Lithium Ion Conductivity Research Articles

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).

A Review of the Application of Metal-Based Heterostructures in Lithium–Sulfur Batteries

Lithium–sulfur (Li-S) batteries are recognized as a promising alternative in the energy storage domain due to their high theoretical energy density, environmental friendliness, and cost-effectiveness. However, challenges such as polysulfide dissolution, the low conductivity of sulfur, and limited cycling stability hinder their widespread application. To address these issues, the incorporation of heterostructured metallic substrates into Li-S batteries has emerged as a pivotal strategy, enhancing electrochemical performance by facilitating better adsorption and catalysis. This review delineates the modifications made to the cathode and separator of Li-S batteries through metallic heterostructures. We categorize the heterostructures into three classifications: single metals and metal compounds, MXene materials paired with metal compounds, and heterostructures formed entirely of metal compounds. Each category is systematically examined for its contributions to the electrochemical behavior and efficiency of Li-S batteries. The performance of these heterostructures is evaluated in both the cathode and separator contexts, revealing significant improvements in lithium-ion conductivity and polysulfide retention. Our findings suggest that the strategic design of metallic heterostructures can not only mitigate the inherent limitations of Li-S batteries but also pave the way for the development of high-performance energy storage systems.

Enhancing ionic conductivity and expanding the electrochemical window in polymer electrolytes via ferroelectric-metal-organic-frameworks to manipulate charge spatial distribution.

Poly (ethylene oxide) (PEO)-based polymer electrolytes have promising applications in all-solid-state lithium metal batteries. However, their wide range of practical applications is severely limited by their relatively low room temperature lithium ion conductivity and narrow electrochemical window. In this paper, based on the ability of spontaneous polarization of ferroelectric materials to generate polarization field under applied electric field and the characteristics of Metal-Organic-Frameworks (MOFs) materials with regular adjustable pore structure, a Nano material combining ferroelectric materials and MOF (NUS-6(Hf)-MOF) was first proposed to be added to PEO polymer electrolyte as a filler. NUS-6(Hf)-MOF can provide rapid transport channel for lithium ion, born under the applied electric field of the latter's consistent dipole polarization field can adjust the interface of the space charge distribution, the composite polymer electrolyte (NUSCPE) modified with NUS-6(Hf)-MOF has high ionic conductivity (1.16×10-3Scm-1) and lithium ion mobility (0.33) at 60°C. Simultaneously, the phenomenon of self-polarization causes the surface electronization, this results in a higher susceptibility to oxidation compared to PEO, thereby expanding the electrochemical window to 4.7V, and when paired with commercial LiNi0.8Co0.1Mn0.1O2 cathode, the capacity is maintained at 85% after 50 stable cycles at 0.2C at 60°C. The polymer electrolyte NUSCPE modified by NUS-6(Hf)-MOF provides a novel design idea for all solid-state lithium batteries with excellent electrochemical performance.

Significantly promoting the lithium-ion transport performances of MOFs-based electrolytes via a strategy of introducing fluoro groups in the crystal frameworks.

Metal-organic frameworks (MOFs) with well-ordered channels are considered ideal solid-state electrolytes (SSEs) for lithium ionic conductors and are expected to be utilized in all-solid-state Li-ion batteries. However, the outstanding Li+ conductivity of MOFs, especially the properties at low temperatures, has become a crucial problem to overcome. Herein, a breakthrough is first realized to cope with this challenge via a strategy of introducing fluoro-substituted bridging ligands in MOFs. Benefiting from the fluorinated strategy in MOFs (Cu-MOF-F4), an outstanding Li+ conductivity of 1.16 × 10-3 S cm-1 at room temperature, a low activation energy of 0.15 eV, and a high transference number of 0.84 are achieved. In particular, Cu-MOF-F4 shows high conductivities of (0.15-2.99) × 10-3 S cm-1 in the temperature range of -40 to 110 °C. The proposed novel fluoro-substituted strategy of bridging ligands in MOFs is of great significance for developing high-performance SSEs for solid-state lithium batteries.

The enhancement of Li-ion conductivity in 2D metalloid organic frameworks via nodal element substitution.

The development of solid-state electrolytes has become crucial for promoting the safety and performance of lithium-ion batteries. Herein, the substitution of nodal elements from Si to Ge significantly improved the lithium ionic conductivity in 2D metalloid organic frameworks, resulting in an enhancement of approximately one order of magnitude.

Ionic covalent organic framework based quasi-solid-state electrolyte for high-performance lithium metal battery

Lithium metal solid-state batteries are promising as rechargeable energy storage devices due to their non-combustible nature, resistance to high temperatures, and non-corrosive properties. However, their widespread application is hindered by low lithium-ion conductivity and poor compatibility at the electrode/electrolyte interface. To address these challenges, two covalent organic frameworks (COFs), one with functional imidazolium groups (Dha-COFim) and one without (Dha-COF), were synthesized. Ionic liquids (ILs) were then incorporated into these COFs to create quasi-solid-state electrolytes (Dha-COFim-IL and Dha-COF-IL). The Dha-COFim, with its ordered porous structure, forms interconnected ion channels that enable fast lithium-ion transport and enhance lithium salt dissociation, achieving excellent thermal stability, high ionic conductivity (1.74 × 10⁻³ S cm⁻1), and a wide electrochemical window at room temperature. Density functional theory (DFT) calculations showed that the fixed imidazolium groups in Dha-COFim enhance interactions with TFSI⁻ anions, improving lithium salt dissociation. This allows free lithium ions to move quickly through the channels with minimal energy loss. Additionally, the formation of a stable SEI layer rich in LiF and Li3N at the lithium metal/electrolyte interface accelerates Li⁺transport, ensuring uniform lithium deposition and superior battery performance. When combined with a LiFePO4 cathode, the LiFePO4‖Dha-COFim-IL‖Li cell delivers high discharge capacity and excellent cycling stability, providing a new strategy for designing quasi-solid-state electrolytes for high-energy-density lithium batteries.

A critical review on Li-ion transport, chemistry and structure of ceramic-polymer composite electrolytes for solid state batteries.

In the transition to safer, more energy-dense solid state batteries, polymer-ceramic composite electrolytes may offer a potential route to achieve simultaneously high Li-ion conductivity and enhanced mechanical stability. Despite numerous studies on the polymer-ceramic composite electrolytes, disagreements persist on whether the polymer or the ceramic is positively impacted in their constituent ionic conductivity for such composite electrolytes, and even whether the interface is a blocking layer or a highly conductive lithium ion path. This lack of understanding limits the design of effective composite solid electrolytes. By thorough and critical analysis of the data collected in the field over the last three decades, we present arguments for lithium conduction through the bulk of the polymer, ceramic, or their interface. From this analysis, we can conclude that the unexpectedly high conductivity reported for some ceramic-polymer composites cannot be accounted for by the ceramic phase alone. There is evidence to support the theory that the Li-ion conductivity in the polymer phase increases along this interface in contact with the ceramic. The potential mechanisms for this include increased free volume, decreased crystallinity, and modulated Lewis acid-base effects in the polymer, with the former two to be the more likely mechanisms. Future work in this field requires understanding these factors more quantitatively, and tuning of the ceramic surface chemistry and morphology in order to obtain targeted structural modifications in the polymer phase.

POLYMERIC ION-CONDUCTING MEMBRANES BASED ON PEO-CONTAINING INTRAMOLECULAR POLYCOMPLEXES

In the present study, two series of solid solvent-free polymeric membranes based on diblock copolymers MePEO-b-PAAm (DBC) and triblock copolymers PAAm-b-PEO-b-PAAm (TBC), comprising chemically complementary poly(ethylene oxide) and poly(acryl amide) have been prepared by using casting technique. The dielectric properties of the prepared membranes in the frequency range of 102–105 Hz at room temperature as a function of water content and the length of the PEO block, as well as the peculiarities of water absorption processes under variable humidity, were investigated. It was found out that increasing the length of the PEO block led to an increase in the ionic conductivity of the obtained membranes. Such results confirmed the significant contribution of oxyethylene chains in ensuring the conductivity of lithium and solar cell batteries. The increase of relative humidity from 33% to 98% resulted in the increase of conductivity of DBC and TBC membranes up to 2.77·10-6–8.48·10-4 S·cm-1. According to the obtained results, block copolymers containing the interacting polymer components can be considered as potential solid polymer matrices for proton exchange membranes and they open the way for their application in fuel cells.

Enhancing Quasi-Solid-State Lithium-Metal Battery Performance: Multi-Interlayer, Melt-Infused Lithium and Lithiophilic Coating Strategies for Interfacial Stability in Li||VS2-DSGNS-LATP|PEO-PVDF||NMC622-Al2O3 Systems.

The development of quasi-solid-state lithium metal batteries (QSSLMBs) is hindered by inadequate interfacial contact, poor wettability between electrodes and quasi-solid-state electrolytes, and significant volume changes during long-term cycling, leading to safety risks and cataclysmic failures. Here, we report an innovative approach to enhance interfacial properties through the in situ construction of QSSLMBs. A multilayer design integrates a microwave-synthesized Li1.3Al0.3Ti1.7(PO4)3 (LATP) ceramic electrolyte, which is surface-coated with a lithiophilic conductive ink comprising VS2 and disulfonated functionalized graphene nanosheets (VS2-DSGNS) using a low-cost nail-polish binder. Subsequently, a few drops of LiPF6 in EC/DMC liquid electrolyte (LE) are impregnated into the uncoated side of the LATP surface. The quasi-solid-state electrolyte pellet of LATP-VS2-DSGNS surface was allowed to be in contact with the molten Li and held until Li flowed into the LATP-VS2-DSGNS surface completely via a "melt-infusion strategy" as an anode side. Additionally, a heterogeneous polymer matrix consisting of poly(ethylene oxide) (PEO) and poly(vinylidene difluoride) (PVDF) as a polymer interlayer is fabricated using a solution casting technique for improving the wettability between the LE impregnated side of LATP and cathode, to enhance overall charge transfer kinetics. The assembled symmetric cells, Li||LATP-VS2-DSGNS||Li and Li||PEO-PVDF/LE-LATP||Li, demonstrate high lithium-ion conductivities of 3.69 × 10-4 and 1.02 × 10-3 S cm-1, respectively, with impressive lithium-ion transfer numbers of 0.84 and 0.93 at 25 °C. Both cells exhibit a highly reversible lithium stripping/plating cycling process for over 600 h, with minimal voltage polarization of 10 and 31.6 mV, across a broad redox window (-1 to 6 V), effectively inhibiting lithium dendrite formation. Furthermore, the combination of a surface-modified Al2O3 dry-coated, high-nickel NMC622 cathode with the PEO-PVDF|LATP-VS2-DSGNS||Molten-Li architecture in a CR2032 coin-type full-cell delivers a galvanostatic discharge capacity of 130.6 mAh g-1 at a 1C rate after 200 cycles, achieving 84.3% capacity retention, thereby demonstrating substantial reduction in interfacial resistance and enhanced stable battery performance of QSSLMBs.

Расчет удельной электропроводности расплавов смесей LiF+NaF

The calculation of the specific electrical conductivity of lithium and sodium fluorides mixtures melts is presented. The Iinterest in the LiF–NaF system melts is determined by their practical significance. Melts of LiF+NaF mixtures are used in heat-storing compositions and in metallurgy. They are part of various multicomponent systems. The specific electrical conductivity calculation by isoconcentration, isothermal and interpolation methods is given for LiF+NaF mixtures melts of various compositions using known reference data for the temperature range 1020...1340 K. A calculation has been performed for the eutectic composition. The resulting analytical equations have been used to describe and calculate the specific electrical conductivity of the eutectic mixture for temperatures 5°, 10°, 50°, 75°, 100° above the liquidus. The specific electrical conductivity of the eutectic mixture melt is calculated on isotherms by interpolation for the isoconcentration dependences of hypoeutectic and hypereutectic mixtures. Isotherms of electrical conductivity (1020...1340 K) of melts depending on the content of LiF and NaF components are described by a third-degree polynomial. Depending on the temperature, the coefficients in the resulting equation change linearly. A comparison has been made of the values of specific electrical conductivity ϰ(LiF+NaF), calculated from the obtained equations. The description of ϰ(LiF+NaF) by isoconcentration and isothermal methods has showed satisfactory convergence of calculation results and makes it possible to calculate the specific electrical conductivity of LiF+NaF mixtures melts of any given composition, including eutectic.

Lithium-ion battery equivalent thermal conductivity testing method based on Bayesian optimization algorithm

Lithium-ion battery equivalent thermal conductivity testing method based on Bayesian optimization algorithm

The Manipulation of Ring-Open Polymerization Process to Boost the Electrochemical Performance for Solid-State Lithium Metal Batteries.

Solid-state polyether electrolytes formed by in-situ ring-opening polymerization (ROP) of 1,3-dioxolane (DOL) have attracted great attention due to their high lithium-ion conductivity, and good interface compatibility. However, DOL ring-opening polymerization is difficult to control, resulting in the formation of poly(1,3-dioxolane) (PDOL) with high molecular weight and high crystallinity, which hinder Li+ diffusion and deteriorate the interfacial contact. Herein, trimethylsilyl isocyanate (IPTS) was introduced into DOL ring-opening system as a moisture eliminating agent to weaken the Li salt-based initiating system and regulate the polymerization process. Based on this, the resultant PDOL electrolytes with 3 wt.% IPTS exhibit ionic conductivity of 2.8×10-4 S cm-1, a high Li+ transference number (0.68) and excellent stability with Li anode. The Li|PDOL-3 %IPTS|Li battery exhibits a stable cycling performance for more than 1100 h under 0.5 mA cm-2 and 0.5 mAh cm-2. Furthermore, the LiFePO4|PDOL-3 %IPTS|Li cell shows a capacity retention rate of 89.2 % after 200 cycles (25 °C, 1 °C) and 94.5 % (60 °C, 1 °C) after 500 cycles, which is much higher than that of PDOL (6.6 %) after 70 cycles (25 °C, 1 °C). This work provides guidance for the manipulation of ROP process further to enhance the performance of solid-state lithium metal batteries.

Phthalocyanine-based solid-state electrolyte for high-capacity and long-life lithium-ion batteries

A new solid-state electrolyte (SSE) with low energy activation for lithium-ion conduction was designed and tested in an all-solid-state battery configuration with a lithium metal anode and a lithium iron phosphate (LiFePO[Formula: see text] cathode. The aromatic character of the phthalocyanine-based SSE facilitates cell stabilization against lithium metal dendrites, and the low energy of activation enables battery cycling at -20[Formula: see text]C. The use of the phthalocyanine-based SSE necessitated the development of an in-situ process for the formation of an effective solid electrolyte interphase (SEI) layer between the anode and the SSE. Such a procedure enabled battery cycling over a 12-to-16-month time frame. The cells delivered high discharge capacities of up to 291.3 mAh/g at 23[Formula: see text]C and 194.5 mAh/g at -20[Formula: see text]C. All cells were fabricated in a dry room via simple solution casting of the soluble SSE onto either an aerosol-jet-deposited or tape-cast LiFePO4 cathode.

Engineering d-p Orbital Hybridization in a Single-Atom-Based Solid-State Electrolyte for Lithium-Metal Batteries.

Regulating lithium salt dissociation kinetics by enhancing the interaction between inorganic fillers and lithium salts is vital for enhancing the ionic conductivity in solid-state composite polymer electrolytes (CPEs). However, the influence of fillers' external electronic environments on lithium salt dissociation dynamics remains unclear. Here, we design single-atom sites in metal-organic framework fillers for poly(ethylene oxide) (PEO)-based CPEs, boosting lithium salt dissociation through an electrocatalytic strategy. This strategy enhances lithium-ion conductivity by tuning the coupling strength between the d and p orbitals of the fillers, as captured by a newly identified descriptor (λ) via high-throughput density functional theory (DFT) calculations and machine learning. The optimal single atom (Ti) sites are incorporated into a ZIF-8 matrix for PEO-based CPEs, achieving an ionic conductivity exceeding 10-3 S cm-1 at 30 °C. Additionally, the electrolyte forms a robust solid electrolyte interphase and is compatible with LiCoO2, LiNi0.9Co0.05Mn0.05O2, and sulfur cathodes. Consequently, the solid-state lithium metal battery with the electrolyte demonstrates excellent cycling stability, maintaining performance over 5000 cycles at 10 C with LiFePO4 cathodes and stable operation at -30 °C. These findings highlight the transformative potential of engineering d-p orbital hybridization by incorporating single-atom sites into inorganic fillers for designing highly ion-conductive CPEs.

Coordination-Driven Crosslinking Electrolytes for Fast Lithium-Ion Conduction and Solid-State Battery Applications.

Rechargeable batteries paired with lithium (Li) metal anodes are considered to be promising high-energy storage systems. However, the use of highly reactive Li metal and the formation of Li dendrites during battery operation would cause safety concerns, especially with the employment of highly flammable liquid electrolytes. Herein, a general strategy by engineering coordination-driven crosslinking networks is proposed to achieve high-performance solid polymer electrolytes. Through the coordination of metal-organic polyhedra (MOPs) with cellulose-based copolymers, the Li+-conducted hypercrosslinked MOP (CHMOP-Li) polymer network is capable of enabling the rapid transport of Li+. In addition to the high Li+ conductivity (1.02×10-3 S cm-1 at 25 °C), CHMOP-Li electrolyte also exhibits a high Li+ transference number (0.75) and a wide electrochemical stability window. Benefiting from the thermally stable and mechanically strong CHMOP-Li electrolyte film, the short-circuiting of the symmetric batteries is prevented even after 3200 h of cycling and a high specific energy of 300 Wh kg-1 is achieved for the Li-metal battery. The solid-state Li-O2 batteries fabricated with CHMOP-Li electrolyte also show good cycling performance (500 cycles) and high discharge capacity (15740 mAh g-1). The proposed coordination-driven crosslinking strategies offer an alternative route to design high-performance next-generation sustainable battery chemistries.

Reconstruction of LATP-LT composite solid electrolyte and analysis of Li+ conduction mechanism using 3D CT

Li1+xAlxTi2-x(PO4)3 (LATP) is a highly promising solid-state electrolyte, known for its high lithium-ion conductivity and stability at room temperature. This study successfully prepared LATP-LT composite solid-state electrolytes by combining LATP with Li2O-TeO2 (LT) glass, utilizing the molten state of the glass at high temperatures. The investigation focused on the effects of different ratios and sintering conditions on the performance of the LATP-LT composites. Results indicate that an appropriate amount of LT enhances the material's sinterability, facilitating continuous lithium-ion conductivity while inhibiting the diffusion of lithium dendrites within the pores. The LATP-LT composite solid electrolyte achieved an ionic conductivity of 1.81×10-4 S/cm at room temperature. Thus, selecting an optimal concentration of LT can serve as a breakthrough in the development of all-solid-state lithium-ion batteries, advancing the field of solid-state electrolytes.

High dielectric constant and enhanced lithium ionic conductivity in Ca doped NASICON type materials

High dielectric constant and enhanced lithium ionic conductivity in Ca doped NASICON type materials

A PET-enhanced PEO-ionic liquid-based gel polymer electrolyte for solid state lithium metal batteries

Gel polymer electrolytes (GPEs) are attractive for their promising prospect in lithium metal batteries (LMBs) owing to their outstanding thermal stability and remarkable electrochemical performance. Nevertheless, the practical application of traditional GPEs is significantly impeded by their limited mechanical strength. In order to address this issue, this study introduces an ultrathin and mechanically-strong poly(ethylene terephthalate) (PET) nonwoven fabric (PET-NW) as a rigid support layer for the GPEs composed of poly (ethylene oxide) (PEO) and ionic liquid (IL) EMIM-TFSI. The resulting PEO-IL/PET-NW-based GPE (NW GPE) demonstrates an excellent lithium ionic conductivity of 4.21 × 10−4 S cm−1, a lithium ion transference number of 0.20, and an ultrahigh mechanical strength of 53.2 MPa. These characteristics collectively contribute to the suppression of lithium dendrites growth and improved electrochemical performance of Li|NW GPE|LiFePO4 full cells which exhibit enhanced rate capability and cycling stability in comparison with Li|GPE-I30|LiFePO4 full cells. The employment of PET-NW in the fabrication of GPEs can pave a viable way for significant advancements in high-performance solid state LMBs for various practical applications.

In Situ Welding Ionic Conductive Breakpoints for Highly Reversible All-Solid-State Lithium-Sulfur Batteries.

Poly(ethylene oxide) (PEO)-based solid-state lithium-sulfur batteries (SSLSBs) have garnered considerable interest owing to their impressive energy density and high safety. However, the dissolved lithium polysulfide (LiPS) together with sluggish reaction kinetics disrupts the electrolyte network, bringing about ionic conductive breakpoints and severely limiting battery performance. To cure this, we propose an in situ welding strategy by introducing phosphorus pentasulfide (P2S5) as the welding filler into PEO-based solid cathodes. P2S5 can react with LiPS to form ion-conducting lithium polysulfidophosphate (LSPS), which suppresses the interaction with PEO and in situ weld breakpoints within the ionic conductive network. Of interest, LSPS also shows another function, that is, to catalyze sulfur redox reactions by decreasing the activation energy of sulfur reduction reaction from 0.87 to 0.75 eV, mitigating the shuttle effect. The in situ welding strategy helps the assembled SSLSB to feature exceptional cycling stability and a high energy density of up to 358 Wh·kg-1 due to the high sulfur utilization. Our findings pave an avenue for practical high-performance SSLSBs with a novel welding filler for in situ welding of ionic conductive network.

In–situ construction of LixFeyOz coatings on cobalt–free lithium–rich cathode materials for enhanced structural stability and electrochemical performance

Environmentally benign and cost–effective cobalt–free lithium–rich cathode materials have garnered significant interest. Nevertheless, the irreversible loss of lattice oxygen compromises their structural integrity, leading to capacity fade, voltage decay, and sluggish kinetics, which collectively impede their commercial viability. To address these challenges, this study introduces an in–situ formation of LixFeyOz coatings on the surface of cobalt–free lithium–rich materials by utilizing residual lithium compounds. At elevated temperatures, the residual lithium compounds on the surface of Li1.2Mn0.6Ni0.2O2 (LMNO) react with FeO to generate a LixFeyOz protective layer. This coating not only shields the bulk material from direct exposure to the electrolyte but also effectively consumes residual lithium compounds to suppress interfacial side reactions, thereby enhancing structural stability. The LixFeyOz layer acts as a lithium–ion conductor, facilitating the migration of lithium ions and markedly boosting the material's electrochemical performance. Experimental results indicate that at a current density of 1C, the initial discharge specific capacity of LMNO@Fe is 235.24 mAh g−1 with a capacity retention of 91.33 % after 100 cycles, compared to 211.62 mAh g−1and 77.95 % for LMNO, respectively. Even at a higher current density of 5C, the LMNO@Fe maintains a discharge specific capacity of 148.30 mAh g−1. This research demonstrates that the LixFeyOz coating on cobalt–free lithium–rich cathode materials offers a promising strategy for achieving high–performance lithium–ion batteries.