Conductivity Of Electrolyte Research Articles

On analytical theories for conductivity and self-diffusion in concentrated electrolytes.

Describing analytically the transport properties of electrolytes, such as their conductivity or the self-diffusion of the ions, has been a central challenge of chemical physics for almost a century. In recent years, this question has regained some interest in light of Stochastic Density Field Theory (SDFT) - an analytical framework that allows the approximate determination of density correlations in fluctuating systems. In spite of the success of this theory to describe dilute electrolytes, its extension to concentrated solutions raises a number of technical difficulties, and requires simplified descriptions of the short-range repulsion between the ions. In this article, we discuss recent approximations that were proposed to compute the conductivity of electrolytes, in particular truncations of Coulomb interactions at short distances. We extend them to another observable (the self-diffusion coefficient of the ions) and compare them to earlier analytical approaches, such as the mean spherical approximation and mode-coupling theory. We show how the treatment of hydrodynamic effects in SDFT can be improved, that the choice of the modified Coulomb interactions significantly affects the determination of the properties of the electrolytes, and that comparison with other theories provides a guide to extend SDFT approaches in this context.

Scalable Production of Separator and Cathode Suspensions via Extrusion for Sulfidic Solid‐State Batteries

AbstractDue to their high ionic conductivity, sulfidic solid electrolytes are considered to have great potential as a key element of solid‐state batteries. Such batteries could offer safety, thermal stability, and high energy densities. A key requirement is the scalable production of separators and electrodes, taking into account the high demands the moisture‐sensitive material imposes on the surrounding atmosphere. Therefore, in this publication we will demonstrate the establishment of an extrusion process under argon atmosphere for the continuous production of separator and cathode suspensions. After systematically investigating the influence of the process parameters speed, temperature and mass flow on the adhesive strength, ionic conductivity and capacity, the obtained knowledge is used for the fabrication of improved layers. The Li3PS4 based separators show a comparatively high ionic conductivity of 0.036 mS cm−1 (conductivity of pure solid electrolyte: 0.05 mS cm−1), the cells reach specific capacities of up to 156 mAh g−1 in the 1st cycle.

Role of cerium pyrophosphate for improving protonic conduction and stabilization of SDP.2H2O composite electrolytes

Proton-conducting (1-x)NaH2PO4·2H2O/xCeP2O7 (x = 0.1–0.4) composites were prepared and the conduction behaviour was investigated at intermediate temperatures. The presence of water in CeP2O7 increased the number of jump sites and facilitated the hopping of protons, thereby increasing the proton conductivity of the composite electrolytes. In this work, we systematically addressed some aspects and presented an overview of the factors affecting the proton conductivity in (1-x)NaH2PO4·2H2O/xCeP2O7. The effect of CeP2O7 on the ionic conductivity of NaH2PO4·2H2O was observed under confined conditions. NaH2PO4·2H2O and cerium pyrophosphate have gained significant interest for electrolyte application as proton conductors in intermediate-temperature fuel cells.

Facile Preparation of Higher Conductivity Porous Polyimide‐based Separators by Phase Inversion and its Overcharge‐sensitive Modification for Lithium‐ion Batteries

AbstractSeparator plays multiple roles in the performance and safety of lithium‐ion batteries owing to the lower conductivity of the organic electrolyte and the hyperactive electrode materials. However, the commercial polyolefin separator suffers from the poor thermal stability, weak electrolyte‐wettability, low porosity as well as the demanding and costly manufacturing. Herein, we demonstrate the facial synthesis of a sponge‐like, isotropic, polyimide‐based separator by phase inversion, which possessed the higher electrolyte‐saturating conductivity (1.74 mS cm−1) and ion transference number (0.81) besides its excellent wettability and thermal stability. Meanwhile, the bearable stress was further promoted by 60 % with the 30 wt % epoxy‐strengthening tactic and the high porosity (67 %) and conductivity (1.47 mS cm−1) still preserved. Additionally, an overcharge‐sensitive PI separator was further developed by combining the conductive copolymer of coumarin‐triphenylamine by virtue of the eminent processability of PI, which demonstrated the outstanding voltage‐restraining capability for LiFePO4‐based cell during overcharge. Therefore, polyimide‐based separator could be a quite promising candidate due to its facile manufacturing, preferable performance and versatile functionalizing.

A flexible PEO-based polymer electrolyte with cross-linked network for high-voltage all solid-state lithium-ion battery

Solid state lithium-ion batteries (SLIBs) have been considered as one of the most promising sustainable next-generation technologies for energy storage. However, the poor interfacial compatibility and low ion conductivity of solid electrolytes still remain a major challenge for SLIBs. Herein, a free-standing flexible solid polymer LA-PAM-PEO electrolyte is constructed through the electrospinning technology featuring with high Li+ conductivity (6.1 × 10−4 S cm−1), strong mechanical strength and high Li+ migration number (0.32), which breaks the restriction between ionic conductivity and mechanical strength in polymer solid electrolyte. The cross-linking between LA, PAM and PEO is verified to decrease the crystalline of PEO, thus increasing the Li+ conductivity. Moreover, benefiting from the 3D network composed of interconnected nanofibers and the covalent bonds between LA, PAM and PEO, the mechanical strength of LA-PAM-PEO SPE was also effectively improved. The LA-PAM-PEO SPE also delivers a high electrochemical window (4.95 V), and low interface resistance (243.8 Ω). As a result, the Li/Li symmetrical cell with the LA-PAM-PEO displayed outstanding stability after 1000 h with the uniform Li deposition on the interface of Li electrode, in sharp contrast to the PEO SPE. In addition, the Li/LA-PAM-PEO SPE/LFP displays a discharge capacity of 135 mA h g−1 after 1000 cycles at the rate of 1 C, with a capacity retention of 93.5%. The proposed LA-PAM-PEO SPE thus opens new possibilities for the fabrication and engineering of solid-state Li-ion batteries.

Innovative low-critical raw materials and medium-entropy perovskite for intermediate temperature solid oxide electrochemical cells

Ceramic proton conductive electrolytes are promising materials for reducing the operating temperatures of solid oxide cells. It is desirable to achieve such a target because, as a result, durability, cost of materials, electrochemical reactions and flexibility of its use can be significantly enhanced. A medium-entropy perovskite with the stoichiometric formula Ba0.5Sr0.5Zr0.5Zn0.5O3 was studied in the present work using limited amounts of critical raw materials. According to the performed analysis, it is possible to achieve complete phase purity at 1300 °C. Based on dilatometric measurements, the material can undergo significant densification starting at 1200 °C; at about 1550 °C the produced perovskite melts and degrades simultaneously. One of the most effective characteristics of the pure phase is its ability to absorb moisture and the excellent stability to redox mechanism. This material's characteristic was confirmed by a series of thermochemical procedures and XRD analyses. As a result of electrochemical measurements carried out on 93% dense pellet consolidated at 1350 °C, the material has a much better conductivity and activation energy than BZY.

A high ion conductive solid electrolyte film and interface stabilization strategy for solid-state Li-S battery

Lithium-sulfur (Li-S) batteries are regarded as a potential next-generation electrochemical energy storage technology. However, polysulfide shuttle effect and lithium dendrite growth always worsen the battery's cycling performance, especially, the safety problem of liquid electrolyte has also become a major challenge to the development and application of Li-S batteries. Herein, a high ion conductive poly(1,3-dioxolane) solid electrolyte film (PDOL) was introduced in Li-S battery, which hinders the shuttle of polysulfides, and forms a uniform LiF protective layer on the lithium metal contact surface to inhibit the growth of lithium dendrites. Meanwhile, the problem of high interfacial impedance in solid-state Li-S batteries was also solved by adding a trace amount of flexible organic ether electrolyte to the solid electrolyte/electrode interface. The assembled quasi-solid-state S/PDOL/Li cell shows low interfacial impedance less than 75 Ω and can be stably cycled over 500 times at 0.1 C. This rigid-flexible solid electrolyte design method provides a practical idea for the development of high-performance solid-state Li-S batteries.

Building a Flexible and Highly Ionic Conductive Solid Electrolyte Interphase on the Surface of Si@C Anodes by Binary Electrolyte Additives.

Si@C as a high specific capacity anode material for lithium batteries (LIBs) has attracted a lot of attention. However, the severe volume change during lithium de-embedding causes repeated rupture/reconstruction of the solid electrolyte interphase (SEI), resulting in poor cycling stability of the Si-based battery system and thus hindering its application in commercial batteries. Using electrolyte additives to form an excellent SEI is considered to be a cost-effective method to meet this challenge. Here, the classical film-forming additive vinyl carbonate (VC), and the newly emerging lithium salt additive lithium difluorophosphate (LiDFP), are chosen as synergistic additives to improve the electrode-electrolyte interface properties. Final results show that the VC additive generates flexible polycarbonate components at the electrode/electrolyte interface, preventing the fragmentation of Si particles. However, the organic components show high impedance, inhibiting the fast transport of Li+. This defect can be supplemented from the decomposition substances of the LiDFP additive. The derived inorganic products, such as LiF and Li3PO4, can strengthen the reaction kinetics of the electrode, reduce the interfacial impedance, and promote the Li+ transport. Thus, the synergistic effect of VC and LiDFP additives builds an effective SEI with good flexibility and high ionic conductivity and then significantly improves the cycling and rate stability of Si@C anodes. The experimental results show that the utilization of LiDFP and VC additives to modify the Si@C anode interface enhances the capacity retention of the Si@C/Li half-cell after 100 cycles from 68.2% to 85.1%. Besides, the possible mechanism of action between VC and LiDFP is proposed by using the spectral characterization technique and density functional theory (DFT) calculations. This research opens up a new possibility for improvement of SEI, and provides a simple way to achieve high-performance Si-based LIBs.

Exploring Li-CO2 batteries with electrospun PAN-derived carbon nanofibers and Li1.4Al0.4Ti1.6(PO4)3 solid-state electrolyte

This study introduces a highly stable and conductive sodium super ionic conductor-type solid electrolyte, Li1.4Al0.4Ti1.6(PO4)3 (LATP), to address safety concerns and mesoporous-structured polyacrylonitrile (PAN)-derived carbon nanofibers (CNFs) as a cathode material, which has the advantages of high affinity and adsorption of CO2 gas. LATP, an inorganic solid electrolyte, was synthesized using a solution-based method and its structural properties were assessed using X-ray diffraction and Raman spectroscopy. The ionic conductivity of LATP pellets was approximately 5.87 × 10−4 S cm−1. The gas adsorption properties and pore size distributions of the electrospun PAN-derived CNFs were analyzed using the Brunauer-Emmett-Teller method. A fabricated Li-CO2 battery successfully operated for 50 cycles with a current density of 50 mA g−1 and a cut-off capacity of 500 mAh g−1. Finally, a post-mortem analysis of the Li-CO2 battery was conducted using field-emission scanning electron microscopy and Raman and X-ray photoelectron spectroscopy to examine the electrode degradation mechanism. The analysis indicated that Li2CO3 was produced by the electrochemical reaction in the Li-CO2 batteries, causing electrode degradation. Therefore, improving the sluggish kinetics of Li2CO3 decomposition using a catalyst embedded in PAN-derived CNFs will realize high-performance Li-CO2 batteries.

Defect Strategy in Solid-State Lithium Batteries.

Solid-state lithium batteries (SSLBs) have great development prospects in high-security new energy fields, but face major challenges such as poor charge transfer kinetics, high interface impedance, and unsatisfactory cycle stability. Defect engineering is an effective method to regulate the composition and structure of electrodes and electrolytes, which plays a crucial role in dominating physical and electrochemical performance. It is necessary to summarize the recent advances regarding defect engineering in SSLBs and analyze the mechanism, thus inspiring future work. This review systematically summarizes the role of defects in providing storage sites/active sites, promoting ion diffusion and charge transport of electrodes, and improving structural stability and ionic conductivity of solid-state electrolytes. The defects greatly affect the electronic structure, chemical bond strength and charge transport process of the electrodes and solid-state electrolytes to determine their electrochemical performance and stability. Then, this review presents common defect fabrication methods and the specific role mechanism of defects in electrodes and solid-state electrolytes. At last, challenges and perspectives of defect strategies in high-performance SSLBs are proposed to guide future research.

Influencing ionic conductivity and mechanical properties of ionic liquid polymer electrolytes by designing the chemical monomer structure

ABSTRACTPolymeric single chloride-ion conductor networks based on acrylic imidazolium chloride ionic liquid monomers AACXImCYCl as reported previously are prepared. The chemical structure of the polymers is varied with respect to the acrylic substituents (alkyl spacer and alkyl substituent in the imidazolium ring). The networks are examined in detail with respect to the influence of the chemical structure on the resulting properties including thermal behavior, rheological behavior, swelling behavior, and ionic conductivity. The ionic conductivities increase (by two orders of magnitude from 10−6 to 10−4 S·cm−1 with increasing temperature), while the complex viscosities of the polymer networks decrease simultaneously. After swelling in water for 1 week the ionic conductivity reaches values of 10−2 S·cm−1. A clear influence of the spacer and the crosslinker content on the glass transition temperature was shown for the first time in these investigations. With increasing crosslinker content, the Tg values and the viscosities of the networks increase. With increasing spacer length, the Tg values decrease, but the viscosities increase with increasing temperature. The results reveal that the materials represent promising electrolytes for batteries, as proven by successful charging/discharging of a p(TEMPO-MA)/zinc battery over 350 cycles.

Advances of Zn Metal-Free "Rocking-Chair"-Type Zinc Ion Batteries: Recent Developments and Future Perspectives.

Aqueous zinc ion battery (AZIBs) has attracted the attention of many researchers because of its safety, economy, environmental protection, and high ionic conductivity of electrolytes. However, the battery greatly suffers from zinc dendrite produced by zinc metal anode leading to poor cycle life and even unsafe problems, which limit its further development for various important applications. It is known that the success of the commercialization of lithium-ion batteries (LIBs) is mainly due to replacement of lithium metal anode with graphite, which avoids the formation of Li dendrite. Therefore, it is an important step to develop aqueous zinc ion anode to replace conventional zinc metal one with zinc-metal free anode material. In this review, the working principle and development prospect of "rocking-chair" AZIBs are introduced. The research progress of different types of zinc metal-free anode materials and cathode materials in "rocking-chair" AZIBs is reviewed. Finally, the limitations and challenges of the Zn metal-free "rocking-chair" AZIBs as well as solutions are deeply discussed, aiming to provide new strategies for the development of advanced zinc-ion batteries.

A new metal–organic rotaxane framework for enhanced ion conductivity of solid-state electrolyte in lithium-metal batteries

The composite polymer electrolyte has been obtained via incorporating LiCUST-701 (a new metal–organic rotaxane framework modified by Li+) into poly(ethylene oxide) (PEO) matrix and give a high ionic conductivity of 4.02 × 10−4 S/cm at 60 °C. DFT calculations were used to visualize the possible diffusion pathway of Li+. The all-solid-state cell assembled with LiFePO4, composite polymer electrolyte and lithium metal foil delivered with excellent cycling capability and stability even under high current densities.

Uniform lithium deposition regulated by lithiophilic Mo3N2/MoN heterojunction nanobelts interlayer for stable lithium metal batteries

Lithium metal batteries (LMBs) are of significant importance for high-energy rechargeable batteries owing to its ultra-high theoretical specific capacity and lowest reduction potential. However, the lithium dendrite growth during the continuous plating/stripping process results in poor cycle property, serious security issues and low Coulombic efficiency to working LMBs. To effectively inhibit lithium dendrite issues, a multifunctional lithiophilic interlayer constructed by heterostructural Mo3N2/MoN nanobelt (MoNx) is exploited as regulator to adjust lithium deposition. The results reveal that MoNx/PP exhibits high lithium-ion transference number, ion conductivity and excellent electrolyte wettability, which action synergistically to regulate lithium-ion diffusion and flux. DFT calculation further demonstrates that the co-existence of heterostructure and polar bonds can effectively enhance the interaction between MoNx and lithium, which can supply more deposition sites for promoting homogenous and smooth lithium plating. The advantages mentioned above endow symmetric Li//Li cell used MoNx/PP with a super-long-life of 1500 h at 5 mA cm−2. Furthermore, Li//LiFePO4 full cell presents excellent cycling stability and ultra-low-capacity decay rate of 0.033 %/cycle after 500 cycles even at 3C. This work offers a creative strategy and insight to reasonably design lithiophilic interlayer to regulate Li uniform depositions in working LMBs.

Porous Cyclodextrin PolymerEnablesDendrite-Free and Ultra-Long LifeSolid-State Zn-I 2 Batteries.

Zn-I2batteries have attracted attention due to their low cost, safety, and environmental friendliness. However, their performance is still limited by the irreversible growth of Zn dendrites, hydrogen evolution reactions, corrosion, and shuttle effect of polyiodide. In this work, we have prepareda newporous polymer (CD-Si) by nucleophilic reactionofβ-cyclodextrin with SiCl4, and CD-Si is applied to the solid polymer electrolyte (denoted PEO/PVDF/CD-Si) to solve above-mentioned problems. Through the anchoring of the CD-Si, a conductive network with dual transmission channels was successfully constructed. Due to the non-covalent anchoring effect, the ionic conductivity of the solid polymer electrolytes(SPE) can reach 1.64 × 10-3S cm-1at 25 ºC. The assembled symmetrical batteries can achieve highly reversible dendrite-free galvanizing/stripping (stable cycling for 7500 h at 5 mA cm-2and 1200 h at 20 mA cm-2). The solid-state Zn-I2battery shows anultra-long life of over 35,000 cycles at 2 A g-1. Molecular dynamics simulations are performed to elucidate the working mechanism of CD-Si in the polymer matrix. This work providesa novel strategy towards solid electrolytes for Zn-I2batteries.

Porous Cyclodextrin Polymer Enables Dendrite‐Free and Ultra‐Long Life Solid‐State Zn‐I2 Batteries

AbstractZn‐I2 batteries have attracted attention due to their low cost, safety, and environmental friendliness. However, their performance is still limited by the irreversible growth of Zn dendrites, hydrogen evolution reactions, corrosion, and shuttle effect of polyiodide. In this work, we have prepared a new porous polymer (CD‐Si) by nucleophilic reaction of β‐cyclodextrin with SiCl4, and CD‐Si is applied to the solid polymer electrolyte (denoted PEO/PVDF/CD‐Si) to solve above‐mentioned problems. Through the anchoring of the CD‐Si, a conductive network with dual transmission channels was successfully constructed. Due to the non‐covalent anchoring effect, the ionic conductivity of the solid polymer electrolytes (SPE) can reach 1.64×10−3 S cm−1 at 25 °C. The assembled symmetrical batteries can achieve highly reversible dendrite‐free galvanizing/stripping (stable cycling for 7500 h at 5 mA cm−2 and 1200 h at 20 mA cm−2). The solid‐state Zn‐I2 battery shows an ultra‐long life of over 35,000 cycles at 2 A g−1. Molecular dynamics simulations are performed to elucidate the working mechanism of CD‐Si in the polymer matrix. This work provides a novel strategy towards solid electrolytes for Zn‐I2 batteries.

A continuous multiphase model for liquid metal batteries

Liquid metal batteries (LMBs) are a promising candidate for large-scale stationary storage of renewably generated energy. Their Earth-abundant electrode materials and highly conductive molten salt electrolytes confer the low costs and high power densities required for grid-scale storage. LMB operation involves a complex interplay between mass transport mechanisms, and as a result their performance potential and operational limits are not fully understood. In this study, a multiphase numerical model is presented that simulates the charge and discharge processes of an LMB based on the Na-Zn couple. The model computes the changes in electrode and electrolyte volume, and resolves the spatial variations in the chemistry of the electrolyte that accompany the interfacial reactions. Volume change and species redistribution were found to be important in predicting the maximum theoretical capacity of the cell when neglecting other transport mechanisms.

Stale urine catalysed resource recovery from source separated urine using magnesium air fuel cell: Insights into the mechanism, its implications and challenges

The current study presents a new concept of “stale urine catalysed resource recovery (SCRR)” in a magnesium air fuel cell (MAFC) to enhance the nutrients (phosphate and ammonia) and energy recovery from source - separated urine. The MAFC consists of a sacrificial Mg anode (AZ31) and a gas diffusion electrode (GDE) as a cathode. The wettability and surface morphology of GDE were examined by water contact angle and FESEM-EDAX analysis. The addition of stale urine to fresh urine catalyzed urea hydrolysis, as a result, struvite production in MAFC was accelerated due to alkaline pH conditions and high NH4+: PO43- ratio. The influential parameters for struvite precipitation were optimised as: (i) pH – 9; (ii) HRT – 24 h; (iii) NH4+: PO43- ratio – 90; (iii) Ca2+: Mg2+ ratio < 0.2. The X-ray diffraction pattern of the recovered precipitates revealed the formation of high-quality struvite. Besides, the FT-IR spectra displayed the presence of N–H and H-O–H bonds, and PO4 units. Moreover, the surface morphology depicted various morphologies (pyramid, wedge-shaped, rod-shaped and disc-shaped) of the crystal structure of struvite. The elemental composition revealed the presence of Mg, P, N, O, Ca, Na, and K. Furthermore, the addition of stale urine increased power density from 3.19 to 4.87 Wm−2 due to increased electrolyte conductivity, high NH4+:PO43- ratio, reduced internal resistance, and spontaneity of Mg anode dissolution. A current efficiency (CE) > 100 % indicated the passivation of anode, however, a stable CE was achieved with high NH4+: PO43- ratios, indicating the suitability of SCRR in the MAFC.

High-capacity all-solid-state lithium battery with stable interfaces enabled by ultra-thin polyvinylidene fluoride/Li3InCl6 composite solid electrolyte

The practical application of all-solid-state lithium batteries (ASSLBs) is inhibited by the poor ionic conduction of solid electrolytes and the large interfacial resistance in ASSLBs. To solve these issues, a simple sol-gel and coating process is developed to prepare self-standing ultra-thin composite solid electrolytes with polyvinylidene fluoride (PVDF) as the matrix and Li3InCl6 (LIC) as the inorganic filler. The introduction of LIC can effectively reduce the crystallinity of PVDF, provide new Li+ migration channels and enhance the ion conductivity of the electrolyte. The flexible PVDF matrix can improve the interfacial contact between the electrolyte and electrodes to promote uniform Li deposition. The constructed PVDF/LIC electrolyte not only reduces the interface impedance but also produces good mechanical strength to inhibit the growth of lithium dendrites, thus exhibiting good electrochemical performance. The assembled Li|PVDF/LIC-15%|LiFePO4 ASSLBs have a high capacity of 161.8 mAh g−1 with a capacity retention of 82.8% after 200 cycles. In addition, the PVDF/LIC electrolyte can be assembled with the high-voltage cathode (NCM811) to form ASSLBs. The proposed preparation method is simple, safe, and has good practical application prospects.

Physiological, transcriptional and metabolomic evidence for arbuscular mycorrhizal fungi and Lactobacillus plantarum in peanut resistance to salinity stress

AbstractArbuscular mycorrhizal fungi (AMF) and Lactobacillus plantarum (LP) play pivotal roles in plant salinity resistance; however, difficulties are still exist in ascertaining their synergistic effects in counteracting legume soil salinity. Here, two peanut cultivars (salt‐tolerant and salt‐sensitive) were subjected to salinity stress, and the alleviation effects of combined microbial agent (CMA, inoculation with AMF + application with LP) on peanut salinity tolerance have been comprehensively characterized. CMA significantly enhanced the biomass production, leaf relative water content, increased the net photosynthetic rate, the maximal photochemical efficiency of photosystem II (PSII) and strengthened the antioxidant system, while dramatically decreased the reactive oxygen species (ROS) accumulation, lipid peroxidation and relative electrolyte conductivity under salinity conditions. Moreover, transcriptional and metabolomic evidence advocated that a subset of stress‐responsive pathways involved in plant growth (e.g. sucrose and starch), photosystem, antioxidant response, signal transduction (e.g. phytohormone and MAPK), osmotic homeostasis (e.g. total soluble sugar and amino acids) and root metabolism (e.g. asparagine and phenylpropanoid) have been regulated by CMA. Taken together, the physiological, transcriptional and metabolomic results indicate that CMA could induce peanut salinity tolerance through increasing plant growth performance, maintaining photosynthetic apparatus integrity, enhancing antioxidant system and regulating root metabolism. This study provides a promising CMA product and would be important for deepening the knowledge of the mechanisms regarding bacterial–fungal interactions.