Screen-Printable Hexagonal Boron Nitride Ionogel Electrolytes for Mechanically Deformable Solid-State Lithium-Ion Batteries.

Ionogel electrolytes present several benefits for solid-state lithium-ion batteries including nonflammability, favorable electrochemical properties, and high thermal stability. However, limited processing methods are currently available for ionogel electrolytes, restricting their practical applications. Here, we present a screen-printable ionogel electrolyte formulation based on hexagonal boron nitride (hBN) nanoplatelets. To achieve screen-printable rheological properties, hBN nanoplatelets are mixed with an imidazolium ionic liquid in ethyl lactate. Following screen printing, the resulting spatially uniform and mechanically flexible hBN ionogel electrolytes achieve high room-temperature ionic conductivities >1 mS cm-1 and stiff mechanical moduli >1 MPa. These hBN ionogel electrolytes enable the fabrication of fully screen-printed lithium-ion batteries with high cycling stability, rate performance, and mechanical resilience against flexion and external forces, thus providing a robust energy storage solution that is compatible with scalable additive manufacturing.

Thermal initiation/ultraviolet cross-linking process in polyethylene oxide@Li6·75La3Zr1·75Ta0·25O12-based composite electrolyte with high room-temperature ionic conductivity and long life cycle

Organic-inorganic composite electrolytes (PL-SCEs) based on polyethylene oxide (PEO) and Li6·75La3Zr1·75Ta0·25O12 (LLZTO) are considered to be one of the most promising solid electrolytes. However, the low room-temperature ionic conductivity caused by the inherent high crystallinity of PEO severely hinders its practical application. Herein, a novel PL-SCE is synthesized through a facile thermal induction and ultraviolet crosslinking process, using fluoroethylene carbonate (FEC) and 4-methylbenzophenone as thermal/ultraviolet triggers, and tetraethylene glycol dimethyl ether (TEGDME) as an ion conductive plasticizer. The F atom in the FEC can attack the C–O bond in the PEO chain and abstract the hydrogen attached to the C atom to form an active site, prompt TEGDME and PEO to achieve a higher degree of cross-linking, thus endowing PL-SCE with high Li-ion conductivity of 5.35 × 10−4 S cm−1 at 25 °C. Besides, the obtained PL-SCE exhibits excellent wettability and compatibility with Li metal anodes, the interfacial impedance is only 44 Ω cm2. The LiFePO4||Li full cell based on the proposed PL-SCE exhibits an excellent room-temperature cycling performance with a capacity retention rate up to 88% and the average Coulombic efficiency above 98% upon 450 cycles at 1 C. Prospectively, this work provides a promising alternative method for the practical application of PL-SCEs.

Argyrodite-type advanced lithium conductors and transport mechanisms beyond paddle-wheel effect

Development of next-generation solid-state Li-ion batteries requires not only electrolytes with high room-temperature (RT) ionic conductivities but also a fundamental understanding of the ionic transport in solids. In spite of considerable work, only a few lithium conductors are known with the highest RT ionic conductivities ~ 0.01 S/cm and the lowest activation energies ~0.2 eV. New design strategy and novel ionic conduction mechanism are needed to expand the pool of high-performance lithium conductors as well as achieve even higher RT ionic conductivities. Here, we theoretically show that lithium conductors with RT ionic conductivity over 0.1 S/cm and low activation energies ~ 0.1 eV can be achieved by incorporating cluster-dynamics into an argyrodite structure. The extraordinary superionic metrics are supported by conduction mechanism characterized as a relay between local and long-range ionic diffusions, as well as correlational dynamics beyond the paddle-wheel effect.

Li3PO4 electrolyte of high conductivity for all-solid-state lithium battery prepared by plasma spray

Li3PO4 (LPO) deposits were prepared for the electrolytes of all-solid-state lithium batteries (ASS-LBs) by atmospheric plasma-spraying (APS) with sintered powders of three different sizes. The effect of LPO particle size on the microstructure, chemical composition, lattice structure, and ion conductivity of LPO deposits was systematically investigated. Results showed that instead of the conventional lamellar-structured splats with limited inter-splat bonding, columnar-structured grains with chemical inter-splat bonding were formed in APS LPO due to its low melting point. The porosity of the deposits decreases with the decrease in feedstock particle size and deposits with porosity less than 1% can be deposited by using powders smaller than 50 µm. The XRD presented that all deposits have the same phase compositions as that of the sintered powders. Due to more intensively vaporization of P than Li from the molten droplets during APS, the Li/P atomic ratio in the deposits was higher than the stoichiometric ratio of 3 and ranges from 3.02 to 3.17. Owning to the high-quality inter- splat bonding and the slightly deviated Li/P atomic ratio, a high room-temperature ionic conductivity of 4.65 × 10−8 S.cm−1 was achieved for APS LPO deposit by using the LPO particles with sizes of less than 30 µm.

Improvement of ionic conductivity and densification of Na3Zr2Si2PO12 solid electrolyte rapidly prepared by microwave sintering

Na3Zr2Si2PO12 (labeled as NZSP) material is one of the most promising solid-state electrolytes for solid Na+ batteries. In this paper, the NZSP electrolytes were prepared by the microwave-assisted solid-phase reaction method, and the effects of different sintering temperatures (1050 °C–1150 °C) on phase composition, microstructure, densification, and ionic conductivity of NZSP samples were probed. XRD results demonstrated the NZSP phase could be formed by using microwave sintering at 1050 °C for 2 h. With the increase of sintering temperature, the density and the room-temperature ionic conductivity of the NZSP samples were gradually improved. After microwave sintering at 1125 °C, the NZSP electrolyte with the room-temperature ionic conductivity of 5.26 × 10−4 S/cm was achieved. Besides, the influences of sintering aid NaF with different contents (y wt%) on the densification and ionic conductivity of NZSP were also studied. It was found that the addition of NaF not only increased the density but also improved the ionic conductivity of NZSP samples. The NZSP ceramics with 0.2 wt% NaF additive sintered at 1125 °C showed a relatively high room-temperature ionic conductivity of 6.02 × 10−4 S/cm. Moreover, the activation energy was evaluated by the Arrhenius equation. The Arrhenius plot revealed the specimen with 0.2 wt% NaF exhibited the lowest activation energy of 0.29 eV.

Bio-inspired design of electrospun poly(acrylonitrile) and novel ionene based nanofibrous mats as highly flexible solid state polymer electrolyte for lithium batteries

All-solid-state polymer electrolytes (ASSPEs) have significant importance in the development of rechargeable lithium batteries with superior safety. Herein, a unique ionene oligomer is synthesized from 1,4-Diazabicyclo [2.2.2] octane (DABCO) and diethylene glycol bis(2-chloroethyl)ether having bis(trifluoromethanesulfonyl) imide (TFSI−) as the anion (PO3TFSI, where, ‘P’ indicates the oligomer and ‘O3′ denotes the 3 oxyethylene units). The ASSPE was fabricated by a straightforward viable procedure involving uniaxial electrospinning of poly(acrylonitrile) (PAN) blended with PO3TFSI and doped with lithium bis (trifluoromethanesulfonyl)imide salt (LiTFSI). The prepared electrospun (PAN/PO3TFSI/LiTFSI) ASSPE presented an intriguing morphology following heat-treatment like the venation found on a leaf blade where the network of veins is responsible for providing support to the entire lamina. The final structure consists of a PAN framework with the ionene oligomer flowing out of and around the fibers, closing the pores of the nanofibrous mat in the process. The ASSPE having such leaf blade inspired veined morphology with closed pores exhibits a high room-temperature ionic conductivity of 1.01 × 10−3 S cm−1, an electrochemical stability window of ∼ 4.6 V, and outstanding thermal stability. The solid-state Li/LiFePO4 (LFP) batteries assembled with the (PAN/PO3TFSI/LiTFSI) ASSPE showed good Coulombic efficiency above 98% when cycled at 0.2C for 100 cycles at both 25 °C and 60 °C. Furthermore, the ASSPE showed potential application in all-solid-state lithium sulfur battery. Additionally, a flexible Li/ASSPE/LFP custom made cell was demonstrated to work even in extremely deformed conditions, such as being folded, crimped and rolled, indicating the high flexibility of the fiber based solid electrolyte.

The role of salts selection on phase formation and electrical properties of K0.5Bi0.5TiO3 ceramics fabricated via molten salt synthesis

The present study reveals the effect of salts (NaCl and KCl) on the chemical composition, structural, and electrical properties of intended K0.5Bi0.5TiO3 (KBT) ceramics fabricated via the molten salt synthesis (MSS) route. The average grain size (∼6 μm (±1.1 μm)) and elemental distribution observed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) on KBT ceramics prepared using NaCl as the salt (named KBT-Na) signify the formation of Na0.5Bi0.5TiO3 (NBT) phase instead of KBT ceramic. The Rietveld refinement on X-ray diffraction (XRD) data and temperature-dependent dielectric behaviour of KBT-Na sample further validate the formation of NBT phase. The obtained results suggest the reaction of NaCl salt during the MSS of the KBT-Na sample. Moreover, the structural analyses of KBT ceramic synthesized using KCl salt (named KBT-K) suggested the presence of a minor Aurivillius phase (K0.5Bi4.5Ti4O15) which could be related to undesired reaction kinetics in MSS. The higher room temperature conductivity (∼10−6 Scm−1) and lower piezoelectric coefficient ((d33) ∼ 4–5 pC/N) indicate the loss of stoichiometry in both KBT-Na and KBT-K ceramics during the removal of salts. The observed results in KBT-Na & KBT-K were systematically compared with pure NBT & KBT ceramics prepared using the conventional solid-state synthesis route. The possible reasons for the lossy behavior of MSS synthesized samples are also discussed.

Effects of Salt Aggregation in Perfluoroether Electrolytes

Electrolytes comprised of polymers mixed with salts have great potential for enabling the use of Li metal anodes in batteries for increased safety. Ionic conductivity is one of the key performance metrics of these polymer electrolytes and achieving high room-temperature conductivity remains a challenge to date. For a bottom-up design of the polymer electrolytes, we must first understand how the structure of polyelectrolytes on a molecular level determines their properties. Here, we use classical molecular dynamics to study the solvation structure and ion diffusion in electrolytes composed of a short-chain perfluoroether with LiFSI or LiTFSI salts. Density functional theory is also used to provide some insights into the structures and energies of the salt interactions with the perfluoroether. We observe the formation of aggregates of salts in the fluorinated systems even at low salt concentrations. The fluorine-fluorine attraction in the solvent is the governing factor for creating the salt aggregates. The aggregates’ size and lifetime change with concentration and anion. These simulations provide an insight into the structure and dynamics of perfluoroether based electrolytes that can be used to improve Li-ion batteries.

A thin composite polymer electrolyte with high room-temperature conductivity enables mass production for solid-state lithium-metal batteries

Researchers pursue mass production of thin solid electrolytes with high room-temperature (RT) conductivity for solid state batteries with high energy and safety. A novel solid-state composite polymer electrolyte (CPE) with high room-temperature conductivity is obtained by UV-polymerization method and applied for solid-state Li-metal batteries. A commercial PE separator is used as a framework to straighten the CPE. The thickness of this CPE is only 16 µm, which is consist with the thickness of the PE film. It shows a high ionic conductivity of 1.11 × 10−4 S cm−1 at RT. Li//Li cell can stably cycle for more than 1000 h at 0.1 mA cm−2 current density at RT, and LiCoO2//Li solid-state batteries possess excellent rate performance and cycling stability with a capacity retention of 76.1% after 385 cycles from 145.3 mAh g−1 to 110.6 mAh g−1 with a 0.2 C rate at RT.

High entropy lithium garnets – Testing the compositional flexibility of the lithium garnet system

There is a pressing need for higher energy density, safer batteries for electric vehicles and grid energy storage. The current consensus is that these batteries need to be replaced with fully solid equivalents, however the discovery of a suitable solid state electrolyte has proven troublesome. Of the promising materials, lithium garnets are popular due to their wide electrochemical window, good ionic mobility (>0.1 ​mS ​cm-1) and compatibility with Li metal. However, numerous issues remain relating to interfacial resistance, time consuming and energy demanding synthesis and special handling requirements to ensure the best performing membranes. Of these challenges, little work has been done on the effect of entropy in the cubic lithium garnet systems, for example by addition of multiple elements on multiple sites. Such strategies have given interesting results in other areas (e.g. battery cathodes, metal alloys) and could well enable better performing membranes by increasing the, already high, disorder and take advantage of the numerous dopants reports which often singularly enable favourable properties (such as increased density, higher conductivity, lower interfacial resistance). Herein we test the compositional flexibility of the lithium garnet system with a 9 (Ga0.2Li5.75La2.5Nd0.5Nb0.65Ce0.1Zr1Ti0.25O12) and 11 (Ga0.2Li5.75La2.5Nd0.5Nb0.35Ta0.3Ce0.1Zr0.75Hf0.25Ti0.25O12) element system. Surprisingly, we did not find the limit of the garnet system, rather it was shown that (outside of the stoichiometric weighing) these systems were easy to synthesise, had high room temperature conductivity (0.2 ​mS ​cm-1), and high density even when processed in air.

A Nanoscale Design Approach for Enhancing the Li-Ion Conductivity of the Li10GeP2S12 Solid Electrolyte.

The discovery of the lithium superionic conductor Li10GeP2S12 (LGPS) has led to significant research activity on solid electrolytes for high-performance solid-state batteries. Despite LGPS exhibiting a remarkably high room-temperature Li-ion conductivity, comparable to that of the liquid electrolytes used in current Li-ion batteries, nanoscale effects in this material have not been fully explored. Here, we predict that nanosizing of LGPS can be used to further enhance its Li-ion conductivity. By utilizing state-of-the-art nanoscale modeling techniques, our results reveal significant nanosizing effects with the Li-ion conductivity of LGPS increasing with decreasing particle volume. These features are due to a fundamental change from a primarily one-dimensional Li-ion conduction mechanism to a three-dimensional mechanism and major changes in the local structure. For the smallest nanometric particle size, the Li-ion conductivity at room temperature is three times higher than that of the bulk system. These findings reveal that nanosizing LGPS and related solid electrolytes could be an effective design approach to enhance their Li-ion conductivity.

Diglyme-Incorporated Gelled Polymer: An Efficient Quasi-Solid-State Electrolyte for Sodium-Ion Batteries

Glyme-based electrolytes have been gaining increasing attention in sodium-ion batteries (NIBs) for their attractive electrochemistry involving good complexation ability with Na-ions, high electrochemical stability, good transport characteristics, low volatility, and high safety. Here, we report a flexible and freestanding sodium-ion conducting gel polymer electrolyte containing an equimolar ratio of Na-salt NaTFSI and diglyme (G2), referred to as a solvate ionic liquid (SIL), immobilized inside host polymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP). Fourier-transform infrared (FTIR) and Raman analyses are employed to investigate the conformational evolutions in PVdF-HFP on incorporating G2 and NaTFSI, whereas structural changes are observed using X-ray diffraction. The electrochemical investigations on the electrolyte revealing a wide electrochemical stability window (∼5.2 V) versus Na/Na+, high room-temperature ionic conductivity (∼1.12 × 10–3 S cm–1), and a large Na+ transference number (tNa+ ∼ 0.58) along with thermal stability up to ∼100 °C render the electrolyte suitable for Na-storage applications. The Na deposition/extraction tests over a long period indicate excellent cyclic stability of the cells, revealing low and stable polarization with values limited to ±19 mV at a current density of 0.01 mA cm–2. Further, the prepared solvate ionic liquid-incorporated gel polymer electrolyte (SIL-GPE) is tested in Na-ion battery cells comprising Na0.7CoO2 cathode using galvanostatic charge–discharge cycling, with a first discharge capacity of ∼91.76 mA h g–1 at a 0.05C rate. Studies indicate a class of gel polymer electrolytes based on solvate ionic liquids, suitable for Na-storage applications.

Origin of high electrochemical stability of multi-metal chloride solid electrolytes for high energy all-solid-state lithium-ion batteries

All-solid-state batteries (ASSBs) have gained substantial attention because of their intrinsic safety and potentially high energy density. To enable ASSBs, developing solid-state electrolytes (SSEs) with high electrochemical stability is of foremost significance. Here we report a multi-metal chloride SSEs with an excellent electrochemical stability (up to 4.5 V vs. Li+/Li), which originates from the strong Zr-Cl bonding. In addition, a high room-temperature ionic conductivity of 1.58 mS/cm was achieved via increasing the Li vacancies in the structure as well as balancing carrier and vacancy concentration. Coupled with nickel-rich cathodes (LiNi0.83Co0.12Mn0.05O2) and high-voltage LiCoO2 (4.5 V vs. Li+/Li), ASSBs demonstrated superb electrochemical performance. This work provides an in-depth structural understanding of multi-metal chloride SSEs and feasible strategies to realize high-energy-density ASSBs.

A Flexible, Fireproof, Composite Polymer Electrolyte Reinforced by Electrospun Polyimide for Room-Temperature Solid-State Batteries.

Solid-state batteries (SSBs) have attracted considerable attention for high-energy-density and high-safety energy storage devices. Many efforts have focused on the thin solid-state-electrolyte (SSE) films with high room-temperature ionic conductivity, flexibility, and mechanical strength. Here, we report a composite polymer electrolyte (CPE) reinforced by electrospun PI nanofiber film, combining with succinonitrile-based solid composite electrolyte. In situ photo-polymerization method is used for the preparation of the CPE. This CPE, with a thickness around 32.5 μm, shows a high ionic conductivity of 2.64 × 10−4 S cm−1 at room temperature. It is also fireproof and mechanically strong, showing great promise for an SSB device with high energy density and high safety.