Conductivity Of Solid Electrolytes Research Articles

Homogeneous Fluorine Doping toward Highly Conductive and Stable Li10GeP2S12 Solid Electrolyte for All-Solid-State Lithium Batteries.

The unique structure and exceptionally high lithium ion conductivity over 10mScm-1 of Li10GeP2S12 have gained extensive attention in all-solid-state lithium batteries. However, its poor resistivity to moisture and chemical/electrochemical incompatibility with lithium metal severely impede its practical application. Herein, a fluorine functionalized Li10GeP2S12 is synthesized by stannous fluoride doping and employed as a monolayer solid electrolyte to realize stable all-solid-state lithium batteries. The atomic-scale mechanism underlying the impact of fluorine doping on both moisture and electrochemical stability of Li10GeP2S12 is revealed by density functional theory calculations. Fluorine surface doping significantly reduces surface hydrophilicity by electronic regulation, thereby retarding the hydrolysis reaction of Li10GeP2S12. After exposed to a relative humidity of 35%-40% for 20min, the ionic conductivity of Li9.98Ge0.99Sn0.01P2S11.98F0.02 maintains as high as 2.21mScm-1, nearly one order of magnitude higher than that of Li10GeP2S12 with 0.31mScm-1. Meanwhile, bulk doping of highly electronegative fluorine promotes the formation of lithium vacancies in the Li10GeP2S12 system, thus allowing stable lithium plating/stripping in Li | Li symmetric batteries, boosting a critical current density reaching 2.1mAcm-2. The LiCoO2 | lithium all-solid-state batteries display improved cycling stability and rate capability, showing 80.1% retention after 600 cycles at 1C.

12‐Ah‐Level Li‐Ion Pouch Cells Enabling Fast Charging at Temperatures between −20 and 50 °C

AbstractAchieving fast‐charging capabilities in Li‐ion batteries (LIBs)—charging 80% of the battery capacity within 15 minutes—while maintaining an acceptable cycle life remains challenging due to various polarizations occurring at elevated charge rates. Such a goal is more tough at subzero, as temperature reduction slows the kinetics process including electrolyte mass transport and electrode charge transfer, substantially increasing the risk of lithium plating. Herein, it is found that adding LiFSI to a LiPF6 carbonate‐based electrolyte alters the Li+ solvation structure, endowing the dual‐salt electrolyte with a higher Li+ diffusion coefficient and lower desolvation energy. Benefit from the smaller structural change and the formation of a robust, conductive solid electrolyte interphase, the 12Ah‐pouch cells based on LiNi0.52Co0.2Mn0.28O2 cathodes and graphite anodes demonstrate fast‐charging capabilities and stable cycling performance across a wide temperature range of −20 to 50 ℃: charging 89% and 93% of pouch cell capacity within 4 minutes at 25 and 50 ℃ and 82% within 15 minutes at −20 ℃, maintaining capacity retention of 94% after 2000 cycles at 8C at 0 ℃ and 89% after 350 cycles at −20 ℃ at 4C. This work might offer new insights into enhancing the fast‐charging capabilities of LIBs under extreme conditions.

Highly Conductive and Stable Composite Polymer Electrolyte with Boron Nitride Nanotubes for All-Solid-State Lithium Metal Batteries.

All-solid-state lithium metal batteries (ASSLMBs) have emerged as the most promising next-generation energy storage devices. However, the unsatisfactory ionic conductivity of solid electrolytes at room temperature has impeded the advancement of solid-state batteries. In this work, a multifunctional composite solid electrolyte (CSE) is developed by incorporating boron nitride nanotubes (BNNTs) into polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). BNNTs, with a high aspect ratio, trigger the dissociation of Li salts, thus generating a greater population of mobile Li+, and establishing long-distance Li+ transport pathways. PVDF-HFP/BNNT exhibits a high ionic conductivity of 8.0×10-4S cm-1 at room temperature and a Li+ transference number of 0.60. Moreover, a Li//Li symmetric cell based on PVDF-HFP/BNNT demonstrates robust cyclic performance for 3400h at a current density of 0.2mA cm-2. The ASSLMB formed from the assembly of PVDF-HFP/BNNT with LiFePO4 and Li exhibits a capacity retention of 93.2% after 850 cycles at 0.5C and 25°C. The high-voltage all-solid-state LiCoO2/Li cell based on PVDF-HFP/BNNT also exhibits excellent cyclic performance, maintaining a capacity retention of 96.4% after 400 cycles at 1C and 25°C. Furthermore, the introduction of BNNTs is shown to enhance the thermal conductivity and flame retardancy of the CSE.

“Seaweed Structure” design for solid gel electrolyte with hydroxide ion conductivity enabling flexible zinc air batteries

The construction of solid-state electrolytes for flexible zinc-air batteries is extremely challenging. A flexible and highly conductive solid electrolyte designed with a “seaweed structure” is reported in this work. Sodium alginate serves as the backbone to form a robust network structure, and the grafted quaternary ammonium groups provide channels for rapid ion transport, achieving excellent flexibility and hydroxide conductivity. The conductivity of the modified electrolyte membrane (QASA) is 5.23 × 10−2 S cm−1 at room temperature and reaches up to 8.51 × 10−2 S cm−1 at 75 °C. In the QASA based battery, bending at any angle is realized, and the power density is up to 57.28 mW cm−2. This work provides a new way to prepare high conductivity, green solid-state zinc-air batteries, and opens up a research line of thought for flexible energy storage materials.

“Seaweed Structure” design for solid gel electrolyte with hydroxide ion conductivity enabling flexible zinc air batteries

The construction of solid-state electrolytes for flexible zinc-air batteries is extremely challenging. A flexible and highly conductive solid electrolyte designed with a “seaweed structure” is reported in this work. Sodium alginate serves as the backbone to form a robust network structure, and the grafted quaternary ammoniumgroups provide channels for rapid ion transport, achieving excellent flexibility and hydroxide conductivity. The conductivity of the modified electrolyte membrane (QASA) is 5.23 × 10−2 S cm−1 at room temperature and reaches up to 8.51 × 10−2 S cm−1 at 75 °C. In the QASA based battery, bending at any angle is realized, and the power density is up to 57.28 mW cm−2. This work provides a new way to prepare high conductivity, green solid-state zinc-air batteries, and opens up a research line of thought for flexible energy storage materials.

Topological Defect-Regulated Porous Carbon Anodes with Fast Interfacial and Bulk Kinetics for High-Rate and High-Energy-Density Potassium-Ion Batteries.

Carbonaceous materials are regarded as one of the most promising anodes for potassium-ion batteries (PIBs), but their rate capabilities are largely limited by the slow solid-state potassium diffusion kinetics inside anode and sluggish interfacial potassium ion transfer process. Herein, high-rate and high-capacity PIBs are demonstrated by facile topological defect-regulation of the microstructure of carbon anodes. The carbon lattice of the as-obtained porous carbon nanosheets (CNSs) with abundant topological defects (TDPCNSs) holds relatively highpotassium adsorption energy yet low potassium migration barrier, thereby enabling efficient storage and diffusion of potassium inside graphitic layers. Moreover, the topological defects can induce preferential decomposition of anions, leading to the formation of high potassium ion conductive solid electrolyte interphase (SEI) film with decreased potassium ion de-solvation and transfer barrier. Additionally, the dominant sp2-hybridized carbon conjugated skeleton of TDPCNSs enables high electrical conductivity (39.4 S cm-1) and relatively low potassium storage potential. As a result, the as-constructed TDPCNSs anode demonstrates high potassium storage capacity (504mA h g-1 at 0.1 A g-1), remarkable rate capability (118mA h g-1 at 40 A g-1), as well as long-term cycling stability.

Effects of Cr2O3 doping on crystallization behavior and electrochemical properties of Li2O–Al2O3–TiO2–P2O5–SiO2 glass-ceramics

Bulk glass-ceramic solid electrolytes of the Li2O–Al2O3–TiO2–P2O5–SiO2 system were prepared by melt-quenching and one-step heat treatment method in this work. The effects of the gradual substitution of Al3+ by Cr3+ and the elevation of the heat treatment temperature on the phase composition, microstructure, and ionic conductivity of the solid electrolytes were systematically investigated. The results show that the major crystalline phase is LiTi2(PO4)3, and the conductivity of the glass-ceramics initially enhances and then decreases as the Cr2O3 content increases from 0 mol% to 3 mol%. The highest conductivity is obtained when the Cr2O3 content is 2 mol%, measuring 4.45 × 10−4 S/cm at 25 °C. Additionally, the mechanism of the surface exfoliation of the glass-ceramics and the enhancement achieved by doping with Cr3+ are explained according to microstructure analysis. This work provides a simple method to enhance the electrical conductivity and physical properties of LATP glass-ceramic solid electrolytes, which is of great significance for the design of lithium-ion solid electrolytes.

Investigating advanced strategies for enhancing energy density in lithium-ion batteries

Lithium-ion batteries have become a versatile energy storage solution for various applications, such as portable electronics and electric vehicles, due to their numerous advantages. The increasing demand for higher energy density has prompted researchers to explore innovative strategies to improve the performance of these batteries. This study systematically investigates cutting-edge techniques aimed at enhancing the energy density of lithium-ion batteries. By conducting a detailed analysis of different battery components, this study evaluates the feasibility, efficiency, and potential impact of these approaches on future battery technologies. By giving some concrete examples, such as NMA(LiNi1-x-yMnxAlyO2), LFP(LiFePO4) batteries in cathode, popular silicon-based materials in anode, novel dual conductive binder and solid electrolyte (solid electrolyte interface), some of the working principles are described and the electrochemical properties of the batteries are comparatively analysed. This research aims to provide readers with a comprehensive understanding and research direction for advancing the energy density capabilities of lithium-ion batteries.

Calcium Doped NASICON Electrolyte with Graphite Coating for Stable All-solid-state Sodium Metal Batteries.

All-solid-state sodium metal batteries face the challenges of low ionic conductivity of solid electrolytes and poor wettability towards metallic Na anode. Herein, Na3Zr2Si2PO12 solid electrolyte is doped with Ca2+, obtaining a high ionic conductivity of 2.09×10-3 S cm-1 with low electronic conductivity of 1.43×10-8 S cm-1 at room temperature, which could accelerate Na+ transportation and suppress sodium dendrite growth. Meanwhile, a graphite-based interface layer is coated on Na3.4Zr1.8Ca0.2Si2PO12 (Na3.4Zr1.8Ca0.2Si2PO12-G) in order to improve the solid-solid contact between solid electrolyte and Na anode, realizing a uniform current distribution and smooth Na metal plating/stripping, and thus achieving a triple higher critical current density of 3.5 mA cm-2 compared with that of Na3.4Zr1.8Ca0.2Si2PO12. In addition, the assembled Na3V2(PO4)3/Na3.4Zr1.8Ca0.2Si2PO12-G/Na all-solid-state battery exhibits excellent electrochemical performances with a reversible capacity of 81.47 mAh g-1 at 1 C and capacity retention of 97.75 % after 500 cycles.

Machine Learning on Microstructure-Property Relationship of Lithium-Ion Conducting Oxide Solid Electrolytes.

Understanding the structure-property relationship of lithium-ion conducting solid oxide electrolytes is essential to accelerate their development and commercialization. However, the structural complexity of nonideal materials increases the difficulty of study. Here, we develop an algorithmic framework to understand the effect of microstructure on the properties by linking the microscopic morphology images to their ionic conductivities. We adopt garnet and perovskite polycrystalline oxides as examples and quantify the microscopic morphologies via extracting determined physical parameters from the images. It directly visualizes the effect of physical parameters on their corresponding ionic conductivities. As a result, we can determine the microstructural features of a Li-ion conductor with high ionic conductivity, which can guide the synthesis of highly conductive solid electrolytes. Our work provides a novel approach to understanding the microstructure-property relationship for solid-state ionic materials, showing the potential to extend to other structural/functional ceramics with various physical properties in other fields.

Improved ionic conductivity and Li7P3S11 solid electrolyte based all-solid state batteries for practical applications

Improved ionic conductivity and Li7P3S11 solid electrolyte based all-solid state batteries for practical applications

Quasi-solid electrolytes based on ZIF-8 to improve the electrochemical properties of lithium-ion batteries across a wide temperature range

Poor safety of liquid electrolytes and low ionic conductivity of solid electrolytes under room temperature are two major constraints for high energy density, long-term stability and safety of lithium-ion batteries (LIBs). In order to remedy the deficiencies, a quasi-solid electrolyte (QSE) is developed by immobilizing liquid electrolyte into the host of porous 2-Methylimidazole zinc salt (ZIF-8), and then mixing them with solid polymer electrolyte solvent of polyoxyethylene (PEO). The QSE has an ionic conductivity of 0.44 mS cm−1 at 20 °C and 2.27 mS cm−1 at 50 °C. The assembled LiFePO4/QSE/Li batteries exhibit excellent electrochemical performance in a wide temperature range. A reversible capacity of 129.7 mAh g−1 at 0.5 C and 20 °C and high capacity retentation of 94.7% at 0.5 C and 50 °C are achieved after 100 cycles. Especially, the LiFePO4/QSE/graphite pouch full cell exhibits a capacity retention of 97.7% at 0.5 C and 25 °C. These results indicate that QSE is a suitable candidate for enhancing the electrochemical performance of LIBs.

Li10GeP2S12-based solid electrolyte induced by high pressure for all-solid-state batteries: A facile strategy of low-grain-boundary-resistance

Solid electrolytes (SEs) with high ionic conductivity are crucial for the collaborative design of high-performance all-solid-state lithium batteries (ASSLBs). Besides the common element substitution and doping, it is anticipated that there is still room for pressure to improve ionic conductivity in SEs by modifying their crystal structure and microstructure. Herein, we applied in-situ high pressure to monitor the effect of compression on the structure–property relation in Li10GeP2S12 (LGPS). The lattice contraction (<2%) of LG was monitored within 2 GPa, which does not affect the optimal size of the ionic channel. In contrast to the fact that the grain resistance can be markedly decreased by low pressing, grain boundary resistance is found to be minimized by virtue of 1.5 GPa, and accordingly, interfacial Li± ionic diffusion between flexible grain bodies and electrode surface is primarily facilitated by enhancing the charge carrier mobility. In addition, we report for the first time that powder LGPS could be pressed as a ceramic-sulfide pellet without breakage under 1.5 GPa and assembled as a solid electrolyte within the LiFePO4/Li10GeP2S12/Li configuration of ASSLBs. This cell exhibits improved capacity and cycling stability compared to the cell using no-pressure-treated electrolyte. The present study advances our understanding of solid electrolytes and provides an important framework for developing high-performance ASSLBs with low fabrication costs in the future.

Robust Solid-State Na-CO2 Battery with Na2.7Zr2Si2PO11.7F0.3-PVDF-HFP Composite Solid Electrolyte and Na15Sn4/Na Anode.

Solid-state Na-CO2 batteries are a kind of energy storage devices that can immobilize and convert CO2. They have the advantages of both solid-state batteries and metal-air batteries. High-performance solid electrolyte and electrode materials are important for improving the performance of solid-state Na-CO2 batteries. In this work, we investigate the influence of fluorine doping on the structure and ionic conductivity of Na3Zr2Si2PO12 (NZSP). An ionic conductive solid electrolyte membrane was prepared by compositing the inorganic solid electrolyte Na2.7Zr2Si2PO11.7F0.3 (NZSPF3) with poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP). It shows an ionic conductivity of up to 2.17 × 10-4 S cm-1 at room temperature, a high sodium ionic transfer number of ∼0.70, a broad electrochemical window of ∼5.18 V, and better mechanical strength. Furthermore, we studied the Na15Sn4/Na composite foil with the ability to inhibit dendrite as the anode for solid-state Na-CO2 batteries. Through density functional theory (DFT) calculations, the Na15Sn4 particle has been verified with a strong sodiophilic property, which reduces the nucleation barrier during the deposition process, leading to a lower overpotential. The symmetric cell assembled with the composite solid-state electrolyte NZSPF3-PVDF-HFP and Na15Sn4/Na composite anode can inhibit the growth of Na dendrites effectively and maintain the stability of the whole cell structure. Solid-state Na-CO2 batteries assembled with Ru-carbon nanotube (Ru-CNTs) as cathode catalysts exhibit a high discharge capacity of 6371.8 mAh g-1 at 200 mA g-1, excellent cycling stability for 1100 h, and good rate performance. This work provides a promising strategy for designing high-performance solid-state Na-CO2 batteries.

Dual LiF/LiCl‐Rich Solid Electrolyte Interphases with Robust and Li+‐conductive Characteristics for 4.8 V Lithium Metal Batteries

AbstractLithium metal batteries, which are constructed by lithium‐rich manganese‐based oxide (LRMO) cathode and Li metal anode, have attracted intensive attention due to its high energy density. However, the instability of both cathode and anode limits the practical application due to undesirable electrolyte decomposition at high voltage. To address these issues, an electrolyte engineering strategy is proposed for constructing robust, highly Li+‐conductive solid electrolyte interphases on both cathode and anode with chlorobenzene as the additive. Due to the high mechanical stability and interface dynamics of the LiCl‐endorsed, LiF‐rich cathode electrolyte interphase, both the electrolyte decomposition and transition metal ion dissolution are effectively inhibited. Meanwhile, robust LiF/LiCl‐rich solid electrolyte interphase can effectively repress the overgrowth of Li dendrites. The Li||LRMO battery with optimized 2.0 wt.% chlorobenzene demonstrates a high‐capacity retention of 86.1% after 200 cycles at 0.5 C.

Size dependent lithium-ion conductivity of solid electrolytes in machine learning molecular dynamics simulations

Solid-state electrolytes are key ingredients in next-generation devices for energy storage and release. Machine learning molecular dynamics (MLMD) has shown great promise in studying the diffusivity of mobile ions in solid-state electrolytes, with much higher efficiency than conventional ab initio molecular dynamics (AIMD). In this work, we combine an efficient embedded atom neural network (EANN) approach and an uncertainty-driven active learning algorithm that optimally selects data points from high-temperature AIMD trajectories to construct ML potentials for solid-state electrolytes and validate this strategy in a benchmark system, Li3YCl6, for which several controversy theoretical results exist. Through systematic MLMD simulations, we find that a typically used small supercell in AIMD simulations fails to predict the supersonic transition at a critical temperature, leading to a significant overestimation of the Li+ conductivity in Li3YCl6 at room temperature. Fortunately, thanks to the scalability of the EANN potential, extended MLMD simulations in a sufficiently large cell does yield a notable change of temperature-dependence in conductivity at ∼420 K and a much lower room-temperature conductivity in excellent with experiment. Interestingly, our results are all based on a semi-local PBE density functional, which was argued unable to predict the superionic transition. We analyze possible reasons of the seemingly inconsistent MLMD results reported in literature with different ML potentials. This work paves the way of simply using high-temperature AIMD data to generate more reliable MLMD results of low-temperature ionic conductivities in solid-state electrolytes.

Tungsten and Boron Codoping toward High Ionic Conductivity and Stable Sodium Solid Electrolyte for All-Solid-State Sodium Batteries.

Sodium solid electrolytes with high ionic conductivity and good interfacial stability with sodium metal are crucial to realize high-performance all-solid-state sodium batteries. In this work, W and B-codoped Na3Sb1-xWxS4-xBx solid electrolytes are prepared by melt-quenching with further annealing. The synthesized Na3Sb0.95W0.05S3.95B0.05 solid electrolyte possesses a high ionic conductivity of 11.06 mS cm-1 under 25 °C and shows significantly improved interface compatibility with metal sodium. Specifically, Na/Na3Sb0.95W0.05S3.95B0.05/Na symmetric cell can stable cycle for 500 h under a current density of 0.05 mA cm-2. In addition, the resultant TiS2/Na3Sb0.95W0.05S3.95B0.05/Na battery exhibits an initial charge capacity of 164.1 mAh g-1 at 0.1 C with a capacity retention of 76.4% after 100 cycles. This work provides a new strategy to realize the high ionic conductivity of sodium solid electrolytes with improved interfacial stability with sodium anode.

Interconnected Three-Dimensional Porous Alginate-Based Gel Electrolytes for Lithium Metal Batteries.

Lithium batteries have been widely used in our daily lives for their high energy density and long-term stability. However, their safety problems are of paramount concern for consumers, which restricts their scale applications. Gel polymer electrolytes (GPEs) compensate for the defects of liquid leakage and lower ionic conductivity of solid electrolytes, which have attracted a lot of attention. Herein, a 3D interconnected highly porous structural gel electrolyte was prepared with alginate dressing as a host material, poly(ethylene oxide) (PEO), and a commercial liquid electrolyte. With rich polar functional groups and (CH2-CH2-O) segments on the polymer matrix, the transportation of Li+ is faster and uniform; thus, the formations of lithium dendrite were significantly inhibited. The cycle stability of symmetrical Li||Li batteries with modified composite electrolytes (SAA) is greatly improved, and the overpotential remains stable after more than 1000 h. Meanwhile, under the same conditions, the cycle performance of batteries with unmodified electrolytes is inferior and overpotentials are nearly 1 V after 100 h. Additionally, the capacity retention of Li||LiFePO4 with SAA is more than 95% after 200 cycles, while those of the others declined sharply. The alginate dressing-based GPEs can greatly enhance the mechanical and thermal stability of PEO-based GPEs, which provides an environmentally friendly avenue for gel electrolytes' applications in lithium batteries.

Supervalent doping and its effect on the thermal, structural and electrochemical properties of Li7La3Zr2O12 solid electrolytes

Supervalent doping is a method used to obtain highly conductive LLZO solid electrolytes. As the dopants affect differently on the properties of the LLZOs, we explore their influence on the synthesis, structure and electrochemical performance.

Hydrothermal synthesis of zirconia doped with naturally mixed rare earths oxides and their electrochemical properties for possible applications in solid oxide fuel cells

Solid oxide fuel cells (SOFC) are electrochemical conversion devices that produces electricity directly from oxidizing a fuel and their development became of high importance to drastically reduce the greenhouse emission. Rare earth elements (REEs) are widely used as materials and dopants in controlling the ionic conductivity of solid electrolytes for SOFCs. Their criticality and high costs for separation to individual REEs lead to first studies aiming to search possible use of mixed REEs with natural occurrence as extracted from concentrates. This paper focused on obtaining sintered pellets based on zirconia doped with natural mixture of REEs extracted from monazite and study their microstructure, impedance spectra and dielectric properties vs. operating temperatures to assess their potential applications as solid electrolyte. ZrO2 doped powders with 8% natural mixture of REEs (8ZrMZ) were synthesized by hydrothermal process. ZrO2 doped with 4% Y2O3 (4ZrY) and 8%Y2O3 (8ZrY) were also obtained by the same route and used as standard materials already used in commercial SOFCs. All powders were uniaxially pressed and sintered in air, with highest densities obtained for 1400 °C. The Niquist diagrams for 8ZrMZ samples show significantly lower ionic conductivity compared to standards 4ZrY and 8 ZrY. This may be attributed to the presence of detrimental Fe and Si impurities following the mixed REE after Th and U removal from monazite concentrates and the ratio of REEs in the dopant composition affecting the ionic conductivity due to possible association of structural defects. Research works are further needed to improve the receipt for using naturally mixed REEs and asses their possible use as a competitive dopant for solid electrolytes.