Solid-state Composite Electrolyte Research Articles

Constructing an All Solid-state Flexible Lithium-Manganese Battery with High Performance

Abstract Due to a lack of portable flexible power supply, flexible electronic products can still not be applied in a large scale, particularly in the high energy density devices. To resolve this issue, flexible solid-state lithium batteries with a high safety, excellent mechanical property, and high energy densit，is proposed. In this paper, a flexible solid-state lithium-manganese battery is developed, which is assembled with a lithium cloth composite anode, a composite solid-state electrolyte poly (vinylidene fluoride)-hexafluoropropylene (PVDF-HFP)/Li6.4La3Ta0.6O12 (LLZTO), and a composite cathode (Fe ion-doped MnO2-carbon cloth). To improve the conductivity and stability of cathode, a mixture of conductive carbon black (Super P) and sodium alginate (SA) is employed. To ensure the high capacity and low price, the MnO2-based cathode is used.The obtained solid state batteries can deliver an initial capacity of 275.9 mAh g-1 at a current density of 1 C and a capacity retention of 57.9% (159.7 mAh g-1 ) after 1000 cycles. Also the produced flexible punch cell can light up the light-emitting diode(LED), and its capacity is 0.58 mAh cm-2 after 100 cycles at current density of 0.2 C.

12.6 μm-Thick Asymmetric Composite Electrolyte with Superior Interfacial Stability for Solid-State Lithium-Metal Batteries

HighlightsUltra-thin asymmetric composite solid-state electrolytes with ultralight areal density were designed for solid-state lithium metal batteries, achieving interfacial stability to Li metal and high-voltage cathode.The improved mechanical properties of the electrolyte contribute to the inhibition of Li dendrite growth was demonstrated by both experimental and theoretical simulations.The assembled pouch cell exhibited a high gravimetric/volume energy density of 344.0 Wh kg−1/773.1 Wh L−1.

Cation Framework Nanowires Enabling Composite Solid‐State Electrolyte with Anion Exchange Platform for Rapid Li+ Conduction

AbstractAll‐solid‐state lithium metal batteries (ASSLMBs) have attracted significant attention due to their high energy density and improved safety performance. However, the application of ASSLMBs in energy storage fields is hindered by their low ionic conductivity, which arises from the limited availability of free Li+ in composite solid‐state electrolytes (CSEs). Herein, a unique nanowire with the 3D cation framework is employed as an inorganic filler to increase the availability of free Li+ with the anion exchange platform. The cation framework with active Cl− can serve as the exchange platform to attract the TFSI−, thereby promoting the dissociation of LiTFSI and the release of additional free Li+. Furthermore, cation framework nanowires exhibit the stable framework structure and highly ordered channels, which form the 1D continuous organic–inorganic interface, facilitating the practical pathways for directional Li+ conduction. As a result, the YBFPL electrolyte exhibits the high ionic conductivity (0.267 mS cm−1) at room temperature, the high Li+ transference number (0.63), and the more mobile Li+ ratio (40%). This study designs the 1D continuous cation framework nanostructure, which realizes the rapid Li+ transport through the anion exchange platform at the organic and inorganic interface.

Dielectric LiNbO3 electrolyte regulating internal electric field in composite solid-state electrolyte to fundamentally boost Li-ion transport

Dielectric LiNbO3 electrolyte regulating internal electric field in composite solid-state electrolyte to fundamentally boost Li-ion transport

Constructing Enhanced Composite Solid-State Electrolytes with Sb/Nb Co-Doped LLZO and PVDF-HFP

Composite solid-state electrolytes are viewed as promising materials for solid-state lithium-ion batteries due to their combined advantages of inorganic solid-state electrolytes and solid-state polymer electrolytes. In this study, the solid electrolytes Li6.7−xLa3Zr1.7−xSb0.3NbxO12 (LLZSNO) with Sb and Nb co-doping were prepared by a high-temperature solid-phase method. Results indicate that Sb/Nb co-doping causes lattice deformation in LLZO and increases the lithium vacancy concentration and conductivity of LLZO. Then, with the co-doped LLZSNO as an inorganic filler, a composite solid electrolyte of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) was prepared with a casting method. The obtained composite solid electrolyte exhibits a high ionic conductivity of 1.76 × 10−4 S/cm at room temperature, a wide electrochemical stable window of 5.2 V, and a lithium-ion transfer number of 0.32. The Li|LiFePO4 coin battery with the composite solid electrolyte shows a high specific capacity of 161.2 mAh/g and a Coulombic efficiency close to 100% at 1 C. In addition, the symmetrical lithium battery Li|Li with the composite electrolyte could cycle stably for about 1500 h without failure at room temperature.

High-Performance PVDF-HFP-PVAc-LLZTO Composite Solid-State Electrolyte for Lithium Metal Battery

Composite solid-state electrolytes are highly promising contenders for next-generation lithium-metal batteries due to their high safety, good flexibility, and compatibility with lithium metal. In this work, Poly(vinyl acetate) (PVAc) was incorporated into PVDF-HFP in order to reduce the crystallinity of the PVDF-HFP matrix, improve the ionic conductivity of the electrolyte, and greatly reduce the interfacial impedance of the electrolyte by utilizing the low-temperature flexibility, excellent amorphous nature, and strong bonding properties of PVAc. On this basis, the active filler LLZTO was introduced to further reduce the crystallinity of the PVDF-HFP matrix and provide more Li+ transport channels. The PP60-10LLZTO composite solid electrolyte has exceptional mechanical and electrochemical characteristics with a high ionic conductivity of 7.2*10−4 S cm−1 and the Li+ transference number of 0.57 at 30 °C. The assembled LFP/Li battery can be stably cycled for 450 cycles at 30 °C and 0.5C, and its capacity retention rate is as high as 89%. The strategy of constructing composite solid-state electrolytes in this paper presents new insights for designing and developing high-performance solid-state lithium metal batteries.

Lithium Superionic Conductive Nanofiber-Reinforcing High-Performance Polymer Electrolytes for Solid-State Batteries.

Although composite solid-state electrolytes (CSEs) are considered promising ionic conductors for high-energy lithium metal batteries, their unsatisfactory ionic conductivity, low mechanical strength, poor thermal stability, and narrow voltage window limit their practical applications. We have prepared a new lithium superionic conductor (Li-HA-F) with an ultralong nanofiber structure and ultrahigh room-temperature ionic conductivity (12.6 mS cm-1). When it is directly coupled with a typical poly(ethylene oxide)-based solid electrolyte, the Li-HA-F nanofibers endow the resulting CSE with high ionic conductivity (4.0 × 10-4 S cm-1 at 30 °C), large Li+ transference number (0.66), and wide voltage window (5.2 V). Detailed experiments and theoretical calculations reveal that Li-HA-F supplies continuous dual-conductive pathways and results in stable LiF-rich interfaces, leading to its excellent performance. Moreover, the Li-HA-F nanofiber-reinforced CSE exhibits good heat/flame resistance and flexibility, with a high breaking strength (9.66 MPa). As a result, the Li/Li half cells fabricated with the Li-HA-F CSE exhibit good stability over 2000 h with a high critical current density of 1.4 mA cm-2. Furthermore, the LiFePO4/Li-HA-F CSE/Li and LiNi0.8Co0.1Mn0.1O2/Li-HA-F CSE/Li solid-state batteries deliver high reversible capacities over a wide temperature range with a good cycling performance.

Polyethylene oxide-Based solid electrolytes with fast Li-ion transport channels constructed from 2D montmorillonite for solid-state lithium-metal batteries

Polyethylene oxide (PEO)-based solid-state electrolytes (SSEs) typically struggle with poor ionic conductivity, low lithium (Li)-ion transference number, and narrow electrochemical window. For overcoming these drawbacks, we designed a promising composite SSE (CSSE), i.e., a Li-containing ionic liquid (LiIL) was inserted into the Li-montmorillonite (LiMNT) layered structure to form an active filler (LiIL@LiMNT), involving two-dimensional (2D) fast transport channels of Li-ion inside PEO electrolyte. Benefitting from an enhancement of the 2D Li-ion transport channels, the obtained CSSE exhibited an excellent ion conductivity of 1.38 × 10−4 S cm−1 at 30 °C as well as a satisfactory Li-ion transference number (0.38). A Li symmetric battery with the CSSE exhibited a steady cycle for 3000 h with 0.2 mA cm−2 at 60 °C. Under the rate of 0.5C at 60 °C, the solid-state Li-metal batteries (SSLMBs) assembled with LiFePO4 and LiNi0.33Co0.33Mn0.33O2 cathodes maintained a considerable reversible capacity after 400 and 100 cycles, respectively. The assembled SSLMB also achieved a satisfactory performance at 40 °C. The 2D active filler prepared in this work forms efficient 2D Li-ion transport channels inside the CSSE while maintaining a tight interfacial contact with electrodes, which is crucial to achieve a superior performance for CSSEs. This strategy of constructing 2D ion transport channels in polymer electrolytes also provides another way for the design of other CSSEs.

Regulating and understanding the compatibility of sulfide composite solid-state electrolyte in nickel-rich lithium metal batteries

In the pursuit of high-energy-density lithium batteries, composite solid-state electrolytes are highly favored due to the combination of flexibility and acceptable ionic conductivity. However, challenges such as unpredictable lithium dendrite growth, cathode material structural instability, and oxidative resistance at high voltages pose significant hurdles for solid-state batteries. To investigate the synergistic interactions of polymers and sulfides, a hybrid poly (1,3-dioxolane) and poly (polyethylene glycol diacrylate) blend was designed through in-situ polymerization, allowing LiFePO4//Li batteries to achieve an average coulombic efficiency exceeding 99% at 0.5C and stable cycling for at least 1000 h in lithium symmetric cells. Computational analysis and component detection demonstrate the stability of the components and the formation of a LiF-stabilized anode from lithium salt decomposition. Similarly, on the cathode side, when Li3PO4-coated LiNi0.6Co0.2Mn0.2O2 is used as the cathode material, a more stable interface suppresses cathode particles' collapse and harmful electrolytes’ decomposition. In ambient environments, after 200 cycles at 0.5C, the capacity retention remains as high as 90.48%. Impedance changes by in-situ methods and component composition were further analyzed. This work integrates multiple methods and stabilizes and validates the anode and cathode interface, providing a promising approach and strategy for designing high-performance sulfide composite solid-state batteries.

Cold Sintering Enables the Reprocessing of LLZO-Based Composites.

All-solid-state batteries have the potential for enhanced safety and capacity over conventional lithium ion batteries, and are anticipated to dominate the energy storage industry. As such, strategies to enable recycling of the individual components are crucial to minimize waste and prevent health and environmental harm. Here, we use cold sintering to reprocess solid-state composite electrolytes, specifically Mg and Sr doped Li7 La3 Zr2 O12 with polypropylene carbonate (PPC) and lithium perchlorate (LLZO-PPC-LiClO4 ). The low sintering temperature allows co-sintering of ceramics, polymers and lithium salts, leading to re-densification of the composite structures with reprocessing. Reprocessed LLZO-PPC-LiClO4 exhibits densified microstructures with ionic conductivities exceeding 10-4  S/cm at room temperature after 5 recycling cycles. All-solid-state lithium batteries fabricated with reprocessed electrolytes exhibit a high discharge capacity of 168 mA h g-1 at 0.1 C, and retention of performance at 0.2 C for over 100 cycles. Life cycle assessment (LCA) suggests that recycled electrolytes outperforms the pristine electrolyte process in all environmental impact categories, highlighting cold sintering as a promising technology for recycling electrolytes.

Built-in garnet-rich composite solid electrolyte towards fast ion transport and dendrite-free for high-energy lithium batteries

Composite solid-state electrolytes (CSEs), which could provide greater flexibility to harness the advantages of single-phase electrolytes, are promising candidates for solid-state lithium (Li) batteries. However, the agglomeration of inorganic phase obstructs the efficient ion-conduction channel and accelerates dendrite growth, limiting the practical application of CSEs. Herein, a flexible garnet-rich composite skeleton is prepared by incorporating well-dispersed Li6.4La3Zr1.4Ta0.6O12 (LLZTO) with robust polyimide scaffold through a simple method. Subsequently, a compact composite bi-phase electrolyte with abundant and well-dispersed built-in LLZTO could be attained via in-situ curing of a poly(ethylene glycol)diacrylate-based polymer electrolyte within this skeleton. Capitalizing on the rapid Li+ pathways contributed by the high fraction and well-distributed ceramic phase, this electrolyte demonstrates remarkably ionic conductivity and Li+ transference number of 0.95 mS cm−1 and 0.81, respectively. The deigned bi-phase composite enables a stable and uniform Li stripping/plating in symmetrical Li||Li batteries over 1000 h at 0.2 mA cm−2 and a high critical current density of 1.9 mA cm−2, facilitated by enhanced Li+ conduction dynamics and homogenous Li+ flux. LiNi0.8Co0.1Mn0.1O2||Li cells using this electrolyte exhibit favorable battery performances (159.8 mAh g−1, 96.4%@180 cycles, 0.5C). Furthermore, this scalable fabrication process for this composite electrolyte holds great potential in grid-scale production for safe and high-energy Li batteries.

Win-Win on both ion-conducting and mechanical properties achieved in PEO-based solid electrolytes through microstructure regulation

Solid state electrolytes are of great importance in the design of all-solid-state lithium metal batteries (ASLMBs) that with excellent properties and glorious working stability. And solid polymer electrolytes (SPEs) are the attention-getting candidate, because of its flexibility lightweight and suitable ionic transportation ability. However, current SPEs always need balance between ionic conductivity (σ) and the mechanical strength. To this end, organic-inorganic composite solid-state electrolytes (CSEs) are designed by introduction of BN nanosheets into the polymer matrix, coupled with using the electrospinning technique. It is proved show that the PEO crystallinity in the fibrous electrolyte is significantly suppressed, with only 1 wt% BN adding. And the σ of the designed sample is raised to 1.93×10−4 S∙cm−1 at 40 ℃, on account of that the BN layered structure and three-dimensional fibrous framework help to provide dual channels for Li+ transport. Also better interfacial miscibility with Li metal is realized in the obtained fibrous CPEs and the Galvanostatic cycling of the symmetric Li//Li cell sustains as long as 850 h with 0.1 mA·cm−2 current density. Compared with the solution-casted sample with the same composition, the tensile strength (0.88 MPa) and electrochemical stability of the electrospun membrane (5.1 V) are both significantly enhanced. In addition, the obtained LiFePO4|PEO/LiClO4/BN CSE|Li all solid state coin cells exhibit excellent cycling and rate performances. The initial discharge specific capacity reaches to 144.1 mAhg−1. And coin cells cycled at 1 C current and at 80℃ give a capacity retention ratio of 81.1% after 200 cycles. It demonstrates that thin and flexible CSEs with excellent electrochemical performance can be accomplished through electrospining technique.

Low-cost and high-safety montmorillonite-based solid electrolyte for lithium metal batteries

Composite solid-state electrolyte have good interfacial compatibility and mechanical properties, but their safety (such as easy to catch fire) and economic cost are still problems. In present work, an composite solid-state electrolyte was prepared by inserting poly(vinylidene fluoride)-based polymer electrolyte matrix into the interlayer of a low cost clay mineral-montmorillonite. The composite electrolyte exhibited remarkable characteristics, including excellent flame retardancy, high room temperature ionic conductivity of 2.28 × 10−4 S cm−1, wide electrochemical stability window of 4.8 V, high lithium-ion transference number of 0.57 and good mechanical strength of 12.58 MPa. Furthermore, LiFePO4-based solid-state battery, utilizing this composite solid-state electrolyte, exhibited stable cycling with discharge specific capacity of 130 mAh g−1 for over 100 cycles at a rate of 0.5C at room temperature. This successful performance demonstrated the potential of utilizing low-cost and environmentally friendly raw clay mineral materials in high energy density solid-state battery applications.

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.

A novel reinforced concrete-like composite solid-state electrolyte with enhanced performance for all-solid-state lithium batteries

A novel reinforced concrete-like composite solid-state electrolyte with enhanced performance for all-solid-state lithium batteries

Remarkably improved ionic conductivity and lithium metal compatibility of LLZTO-Li4(BH4)3I composite solid-state electrolyte

With superior ionic conductivity and (electro)chemical stability, garnet-type oxide Li6.4La3Zr1.4Ta0.6O12 (LLZTO) has been extensively studied and explored as advanced solid-state electrolyte (SSEs) for lithium ion batteries (LIBs). However, high-temperature sintering treatment at ∼1200 °C to fabricate dense sheets is necessary to attain high ionic conductivity, whereas at the expense of degraded mechanical properties and poor contact with electrodes. Herein, we demonstrate a novel LLZTO-Li4(BH4)3I composite solid electrolyte prepared by mechanical milling, which features a bilayer coating structure where LiBO2 in the inner layer and Li4(BH4)3I in the outer layer. The electrolyte pellets fabricated by a simple cold pressing treatment deliver an ionic conductivity of 3.69 × 10−5 S cm−1 at 30 °C and a Li+ transference number of 0.9999, which successfully prevents the formation of lithium dendrites. Using this electrolyte, Li|Li symmetric batteries can work continuously for more than 2200 h at 35 and 60 °C. Such performance improvement is ascribed to the sharp reduction in porosity, the enhanced mechanical properties and the improved interface contact after cold pressing the Li4(BH4)3I-modified LLZTO composite to form an electrolyte pellet.

Revealing the specific role of sulfide and nano-alumina in composite solid-state electrolytes for performance-reinforced ether-nitrile copolymers

Composite solid-state electrolytes represent a critical pathway that balances the interface compatibility and lithium-ion conductivity in all-solid-state batteries. The quest for stable and highly ion-conductive combinations between polymers and fillers is vital, but blind attempts are often made due to a lack of understanding of the mechanisms involved in the interaction between polymers and fillers. Herein, we employ in-situ polymerization to prepare a polymer based on an ether-nitrile copolymer with high cathode stability as the foundation and discuss the performance enhancement mechanisms of argyrodite and nano-alumina. With 1% content of sulfide interacting with the polymer at the two-phase interface, the local enhancement of lithium-ion migration capability can be achieved, avoiding the reduction in capacity due to the low ion conductivity of the passivation layer during cycling. The capacity retention after 50 cycles at 0.5 C increases from 83.5% to 94.4%. Nano-alumina, through anchoring the anions and interface inhibition functions, eventually poses an initial discharge capacity of 136.8 mA h g−1 at 0.5 C and extends the cycling time to 1000 h without short-circuiting in lithium metal batteries. Through the combined action of dual fillers on the composite solid-state electrolyte, promising insights are provided for future material design.

Solid-state composite electrolytes: turning the natural moat into a thoroughfare

Solid-state composite electrolytes bridge the gap between solid-state polymer electrolytes and solid-state inorganic electrolytes, which play an important role in developing the expected solid-state Li-ion batteries.

The sensitive aspects of modelling polymer-ceramic composite solid-state electrolytes using molecular dynamics simulations.

Solid-state composite electrolytes have arisen as one of the most promising materials classes for next-generation Li-ion battery technology. These composites mix ceramic and solid-polymer ion conductors with the aim of combining the advantages of each material. The ion-transport mechanisms within such materials, however, remain elusive. This knowledge gap can to a large part be attributed to difficulties in studying processes at the ceramic-polymer interface, which are expected to play a major role in the overall ion transport through the electrolyte. Computational efforts have the potential of providing significant insight into these processes. One of the main challenges to overcome is then to understand how a sufficiently robust model can be constructed in order to provide reliable results. To this end, a series of molecular dynamics simulations are here carried out with a variation of certain structural (surface termination and polymer length) and pair potential (van der Waals parameters and partial charges) models of the Li7La3Zr2O12 (LLZO) poly(ethylene oxide) (PEO) system, in order to test how sensitive the outcome is to each variation. The study shows that the static and dynamic properties of Li-ion are significantly affected by van der Waals parameters as well as the surface terminations, while the thickness of the interfacial region - where the structure-dynamic properties are different as compared to the bulk-like regime - is the same irrespective of the simulation setup.

Flexible self-supporting inorganic nanofiber membrane-reinforced solid-state electrolyte for dendrite-free lithium metal batteries.

Compounding of suitable fillers with PEO-based polymers is the key to forming high-performance electrolytes with robust network structures and homogeneous Li+-transport channels. In this work, we innovatively and efficiently prepared Al2O3 nanofibers and deposited an aqueous dispersion of Al2O3 into a membrane via vacuum filtration to construct a nanofiber membrane with a three-dimensional (3D) network structure as the backbone of a PEO-based solid-state electrolyte. The supporting effect of the nanofiber network structure improved the mechanical properties of the reinforced composite solid-state electrolyte and its ability to inhibit the growth of Li dendrites. Meanwhile, interconnected nanofibers in the PEO-based electrolyte and the strong Lewis acid-base interactions between the chemical groups on the surface of the inorganic filler and the ionic species in the PEO matrix provided facilitated pathways for Li+ transport and regulated the uniform deposition of Li+. Moreover, the interaction between Al2O3 and lithium salts as well as the PEO polymer increased free Li+ concentration and maintained its stable electrochemical properties. Hence, assembled Li/Li symmetric cells achieved a cycle life of more than 2000 h. LFP/Li and NMC811/Li cells provided high discharge specific capacities of up to 146.9 mA h g-1 (0.5C and 50 °C) and 166.9 mA h g-1 (0.25C and 50 °C), respectively. The prepared flexible self-supporting 3D nanofiber network structure construction can provide a simple and efficient new strategy for the exploitation of high-performance solid-state electrolytes.