Conductivity Of Electrolyte Research Articles

In situ establishment of rapid lithium transport pathways at the electrolytes-electrodes interface enabling dendrite-free and long-lifespan solid-state lithium batteries

Composite solid-state electrolytes (CSEs) exhibit the high ionic conductivity of ceramic electrolytes and the facile processing and good flexibility of polymer electrolytes, representing the most promising class of solid-state electrolytes for the industrialization of lithium batteries. Nevertheless, CSEs continue encountering substantial interfacial resistance, which impedes their practical deployment. In response to these issues, a Li6.4La3Zr1.4Ta0.6O12/poly(vinylidene fluoride) (LLZTO/PVDF) solid electrolyte membranes with a thickness of 25 μm were prepared by the doctor blade method. In situ polymerization of 1,3-dioxolane (DOL) at the electrolyte–electrode interface was initiated by lithium hexafluorophosphate (LiPF6) and lithium difluoro(oxalate)borate (LiDFOB) dual-salts to produce poly(1,3-dioxolane) (PDOL). The presence of PDOL in LLZTO/PVDF@PDOL results in a high room temperature ionic conductivity of 3.578 mS cm−1. Moreover, the Li||LLZTO/PVDF@PDOL||LiFePO4(LFP) battery exhibits a discharge-specific capacity of 143 mAh g−1 and capacity retention of 81.7 % after 1000 cycles at 2 C, and the pouch cell with LLZTO/PVDF@PDOL achieved a high energy density of 190 Wh kg−1. The findings of this study may facilitate the industrial application of CSEs.

Ultrafast Li-Rich Transport in Composite Solid-State Electrolytes.

Solid-state lithium (Li) metal batteries (SSLMBs) have garnered considerable attention due to their potential for high energy density and intrinsic safety. However, their widespread development has been hindered by the low ionic conductivity of solid-state electrolytes. In this contribution, a novel Li-rich transport mechanism is proposed to achieve ultrafast Li-ion conduction in composite solid-state electrolytes. By incorporating cation-deficient dielectric nanofillers into polymer matrices, it is found that negatively charged cation defects effectively intensify the adsorption of Li ions, resulting in a high Li-ion concentration enrichment on the surface of fillers. More importantly, these formed Li-rich layers are interconnected to establish continuous ultrafast Li-ion transport networks. The composite electrolyte exhibited a remarkably low ion transport activation energy (0.17eV) and achieved an unprecedented ionic conductivity of approaching 1×10⁻3Scm⁻1 at room temperature. The Li||LiNi0.8Co0.1Mo0.1O2 full cells demonstrated an extended cycling life of over 200 cycles with a capacity retention of 70.7%. This work provides a fresh insight into improving Li-ion transport by constructing interconnected Li-rich transport networks, paving the way for the development of high-performance SSLMBs.

Defect-Induced Li-Ion Trapping and Hopping in a Grain Boundary-Engineered Li1.3Al0.3Ti1.7(PO4)3 Solid-State Electrolyte.

Understanding lithium-ion dynamics across defect-rich grain boundaries (GBs) is crucial for solid-state electrolytes. This study examines local electronic and structural changes in a Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte via X-ray absorption spectroscopy (XAS) and their correlation with ion transport properties. GBs were tailored through conventional isothermal sintering (CIS) and spark plasma sintering (SPS). Ti L2,3-, Ti K-, O K-, and P L2,3-edges from XAS revealed octahedral symmetry in bulk regions of both LATP-CIS and LATP-SPS. However, Ti L2,3-edge spectra in total electron yield mode and Ti K-edge white line intensity shifts in LATP-SPS indicate lower oxidation states and structural distortions due to a significant amorphous GB fraction. Modulations in O K-edge and P L2,3-edge spectra further highlight local structural differences in GB regions of LATP-CIS and LATP-SPS. Electron energy loss spectroscopy (EELS) also reveals variations in Ti L2,3-edge splitting and pre-edge peak intensities, consistent with X-ray absorption near-edge spectroscopy analysis. LATP-SPS exhibits a higher Li content in the GB region than LATP-CIS. The GB ionic conductivity of LATP-SPS (σgb,300K ∼ 1.36 × 10-3 S/cm) is two orders higher than that of LATP-CIS (σgb,300K ∼ 3.84 × 10-5 S/cm), while grain conductivity remains similar. Trapping and hopping enthalpy estimations suggest that trapped Li ions contribute ∼27% of activation energy for LATP-SPS compared to ∼17% for LATP-CIS. Enhanced ion diffusion in polycrystalline LATP GBs is predicted from molecular dynamics simulations, where liquid-like ion pair correlations improve mobility. This work highlights the significant influence of GB-induced structural distortions, probed through XAS and EELS, on the ionic conductivity and charge transport in LATP electrolytes.

Breaking Aggregation State to Achieve Low‐Temperature Fast Charging of Lithium Metal Batteries

Insufficient ionic conductivity and elevated desolvation energy barrier of electrolytes limit the lithium metal batteries (LMBs) low‐temperature applications. Weakly solvating electrolytes (WSEs), with limited lithium salt dissociation capability, are prone to desolvate and drive anion‐rich aggregates (AGGs). However, significant AGGs result in increased viscosity and low ionic mobility, contributing to battery failure at low temperatures (≤ −20 oC). Here, we propose and achieve a transformation of solvation structures from AGGs to contact ion pairs (CIPs) through modulating the overall solvation capability, thereby achieving the balance between weak Li+ ‐ solvent interactions and desired ion migration kinetics. Remarkly, CIPs‐dominated electrolyte shows a ten‐fold increase in ionic conductivity compared to conventional WSEs. The Li||LiFePO4 (LFP) battery achieves more than 1400 cycles with 86.9% capacity retention at 5 C. The practical 1.2 Ah LFP pouch cell delivered 69% of the capacity at 25 oC when cycled at −40 oC. This strategy for solvation structure transformation in WSEs provides a novel approach for the development of electrolytes for low‐temperature batteries.

Breaking Aggregation State to Achieve Low-Temperature Fast Charging of Lithium Metal Batteries.

Insufficient ionic conductivity and elevated desolvation energy barrier of electrolytes limit the lithium metal batteries (LMBs) low-temperature applications. Weakly solvating electrolytes (WSEs), with limited lithium salt dissociation capability, are prone to desolvate and drive anion-rich aggregates (AGGs). However, significant AGGs result in increased viscosity and low ionic mobility, contributing to battery failure at low temperatures (≤ -20 oC). Here, we propose and achieve a transformation of solvation structures from AGGs to contact ion pairs (CIPs) through modulating the overall solvation capability, thereby achieving the balance between weak Li+ - solvent interactions and desired ion migration kinetics. Remarkly, CIPs-dominated electrolyte shows a ten-fold increase in ionic conductivity compared to conventional WSEs. The Li||LiFePO4 (LFP) battery achieves more than 1400 cycles with 86.9% capacity retention at 5 C. The practical 1.2 Ah LFP pouch cell delivered 69% of the capacity at 25 oC when cycled at -40 oC. This strategy for solvation structure transformation in WSEs provides a novel approach for the development of electrolytes for low-temperature batteries.

Study on the preparation of high intrinsic conductivity Perovskite Li0.33La0.56TiO3 solid-state electrolyte by systematic process optimization

Abstract Li0.33La0.56TiO3 (LLTO) perovskite-type solid-state electrolyte is one of the solid-state electrolytes that is expected to achieve industrial production. However, research focused on a single factor and the simplification of the preparation process have constrained the bulk conductivity of LLTO. This study systematically investigated the influence of process parameters on the intrinsic conductivity of perovskite-type solid-state electrolytes, focusing on pre-sintering temperature, lithium compensation, and sintering temperature, which are important processes for LLTO. The experimental results show that the optimization of process parameters can promote grain growth to a certain extent, increase the uniformity of grain size and promote the densification of materials, and a certain degree of lithium compensation can effectively suppress the formation of secondary phases caused by lithium deficiency, thereby improving the intrinsic conductivity of the material. Among them, the material prepared under the conditions of a lithium compensation amount of 20 wt%, a pre-sintering temperature of 800 °C, and a sintering temperature of 1300 °C showed the highest bulk conductivity of 3.41 × 10−3 S·cm−1 at 50 °C, the highest bulk density of material reaching 4.95 g·cm−3, which is 98.78 % of the relative bulk density of LLTO solid-state electrolyte, and the lowest conductivity activation energy of 0.24 eV for the sample.

Strategies and Prospects for Engineering a Stable Zn Metal Battery: Cathode, Anode, and Electrolyte Perspectives.

ConspectusZinc metal batteries (ZMBs) appear to be promising candidates to replace lithium-ion batteries owing to their higher safety and lower cost. Moreover, natural reserves of Zn are abundant, being approximately 300 times greater than those of Li. However, there are some typical issues impeding the wide application of ZMBs. Traditional inorganic cathodes exhibit an unsatisfactory cycling lifetime because of structure collapse and active materials dissolution. Apart from inorganic cathodes, organic materials are now gaining extensive attention as ZMBs cathodes because of their sustainability, high environmental friendliness, and tunable molecule structure which make them usually exhibit superior cycling life. Nevertheless, due to the inferior conductivity of organic materials, their mass loading and volumetric energy density still cannot meet our demands. In addition, the specific working mechanism of inorganic/organic cathodes also needs further investigation, necessitating the use of advanced in situ characterization technologies. Reversibility of metallic Zn anodes is also crucial in determining the overall cell performances. Like Li and Na anodes, uncontrolled dendrite growth is also an annoying problem for Zn anodes, which may penetrate the separator and cause inner short circuit. In aqueous electrolyte, highly reactive H2O molecules easily attack metallic Zn anode, leading to undesired Zn corrosion. Furthermore, during cell operation, hydrogen evolution reaction (HER) occurs, which leads to continuous consumption of electrolytes and formation of insulating byproducts on Zn anodes. Although strategies like novel Zn anode design and artificial SEI layer construction are proposed to inhibit dendrites growth and protect Zn anodes from active H2O attack, the corresponding manufacturing process remains complex. Modifying electrolyte components is relatively simple to implement and effectively stabilizes Zn anodes. However, HER cannot be completely eliminated when H2O exists in the modified electrolytes. Under such conditions, nonaqueous electrolytes appear to be a promising solution for ZMBs in the future due to their aprotic nature and high stability with the Zn anodes. However, the ionic conductivity of nonaqueous electrolytes is relatively low compared to that of aqueous electrolytes. Most of the previous reviews focus only on the individual components of ZMBs. A review of ZMBs from a higher perspective, focusing on advanced ZMBs system design, is currently lacking.In this Account, we begin with a brief overview of ZMBs, highlighting their advantages and current challenges. Subsequently, we give a summary of the development of inorganic cathodes (such as MnO2) for ZMBs. Specifically, development history and representative modification strategy of inorganic cathodes are illustrated. Following this, representative organic cathodes are discussed, along with introduction of novel modification strategies for organic cathodes. Afterward, Zn anode form design, additive selection and artificial solid electrolyte interface (SEI) layer are briefed for development of Zn anodes. Thereafter, formulation of electrolyte components is systematically discussed, highlighting potential future of nonaqueous electrolyte in ZMBs. Unlike other reviews giving very detailed information in one aspect, this Account offers an overview of current opportunities and challenges faced by ZMBs. We hope this Account can provide researchers with deeper insights into the evolution of ZMBs, encouraging them to devise effective and innovative strategies that will accelerate widespread application of ZMB technology.

Data-driven exploration of weak coordination microenvironment in solid-state electrolyte for safe and energy-dense batteries

The unsatisfactory ionic conductivity of solid polymer electrolytes hinders their practical use as substitutes for liquid electrolytes to address safety concerns. Although various plasticizers have been introduced to improve lithium-ion conduction kinetics, the lack of microenvironment understanding impedes the rational design of high-performance polymer electrolytes. Here, we design a class of Hofmann complexes that offer continuous two-dimensional lithium-ion conduction channels with functional ligands, creating highly conductive electrolytes. Assisting with unsupervised learning, we use Climbing Image-Nudged Elastic Band simulations to screen lithium-ion conductors and screen out five potential candidates that elucidate the impact of lithium coordination environment on conduction behavior. By adjusting the covalency competition between Metal−O and Li−O bonds within Hofmann complexes, we can manipulate weak coordination environment of lithium-ion for rapid conduction kinetics. Li | |sulfurized polyacrylonitrile (SPAN) cell using solid-state polymer electrolytes with predicted Co(dimethylformamide)2Ni(CN)4 delivers an initial discharge capacity of 1264 mAh g−1 with a capacity retention of 65% after 500 cycles at 0.2 C (335 mA g−1), at 30 °C ± 3 °C. The assembled 0.6 Ah Li | |SPAN pouch cell delivers an areal discharge capacity of 3.8 mAh cm−2 at the second cycle with a solid electrolyte areal mass loading of 18.6 mg cm−2 (mass-to-capacity ratio of 4.9).

Disorder-induced enhancement of lithium-ion transport in solid-state electrolytes

Enhancing the ion conduction in solid electrolytes is critically important for the development of high-performance all-solid-state lithium-ion batteries (LIBs). Lithium thiophosphates are among the most promising solid electrolytes, as they exhibit superionic conductivity at room temperature. However, the lack of comprehensive understanding of their ion conduction mechanism, especially the effect of structural disorder on ionic conductivity, is a long-standing problem that limits further innovations in all-solid-state LIBs. Here, we address this challenge by establishing and employing a deep learning potential to simulate Li3PS4 electrolyte systems with varying levels of disorder. The results show that disorder-driven diffusion dynamics significantly enhances the room-temperature conductivity. We further establish bridges between dynamical characteristics, local structural features, and atomic rearrangements by applying a machine learning-based structure fingerprint termed “softness”. This metric allows the classification of the disorder-induced “soft” hopping lithium ions. Our findings offer insights into ion conduction mechanisms in complex disordered structures, thereby contributing to the development of superior solid-state electrolytes for LIBs.

Dehydroxylated Polyvinyl Alcohol Separator Enables Fast Kinetics in Zinc-Metal Batteries.

Separators are critical components of zinc-metal batteries (ZMBs). Despite their high ionic conductivity and excellent electrolyte retention, the widely used glass fiber (GF)membranes suffer from poor mechanical stability and cannot suppress dendrite growth, leading to rapid battery failure. Contrarily, polymer-based separators offer superior mechanical strength and facilitate more homogeneous zinc (Zn)deposition. However, they typically suffer from sluggish ion transport kinetics and poor wettability by aqueous electrolytes, resulting in unsatisfactory electrochemical performance. Here a dehydroxylation strategy is proposed to overcome the above-mentioned limitations for polyvinyl alcohol (PVA) separators. A dehydroxylated PVA-based membrane (DHPVA) is synthesized at a relatively low temperature in a highly concentrated alkaline solution. Part of the hydroxyl groups are removed and, as a result, the hydrogen bonding between PVA chains, which is deemed responsible for the sluggish ion transport kinetics, is minimized. At 20°C, the ionic conductivity of DHPVA reaches 12.5mScm-1, which is almost 4 times higher than that of PVA. Additionally, DHPVA effectively promotes uniform Zn deposition, leading to a significantly extended cycle life and reduced polarization, both in a/symmetric (Cu/Zn and Zn/Zn) and full cells (Zn/NaV3O8). This study provides a new, effective, yet simple approach to improve the performance of ZMBs.

Revisiting the in-plane and in-channel diffusion of lithium ions in a solid-state electrolyte at room temperature through neural network-assisted molecular dynamics simulations.

Developing superionic conductor (SIC) materials offers a promising pathway to achieving high ionic conductivity in solid-state electrolytes (SSEs). The Li10GeP2S12 (LGPS) family has received significant attention due to its remarkable ionic conductivity among various SIC materials. Ab initio molecular dynamics (AIMD) simulations have been extensively used to explore the diffusion behavior of Li+ ions in Li10GeP2S12. These simulations indicate that Li+ ions diffuse rapidly along a one-dimensional (1D) chain direction, specifically along the c-axis, a process known as in-channel diffusion. In addition, these computational studies have identified additional diffusion pathways within the ab planes, referred to as in-plane diffusion. However, there are still notable limitations in the time scale associated with AIMD simulation techniques for studying the dynamic behavior of Li10GeP2S12 at room temperature. In this study, we trained a deep potential (DP) model for the LGPS system and performed a 300-nanosecond DeePMD simulation to investigate the diffusion behavior of Li10GeP2S12 at room temperature. The neural network (NN) assisted simulation showed that the framework structure of LGPS remained remarkably stable over the entire 300-nanosecond period. Following this, our investigation focused on the two-dimensional (2D) diffusion pathways within the ab plane (in-plane diffusion mechanism) and the 1D diffusion channel along the c-axis (in-channel diffusion mechanism). Upon analyzing the DeePMD simulation results, we identified two distinct pathways for in-plane Li+ diffusion within the ab plane: the Li-2 and Li-4 pathways. We determined the energy barriers for the two diffusion pathways to be 0.23 eV and 0.34 eV, respectively, in qualitative agreement with recent experimental and theoretical results. For the in-channel diffusion along the c-axis, our calculated energy barrier was approximately 0.083 eV, closely matching the previous one-particle potential (OPP) analysis. Our results confirm experimental and theoretical studies, indicating that lithium ions experience significantly less resistance when diffusing through the in-channel pathway compared to the in-plane migration mechanism. However, our findings suggest that despite having a higher energy barrier than the Li-4 pathway, the Li-2 pathway remains a viable option for in-plane lithium-ion migration.

Fast-Charging High-Specific Lithium Metal Batteries Enabled by Oleophilic Garnet Suspension Electrolyte.

Realizing fast charging in high-specific-energy lithium metal batteries (LMBs) remains a significant challenge. Here, a oleophilic garnet suspension electrolyte design is reported, using inorganic solid electrolyte modified by low-surface-energy 1H,1H,2H,2H-perfluorooctyl trichlorosilane (PFOTS), to address the dilemma of fast charging and high specific energy in LMBs. With the oleophilic suspension electrolytes, the ionic conductivity of carbonate electrolyte is increased by ≈20%. Importantly, Li+ transference number is increased by ≈50% (reaching 0.57). Furthermore, the oleophilic suspension electrolyte regulates the solid electrolyte interphase (SEI), resulting in improved Coulombic efficiency (from 98.9% to 99.5%) and decreased Li/electrolyte interfacial impedance (from 263 to 86.5 Ω). As a result, LMBs using LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode and the oleophilic suspension electrolyte achieves a remarkable capacity retention of 81.7% at the 500th cycle under fast charging of 4 C rate. In the LMBs at high NCM811 loading of 18mg cm-2, a cyclability of 89% capacity retention after 200 cycles along with limited increase in electrode overpotential is accomplished at a critical current density of 1.08mA cm-2. The fast charging and remarkable cyclability are attributed to the enhancement of electrolyte transport capabilities and generation of a favorable solid electrolyte interphase at the Li surface.

Exploring Tetra-/Penta-/Hexavalent Ion Substitution in Yttrium-Based Halide Solid-State Electrolytes.

Although aliovalent ion substitution is an important strategy for enhancing ionic conductivity in halide electrolytes, the choice of doping ions is often restricted to tetravalent ions, and investigations into the intrinsic origin of the doping mechanism are lacking. In this work, we investigated the effects of Zr4+, Ta5+ and W6+ doping on the crystal structure and ionic conductivity of yttrium-based rare-earth halides. Only Zr4+ achieves fast ion diffusion in both the (001) and (002) crystal planes by affecting the volume of the octahedron and the tetrahedral interstitial space, whereas Ta5+ significantly enhances the ion diffusion rate in the (001) crystal plane while suppressing it in the (002) plane, and W6+ does the opposite. As a result, an optimal ionic conductivity (0.437 mS cm-1) is obtained for Zr4+ substitution, while the corresponding full battery also exhibits excellent capacity, cycling and rate performance.

Incorporating Ionic Liquid 1‐Ethyl‐3‐Methylimidazolium Bromide Into PVA‐LiAc–Based Solid Polymer Electrolytes to Achieve Advanced Solid‐State Lithium‐Ion Batteries

ABSTRACTSolid polymer electrolytes (SPEs) serve as both separators and electrolytes, enhancing the safety of energy storage devices by eliminating liquid components. In this study, we present SPEs prepared from a blend of polyvinyl alcohol (PVA), lithium acetate (LiAc), and the ionic liquid 1‐ethyl‐3‐methylimidazolium bromide ([EMIm]Br). This combination prevents leakage issues common with liquid electrolytes and addresses the low conductivity of typical solid electrolytes. The prepared SPEs are easy to produce, highly transparent, thermally stable up to 271°C, and exhibit high ionic conductivity, with values of 2.21 × 10−5 S cm−1 when 40% [EMIm]Br is added to the PVA/10% LiAc membrane. Additionally, this composition demonstrates a mechanical strength of 20.40 MPa and an elongation of 485.12%. These findings highlight the strong potential of [EMIm]Br–based SPEs for lithium‐ion batteries.

An Investigation into the Potential Capabilities of a YSZ-SDCC Composite Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells

The development and analysis of Yttria-Stabilized Zirconia-Samarium-Doped Ceria Carbonate (YSZ-SDCC) composite electrolytes that are intended for use in Solid Oxide Fuel Cells (ITSOFC) at intermediate temperatures is the primary focus of this study, which represents a significant advancement in the technology of SOFC. When it comes to assessing the efficiency of fuel cells, which is a strategy that shows promise for the conversion of energy, the electrolyte material is one of the most significant components that must be considered. In this study, several different compositions of YSZ-SDCC composite electrolytes were investigated in detail. Electrochemical impedance spectroscopy, often known as EIS, was applied in order to carry out a thorough investigation into the conductivity and area-specific resistance (ASR) of these composite electrolytes. This

Electrochemically stable and ultrathin polymer-based solid electrolytes for dendrite-free all-solid-state lithium-metal batteries

Abstract Polymer-based composite solid electrolytes (PCSEs) are increasingly studied in all-solid-state lithium-metal batteries (ASSLMBs) due to the combined advantages of better flexibility of polymer and higher ion conductivity of ceramic electrolytes. However, most reported PCSEs are overly thick, increasing internal resistances. Besides, the poor stability at the Li metal-electrolyte interfaces often leads to severe lithium dendrite formation and reduced cycling stability. Here, we fabricate an ultrathin PCSE with a thickness of 12.4 μm, incorporating polyacrylonitrile (PAN) nanofibers as the structural matrix, and a filler with polyethylene oxide and Li6.5La3Zr1.5Ta0.5O12 (LLZTO). Due to the formation of the LiCN layer on the surface of the lithium metal and the Li-ion transport pathways induced by the dehydrocyanation reaction at the LLZTO/PAN interfaces, the PCSE exhibits a high critical current density of 1.8 mA cm-2 and a low energy barrier of 0.278 eV for Li-ion transfer, accommodating the fast Li-ion migration to avoid Li-dendrite growth. In addition, the stable nitrile groups and the dehydrocyanation reaction ensure the electrochemical stability of the PCSE with a high oxidation voltage of 5.5 V and an exceptional cycling stability (2100 h) in Li||PCSE||Li symmetric cells. Additionally, the Li||PCSE||LiFePO4 full cells demonstrate a high volumetric energy density of 338.3 Wh L-1 at 0.1 C and a robust stability over 100 cycles at 0.5 C. The study offers a new approach for fabricating ultrathin PCSEs and provides insights into the mechanisms of dendrite-free formation, guiding the development of high-performance PCSEs for ASSLMBs.

High-Rate 4.2 V Solid-State Potassium Batteries by In Situ Polymerized Epoxide Ether Electrolyte.

Solid-state metallic potassium batteries (SSMPBs) afresh have attracted incremental attention because of their potential to supplement solid-state metallic lithium batteries. However, SSMPBs suffer poor electrochemical performances due to the low ionic conductivity of solid electrolytes and huge electrode/electrolyte interfacial resistance. Herein, high-rate SSMPBs are achieved by in situ ring-opening polymerization of 1,3-dioxolane with succinonitrile as a plasticizer and Al(OTf)3 as the catalyst, where the succinonitrile enables short-chain polyether electrolytes. The in situ polymerized electrolytes deliver a high ionic conductivity of 4.5 × 10-5 S cm-1 at room temperature and excellent stabilities at high oxidation potentials (4.2 V vs K+/K) and against metallic K anodes. All these result in SSMPBs with a discharge capacity of 69 mAh g-1 under a high rate of 100 mA g-1 and a retention of 88.8% after 100 cycles, and the rate and capacity retention are higher than those in previous work on SSMPBs.

Trace NaBF4 Modulated Ultralow‐Concentration Ether Electrolyte for Durable High‐Voltage Sodium‐Ion Batteries

AbstractUltralow‐concentration ether electrolytes hold great promise for cost‐effective sodium‐ion batteries (SIBs), while their inferior cycle stability under high voltages remains an awkward challenge. Herein, ultralow‐concentration diglyme (G2)‐based electrolytes with single sodium salt are found to manifest high‐rate capability when employed for high‐voltage Na3(VOPO4)2F (NVOPF) cathode, but their specific capacity rapidly depletes to exhaustion during long‐term cycling. To address this issue, trace NaBF4 (0.03 m) as electrolyte additive is introduced, which minimally affects ion conductivity of the pristine electrolyte, yet weakens the coordination between Na+ ions and G2 molecules. This allows more PF6− to enter the solvation sheath of Na+ ions, forming a more stable cathode electrolyte interphase and enhancing the cycle performance without sacrificing high‐rate performance (up to 20 C). As a result, the trace NaBF4 modulated G2‐based electrolyte enables the NVOPF cathode to cycle steadily, with a capacity retention of 94.2% over 1000 cycles at a low rate of 1 C. This work provides valuable insights into the modulation of ultralow‐concentration ether electrolytes for use in durable high‐voltage SIBs.

Room-Temperature CsPbI3-Quantum-Dot Reinforced Solid-State Li-Polymer Battery.

A novel polymer electrolyte based on CsPbI3 quantum dots (QDs) reinforced polyacrylonitrile (PAN), named as PIL, is exploited to address the low room-temperature (RT) ion conductivity and poor interfacial compatibility of polymer solid-state electrolytes. After optimizing the content of CsPbI3 QDs, RT ion conductivity of PIL largely increased from 0.077 to 0.56 mS cm-1, and its Li-ion transference number ( ) from 0.20 to 0.63. It is revealed that the synergistic enhancement of Li-ion transport and interface stability is realized by CsPbI3 QDs through Lewis acid-base interaction, ordered polarization of PAN, and interface chemical regulation. These two effects guarantee the robust solid-electrolyte interface (SEI) in PIL-based solid-state batteries. Consequently, PIL electrolyte enables solid-state Li-metal batteries to deliver extraordinary RT cycling performance as verified by excellent cycling stability (>2000h at 0.1mA cm-2) of Li|PIL|Li symmetric batteries. Moreover, Li|PIL|LFP (LFP is LiFePO4) and Li|PIL|NCM811(NCM811 is Li(Ni0.8Co0.1Mn0.1)O2) batteries maintain capacity retention of 81.2% and 77.9%, respectively, after 600 cycles at 0.5 C, as well as good rate-capability and very high Coulombic efficiency at RT.

Toward Higher Energy Density All‐Solid‐State Batteries by Production of Freestanding Thin Solid Sulfidic Electrolyte Membranes in a Roll‐to‐Roll Process

AbstractAll‐solid‐state batteries (SSB) show great promise for the advancement of high‐energy batteries. To maximize the energy density, a key research interest lies in the development of ultrathin and highly conductive solid electrolyte (SE) layers. In this work, thin and flexible sulfide solid electrolyte membranes are fabricated and laminated onto a non‐woven fabric using a scalable and solvent‐free, continuous roll‐to‐roll process (DRYtraec). These membranes show significantly improved tensile strength compared to unsupported sheets, which facilitates cell assembly and allows a continuous component production using a single‐step calendering process. By tuning the thickness, densified membranes with thicknesses ranging from 40 to 160 µm are obtained after a compression step. The resulting SE membranes retain a high ionic conductivity (1.6 mS cm−1) at room temperature. An excellent rate capability is demonstrated in a SSB pouch cell with a Li2O–ZrO2‐coated LiNi0.9C0.05Mn0.05O2 cathode, a 55 µm thin SE membrane, and a columnar silicon anode fabricated by a scalable physical vapor deposition process. At stack level, a promising energy density of 673 Wh L−1 (and specific energy of 247 Wh kg−1) is achieved, showcasing the potential for high energy densities by reducing the SE membrane thickness while retaining good mechanical properties.