Lithium Ion Transference Research Articles

On the Electrochemical Properties of Poly(Vinylidene Fluoride)/Polythiophene Blends Doped with Lithium‐Based Salt

AbstractIn this study, polymer blends of polythiophene (PTH) and poly(vinylidene fluoride) (PVDF) are investigated by focusing on their structural and electrochemical characteristics. These blends displayed immiscibility confirmed through field emission scanning electron microscopy (FE‐SEM) and interaction assessments. PTH's role as a plasticizer is evident, diminishing crystallinity. A rise in PTH level led to a lower glass transition temperature and a higher melting point, suggesting reduced intermolecular forces and increased polymer chain flexibility. Conversely, a dispersed phase presence elevated the melting point, restricting chain movement and crystallization. The thermal properties of blends are enhanced by increased PTH content. Applying the Vogel–Tammann–Fulcher model to ionic conductivity measurements, it observed a direct relationship between temperature and free volume, impacting conductivity and ion transport numbers. Certain materials exhibit increased activation energies, indicating substantial thermodynamic barriers to local motion. Higher PTH content within the PVDF matrix notably increased the lithium ion transfer number from 0.22 to 0.71, a change tied to the C–S–C structure of polythiophene. However, elevated PTH levels also led to diminished negative charge transfer and ionic conductivity in the PTH‐PVDF blend compared to pure PVDF, likely due to an ionic conduction hindrance.

Electric Field and Nanocontact Effects in Metal-Organic Framework/Li6.4La3Zr1.4Ta0.6O12 Ionic Conductors for Fast Interfacial Lithium-Ion Transport Kinetics.

The slow ion transport kinetics inside or between the nanofillers in composite polymer electrolytes (CPEs) lead to the formation of lithium dendrites for solid-state lithium batteries. To address the critical issues, CPEs (U@UNL) composed of a UIO-66@UIO-66-NH2 (U@UN) core-shell heterostructure and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) filler is designed. Due to the different band structures of the U@UN heterostructure, a built-in electric field is constructed to promote the transfer kinetics of carriers. Besides, the introduction of LLZTO facilitates the formation of a close nanometer contact interface between U@UN and LLZTO, reducing interface impedance and accelerating the lithium-ion transfer rate. As a benefit from the built-in electric field and the nanometer contact interface, U@UNL exhibits a wide electrochemical window of 5.17 V, a large lithium-ion transference number of 0.76, and a high ionic conductivity of 3.50 × 10-3 S cm-1. Consequently, the U@UNL electrolyte possesses excellent interfacial stability against Li metal after 1200 h at 0.1 mA cm-2 and shows a high specific capacity of 160.2 and 152.6 mAh g-1 at 0.5 and 1 C, respectively. This work proposes a complete strategy for building high-performance solid-state lithium batteries by a built-in electric field and nanometer contact interface between U@UN and LLZTO.

Recyclable cellulose-based vitrimer electrolytes for lithium ion batteries

Cellulose as polymer electrolytes in lithium-ion batteries (LIBs) has a number of advantages such as low cost, readily available, abundant, environmentally friendly, and contains electron-donating groups within its structure. Beside, vitrimers are a novel class of polymer materials made of dynamic covalent networks that can undergo bond-exchange processes. Beyond cellulose's special qualities, cellulose-based vitrimer production is highly desired for enhancing electrolytes mechanical qualities, thermal stability, cyclability, and ionic conductivity. In this study, cellulose-based vitrimeric polymer electrolytes are prepared. At first, poly(glycidyl methacrylate-co-methyl acrylate) by different ratios of comonomers is prepared and then cellulose is cross-linked by prepared copolymers. Prepared vitrimers are recycled four steps through transesterification reaction and as-prepared and recycled crosslinked celluloses are used as gel polymer electrolytes (GPEs). The results showed the best ionic conductivity of as-prepared samples in order of 10−4 S/cm whereas ionic conductivity increased to order of 10−3 S/cm for recycled samples. Also, high lithium-ion transfer number of >0.8 was achieved for recycled samples. All as-prepared and recycled electrolytes had excellent electrochemical stability window (> 5 V). Also, improved specific capacity (>178 mA h g−1 with capacity retention upper than 90 % after 200 cycles at 0.2C of LiCoO2/GPEs/Gr) was attained.

Synergistic Dual Electrolyte System of LATP and In‐ Situ Solod‐State PDOL System and its Improvement on the Performance of NCM811 Batteries

Abstract1,3‐Dioxolane (DOL) can undergo in‐situ polymerization in batteries to form solid‐state organic electrolyte PDOL. When applied to NCM811||Li battery system, PDOL electrolyte helps optimize the contact and interface stability between electrolyte and electrodes. This study explores the effects of PDOL with PE separators coated with Li1.3Al0.3Ti1.7(PO4)3(LATP) on the performance of NCM811||Li batteries. 2,2,2‐trifluoroethyl phosphite (DETFPi), was mixed with DOL at a 1 : 35 mass ratio. Then, LiBF4 was used to initiate in‐situ polymerization and thereby obtained DETFPi‐PDOL electrolyte after 24 h at room temperature. The composite electrolyte exhibits enhanced ion conductivity (1.59×10−4 S cm−1), high lithium ion transference number (0.78), wide electrochemical stability window (4.53 V), and high critical current density (2.2 mA cm−2). Li||PDOL@LATP||Li battery shows extremely low overpotential (35 mV) after a constant current stable cycle of 500 h at 1.0 mA cm−2. After 500 cycles at 1 C, the remaining capacity is 153.9 mAh g−1 with a capacity retention of 82.1 % in NCM811||PDOL@LATP||Li batteries. This indicates that the LATP coating on the surface of the PE separator plays an important role in optimizing the performance of DETFPI‐PDOL electrolyte batteries. LATP and DETFPI‐PDOL are effective in improving the cycling stability, rate performance, and interface state of NCM811 batteries.

Organic-Inorganic Dual-Network Composite Separators for Lithium Metal Batteries.

The suboptimal ionic conductivity of commercial polyolefin separators exacerbates uncontrolled lithium dendrite formation, deteriorating lithium metal battery performance and posing safety hazards. To address this challenge, a novel organic-inorganic composite separator designed is prepared to enhance ion transport and effectively suppress dendrite growth. This separator features a thermally stable, highly porous poly(m-phenylene isophthalamide) (PMIA) electrospun membrane, coated with ultralong hydroxyapatite (HAP) nanowires that promote "ion flow redistribution." The synergistic effects of the nitrogen atoms in PMIA and the hydroxyl groups in HAP hinder anion transport while facilitating efficient Li+ conduction. Meanwhile, the optimized unilateral pore structure ensures uniform ion transport. These results show that the 19µm-thick HAP/PMIA composite separator achieves remarkable ionic conductivity (0.68mS cm-1) and a high lithium-ion transference number (0.51). Lithium symmetric cells using HAP/PMIA separators exhibit a lifespan exceeding 1000h with low polarization, significantly outperforming commercial polypropylene separators. Furthermore, this separator enables LiFePO4||Li cells to achieve an enhanced retention of 97.3% after 200 cycles at 1C and demonstrates impressive rate capability with a discharge capacity of 72.7mAh g-1 at 15C.

Polyacrylonitrile and aluminum metal dual functionalization interconnected network for superior lithium storage in silicon anode

Currently, silicon-based anode is one of the most promising anode materials that can be applied in next-generation lithium-ion batteries. However, the high activity of the electrode–electrolyte interface and low electronic conductivity of Si anode during the cycling process greatly limits its large-scale application. Aluminum (Al) is the metallic current collector known to promote electronic conductivity and lithium-ion transfer at low cost. However, to our knowledge, scalable interface engineering incorporating Al with carbonized polymer has not been reported. Herein, a polyacrylonitrile (PAN) and aluminum metal dual functionalization interconnected network is achieved via a simple sol-gel method followed by high-temperature calcination to obtain a stable solid electrolyte interphase (SEI) while allowing fast Li+ transmission. The calculated diffusion energy barrier for lithium ions in Al is 0.2198 eV, significantly lower than that in Cu and Fe. Benefiting from the enhanced interfacial protection and kinetics of Si with polyacrylonitrile/Al, the prepared Si@Al@CPAN anode exhibits high lithium storage capacity (2034.90 mAh/g after 150 cycles at 0.84 A/g). At the same time, the prepared Si@Al@CPAN anode outperforms the pure Si anode in rate performance at 12.6 A/g (1116.75 mAh/g vs. 2.84 mAh/g). The present work delivers new design ideas for high-performance Si anode with a multi-functionalization interface.

Synergistic implementation of efficient adsorption-diffusion-conversion in lithium-sulfur batteries via built-in electric field constructed by transition metal selenides

The adsorption of lithium polysulfides (LiPSs), the transport of lithium ions, and the redox kinetics collectively play pivotal roles in determining the application of lithium-sulfur (Li-S) batteries. Herein, a defect-rich p-Co3Se4/n-ZnSe p-n junction (ZCSNC) is engineered by chemical vapor deposition (CVD)-selenation. The n-type semiconductor ZnSe and the p-type semiconductor Co3Se4 contained in ZCSNC effectively anchor LiPSs and promote the catalytic reaction kinetics through synergistic effects, respectively. Meanwhile, the presence of heterogeneous interfaces in the p-n junction and the difference in work functions spontaneously form a built-in electric field, which promotes the transport and transfer of lithium ions and LiPSs. Therefore, the ZCSNC functional material contributes to improving the electrochemical performance of Li-S batteries through the process of adsorption-diffusion-conversion. The Li-S cells with ZCSNC-modified separators show excellent rate performance (741.1 mAh/g at 5C) and long-lasting cycling performance (only 0.04 % capacity decay per cycle over 1000 cycles). Notably, the ZCSNC still has excellent rate discharge capacities (683.9 and 649.7 mAh/g at 2C, respectively) at high sulfur loading and low temperature of 0 °C. This study illustrates that a p-n junction containing a built-in electric field can effectively modulate the kinetics of redox reactions of LiPSs through synergistic interactions.

Lithium p-toluenesulfinate-coated poly(imide) separators for enhanced safety and electrochemical performances of lithium-ion batteries

Increasing the energy density of lithium-ion batteries enhances their applicability; however, ensuring their safety remains a critical issue in the energy society. Herein, we report the development of a lithium p-toluenesulfinate (PTSL)-coated polyimide (PI) separator with improved safety and electrochemical performance during cycling. It is anticipated that integrating PTSL particles into the PI separator will mitigate the risk of internal short circuits by clogging the porous structure of the PI separator and enhance the interfacial stability of the electrode materials. The PTSL is expected to act as an effective component of protective layers, physically separating the cathode from direct contact with electrolytes. The PTSL-embedded PI separator regulated the porous structure inherent to the PI separator, thereby enhancing its physical and thermal properties, such as improved wetting characteristics (evidenced by higher ionic conductivities and lithium-ion transference numbers) and thermal behaviors (reduced shrinkage and more stable thermal decomposition behaviors). During cycling, the cells with the PTSL-coated PI separator demonstrated increased cycling retention compared to the cells with graphite/NCM811 electrodes because the additional PTSL-based protective layers mitigated the electrolyte decomposition upon cycling.

Lamellar COF solid-state electrolytes for robust ambient-temperature lithium-ion transfer enhanced by PEI-driven channel alignment

Ionic covalent organic framework (COF) lamellar membranes are the alternative materials as promising Li+ conductors for all-solid-state lithium batteries. However, COF lamellar membrane suffers from poor structural stability and inevitable cross-layer transfer resistance due to the weak interaction at interface of adjacent nanosheets. Herein, a lamellar polymer-threaded ionic COF (PEI@TpPa-SO3Li) composite electrolyte with single Li+ conduction was prepared by assembling lithium sulfonated COF (TpPa-SO3Li) nanosheets and then threading them with polyethyleneimine (PEI) chains. It reveals that the threaded PEI chains induce the oriented permutation of pore channel of PEI@TpPa-SO3Li electrolyte through electrostatic interaction between –NH2/−NH− and –SO3Li groups. This enables the construction of continuous and aligned –SO3− … Li+ … −NH2/−NH− pairs along pore channels, which act as efficient Li+ conducting sites and afford high Li+ hopping conduction (1.4 × 10−4 S cm−1 at 30 °C) with a high Young's modulus of 408.7 MP and wide electrochemical stability window of 0∼4.7 V. The assembled LiFePO4||Li and LiNi0.8Mn0.1Co0.1O2||Li half-cells achieve high discharge capacities of 155.0 mAh g−1 and 167.2 mAh g−1 at 30 °C under 0.2 C, respectively, with high capacity retention of 98% after 300 cycles. This study provides an alternative route to highly ion-conductive lamellar porous electrolytes for high-performance energy devices.

Biomimetic Channels Design in Metal-Organic Framework Enabling Highly Lithium-Ion Conduction for Lithium-Metal Batteries.

Solid-state electrolytes (SSEs) based on metal-organic frameworks (MOFs) are an ideal material for constructing high-performance lithium metal batteries (LMBs). However, the low ion conductivity and poor interface contact (especially at low temperatures) still seriously hinder its further application. Herein, inspired by the Na+/K+ conduction in biology systems, a series (NH2, OH, NH-(CH2)3-SO3H)-modified MIL-53-X as SSEs is reported. These functional groups are similar to anions suspended in biological ion channels, partially repelling anions while allowing cations to be effectively transported through pore channels. Subsequently, MIL-53-X with hierarchical pore structure (H-MIL-53-X) is obtained by introducing lauric acid as a regulator, and then the effects of structural design and morphology control on its performance are explored. The conductivity of H-MIL-53-NH-SO3Li with multi-level pore structure and modified by sulfonic acid groups reached 2.2×10-3Scm-1 at 25°C, lithium-ion transference number of 0.78. Besides, the H-MIL-53-NH-SO3Li still has an excellent conductivity of 10-4Scm-1 at -40°C. Additionally, LiFePO4/Li batteries equipped with H-MIL-53-NH-SO3Li SSEs could operate stably for over 200 cycles at 0.1C. The strategy of combining structural and morphological design of MOFs with biomimetic ion channels opens new avenues for the design of high-performance SSEs.

An oxygen-defective framework with intensified Lewis acidity reinforcing composite electrolyte for all-solid-state lithium metal batteries

Composite solid electrolytes (CSEs) are considered a key component of all-solid-state lithium metal batteries, regarded as the next generation of energy storage devices with high energy density and long operating life. Numerous studies have shown that the performance of CSEs is closely related to the structure of the fillers and the interactions between fillers and other components, including polymer matrices and lithium salts. To create more abundant interaction sites in CSEs, we designed a nanostructured framework with intensified Lewis acidity (PVDF-HFP/Ov-CeO2) for poly(ethylene) oxide (PEO) electrolyte (denoted as Ov-CeO2-CSE). The mystery concerning the nanostructured framework adsorbs with PEO polymer and dissociates TFSI− and its influence on the electrochemical lithium ions storage performance is meticulously revealed by coupling experimental with theoretical results. Impressively, the prepared Ov-CeO2-CSE shows improved ionic conductivity (1.76 × 10−4 S cm−1 at 30 °C) and a good lithium-ion transference number (0.49). The Li||Ov-CeO2-CSE||Li cell exhibits great cyclability over 3,500 h at a current density of 0.1 mA cm−2 (areal capacity: 0.1 mAh cm−2, 60 °C). Furthermore, the Li||Ov-CeO2-CSE||LFP cell delivers a high specific capacity of 154.6 mAh g−1 at a current density of 0.5 C, stably maintained over 500 cycles. This work provides a potential strategy for designing multifunctional frameworks by efficient interfaces to build advanced all-solid-state lithium metal batteries.

Diethylenetriaminepentaacetic Acid-based Conducting Solid Polymer Electrolytes Impede Lithium Dendrites and Impart Antioxidant Capacity in Lithium-Ion Batteries.

In the development of lithium-ion batteries (LIBs), cheaper and safer solid polymer electrolytes are expected to replace combustible organic liquid electrolytes to meet the larger market demand. However, low ionic conductivity and inadequate cycling stability impede their commercial viability. Herein, a novel flexible conducting solid polymer electrolytes (CSPEs) based on polyvinyl alcohol (PVA) and ion-polarized diethylenetriaminepentaacetic acid (P-DETP) is developed for the first time and applied in LIBs. PVA and P-DETP form a compact polymer network through hydrogen bonding, enhancing the thermomechanical stability of CSPE while restricting the migration of larger anions. Furthermore, density functional theory calculations confirm that P-DETP can facilitate the dissociation of Li+-TFSI- via electrostatic attraction, resulting in increased mobility of lithium ions. Additionally, P-DETP contributes to the formation of a stable electrode-electrolyte interface layer, effectively suppressing the growth of lithium dendrites and improving antioxidant capacity. These synergistic effects enable CSPE to exhibit remarkable properties including high ionic conductivity (2.8 × 10-4 S cm-1), elevated electrochemical potential (5.1V), and excellent lithium transference number (0.869). Notably, the P-DETP/LiTFSI CSPE demonstrates stable performance not only in LiFePO4 batteries but also adapts to high-nickel ternary LiNi0.88Co0.06Mn0.06O2 cathode, highlighting its immense potential for application in high energy density LIBs.

Oriented Crystal Growth of Li0.33La0.557TiO3 Nanowire Induced by One-Dimensional Polymer Sheath toward Rapid Lithium-Ion Transfer.

Superionic conductor-based solid-state electrolytes with preferred crystal structures hold great promise for realizing ultrafast lithium-ion (Li+) transfer, which is urgently desired for all-solid-state lithium batteries. However, the precise control of crystal growth of superionic conductors is still challenging since the crystals always spontaneously grow to disordered structures with the lowest internal energy to ensure thermodynamic stability. Herein, a coaxial nanowire with a polyvinylpyrrolidone (PVP) sheath and a Li0.33La0.557TiO3 (LLTO) precursor core (PVP/LLTO-caNW) is prepared through coaxial electrospinning, followed by sintering into LLTO nanowire with an oriented crystal structure (LLTO-caNW). We demonstrate that the one-dimensional PVP sheath as a sacrificial layer generates uniform and the strongest adsorption ability on the (110) phase among different LLTO crystal planes, which induces the crystal to preferentially grow along the c-axis (the fastest Li+ transfer direction) during the nucleation and growth processes. As a result, the prepared LLTO-caNW displays an ultrahigh bulk ionic conductivity of 3.13 × 10-3 S cm-1, exceeding most LLTO crystals and approaching the theoretical conductivity. Meanwhile, the oriented crystal growth imparts to LLTO-caNW significantly reduced grain boundary resistance, and the grain-boundary conductivity reaches up to 1.09 × 10-3 S cm-1. This endows the composite solid electrolyte with high ionic conduction performance and superior cycle stability in the assembled all-solid-state lithium battery.

In Situ Fabrication of Solvent-Free Solid Polymer Electrolytes for Wide-Temperature All-Solid-State Lithium Metal Batteries.

All-solid-state lithium metal batteries (ASSLMBs) have been regarded as promising candidates to settle the safety issues of liquid electrolytes for rechargeable lithium batteries. However, the currently reported gel polymer electrolytes still have flammable liquid solvents, thus leading to the potential safety hazard. Here, solvent-free deep eutectic solid polymer electrolytes (SPEs) are designed and fabricated via an in situ polymerization, which are composed of a poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) electrospun membrane, succinonitrile (SN), poly(ethylene glycol) diacrylate (PEGDA200, Mn = 200 g mol-1), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium difluoro(oxalato)borate (LiDFOB). The deep eutectic solvent (DES) with SN/LiTFSI provides a superior room-temperature ionic conductivity, while the PEGDA200 precursor acts as cross-linking network to form SPEs under thermal initiation for free radical polymerization, and LiDFOB can form a stable solid electrolyte interface (SEI) layer. The PVDF-HFP electrospun membrane with a three-dimensional nanofibrous network structure for SN/PEGDA200/LiTFSI/LiDFOB SPEs exhibits a wide electrochemical stability window, high lithium-ion transference number, and good compatibility with the lithium metal anode. Furthermore, the obtained SPEs assembled with Li//LiMn0.6Fe0.4PO4, Li//LiFePO4, and Li//LiNi0.8Co0.1Mn0.1O2 asymmetric cells show excellent cycling performance and rate capability at a wide temperature. This strategy provides a promising path in designing high-energy-density ASSLMBs for practical application.

Bimetal Fluorides with Adjustable Vacancy Concentration Reinforcing Ion Transport in Poly(ethylene oxide) Electrolyte.

The poor ambient ionic transport properties of poly(ethylene oxide) (PEO)-based SPEs can be greatly improved through filler introduction. Metal fluorides are effective in promoting the dissociation of lithium salts via the establishment of the Li-F bond. However, too strong Li-F interaction would impair the fast migration of lithium ions. Herein, magnesium aluminum fluoride (MAF) fillers are developed. Experimental and simulation results reveal that the Li-F bond strength could be readily altered by changing fluorine vacancy (VF) concentration in the MAF, and lithium salt anions can also be well immobilized, which realizes a balance between the dissociation degree of lithium salts and fast transport of lithium ions. Consequently, the Li symmetric cells cycle stably for more than 1400 h at 0.1 mA cm-2 with a LiF/Li3N-rich solid electrolyte interphase (SEI). The SPE exhibits a high ionic conductivity (0.5 mS cm-1) and large lithium-ion transference number (0.4), as well as high mechanical strength owing to the hydrogen bonding between MAF and PEO. The corresponding Li//LiFePO4 cells deliver a high discharge capacity of 160.1 mAh g-1 at 1 C and excellent cycling stability with 100.2 mAh g-1 retaining after 1000 cycles. The as-assembled pouch cells show excellent electrochemical stability even at rigorous conditions, demonstrating high safety and practicability.

Core-shell Ru@Co2P synergistic catalyst as polysulfides adsorption-catalytic conversion mediator with enhanced redox kinetics in lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) have emerged as the research hotspot due to their compelling merits, including high specific capacity (1675 mAh g−1), theoretical energy density (2600 Wh kg−1), environmental friendliness, and economic advantages. However, challenges still exist for further application due to their inherent issues such as the natural insulation, shuttle effect, and volume expansion of sulfur cathode during the continuous cycle processes. These factors obstruct the lithium ions (Li+) transfer process and sulfur utilization, resulting in significant impedance and inducing inferior battery performance. Herein, the core–shell nanocube anchoring ruthenium atoms and dicobalt phosphate (Ru@Co2P@NC) were fabricated as the effective catalyst and inhibited barrier for LSBs. On the one hand, the core–shell structure offers numerous channels to expedite Li+ diffusion. On the other hand, ruthenium (Ru) and dicobalt phosphate (Co2P) active sites facilitate the chemical capture of lithium polysulfides (LiPSs), accelerating sluggish kinetics. Ru@Co2P@NC modified cells not only exhibited a high initial specific capacity (1609.35 mAh g−1) at 0.5C and enduring stability with high specific capacity retention of 906.60 mAh g−1 at 0.5C after 400 cycles but also possessed low capacity attenuation rate of 0.07 % per cycle after 600 cycles (1C, Sulfur loading: 1.2 mg). Interestingly, the modified cells demonstrated a high specific capacity and long-cycle stability with high sulfur loading (from 1.984 to 3.137 mg), which provides a promising research approach for high-performance LSBs.

Glass-ceramics and molybdenum doping synergistic approach for Nasicon-type solid-state electrolytes

Advancing energy density, enabling lithium metal anodes, and ensuring unparalleled safety and operational reliability in lithium batteries hinge on advancing inorganic solid-state electrolytes. To overcome current impediments, we present an innovative approach that integrates glass-ceramics with a pioneering new Nasicon strategy involving molybdenum doping. In the conducted study, a series of 14Li2O-9Al2O3-38TiO2-(39-x)P2O5-xMoO3 glasses, denoted as LATPMox, along with their corresponding glass-ceramics (LATPMox-GC), have exhibited a promising characteristic as solid electrolytes. X-ray diffraction (XRD) analysis confirms the formation of the novel Mo-doped Nasicon phases in the glass-ceramics, as validated by Rietveld refinement. Examination of the crystallization kinetic behavior of the glasses reveals a three-dimensional nucleation process with spherical particle growth, featuring an activation energy of 165 kJ mol−1. Transmission Electron Microscopy TEM characterization aligns crystallization behavior with crystallite and distribution within the glass matrix, resulting in a compact and dense microstructure. The structural properties of the resultant phases are examined through FT-IR, Raman spectroscopy, and TEM-SEAD analysis. Vickers indentation tests were employed to assess the microscopic fracture toughness, and both the glass and glass-ceramics materials demonstrated favorable mechanical performance. Optical characterization using UV–visible absorption highlights the reduction of Mo6+ to Mo5+, likely occupying tetrahedral sites within the crystalline lattice. Impedance spectroscopy measurement showcases the effective promotion of ionic conductivity following Mo doping, reaching a total conductivity value of 5.50 × 10−5 Ω−1 cm−1 along with a high lithium transference number of 0.99 at room temperature for LATPMo2.6-GC glass-ceramic. This value is larger than that of many other glass-ceramics as well as that of the well-known lithium phosphorous oxy-nitride LiPON solid electrolyte whose ionic conductivity at RT is around 2 × 10−6 Ω−1 cm−1.

Thickness regulation of electric double layer via electronegative separator to realize High-Performance Lithium-Metal batteries

Lithium metal anode is considered as a promising electrode material for next-generation energy storage systems due to their high theoretical capacity and a low redox potential. However, the uncontrollable growth of Li dendrites severely hindered its practical application. Separators, a vital component in batteries, offer a promising solution to this issue, which can regulate the transport of lithium ions (Li+) and guide the homogenous deposition of Li+. In this study, a three-dimensional porous structure coating layer is constructed on the surface of the commercial polyethylene separator by polymer-induced phase separation (PIPS) and UV-induced cross-linking reactions. The incorporation of synthetized sulfonated SiO2 particles (S-SiO2) enable the successful construction of a negatively charged separator (PE@S-SiO2) based on negatively charged moieties on the surface, which compresses the thickness of the electric double layer (EDL) to optimize the Li+ transport dynamics and suppress dendritic growth. The resulting PE@S-SiO2 separator displays superior electrolyte wettability, much higher thermal resistance, high lithium transference number (0.86), and ionic conductivity (1.15 mS/cm). Consequently, when assembled into lithium metal batteries, the negatively charged separator endows stable cycling over 800 h at a current density of 1 mA cm−2.

Metal-organic frameworks Derived frustrated Lewis acid-base pairs accelerate ion dynamics to dendrite-free solid-state lithium batteries

The Poly(ethylene oxide) (PEO)-based polymer electrolytes exhibit the drawbacks of high crystallinity and low ionic conductivity (<10−5 S m−1), which significantly restrict their application in solid-state lithium metal batteries. This study presents the bismuth metal-organic frameworks (MOFs) as a PEO-based electrolyte filler, incorporating frustrated Lewis acid-base pairs, which is formed in-situ through the coordination of ellagic acid (EA) and bismuth ions (Bi3+). The simultaneous presence of Lewis acids (unsaturated Bi3+) and bases (free nitrate, NO3−) in the MOFs, which effectively transfers and transports the lithium ions through the synergistic interaction based on the polymer matrix and the lithium salts, resulting in the high durable solid-state lithium batteries. Meanwhile, NO3− can further promote the dissociation of lithium ion (Li+) and the formation of inorganic solid electrolyte interfaces (SEIs) with lithium metal, which is conducive to the dynamic repair of SEIs. Characterizations and calculations show that Bi-MOFs promote the increase of composite ionic conductivity (6.4 × 10−4 S cm−1, 60 °C) and lithium transference number (0.52, 60 °C). At a current density of 0.4 mA cm−2, the assembled Li–Li symmetric battery can be continuously cycled for more than 500 h. This strategy opens a new window for improvement of solid-state electrolyte performance.

Chelated Metal-Organic Frameworks for Improved the Performance of High-Nickel Cathodes in Lithium-Ion Batteries.

Lithium-ion batteries have gained widespread use in various applications, including portable devices, electric vehicles, and energy storage systems. High Ni cathode, LiNixCoyMnzO2 (NCM, x ≥ 0.8, x + y + z = 1), have garnered significant attention owing to their high energy density. However, the limited lithium-ion transfer rate and transition metal cross-talk to anode pose obstacles to further improvement of electrochemical performance. To tackle these challenges, metal-organic frameworks (MOFs) with chelating agents are employed as additive materials for electrode. MOFs with chelating agents offer three key attributes: (1) Effective mitigation of transition metal cross-talk to the anode, (2) Partial desolvation of Li+ ions through MOF pores, and (3) Immobilization of anions via metal sites in the MOF. Leveraging these advantages, the chelating MOF-modified NCM cathode demonstrates reduced charge transfer resistance, both in their pristine and cycled states. In addition, they exhibit significantly improved lithium-ion diffusion coefficients after 100 cycles. These findings underscore the potential of MOFs with chelating agents as promising additive materials for enhancing the performance of LIBs.