Polymer Template Synthesis of Soft, Light, and Robust Oxide Ceramic Films

Fabrication electro-spun Poly(vinyl alcohol)-Melamine nonwoven membrane composite separator for high-power lithium-ion batteries

Current commercial separators used in lithium-ion batteries have inherent flaws, especially poor thermal stability, which pose substantial safety risks. This study introduces a high-safety composite membrane made from electrospun poly(vinyl alcohol)-melamine (PVAM) and polyvinylidene fluoride (PVDF) polymer solutions via a dip coating method, designed for high-voltage battery systems. The poly(vinyl alcohol) and melamine components enhance battery safety, while the PVDF coating improves lithium-ion conductivity. The dip-coated PVDF/Esp-PVAM composite separators were evaluated for electrolyte uptake, contact angle, thermal stability, porosity, electrochemical stability and ionic conductivity. Notably, our Dip 1 % PVDF@Esp-PVAM composite separator exhibited excellent wettability and a lithium-ion conductivity of approximately 7.75 × 10⁻⁴ S cm⁻1 at room temperature. These separators outperformed conventional PE separators in half-cells with Ni-rich NCM811 cathodes, showing exceptional cycling stability with 93.4 % capacity retention after 100 cycles at 1C/1C, as compared to 84.8 % for PE separators. Our Dip 1 % PVDF@Esp-PVAM composite separator demonstrates significant potential for enhancing the long-term durability and high-rate performance of lithium-ion batteries, making it a promising option for long-term energy storage applications.

Continuous Rapid Fabrication of Ceramic Fiber Sponge Aerogels with High Thermomechanical Properties via a Green and Low-Cost Electrospinning Technique

Ceramic aerogel is an appealing fireproof and heat-insulation material, but synchronously improving its mechanical and thermal properties is a challenge. Moreover, the expensive discontinuous processing techniques inhibit the large-scale fabrication of ceramic aerogels. Here, we propose a water-based electrospinning method, based on the hydrolysis and condensation reactions of ceramic precursor salts themselves, for the continuous and rapid (0.025 m3/min) fabrication of ceramic fiber sponge aerogels with dual micronano fiber networks, which show synchronous enhanced fireproof, thermal insulation, and resilience performance. The elastic ceramic micro/nano fiber sponge aerogels contain robust silica-based microfibers as a firm skeleton and alumina-based nanofibers as elastic thermal insulation filler. The sponges have a high porosity of >99.8%, a low mass density (6.21 mg/cm3), a small thermal conductivity (0.022 W/m·K), and a large compression strength (21.15 kPa at 80% strain). The ceramic fiber sponges can effectively prevent the propagation of thermal runaway when a lithium battery experiences catastrophic thermal shock (>1000 °C) in the power battery packs. The proposed strategy is feasible for low-cost and rapid synthesizing ceramic aerogels toward effective battery thermal management.

Challenges and Strategies for Synthesizing High Performance Micro and Nanoscale High Entropy Oxide Materials

High-entropy oxide micro/nano materials (HEO MNMs) have shown broad application prospects and have become hot materials in recent years. This review comprehensively provides an overview of the latest developments and covers key aspects of HEO MNMs, by discussing design principles, computer-aided structural design, synthesis challenges and strategies, as well as application areas. The analysis of the synthesis process includes the role of high-throughput process in large-scale synthesis of HEOs MNMs, along with the effects of temperature elevation and undercooling on the formation of HEO MNMs. Additionally, the article summarizes the application of high-precision and in situ characterization devices in the field of HEO MNMs, offering robust support for related research. Finally, a brief introduction to the main applications of HEO MNMs is provided, emphasizing their key performances. This review offers valuable guidance for future research on HEO MNMs, outlining critical issues and challenges in the current field.

Electrospinning Nonspinnable Sols to Ceramic Fibers and Springs

Electrospinning has been applied to produce ceramic fibers using sol gel-based spinning solutions consisting of ceramic precursors, a solvent, and a polymer to control the viscosity of the solution. However, the addition of polymers to the spinning solution makes the process more complex, increases the processing time, and results in porous mechanically weak ceramic fibers. Herein, we develop a coelectrospinning technique, where a nonspinnable sol (<10 mPa s) consisting of only the ceramic precursor(s) and solvent(s) is encapsulated inside a polymeric shell, forming core-shell precursor fibers that are further calcined into ceramic fibers with reduced porosity, decreased surface defects, uniform crystal packing, and controlled diameters. We demonstrate the versatility of this method by applying it to a series of nonspinnable sols and creating high-quality ceramic fibers containing TiO2, ZrO2, SiO2, and Al2O3. The polycrystalline TiO2 fibers possess excellent flexibility and a high Young's modulus reaching 54.3 MPa, solving the extreme brittleness problem of the previously reported TiO2 fibers. The single-component ZrO2 fibers exhibit a Young's modulus and toughness of 130.5 MPa and 11.9 KJ/m3, respectively, significantly superior to the counterparts prepared by conventional sol-gel electrospinning. We also report the creation of ceramic fibers in micro- and nanospring morphologies and examine the formation mechanisms using thermomechanical simulations. The fiber assemblies constructed by the helical fibers exhibit a density-normalized toughness of 3.5-5 times that of the straight fibers due to improved fracture strain. This work expands the selection of the electrospinning solution and enables the development of ceramic fibers with more attractive properties.

Fabrication and Applications of Ceramic-Based Nanofiber Materials Service in High-Temperature Harsh Conditions—A Review

Ceramic-based nanofiber materials have attracted attention due to their high-temperature resistance, oxidation resistance, chemical stability, and excellent mechanical performance, such as flexibility, tensile, and compression, which endow them with promising application prospects for filtration, water treatment, sound insulation, thermal insulation, etc. According to the above advantages, we, therefore, reviewed the ceramic-based nanofiber materials from the perspectives of components, microstructure, and applications to provide a systematical introduction to ceramic-based nanofiber materials as so-called blankets or aerogels, as well as their applications for thermal insulation, catalysis, and water treatment. We hope that this review will provide some necessary suggestions for further research on ceramic-based nanomaterials.

Design strategies, surface functionalization, and environmental remediation potentialities of polymer-functionalized nanocomposites

Inorganic nanoparticles (NPs) have a tunable shape, size, surface morphology, and unique physical properties like catalytic, magnetic, electronic, and optical capabilities. Unlike inorganic nanomaterials, organic polymers exhibit excellent stability, biocompatibility, and processability with a tailored response to external stimuli, including pH, heat, light, and degradation properties. Nano-sized assemblies derived from inorganic and polymeric NPs are combined in a functionalized composite form to import high strength and synergistically promising features not reflected in their part as a single constituent. These new properties of polymer/inorganic functionalized materials have led to emerging applications in a variety of fields, such as environmental remediation, drug delivery, and imaging. This review spotlights recent advances in the design and construction of polymer/inorganic functionalized materials with improved attributes compared to single inorganic and polymeric materials for environmental sustainability. Following an introduction, a comprehensive review of the design and potential applications of polymer/inorganic materials for removing organic pollutants and heavy metals from wastewater is presented. We have offered valuable suggestions for piloting, and scaling-up polymer functionalized nanomaterials using simple concepts. This review is wrapped up with a discussion of perspectives on future research in the field.

Li7La3Zr2O12 Protonation as a Means to Generate Porous/Dense/Porous-Structured Electrolytes for All-Solid-State Lithium-Metal Batteries

Ceramic Li₇La₃Zr₂O₁₂ (LLZO) represents a promising candidate electrolyte for next-generation all-solid-state lithium-metal batteries. However, lithium-metal batteries are prone to dendrite formation upon fast charging. Porous/dense and porous/dense/porous LLZO structures were proposed as a solution to avoid or at least delay the formation of lithium-metal dendrites by increasing the electrode/electrolyte contact area and thus lowering the local current density at the interface. In this work, we show the feasibility of producing porous/dense/porous LLZO by a new and scalable method. The method consists of LLZO chemical deep protonation in a protic or acidic solvent, followed by thermal deprotonation at high temperatures to create the porous structure by water and lithium oxide elimination. We demonstrate that the produced structure extends the lifetime of Li/LLZO/Li symmetric cells by a factor of 8 compared to a flat LLZO at a current density of 0.1 mA/cm² and with a capacity of 1 mAh/cm² per half-cycle. We also show clear improvement of the Li/LLZO/LiFePO₄ full cell performance with a thermally deprotonated LLZO.

Fabrication of Flexible Mesoporous Black Nb2 O5 Nanofiber Films for Visible-Light-Driven Photocatalytic CO2 Reduction into CH4

Achieving high selectivity and conversion efficiency simultaneously is a challenge for visible-light-driven photocatalytic CO₂ reduction into CH₄ . Here, a facile nanofiber synthesis method and a new defect control strategy at room-temperature are reported for the fabrication of flexible mesoporous black Nb₂ O₅ nanofiber catalysts that contain abundant oxygen-vacancies and unsaturated Nb dual-sites, which are efficient towards photocatalytic production of CH₄ . The oxygen-vacancy decreases the bandgap width of Nb₂ O₅ from 3.01-2.25 eV, which broadens the light-absorption range from ultraviolet to visible-light, and the dual sites in the mesopores can easily adsorb CO₂ , so that the intermediate product of CO* can be spontaneously changed into *CHO. The formation of a highly stable NbCHO* intermediate at the dual sites is proposed to be the key feature determining selectivity. The preliminary results show that without using sacrificial agents and photosensitizers, the nanofiber catalyst achieves 64.8% selectivity for CH₄ production with a high evolution rate of 19.5 µmol g^-1 h^-1 under visible-light. Furthermore, the flexible catalyst film can be directly used in devices, showing appealing and broadly commercial applications.

Flexible Ceramic Fibers: Recent Development in Preparation and Application

Flexible ceramic fibers (FCFs) have been developed for various advanced applications due to their superior mechanical flexibility, high temperature resistance, and excellent chemical stability. In this article, we present an overview on the recent progress of FCFs in terms of materials, fabrication methods, and applications. We begin with a brief introduction to FCFs and the materials for preparation of FCFs. After that, various methods for preparation of FCFs are discussed, including centrifugal spinning, electrospinning, solution blow spinning, self-assembly, chemical vapor deposition, atomic layer deposition, and polymer conversion. Recent applications of FCFs in various fields are further illustrated in detail, including thermal insulation, air filtration, water treatment, sound absorption, electromagnetic wave absorption, battery separator, catalytic application, among others. Finally, some perspectives on the future directions and opportunities for the preparation and application of FCFs are highlighted. We envision that this review will provide readers with some meaningful guidance on the preparation of FCFs and inspire them to explore more potential applications.

Ceramic Nanofiber-Based Water-Induced Electric Generator

Water-induced electricity generation as an emerging novel sustainable energy harvesting technology has become a hot research topic recently. Here, we develop a ceramic (SiO₂) nanofiber-based water-induced electric generator via the sol-gel electrospinning technique, followed by calcination, which exhibits superior water-induced electricity generation property with significant softness. This superior performance of the SiO₂ nanofiber-based generator may be attributed to two aspects: the electrokinetic effect generated by water evaporation force and the ion gradient formed between the top and bottom electrodes. The SiO₂ nanofiber-based generator is capable of supplying a continuous voltage and current output of 0.48 V and 0.37 μA, respectively, without weakening after 500 times of bending. Moreover, the high voltage and current output generated by the water-induced generator can be realized in series or parallel and has practical applications, such as in a commercial digital calculator. This environmentally friendly generator, with its low cost, provides great potential for future green energy utilization and opens up new possibilities for portable electronics.

Superior Flexibility in Oxide Ceramic Crystal Nanofibers

Oxide crystal ceramics are commonly hard and brittle, when they are bent they typically fracture. Such mechanical response limits the use of these materials in emerging fields like wearable electronics. Here, a polymer-induced assembly strategy is reported to construct orderly assembled TiO₂ crystals into continuous nanofibers that are stretchable, bendable, and even knottable. Ball-milling the spinning sol and curved-drafting the electrospun nanofibers significantly improve the molecular structural order and reduce pore defects in the precursor nanofibers. Using this method, continuous TiO₂ nanofibers, in which orderly assembled TiO₂ nanocrystals (brick) are connected by twin grain boundaries or an amorphous region (mortar), are formed after sintering. Mechanical measurements and finite element analysis simulation indicate that the dislocation slip of "bricks" and the elastic deformation of "mortar" render the nanofibers with a small bending rigidity of ≈22 mN and a small elastic modulus of ≈20.8 Gpa, thus displaying properties associated with both soft and hard matter. More importantly, the reported approach can be easily extended to synthesize a wide range of soft, yet tough ceramic membranes, such as ZrO₂ and SiO₂ .

Dynamic Regulation of Lithium Dendrite Growth with Electromechanical Coupling Effect of Soft BaTiO3 Ceramic Nanofiber Films

Lithium (Li) metal batteries (LMBs) offer great opportunity for developing high-energy density energy-storage-systems, but the anodes suffer a severe problem of dendrite growth that hinders the practical applications of LMBs. Here, we report a soft BaTiO₃ ceramic nanofiber film with excellent ferroelectricity and piezoelectricity that enables one to transverse the dense deposition of Li metal. During Li plating, the strong ferroelectricity reduces the Li-ion concentration gradient near the anode and thus facilitating their uniform deposition. Once squeezed by these Li deposits, the BaTiO₃ film generates instantaneous piezo-effect to dynamically change the subsequent Li deposition from vertical to lateral. As a result, Li-Cu cells exhibit reversible plating-stripping processes for over 200 cycles with a high Coulombic efficiency of >98.3%. When pairing with high-voltage LiNi_0.8Co_0.15Al_0.05O₂ cathodes, the LMBs can retain >80% capacity in 300 cycles without forming dendrites even under challenging conditions including a high cathode loading of 7.2 mg/cm², a lean electrolyte amount of 7 μL/mg, and high current rates. The findings point to a promising electromechanical coupling strategy to dynamically adjust dendrite growth for designing Li metal anodes.

Polymer Template Synthesis of Flexible SiO2 Nanofibers to Upgrade Composite Electrolytes

Flexible oxide ceramic films offer prospects for revolutionizing diverse fields such as energy and electronics, but their fabrication methods are typically elaborate and cannot be expanded. Here, we report a scalable strategy to fabricate flexible and robust SiO₂ nanofiber films with controllable morphology using a sol-gel electrospinning method followed by low-temperature calcination. When applied to composite polymer electrolytes (CPEs) for solid-state batteries by filling polyethylene oxide into porous ceramic films, SiO₂ nanofibers with large surface areas (51 m²·g^-1) demonstrate strong Lewis interfacial interactions and isotropic ionic transfer channels that mitigate polymer crystallinity and Li⁺-concentration polarization, imparting high conductivity (1.3 × 10^-4 S·cm^-1 at 30 °C) and structural stability to the electrolytes. As a result, all-solid-state LiFePO₄||Li shows great rate capability and long cycling stability with high discharge capacities of 159 and 132 mA·h·g^-1 at 0.5C under 60 and 45 °C, respectively, demonstrating broad commercial prospects for the scale production of efficient solid electrolytes.

Transformation of oxide ceramic textiles from insulation to conduction at room temperature

Oxide ceramics are considered to be nonconductive brittle materials, which limits their applications in emerging fields such as conductive textiles. Here, we show a facile domino-cascade reduction method that enables rapid transformation of ceramic nanofiber textiles from insulation to conduction at room temperature. After putting dimethylacetamide-wetted textiles, including TiO2, SnO2, BaTiO3, and Li0.33La0.56TiO3, on lithium plates, the self-driven chemical reactions induce defects in oxides. These defects initiate an interfacial insulation-to-conductive phase transition, which triggers the domino-cascade reduction from the interface to the whole textile. Correspondingly, the conductivity of the textile sharply increased from 0 to 40 S/m over a period of 1 min. The modified oxide textiles exhibit enhanced electrochemical performance when substituting the metallic current collectors of lithium batteries. This room temperature reduction method can protect the nanostructures while inducing defects in oxide ceramic textiles, appealing for numerous applications.

Polyoxyethylene (PEO)|PEO-Perovskite|PEO Composite Electrolyte for All-Solid-State Lithium Metal Batteries

Composite solid electrolytes (CSEs) are regarded as one of the most promising candidates for all-solid-state lithium metal batteries (ASSLMBs) due to inherited desirable features from both ceramic and polymer materials. However, poor interfacial contact/compatibility between the electrodes and solid electrolytes remains a critical challenge. In this work, we prepare a flexible CSE composed of polyoxyethylene (PEO)-perovskite composite with a layer of PEO on either side. This PEO|PEO-perovskite|PEO structure prevents direct contact between the perovskite and lithium metal at the anode side, avoiding the undesired reaction between the two materials (Ti⁴⁺ + Li → Ti³⁺ + Li⁺). Moreover, the design incorporating the PEO surface on either side enables superb contact between the electrolyte and the electrodes and buffers the change in electrolyte volume from the cathode and lithium metal during repeated cycling, resulting in low interfacial resistances and excellent cycling stability. Meanwhile, perovskite inorganic electrolyte Li_0.33La_0.557TiO₃ (LLTO) 3D nanofiber networks formed by electrospinning enable the CSE to achieve enhanced mechanical strength and high ionic conductivity of 0.16 mS cm^-1 at 24 °C. As a result, a Li|PEO-LiTFSI-LLTO|Li symmetric cell remains stable after 400 h of operation without short-circuiting. Most notably, a Li|PEO-LiTFSI-LLTO|LiFePO₄ full battery is capable of delivering a high capacity of 135.0 mAh g^-1 even at 2 C with a retention rate of 79.0% after 300 cycles at 60 °C. These results demonstrate that the integrated sandwich structure proposed in this work is effective in developing high-performance composite solid electrolytes for ASSLMBs.

Self-Assembled Conductive Metal-Oxide Nanofiber Interface for Stable Li-Metal Anode

Li-metal anodes promise to build high-energy-storage systems, but they suffer from safety problems from severe dendrite growth. Here, we develop a thin and conformal hybrid ionic and electronic conducting metal-oxide nanofiber interface to stabilize Li-anodes without forming dendrites. The thin ionic-conductive Li_0.33La_0.56TiO₃ (LLTO) nanofiber film is first fabricated by electrospinning followed by pyrolysis. After connecting with the electrolytes-wetted Li-metal anodes, due to the self-driven chemical reactions, LLTO is reduced, and a hybrid conducting interface is developed. The interface can act as a reservoir to redistribute the nonuniform Li-ion flux above the anode surface and reduce the driving force of dendrite formation by leveling electric potential distribution, enabling a stable Li plating-stripping with a low overpotential of 80 mV over 800 h at a high current of 5 mA/cm². More practically, the Li-LiNi_0.8Co_0.15Al_0.05O₂ cells deliver a high capacity of 147 mA h/g at 1 C with a Coulombic efficiency of 99% over 150 cycles, offering prospects to achieve reliable Li-metal batteries.

Constructing Ionic Gradient and Lithiophilic Interphase for High-Rate Li-Metal Anode

Li metal is the optimal choice as an anode due to its high theoretical capacity, but it suffers from severe dendrite growth, especially at high current rates. Here, an ionic gradient and lithiophilic inter-phase film is developed, which promises to produce a durable and high-rate Li-metal anode. The film, containing an ionic-conductive Li_0.33 La_0.56 TiO₃ nanofiber (NF) layer on the top and a thin lithiophilic Al₂ O₃ NF layer on the bottom, is fabricated with a sol-gel electrospinning method followed by sintering. During cycling, the top layer forms a spatially homogenous ionic field distribution over the anode, while the bottom layer reduces the driving force of Li-dendrite formation by decreasing the nucleation barrier, enabling dendrite-free plating-stripping behavior over 1000 h at a high current density of 5 mA cm^-2 . Remarkably, full cells of Li//LiNi_0.8 Co_0.15 Al_0.05 O₂ exhibit a high capacity of 133.3 mA h g^-1 at 5 C over 150 cycles, contributing a step forward for high-rate Li-metal anodes.