Quasi-solid State Electrolyte Research Articles

Improvement in the performance of indium free dye sensitized solar cell by the use of polyaniline composite

The photovoltaic study of the fabricated dye sensitized solar cells is revealed in this paper. To provide indium free approach, fluorine doped tin oxide (FTO) and aluminium doped zinc oxide (AZO) glass substrate were used as charge collectors for counter electrodes and photoanode respectively. Also, a novel and natural mixed dye was used as sensitizer and mixture of doped polymer (polyaniline with metallic oxides of tin, vanadium and cerium) and iodide-triiodide couple was utilized as electrolyte for the cell. Optical band gap and light absorption performance of dyes were studied by ultraviolet-visible (UV-vis) spectroscopy. Surface morphology and elemental composition of polymer composites was studied using scanning electron microscopic (SEM) with energy dispersive X ray (EDX) analysis. Phase analysis of the composites was determined by X-ray diffraction and thermal behavior with the help of thermo gravimetric analysis (TGA). Photovoltaic characteristics (I-V) and induced photon to current efficiency (IPCE) measurements were also investigated. Highest IPCE of 17.7% was observed when polyaniline was doped with oxide of vanadium. Hence an efficient, green, indium free and novel cell is fabricated by the usage of different charge collector substrate, natural dye sensitizer and quasi solid-state electrolyte.

Bioinspired Design of Vascularized Glassy Metal-Organic Frameworks Electrolyte for Quasi-Solid-State Sodium Batteries

Quasi-solid-state electrolytes (QSSEs) are regarded as the most promising alternative for next-generation battery technology due to the compatibility of assemble process and high safety. However, the rational design of solid hosts to ensure the high-efficiency utilization of tiny liquid electrolytes and the deep understanding of ion transport mechanisms at heterogeneous structures are still challenging. Herein, inspired by the ion transport in biological blood vessels, we propose a nitrogen vacancy modified glassy metal-organic framework (MOF) as Na-ion QSSEs host, which shows multilevel ions transport channels, isotropy property, and no grain boundaries. The vascularized glassy MOF enables the reasonable distribution of a small amount of solvent (14 wt.% (solvent as a percentage of QSSE by mass)) in both macro and microenvironments with specific functions, boosting the fast Na-ion transport (1.18 × 10−4 S cm–1, 30°C) and Na-ion transfer number (0.92), and homogeneous Na-ion nucleation/propagation even at -50°C. Meanwhile, the quasi-solid-state Na||Na3V2(PO4)3/C cell demonstrates excellent rate capability and long cycling stability (0.0288% capacity decay per cycle after 500 cycles). The bioinspired design of glassy MOF will shed light on new avenues for the development of energy storage and conversion.

Porous Organic Cage-Based Quasi-Solid-State Electrolyte with Cavity-Induced Anion-Trapping Effect for Long-Life Lithium Metal Batteries

Porous organic cages (POCs) with permanent porosity and excellent host–guest property hold great potentials in regulating ion transport behavior, yet their feasibility as solid-state electrolytes has never been testified in a practical battery. Herein, we design and fabricate a quasi-solid-state electrolyte (QSSE) based on a POC to enable the stable operation of Li-metal batteries (LMBs). Benefiting from the ordered channels and cavity-induced anion-trapping effect of POC, the resulting POC-based QSSE exhibits a high Li+ transference number of 0.67 and a high ionic conductivity of 1.25 × 10−4 S cm−1 with a low activation energy of 0.17 eV. These allow for homogeneous Li deposition and highly reversible Li plating/stripping for over 2000 h. As a proof of concept, the LMB assembled with POC-based QSSE demonstrates extremely stable cycling performance with 85% capacity retention after 1000 cycles. Therefore, our work demonstrates the practical applicability of POC as SSEs for LMBs and could be extended to other energy-storage systems, such as Na and K batteries.

Operando Fabricated Quasi-Solid-State Electrolyte Hinders Polysulfide Shuttles in an Advanced Li-S Battery

Lithium-sulfur (Li-S) batteries are a promising option for energy storage due to their theoretical high energy density and the use of abundant, low-cost sulfur cathodes. Nevertheless, several obstacles remain, including the dissolution of lithium polysulfides (LiPS) into the electrolyte and a restricted operational temperature range. This manuscript presents a promising approach to addressing these challenges. The manuscript describes a straightforward and scalable in situ thermal polymerization method for synthesizing a quasi-solid-state electrolyte (QSE) by gelling pentaerythritol tetraacrylate (PETEA), azobisisobutyronitrile (AIBN), and a dual salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium nitrate (LiNO3)-based liquid electrolyte. The resulting freestanding quasi-solid-state electrolyte (QSE) effectively inhibits the polysulfide shuttle effect across a wider temperature range of −25 °C to 45 °C. The electrolyte’s ability to prevent LiPS migration and cluster formation has been corroborated by scanning electron microscopy (SEM) and Raman spectroscopy analyses. The optimized QSE composition appears to act as a physical barrier, thereby significantly improving battery performance. Notably, the capacity retention has been demonstrated to reach 95% after 100 cycles at a 2C rate. Furthermore, the simple and scalable synthesis process paves the way for the potential commercialization of this technology.

Multifunctional quasi-solid state electrolytes based on “reverse” plant cell structure for high-performance lithium metal batteries

Quasi-solid state electrolytes (QSSEs) combine the benefits of both solid and liquid electrolytes, making them promising for high-performance lithium metal batteries (LMBs). However, developing QSSEs that achieve high ionic conductivity, a continuous electrode/electrolyte interface, and significant mechanical robustness remains challenging. Plant cell walls provide mechanical strength, while the cell membrane offers excellent material transport capabilities, making them effective models for quasi-solid electrolytes. However, using plant cells as a model can result in poor interface contacts due to the rigid components on the exterior. To address this, a “reverse” plant cell QSSE with a multifunctional bilayer architecture has been proposed. The outer layer acts as a functional reaction interface to enhance Li⁺ transmission, improve interfacial contact, and significantly reduce interfacial impedance. Meanwhile, the inner layer is designed to provide mechanical robustness and shorten ion transport distances. The QSSE inspired by “reverse” plant cells has an ionic conductivity of 4.26 × 10−3 S cm−1, a Li+ transference number (tLi+) of 0.91, and an electrochemical stability window (ESW) of 4.83 V. Li−LiFePO4 (LFP) full cells based on the “reverse” plant cell QSSE can maintain a cycling capacity of 137 mAh g−1 after 500 cycles at 1 C, with 95 % retention.

Flexible ionic liquid aided “LAGP in PVDF” quasi-solid-state electrolyte for high performance and stable Li metal batteries

The NASICON-type ceramic Li1·5Al0.5Ge1.5(PO4)3 (LAGP) electrolyte has been proposed as the most competitive candidates of electrolyte materials toward solid-state Li metal batteries (LMBs) by reason of its high ionic conductivity, cyclic stability under extreme temperatures and wide voltage window. However, poor interface contact, high interfacial resistance and intractable mechanical properties greatly limit its practical applications. In this work, an inorganic-polymer “LAGP in PVDF” quasi-solid-state electrolyte (QSSE) is developed via solution casting method, in which pyr14TFSI ionic liquid (IL) and LiTFSI are combined as functional wetting interface. Benefiting from the coherent interaction of LAGP nanoparticles incorporated into the polymer matrix, and inherent protection of IL, the overall performance of the optimized QSSE include thermal stability, dense structure, flexibility and electrochemical properties. The XRD, SEM, XPS tests demonstrate that the IL using as a solid/electrolyte modified interlayer can enhance Li+ transport, interfacial infiltration and homogenize lithium deposition. The LiFePO4|PL-25LAGP|Li solid-state battery presents an excellent circulation performance under ambient temperature, which displayed an initial discharge specific capacity of 146.8 mAh g−1 at 0.5C and capacity retention of 96.25 % after 150 cycles. The flexibility PL-LAGP CSE shows superior safety and greater development potential for the “LAGP in PVDF” composite electrolyte in solid state LMBs.

Unleashing the potential of Cu1+/2+ blended quasi-solid-state electrolytes for long-term stability of dye-sensitized solar cells

The pursuit of long-term stability in dye-sensitized solar cells (DSSCs) is crucial for their commercialization. One of the main challenges in achieving long-term stability is the electrolyte. However, concerns about efficiency and long-term stability have hindered the transition of DSSCs from the laboratory to industry and outdoor applications. A recent innovation in this field involves the use of blend combinations of copper redox mediators with nanoparticles in a polymer electrolyte medium, which offers significant advantages. Herein, we introduce a new metallic oxide nano-structure to enhance conductivity and reduce resistivity in a quasi-solid-state electrolyte (QSSE) medium. A comparative study was conducted between synthesised nanoparticles with a copper redox couple ([Cu(ptpbi)2]1+/2+) and an organic additive (MPP) in blend bio-polymer electrolytes. The inclusion of nanoparticles had a positive impact on the light-to-electricity conversion efficiency, which reached 6.19 %, higher than that of the device without nanoparticles. The addition of nanoparticles to the QSSE strongly altered the energy level alignments, reduced recombination at the electrode-redox electrolyte interfaces, and increased the dark exchange current density. The electrical surface-state modifications induced by the diffusion of Cu1+ metal ions in the electrolyte played a significant role in controlling aggregation and charge transfer kinetics.

Rational design and elucidation of interfacial dynamics in PMMA/PVDF compatibilized blends through solution blending for stable quasi-solid-state dye-sensitized solar cells

In the photovoltaic market, the widespread adoption of traditional dye-sensitized solar cells (DSSCs) faces obstacles due to inherent stability challenges. The solution to these issues involves replacing liquid electrolytes with quasi-solid electrolytes. In this work, quasi-solid state electrolytes were synthesized by employing a polymer blend and inorganic salt. The polymeric blends, comprising polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF), were meticulously prepared through the solution blending technique. The investigation of blend compatibility, crystallinity, and stability involved analyses through differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-degradation assessments, respectively. The findings indicated that the concentration of ingredients significantly influenced the compatibility, crystallinity, and stability of the blends. The compatibilized blend was employed in crafting polymer gel electrolytes (PEGs), demonstrating that both the concentration and type of salts significantly influence the ionic conductivity of PEGs. The highest conductivity, reaching 2 mS/cm, was achieved with a mixed salt concentration of 50w%/50w% (NH4I/KI). Subsequently, this electrolyte was incorporated into the fabrication of quasi-solid state DSSC. The results showed that the DSSC with PEG achieved 2.81 % efficiency, while the traditional DSSC had 4.11 % efficiency. Notably, after fifteen days, the efficiency of the traditional DSSC dropped to 0.20 %, while the PEG-based DSSC remained stable (2.58 %).

Quasi-Solid-State Electrolyte Induced by Metallic MoS2 for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are a promising high-energy-density technology for next-generation energy storage but suffer from an inadequate lifespan. The poor cycle life of Li-S batteries stems from their commonly adopted catholyte-mediated operating mechanism, where the shuttling of dissolved polysulfides results in active material loss on the sulfur cathode and surface corrosion on the lithium anode. Here, we report in situ formation of a quasi-solid-state electrolyte (QSSE) on the metallic 1T phase molybdenum disulfide (MoS2) host that extends the lifetime of Li-S batteries. We find that the metallic 1T phase MoS2 host is able to initiate the ring-opening polymerization of 1,3-dioxolane (DOL), forming an integrated QSSE inside batteries. Nuclear magnetic resonance analysis reveals that the QSSE consists of ∼13% liquid DOL in a solid polymer matrix. The QSSE efficiently mediates sulfur redox reactions through dissolution-conversion chemistry while simultaneously suppressing polysulfide shuttling. Therefore, while ensuring high sulfur utilization, it avoids degradation of both electrodes, as well as the concomitant electrolyte consumption, leading to enhanced cycling stability. Under a practical lean electrolyte condition (electrolyte-to-sulfur ratio = 2 μL mg-1), Li-S pouch cell batteries with the QSSE demonstrate a capacity retention of 80.7% after 200 cycles, much superior to conventional liquid electrolyte cells that fail within 70 cycles. The QSSE also enables Li-S pouch cell batteries to operate across a wider temperature range (5 to 45 °C), together with improved safety under mechanical damage.

Revealing the quasi-solid-state electrolyte role on the thermal runaway behavior of lithium metal battery

Replacing flammable non-aqueous organic liquid electrolyte (LE) with high thermal stability solid-state electrolyte (SSE) is considered to overcome the safety issues in lithium metal batteries (LMBs). However, both inorganic solid-state batteries (SSBs) with high mechanical strength and thermal stability, as well as flexible polymer-based SSBs, are not proven to be inherently safe yet. Currently, the reliability of SSBs still require continuous scientific verification. In this work, quasi-solid-state electrolyte (QSE) with practical application prospects was prepared through in-situ polymerization method. The effects of QSE and LE on the thermal runaway behavior of LMBs were systematically compared from four levels: electrolyte, electrolyte/electrode interface, coin cells, and pouch cells. The results showed that higher thermal stability of QSE was conducive for improving the reliability of quasi-solid-state batteries (QSBs) under different abused conditions. The stable and dense solid electrolyte interface (SEI) in QSB could not only inhibit the severe side-reactions of LMBs during cycling at elevated temperature, but also enhance the decomposition temperature with dead lithium. QSE's lower reaction activity towards Li reduced the exothermic reaction inside the battery had been proven to increase the self-exothermic onset temperature and thermal runaway trigger temperature of LMBs, which promoted the safety performance of LMBs. Thus, this study revealed the thermal runaway mechanism of QSE in LMBs, and provided a theoretical guideline for safe QSBs design.

A Thiol Branched 3D Network Quasi Solid-State Polymer Electrolyte Reinforced by Covalent Organic Frameworks for Lithium Metal Batteries.

Quasi solid-state polymer electrolytes (QSPEs) are particularly attractive due to their high ionic conductivity and excellent safety for lithium metal batteries (LMBs). However, it is still a great challenge for QSPEs to achieve strong mechanical strength and high electrochemical performance simultaneously. Herein, a QSPE (SCOF-PEP-PEA) using a covalent organic framework (COF) containing abundant allyl groups (SCOF) as a rigid porous filler as well as a cross-linker to reinforce the polymer network is reported. Benefitting from the unique 3D nanonetwork structure and abundant lithiophilic functional groups, SCOF-PEP-PEA QSPE exhibits high ionic conductivity (4.0 × 10-4 S cm-1) and high lithium-ion transference number (0.82) at room temperature. Moreover, SCOF-PEP-PEA QSPE displays much improved mechanical strength compared to PEP-PEA QSPE (AFM Young's modulus: 453 vs 36MPa). As a result, the Li/LFP full cell with SCOF-PEP-PEA QSPE shows great rate performance of 141 mAh g-1 at 1C and delivers a high specific capacity retention of 92% after 220 cycles at 0.5 C (60 °C). This work provides a new strategy to design and prepare high-performance QSPEs with COFs as porous organic filler, and further expand the application of COFs for energy storage applications.

Application of advanced Wide-Temperature range and flame retardant “Leaf-Vein” Structured functionality composite Quasi-Solid-State electrolyte

Currently the advancement of lithium batteries have led to their widespread adoption in cutting-edge applications, with a heightened focus on their stability and safety in extreme environments. Traditional liquid electrolytes present challenges such as flammability, leakage, and limited operating temperature ranges, impeding the progress of electrochemical energy storage devices. Quasi-solid-state electrolytes(QSE) have emerged as a promising solution to overcome these limitations. Hydrogel electrolytes have garnered significant research attention due to their rapid ion conductivity, flexibility, functionality, low cost, and environmental compatibility. However, hydrogel electrolytes still face challenges such as narrow electrochemical window, low mechanical strength, and susceptibility to freezing. Herein, this study introduces a novel “leaf-vein” structured QSE, fabricated by combining a flexible hydrogel (UV in-situ curing) with a robust nanofiber network (electrospinning). The original QSE exhibits flame retardant (30 min non-flammability), broad electrochemical window (4.2 V), freeze resistance (- 60 °C) with 0.25 MPa, and self-healing capabilities. The assembled full battery demonstrates exceptional electrochemical stability at ultra-low temperatures. This distinctive structure of the QSE indicates novel insights and directions for the design and material selection of advanced electrolyte materials, enabling secure applications of electrochemical energy storage in specialized domains particularly deep space and polar exploration.

Composite Quasi-Solid-State Electrolytes with Organic-Inorganic Interface Engineering for Fast Ion Transport in Dendrite-Free Sodium Metal Batteries.

Quasi-solid-state electrolytes (QSSE) are a promising candidate for addressing the limitations of liquid and solid electrolytes. However, different ion transport capacities between liquid solvents and polymers can cause localized heterogeneous distribution of Na+ fluxes. In addition, the continuous side reactions occurring at the interface between QSSE and sodium anode lead to uncontrollable dendrites growth. Herein, a novel strategy is designed to integrate the composite electrospun membrane of Na3Zr2Si2PO12 and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) into QSSE, aiming to introduce new fast ion conducting channels at the organic-inorganic interface. The efficient ion transfer pathways can effectively promote the homogenization of ion migration, enabling composite QSSE to achieve an ultrahigh ionic conductivity of 4.1 mS cm-1 at room temperature, with a Na+ transference number as high as 0.54. Moreover, the PVDF-HFP is preferentially reduced upon contact with the sodium anode to form a "NaF-rich" solid electrolyte interphase, which effectively suppresses the growth of dendrites. The synergistic combination of multiple strategies can realize exceptional long-term cycling stability in both sodium symmetric batteries (≈700h) and full batteries (2100 cycles). This study provides a new insight for constructing high performance and dendrite-free solid-state sodium metal batteries.

Mns-MWCNT Composite, as a Superior Electrode Material for Asymmetric Flexible Quasi Solid-State Supercapacitors

Nowadays, renewable and sustainable energy sources are being explored and promoted to curb global pollution and to solve the issue of depleting fossil fuel resources. However, these renewable energy sources are intermittent in supply, therefore, it becomes necessary to store them for future usage. The traditional storage devices for electrical energy storage are different kinds of batteries but the sluggish performance of batteries, use of toxic heavy metals, issues pertaining to safety and low cycling efficiency are some of its major drawbacks. Recent proliferation of portable, wearable and flexible electronics and adoption of electric vehicles have forced the scientists to look for fast charging, light weight, leak proof, safe, toxic material free, durable energy storage devices like supercapacitors. Supercapacitors possess fast charge-discharge characteristics, high cycling stability and eco-friendliness in comparison to batteries. But they suffer from extremely low energy density (<10 Wh kg-1), high cost, bulk size, high self-discharge and significant drop in power density while increasing its energy density. The rational synthesis of electrode-materials has a significant impact on the development of high-performance electrodes for energy storage devices. Traditionally semiconducting materials like transition metal oxides are used as pseudocapacitive materials but transition metal oxides have very low electronic and ionic conductivity. Recently, transition metal sulfides, another class of semiconductors, are being investigated as they exhibit better conductivity and reaction kinetics compared to oxides. In this work, α-MnS is selected as an alternative to transition metal oxides. α-MnS is the most stable polymorph among other possible crystal structures of MnS, and has a hexagonal sheet like structure along with high operational potential window than many other metal sulfides. Although it is more conducting than transition metal oxides, it still needs conductivity enhancers like activated carbon, graphene, multiwall carbon nanotubes (MWCNT) etc. External mixing of conductivity enhancers is not effective enough to enhance the conductivity. Hence, MWCNT is mixed during the synthesis step to have a better bonding with α-MnS and create high conductivity channels. α-MnS + MWCNT composite shows a specific capacitance of 115 F g-1 at 1 A g-1 in 3 M KOH electrolyte under 3 electrode configuration. α-MnS + MWCNT composite is deposited on flexible conducting carbon cloth as cathode material and Vulcan carbon is deposited on carbon cloth as anode material. A mixture of poly vinyl alcohol PVA+ 3 M KOH is used as the gel type electrolyte. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge discharge (GCD), electrochemical impedance spectroscopy (EIS), cycling stability are performed to characterize the active material and the device performance. The assembled device shows a potential window of 1.4 V, alongside a specific capacitance of 27.7 F g-1 at 1 A g-1 and with 80% of capacity retention after 10,000 cycles. These results prove that transition metal sulfides can be viable alternative materials for supercapacitor application. This quasi-solid state or gel type electrolyte significantly reduces the conductivity and specific capacitance. Enhancing the ionic conductivity of the gel and finding out the optimum thickness of gel electrolyte layer between the electrodes are expected to open new pathways in enhancing the performance of the device. Figure 1

Toward high-performance ionic liquid-based quasi-solid-state electrolytes: Tunable electrochemical properties by introducing suitable diluents

Superior to conventional liquid electrolytes, incombustible ionic liquids (ILs) with wide electrochemical stability windows show privilege to endow quasi-solid-state electrolyte (QSE) with benign interfacial contact with both metallic Li and high-voltage cathode, which bodes well for implementation of high-performance solid-state Li metal battery. But regardless of its merits, the inherent high-viscosity and frail interphase chemistry of IL towards cathodes still jeopardize ionic conductivity within QSE and even crossing the interface, and should be overcame. Herein, we creatively introduce N, N-Dimethyltrifluoroacetamide (FDMAC) into QSE fabrication, design a quasi-solid-state electrolyte (QSE-EF) by hybridizing FDMAC/EMImFSI-based IL mixture and nano-LLZTO@PVDF-HFP. This FDMAC with well compatibility to IL, significantly decreases the viscosity but without sacrificing noncombustible feature. With the aid of FDMAC, QSE-EF exhibits fast ion-conducting and high Li+ transference number. More importantly, FDMAC also contributes to tuning interphase chemistry, and therefore, the high compatibilities of both QSE-EF|Li and QSE-EF|NCM622 interfaces are fulfilled involving profitable CEI&SEI establishment. Consequently, the assembled NCM622|QSE-EF|Li cell delivers outstanding electrochemical behaviors even at 4.4 V high voltage. 1.0 Ah NCM811ǁLi pouch cell also shows satisfactory energy density (350 Wh·kg−1) with negligible capacity loss. This work provides a feasible strategy to circumvent inherent defect of ionic liquid in QSE, and emphasizes the importance of tuning compatible interfacial chemistry in further QSE design.

Confining Ionic Liquids in Developing Quasi-Solid-State Electrolytes for Lithium Metal Batteries.

The concept of confining ionic liquids (ILs) in developing quasi-solid-state electrolytes (QSSEs) has been proposed, where ILs are dispersed in polymer networks/backbones and/or filler/host pores, forming the so-called confinement, and great research progress and promising research results have been achieved. In this review, the progress and achievement in developing QSSEs using IL-confinement for lithium metal batteries (LMBs), together with advanced characterizations and simulations, were surveyed, summarized, and analyzed, where the influence of specific parameters, such as IL (type, content, etc.), substrate (type, structure, surface properties, etc.), confinement methods, and so on, was discussed. The confinement concept was further compared with the conventional one in other research areas. It indicates that the IL-confinement in QSSEs improves the performance of electrolytes, for example, increasing the ionic conductivity, widening the electrochemical window, and enhancing the cycle performance of the assembled cells, and being different from those in other areas, that is, the IL-confinement concept in the battery area is in a broad extent. Finally, insights into developing QSSEs in LMBs with the confinement strategy were provided to promote the development and application of QSSE LMBs.

Integration of a Flexible, Stretchable, Environment-Benign, and Highly Conductive PVA/H3PO4 Hydrogel as a Quasi Solid-State Electrolyte in Reduced Graphene Oxide Supercapacitors

Integration of a Flexible, Stretchable, Environment-Benign, and Highly Conductive PVA/H₃PO₄ Hydrogel as a Quasi Solid-State Electrolyte in Reduced Graphene Oxide Supercapacitors

Suppressing Dendrite Growth with Eco-Friendly Sodium Lignosulfonate Additive in Quasi-Solid-State Li Metal Battery.

The application of lithium metal batteries is limited by the drawbacks of safety problems and Li dendrite formation. Quasi-solid-state electrolytes (QSSEs) are the most promising alternatives to commercial liquid electrolytes due to their high safety and great compatibility with electrodes. However, Li dendrite formation and the slow Li+ diffusion in QSSEs severely hinder uniform Li deposition, thus leading to Li dendrite growth and short circuits. Herein, an eco-friendly and low-cost sodium lignosulfonate (LSS)-assisted PVDF-based QSSE is proposed to induce uniform Li deposition and inhibit Li dendrite growth. Li symmetric cells with 5%-LSS QSSE possess a high Li+ transfer number of 0.79, and they exhibit a long cycle life of 1000 h at a current density/areal capacity of 1 mA cm-2/5 mAh cm-2. Moreover, due to the fast electrochemical dynamics endowed by the improved compatibility of the electrodes and fast Li+ diffusion, the LFP/5%-LSS/Li full cells still maintain a high capacity of 110 mAh g-1 after 250 cycles at 6C. This work provides a novel and promising choice that uses eco-friendly LSS as an additive to PVDF-based QSSE in Li metal batteries.

Fast Lithium Ion Transport Pathways Constructed by Two-Dimensional Boron Nitride Nanoflakes in Quasi-Solid-State Polymer Electrolyte.

Quasi-solid-state electrolytes (QSSEs) are gaining huge popularity because of their significantly improved safety performance over nonaqueous liquid electrolytes and superior process adaptability over all-solid-state electrolytes. However, because of the existence of liquid molecules, QSSEs typically have low lithium ion transference numbers and compromised thermal stability. In this work, we present the fabrication of a well-rounded QSSE by introducing hexagonal boron nitride nanoflakes (BNNFs) as an inorganic filler in a poly(vinylene carbonate) matrix. BNNFs, in contrast to most inorganic fillers used as anion trappers, are used to build fast lithium ion transport pathways directly on their two-dimensional surfaces. We confirm the attractive coupling between lithium ions and BNNFs, and we confirm that with the help of BNNFs, lithium ions can migrate with less damping and a lower transport energy barrier. As a result, the designed electrolyte exhibits good ion transportability, promoted fire retardancy, and good compatibility with lithium metal anodes and commercial cathodes.

Ordered and Fast Ion Transport of Quasi‐solid‐state Electrolyte with Regulated Coordination Strength for Lithium Metal Batteries

AbstractPolymer based quasi‐solid‐state electrolyte (QSE) has attracted great attention due to its assurance for high safety of rechargeable batteries including lithium metal batteries (LMB). However, it faces the issue of low ionic conductivity of electrolyte and solid‐electrolyte‐interface (SEI) layer between QSE and lithium anode. Herein, we firstly demonstrate that the ordered and fast transport of lithium ion (Li+) can be realized in QSE. Due to the higher coordination strength of Li+ on tertiary amine (−NR3) group of polymer network than that on carbonyl (−C=O) group of ester solvent, Li+ can diffuse orderly and quickly on −NR3 of polymer, significantly increasing the ionic conductivity of QSE to 3.69 mS cm−1. Moreover, −NR3 of polymer can induce in situ and uniform generation of Li3N and LiNxOy in SEI. As a result, the Li||NCM811 batteries (50 μm Li foil) with this QSE show an excellent stability of 220 cycles at ≈1.5 mA cm−2, 5 times to those with conventional QSE. LMBs with LiFePO4 can stably run for ≈8300 h. This work demonstrates an attractive concept for improving ionic conductivity of QSE, and also provides an important step for developing advanced LMB with high cycle stability and safety.