High-performance Solid Electrolytes Research Articles

Preparation, Characterization and Conductivity of SiO2 doped rGO-WO3 Composite for Battery Application

High-performance solid polymer electrolytes are regarded as one of the most promising materials to be used in the development of lithium ion batteries with improved extended life, increased recyclability and increased safety for electric vehicles and energy storage. In this work, a microwave-assisted hydrothermal technique was used to produce SiO2-doped rGO-WO3 composite, which possesses outstanding supercapacitor capabilities. This method is simple, low-cost method without using any other capping and reducing agents. The obtained SiO2 doped rGO-WO3 composite structural, morphology and components have been examined by XRD, FT-IR, FE-SEM, TEM, EDX, UV-visible techniques. It was found that the SiO2 doped rGO-WO3 composite well crystalline and the size range is about 20-30 nm. The SEM morphology results showed that the nanoparticles were stabilized by rGO, having cavity like structure and randomly distributed on the rGO-WO3 matrix. The solid state electrolyte revealed superior lithium ion transference number and cyclic stability. The SiO2 doped rGO-WO3 composite shows improved ionic conductivity of 2.74 × 10-5 S cm-1 at room temperature.

Self-forming Na3P/Na2O interphase on a novel biphasic Na3Zr2Si2PO12/Na3PO4 solid electrolyte for long-cycling solid-state Na-metal batteries

A novel biphasic Na3Zr2Si2PO12/Na3PO4 solid electrolyte is proposed to effectively address critical anode interface challenges for solid-state Na-metal batteries (SSSMBs). The Na3PO4 phase, at an optimal composition of ∼20 mol%, transforms the interface chemistry throughout the NZSP electrolyte, which results in dense electrolytes with high Young's modulus, rapid ion transport (6.2 × 10−4 S cm-1) at low activation barrier (0.19 eV), negligible electronic conductivity, and excellent sodiophilicity. The AIMD/DFT calculations and XPS analysis reveal a self-formed, (electro)chemically stable mixed Na+/electron-conducting interphase, comprising Na3P and Na2O, at the Na anode interface. The interphase not only homogenizes the Na+ flux distribution and accelerates the interfacial charge transport, but prevents continuous interfacial reactions, thereby stabilizing the anode interface against dendrite formation. Benefiting from the low-impedance, dendrite-free anode interface, Na symmetric cells demonstrate a low interface resistance of 12.7 Ω cm2 and exceptional cyclability of 3000 h. Additionally, full cells with Na3V2(PO4)3 cathodes achieve 93 % capacity retention after 550 cycles at 0.5 C. This research comprehensively elucidates and leverages the critical advantages of Na3PO4 in enhancing the bulk and interface properties of Na3Zr2Si2PO12 solid electrolytes. The design strategy of biphasic solid electrolytes presented here offers new insights into the developing high-performance solid electrolytes for advanced SSSMBs.

In-Situ Polymerized Solid/Quasi-Solid Polymer Electrolyte for Lithium-Metal Batteries: Recent Progress and Perspectives.

In pursuit of high energy density, lithium metal batteries (LMBs) are undoubtedly the best choice. However, leakage and inevitable dendrite growth in liquid electrolytes seriously hinder its practical application. Solid/quasi-solid state electrolytes have emerged as an answer to solve the above issues. Especially, polymer electrolytes with excellent interface compatibility, high flexibility, and ease of machining have become a research hotspot for LMBs. Nevertheless, the interface contact between polymer electrolyte and inorganic electrode materials and the low ionic conductivity restrict its development. On account of these, in situ polymerized polymer electrolyte is proposed. Polymer solid electrolytes produced through in situ polymerization promote robust interface contact between the electrolyte and electrode while simplifying the preparation steps. This review summarized the latest research progress in in situ polymerized solid electrolytes for LMBs. These electrolytes were divided into three parts according to their polymerization methods: thermally induced polymerization, chemical initiator polymerization, ionizing radiation polymerization, and so on. Furthermore, we concluded the major challenges and future trends of in situ polymerized solid electrolytes for LMBs. It's hoped that this review will provide meaningful guidance on designing high-performance polymer solid electrolytes for LMBs.

Soy protein as a dual-functional bridge enabling high performance solid electrolyte for Li metal batteries

A high-performance solid electrolyte is critical for all-solid-state Li metal batteries which possess good safety and high energy densities. In this study, inspired by the unique ionic transport function and excellent adhesive properties of natural proteins, we successfully generated a novel solid electrolyte by applying soy protein as a dual-functional bridge to enable additional ion-conduction pathways and improve mechanical performance. The solid electrolyte with soy protein that interacts with both SiO2 nanofabrics and polypolyethylene oxide (PEO) exhibits high ionic conductivity of 10−5 S cm−1 (vs. 10−6 S cm−1 of SiO2/PEO), improved Li+ transference number of 0.550 (vs. 0.446 of SiO2/PEO), high Young's modulus of 1.862 MPa (vs. 0.356 MPa of SiO2/PEO) and excellent flexibility. As a result, the solid-state batteries with LiFePO4 as cathode demonstrate a stable discharge capacity. This work provides a new strategy to advance the performance of solid electrolytes for achieving long-lifespan all-solid-state batteries.

Plasma Coupled Electrolyte Additive Strategy for Construction of High-Performance Solid Electrolyte Interphase on Li Metal Anodes.

High-performance lithium metal anodes are crucial for the development of advanced Li metal batteries. Herein, this work reports a novel plasma coupled electrolyte additive strategy to prepare high-quality composite solid electrolyte interphase (SEI) on Li metal to achieve enhanced performance and stability. With the guidance of calculations, this work selects diethyl dibromomalonate (DB) as an additive to optimize the solvation structure of electrolytes to modify the SEI. Meanwhile, this work groundbreakingly develops DB plasma technology coupled with DB electrolyte additive to construct a combinatorial SEI: inner plasma-induced SEI layer composed of LiBr and Li2CO3 plus additive-reduced SEI containing LiBr/Li2CO3/organic lithium compounds as an outer compatible layer. The optimized hybrid SEI has strong affinity toward Li+ and good mechanical properties, thereby inducing horizontal dispersion and uniform deposition of Li+ and keep structure stable. Accordingly, the symmetrical cells exhibit enhanced cycling stability for 1200h at an overpotential of 23.8mV with average coulombic efficiency (99.51%). Additionally, the full cells with LiNi0.8Co0.1Mn0.1O2 cathode deliver a capacity retention of 81.7% after 300 cycles at 0.5 C, and the pouch cell achieves a volumetric specific energy of ≈664Wh L‒1. This work provides new enlightenment on plasma technology for fabrication of advanced metal anodes for energy storage.

Optimization Design of Fluoro-Cyanogen Copolymer Electrolyte to Achieve 4.7V High-Voltage Solid Lithium Metal Battery.

Raising the charging voltage and employing high-capacity cathodes like lithium cobalt oxide (LCO) are efficient strategies to expand battery capacity. High voltage, however, will reveal major issues such as the electrolyte's low interface stability and weak electrochemical stability. Designing high-performance solid electrolytes from the standpoint of substance genetic engineering design is consequently vital. In this instance, stable SEI and CEI interface layers are constructed, and a 4.7V high-voltage solid copolymer electrolyte (PAFP) with a fluoro-cyanogen group is generated by polymer molecular engineering. As a result, PAFP has an exceptionally broad electrochemical window (5.5V), a high Li+ transference number (0.71), and an ultrahigh ionic conductivity (1.2 mS cm-2) at 25°C. Furthermore, the Li||Li symmetric cell possesses excellent interface stability and 2000 stable cycles at 1mA cm-2. The LCO|PAFP|Li batteries have a 73.7% retention capacity after 1200 cycles. Moreover, it still has excellent cycling stability at a high charging voltage of 4.7V. These characteristics above also allow PAFP to run stably at high loading, showing excellent electrochemical stability. Furthermore, the proposed PAFP provides new insights into high-voltage resistant solid polymer electrolytes.

Ceria Quantum Dot Filler-Modified Polymer Electrolytes for Three-Dimensional-Printed Sodium Solid-State Batteries.

Solid polymer electrolytes have been considered as promising candidates for solid-state batteries (SSBs), owing to their excellent interfacial compatibility and high mechanical toughness; however, they suffer from intrinsic low ionic conductivity (lower than 10-6 S/cm) and large thickness (usually surpassed over 100 μm or even 500 μm), which has a negative influence on the interface resistance and ionic migration. In this work, ceria quantum dot (CQD)-modified composite polymer electrolyte (CPE) membranes with a thickness of 20 μm were successfully manufactured via 3D printing technology. The CQD fillers can reduce the crystallinity of the polymer, and the oxygen vacancies on CQDs can facilitate the dissociation of ion pairs in the NaTFSI salt to release more free Na+, improving the ionic conductivity. Meanwhile, tailoring the thickness of the CPE-CQDs membrane via 3D printing can further promote the migration and transport of Na+. Furthermore, the printed NNM//CPE-CQDs//Na SSB exhibited outstanding rate capability and cycling stability. The combination of CQD modification and thickness tailoring through 3D printing paves a new avenue for achieving high performance solid electrolyte membranes for practical application in Na SSBs.

Novel PEO-based Solid Polymer Electrolyte with High Elasticity and High Ionic Conductivity for Room Temperature Lithium Metal Batteries

The development and application of polyethylene oxide (PEO) based solid polymer electrolyte (SPE) is severely constrained by its low ionic conductivity and poor tensile resistance. To improve the electrochemical performance of SPE without losing its mechanical properties, a benzene sulfonate-based additive is adopted into crosslinking system composed of -CH2-CH2-O- segments to obtain a membrane with a high ionic conductivity of 1.47 × 10−4 S cm−1 and an ionic transference number of 0.70 at room temperature. The activation energy value of 0.128 eV gives evidence for a favorable migration mechanism of PTH-SPE. Anti-dendrite growth and contact optimization can be realized by molecular structure design with a tensile elongation of 490%. The reversible overpotential of Li||Li symmetric cell within 1000 h demonstrates that the compact PTH-SPE can inhibit the growth of lithium dendrite. This work provides a new strategy for designing high-performance solid electrolytes for room temperature via a green solvent-free method.

Synergistic effect of Ti3C2Tx MXene/PAN nanofiber and LLZTO particles on high-performance PEO-based solid electrolyte for lithium metal battery

Solid polymer electrolytes (SPEs) have been considered the most promising separators for all-solid-state lithium metal batteries (ASSLMBs) due to their ease of processing and low cost. However, the practical applications of SPEs in ASSLMBs are limited by their low ionic conductivities and mechanical strength. Herein, we developed a three-dimensional (3D) interconnected MXene (Ti3C2Tx) network and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) particles synergistically reinforced polyethylene oxide (PEO)-based SPE, where the association of Li+ with ether-oxygen in PEO could be significantly weakened through the Lewis acid-base interactions between the electron-absorbing group (Ti–F, −O–) of Ti3C2Tx and Li+. Besides, the TFSI− in lithium salts could be immobilized by hydrogen bonds from the Ti–OH of Ti3C2Tx. The 3D interconnected Ti3C2Tx network not only alleviated the agglomeration of inorganic fillers (LLZTO), but also improved the mechanical strength of composite solid electrolyte (CSE). Consequently, the assembled Li||CSE||Li symmetric battery showed excellent cycling stability at 35 ℃ (stable cycling over 3000 h at 0.1 mA cm−2, 0.1 mAh cm−2) and −2 ℃ (stable cycling over 2500 h at 0.05 mA cm−2, 0.05 mAh cm−2). Impressively, the LiFePO4||CSE||Li battery showed a high discharge capacity of 145.3 mAh/g at 0.3 C after 300 cycles at 35 ℃. This rational structural design provided a new strategy for the preparation of high-performance solid-state electrolytes for lithium metal batteries.

Molecular-scale interaction between sub-1 nm cluster chains and polymer for high-performance solid electrolyte

Organic-inorganic interface in composite solid electrolyte could lead to increased ion transport for solid-state lithium batteries; however, most inorganic fillers have much larger size than polymer chains, which results in severe aggregation of inorganic fillers and poor ionic conductivity. Herein, functional sub-1 nm inorganic cluster chains were integrated with polymer chains to fabricate composite solid electrolyte with enhanced ionic conductivity. Different from all other inorganic fillers, the sub-1 nm inorganic cluster chains with diameter <1 nm have similar size and geometry compared with polymer chains, exhibiting polymer-like solution properties. A transparent sub-1 nm inorganic filler/polymer mixed solution was generated to realize monodispersion of cluster chains as functional fillers in polymer matrix. Meanwhile, abundant oxygen vacancies on cluster chains interact with polymer chains and lithium salts at molecular-scale, which decreases the complexation of polymer segments with Li+ and promote the dissociation of lithium salts, thereby improving Li+ transport. As a result, the composite solid electrolyte exhibits high ionic conductivity (0.4 mS cm−1) and large mobile Li+ distribution (50.8 %). This work pushes the size of nanofillers down to <1 nm, which is a unique approach to the molecular-scale interaction between nanofillers and polymers to boost ion transport in solid electrolytes.

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.

Phonon DOS-Based Machine Learning Model for Designing High-Performance Solid Electrolytes in Li-Ion Batteries

In the present work, a machine learning (ML) model was built to design solid electrolytes with improved ionic conductivity for Li-ion batteries (LIBs), and the model was based on the phonon density of states (PhDOS). Compounds with PhDOS calculations were collected from the Materials Project (MP) and processed to obtain frequencies and PhDOS to calculate the total phonon band center, a proxy for ionic conductivity. Total phonon band centers were involved in a learning process using four ML algorithms (extra random trees (XT), gradient boosting (GB), extreme gradient boosting (XGB), and decision trees (DT)). The cross-validation results from the algorithms showed that the performance of the XT-model was superior and confirmed through density functional theory- (DFT-) based phonon calculations conducted on LiYO3, Li4CO4, LiNiO3, LiGeO3, and LiSiO3. The XT-model was then used to predict the total phonon band centers of new compounds where these had no phonon calculations beforehand. Experimental validation of the XT-model involved electrochemical impedance spectroscopy (EIS) measurements on two compounds: Li2CO3 from the high range and Li6PS5Cl from the low range. Additionally, LiBiO2 that is predicted to have low total phonon band center, according to the XT-model, was considered further to estimate its potential as solid electrolyte in LIBs.

Construction of a High-Performance Composite Solid Electrolyte Through In-Situ Polymerization within a Self-Supported Porous Garnet Framework

HighlightsA scalable tape-casting method produces self-supported porous Li6.4La3Zr1.4Ta0.6O12.Combining the in-situ polymerization approach, a composite solid electrolyte with superior electrochemical properties is fabricated.Solid-state Li|CSE|LiNi0.8Co0.1Mn0.1O2 cells show remarkable cyclability and rate capability.LiF-and B-rich interphase layers mitigate interfacial reactions, enhancing solid-state battery performance.

Long-stable lithium metal batteries with a high-performance dual-salt solid polymer electrolyte

A high-performance dual-salt solid polymer electrolyte, consisting of cross-linked NPGDA-VEC copolymer interpenetrated in a PVDF-HFP nanofiber matrix, with LiTFSI and LiBOB as Li+ sources, was prepared for lithium metal battery applications.

Ionic-liquid Functionalized Metal-organic Framework and Its High Performance Solid Electrolyte for Lithium-ion Conduction

Herein, we report a new type solid-state electrolyte based on MOF matrix and Li+ ionic liquid. By covalent bonding the Li+ ionic liquids (MIMS·LiTFSI) on the stable UiO-67 framework, the...

Vat Photopolymerization of Tantalum-Doped Li₇La₃Zr₂O₁₂ Electrolytes: A New Frontier in Solid-State Battery Design

The advancement of all-solid-state lithium batteries (ASSLBs) necessitates the development of high-performance solid electrolytes that can meet stringent requirements for ionic conductivity, chemical stability, and structural integrity. This study focuses...

Novel PEO-based composite solid electrolytes for All-Solid-State Li-S battery

Solid polymer electrolytes (SPEs) were investigated for several decades due to their good compatibility with electrodes. However, meeting the essential requirements for solid polymer electrolytes, including enhanced ionic conductivity, superior solubility with conductive lithium salts, and robust interface stability when in contact with a Li anode, remains a formidable challenge. In our work, we found that transition metal carbides (NiNbCeC) over mesoporous silica (SBA-15) can be filled into the Polyethylene Oxide (PEO) matrix to form composite solid electrolytes which can greatly improve the ionic conductivity of PEO. We investigate a series of transition metal carbides with varying mass ratios of Cerium (5%, 10%, and 20%) to fabricate All-Solid-State Li-S batteries (ASSLi-S). Our results demonstrate that different mass ratios of Cerium play a pivotal role in enhancing the ionic conductivity of the composite solid electrolytes, reducing impedance levels from 9150 O (20% Ce) to 4000 O (5% Ce) to 1730 O (10% Ce). At room temperature, the high initial specific capacity at 1C and reversible specific capacity after 100 cycles are 525 and 363 mAh/g, 605 and 403 mAh/g, 246.3 mAh/g and 63.28 mAh/g for 5% Ce, 10%, and 20%, respectively. Furthermore, long-term cycling tests of ASSLi-S cells at 0.5C reveal promising performance, with the cell containing 10% Ce solid electrolytes delivering an initial specific capacity of 1165.7 mAh/g and maintaining 335 mAh/g after 200 cycles. This represents a significant breakthrough, demonstrating that PEO-based solid electrolytes can achieve impressive electrochemical results at room temperature. SEM characterization was employed to assess the volume change in the solid electrolyte layer and elemental distribution of solid electrolyte materials through cross-sectional analysis. This analysis revealed that the failure modes of solid-state Li-S cells can also be attributed to the migration of sulfur elements from the cathode to the solid electrolyte layer during the cycling process. XRD was utilized to study the crystallinity of composite solid electrolytes. This study represents a significant stride in the progress of high-performance solid polymer electrolytes for All-Solid-State Li-S batteries, shedding light on the failure modes of such batteries. It underscores the potential of composites based on transition metal carbides in addressing crucial challenges for their practical implementation in Solid-State Lithium-Sulfur Batteries.

Li2GeS3: New Structural Type of Lithium Solid Electrolyte for All-Solid-State Batteries

Sulfide inorganic materials exhibit favorable qualities such as high ionic conductivity and mechanical softness, making them promising candidates for solid electrolytes in Li-ion all-solid-state batteries. Sulfide solid electrolytes exist in various structural types, including β-Li3PS4, Li10GeP2S12, argyrodite, Li4PS4I, Li7P3S11, and Li1.82SiP0.036S3. While these materials exhibit high ionic conductivities of up to ~10− 2 S cm− 1 at room temperature and possess mechanical softness, they also have limitations, such as a narrow electrochemical stability window and air instability, which can hinder their scalability. The electrochemical and air stabilities of a solid electrolyte (Li–M–S, where M = non-Li metal ions) are largely governed by its stability of crystal structure consisting of MSn polyhedra and Li ions. A material with a different crystal structure would show its distinct properties. However, despite extensive research, no single structure known to date has proven superior in all aspects of performance. Given the importance of crystal structure in developing high-performance solid electrolytes, exploring and identifying novel ion-conducting materials with unique crystal structures is imperative. Additionally, once a new structural type of material is discovered, its performance can be adjusted, enhanced, or optimized through various techniques, such as chemical substitution, morphology and particle size control, and surface coating. In this work, we discovered a new crystal structural type of Li-ion conductor Li2GeS3. It was first known in 2000 by Kanno et al., with only orthorhombic unit cell dimension reported. However, our study using ab initio structure determination techniques from powder X-ray diffraction data, similar to our previous works, unveiled its structure possessing a hexagonal P61 symmetry with lattice parameters of a = 6.80098(4) Å and c = 17.92827(11) Å, revealing a new type of crystal structure. Its structure is comprised of a distorted hexagonal close-packed arrangement of sulfur anions with three asymmetric metal atoms: Ge and Li2 are in tetrahedral cavities surrounded by sulfur atoms; Li1 is in the trigonal bipyramidal cavity. The material displayed an ionic conductivity of 1.63 × 10− 8 S cm− 1 at 303 K and 2.45 × 10− 7 S cm− 1 at 383 K. Bond valence energy landscape calculations revealed three-dimensional lithium diffusion pathways within the structure. These results suggest that Li2GeS3 is expected to be a host structure from which improved ionic conductors can be derived through appropriate chemical substitution.

Developing flexible and safety-reinforced 3D polymer electrolytes based on polyethylene oxide for solid-state lithium metal batteries

Poly (ethylene oxide) (PEO) is a potential material for solid-state lithium batteries. However, the present polymer electrolyte is hampered by its low ionic conductivity at room temperature and poor mechanical properties, which are significant barriers to its practical application. Herein, we designed a high-performance composite solid electrolyte (PLSP) by incorporating PEO, LiTFSI, and the solid plasticizer butanedinitrile into a 3D polyethylene terephthalate (PET) nonwoven framework with excellent mechanical properties. The PLSP achieved an impressive ionic conductivity of 5.45 × 10−4S cm−1, nearly 100 times higher than the original PEO electrolyte (6.1 × 10−6 S cm−1) at room temperature. Additionally, the optimized composite electrolyte exhibited an extended electrochemical window of up to 5.2 V vs. Li+/Li and a remarkable tensile strength exceeding 8.55 MPa. The stability of the lithium symmetrical battery's charge and discharge voltage platform after 400 h of cycling indicated favorable interfacial compatibility between the PLSP and lithium metal. Furthermore, the assembled Li/PLSP/LFP configuration displayed a discharge specific capacity of 131.4 mA h g−1 and a capacity retention of 93.8 % after 100 cycles at 1C at room temperature, highlighting the promising potential of the composite electrolyte for solid-state lithium batteries.

Insight into the Isoreticularity of Li-MOFs for the Design of Low-Density Solid and Quasi-Solid Electrolytes.

Isoreticularity in metal organic frameworks (MOFs) allows the design of the framework structure and tailoring the pore aperture at the molecular level. The optimal pore volume, long-range order of framework expansion, and crystallite size (grain size) could enable improving Li-ion conduction, thereby providing a unique opportunity to design high-performance solid and quasi-solid electrolytes. However, definitive understanding of the pore aperture, framework expansion, and crystallite size on the Li-ion conduction and its mechanism in MOFs remains at the exploratory stage. Among the different MOF subfamilies, Li-MOFs created by the isoreticular framework expansion using dicarboxylates of benzene, naphthalene, and biphenyl building blocks emerge as low-density porous solids with exceptional thermal stability to study the solid-state Li+ transport mechanisms. Herein, we report the subtle effect of the isoreticularity in Li-MOFs on the performance of solid and quasi-solid-state Li+ conduction, providing new insight into Li+ transport mechanisms in MOFs for the first time. Our experimental and computational results show that the reticular design on an isostructural extended framework structure with the optimal pore aperture and crystallite size can influence the Li+ conductivity, exhibiting comparable ionic conductivities to solid polymer electrolytes at room temperature. Aligning with the computational studies, our experimental absorption spectral traces of solid electrolytes prepared by encapsulating lithium salt (LiClO4) and the plasticizer (ethylene carbonate) with Li-MOFs confirm the participation of the free and bound states of Li+ in a pore filling-driven ion conduction mechanism. We postulate that porous channels of Li-MOFs aid free Li+ to move through the pores via a vehicle-type mechanism, in which the pore-filled plasticizer acts as a carrier for mobile Li+ while the framework's functional sites transport the bound state of Li+ via an ion hopping mechanism from one crystallite site to another. Our computational studies performed on the Li+ conduction pathway validated the postulated pore filling mechanism and confirmed the involvement of bridging complexes, formed by binding Li+ onto the framework's functional sites as well as to the pore-filled ethylene carbonates. The Li+ diffusion energy barrier profiles along with the respective conformational changes during the diffusion of Li+ in solid electrolytes prepared from Li-BDC MOF and Li-NDC MOF strongly support the cooperative movement of Li+ ions via ion hopping along the framework's edges and vehicle-type transfer, involving the pore-filled plasticizer. Our findings suggest that cooperative function of the optimal pore volume, framework expansion, and crystallite size play a unique role in Li-ion conduction, thereby providing design guidelines for the low-density solid and quasi-solid electrolytes.