Applications of Polymer Electrolytes in Lithium-Ion Batteries: A Review

A single-ion conductive composite gel electrolyte based on helical mesoporous silica nanofibers for high-performance lithium-ion batteries

Gel polymer electrolytes (GPEs) combined with organic liquid plasticizer, lithium salt and solid-state polymer are expected to achieve the fusion of high safety, high ionic conductivity and good electrode-electrolyte interface compatibility. Meanwhile, single-ion conductive electrolyte with high lithium-ion transference number (tLi+) can effectively prevent the formation of lithium dendrites and improve the power density of the battery. Therefore, it's meaningful to develop single-ion conductive GPEs to improve the comprehensive property of lithium-ion batteries (LIBs). In this paper, a single-ion conductive composite gel electrolyte (SCGE) was designed and synthesized. Helical mesoporous silica@polydopamine-graft-lithium salt (SPL) nanofibers were dispersed in poly(vinylidene fluoride-hexafluoropropylene) matrix to form a porous SCGE membrane with considerable liquid electrolyte uptake (605 %). The organic/inorganic hybrid SPL anchors the anions of lithium salts, promotes the dissociation of Li+ and helps its rapid conduction, achieving high tLi+ (0.94). When the SPL content in the SCGE membrane is 30 wt% (denoted as S3-CGE), the assembled Li|S3-CGE|Li battery only generates an overpotential of 0.1 V after cycling for 1000 h at the current density of 0.1 mA cm-2. The assembled LFP|S3-CGE|Li battery has a first-cycle specific capacity of 150.1 mAh g-1 at 0.1C and can cycle stably at different current densities. These results show that the SCGE has great potential for practical application in high performance LIBs.

Advances in polymer electrolyte design strategies for highly efficient supercapacitors and Zn-based batteries

Electrolytes play a crucial role in the performance of electrochemical energy storage systems, such as batteries and supercapacitors. Their main function is to act as a medium for ion transport between the electrodes, which is essential for the charge and discharge processes. Beyond this, the electrochemical performance of the device is strongly affected by the various properties of the electrolytes such as their ionic conductivity, chemical, thermal and electrochemical stability, chemical compatibility, etc. The intrinsic limitations of the aqueous electrolytes such as their decomposition during high voltage operations has led to the development of better electrolytes for batteries and supercapacitors. These included non-aqueous electrolytes, inorganic solid-state electrolytes, and gel polymer electrolytes. This feature article reviews the various approaches to designing a highly efficient polymer electrolyte for the targeted application along with the suitable device fabrication strategy adopted in the current literature to achieve a balanced electrochemical performance compared with a liquid electrolyte-based device.

Development of the all-solid-state flexible supercapacitor membranes via RAFT-mediated grafting and electrospun nanofiber modification of track-etched membranes

Developing novel membranes marks a significant advancement in flexible energy storage systems. In this work, a hybrid track-etched membrane (TeM) was synthesized through RAFT-mediated polymerization, where poly(acrylic acid) (PAA) was grafted onto both the nanopore walls and surface of PET-based TeMs (PET-g-PAA), creating a stable and functionalized matrix for further enhancements. The membrane was then modified by incorporating electrospun composite nanofibers made from poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) as the polymer matrix, ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate, EM-IMBF4) as the supporting electrolyte, and graphene oxide (GO) as the ionic conductivity enhancer. The nanofibers (PVDF-HFP_GO) were deposited on either one or both surfaces of the grafted membrane. These modifications substantially improved the membrane's active surface area, porosity, and electrochemical performance, positioning it as a strong candidate for flexible energy storage applications. Comprehensive characterizations verified the successful modification and enhanced properties, including FTIR, SEM-EDX, XPS, TGA, porosity analysis, and contact angle measurements. Electrochemical performance was evaluated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Among the tested membranes, the one modified with 0.5% GO-containing nanofibers demonstrated the highest capacitance and coulombic efficiency. Although the membrane showed strong charge/discharge efficiency and high initial performance, performance degradation was observed after extended cycling, particularly at higher current densities. The ionic conductivity of the hybrid membranes (with a GO concentration of 0.5%) reaches 14.83 × 10-3 mS cm-1 for single-sided nanofiber-covered membranes and 39.08 × 10-3 mS cm-1 for double-sided nanofiber-covered membranes, while for similar samples without addition of GO this values were found to be of 1.42 × 10-3 mS cm-1, which is significantly higher than conventional polymer-based electrolyte membranes (∼10-4 to 10-2 mS cm-1), and comparable to advanced ionic gel-based systems (∼10-2 to 10-1 mS cm-1). The synergistic effects of PAA grafting and PVDF-HFP_GO fibers delivered competitive charge/discharge efficiency when compared to similar systems, though further optimization of current density and cycling stability is required. This study highlights the potential of combining the RAFT-mediated grafting technique with electrospun composite nanofibers in modifying TeMs to develop durable and flexible supercapacitor membranes with promising electrochemical performance.

From Present Innovations to Future Potential: The Promising Journey of Lithium-Ion Batteries

Lithium-ion batteries (LIBs) have become integral to modern technology, powering portable electronics, electric vehicles, and renewable energy storage systems. This document explores the complexities and advancements in LIB technology, highlighting the fundamental components such as anodes, cathodes, electrolytes, and separators. It delves into the critical interplay of these components in determining battery performance, including energy density, cycling stability, and safety. Moreover, the document addresses the significant sustainability challenges posed by the widespread adoption of LIBs, focusing on resource depletion and environmental impact. Various recycling practices, including hydrometallurgy, pyrometallurgy, and direct recycling, are evaluated for their efficiency in metal recovery and ecological footprint. The advancements in recycling technologies aim to mitigate the adverse effects of LIB waste, emphasizing the need for sustainable and scalable solutions. The research underscores the importance of ongoing innovation in electrode materials and recycling methodologies, reminding us of our responsibility and commitment to finding and implementing these solutions, as this continuous improvement is crucial to enhance the performance, safety, and sustainability of LIBs, ensuring their continued relevance in the evolving energy storage landscape.

Unprecedented Cubic Mesomorphic Behaviour of Crown-Ether Functionalized Amphiphilic Cyclodextrins

Amphiphilic supramolecular materials based on biodegradable cyclodextrins (CDs) have been known to self-assemble into different types of thermotropic liquid crystals, including smectic and hexagonal columnar mesophases. Previous studies on amphiphilic CDs bearing 14 aliphatic chains at the secondary face and 7 oligoethylene glycol (OEG) chains at the primary face showed that the stability of the mesophase can be rationally tuned through implementation of terminal functional groups to the OEG chains. Here, we report the syntheses of first examples of crown ether-functionalized amphiphilic cyclodextrins that unexpectedly form thermotropic bicontinuous cubic phases. This constitutes the first reported examples of cyclodextrins forming such phases, which are potentially capable of 3D ion transport. Lithium composites were made to assess lithium conduction in the material. XRD revealed the added lithium salt destabilizes the cubic phase in favour of the smectic phase. Solid-state NMR studies showed that these materials conduct lithium ions with a very low activation energy.

Polymers in Physics, Chemistry and Biology: Behavior of Linear Polymers in Fractal Structures

We start presenting an overview on recent applications of linear polymers and networks in condensed matter physics, chemistry and biology by briefly discussing selected papers (published within 2022-2024) in some detail. They are organized into three main subsections: polymers in physics (further subdivided into simulations of coarse-grained models and structural properties of materials), chemistry (quantum mechanical calculations, environmental issues and rheological properties of viscoelastic composites) and biology (macromolecules, proteins and biomedical applications). The core of the work is devoted to a review of theoretical aspects of linear polymers, with emphasis on self-avoiding walk (SAW) chains, in regular lattices and in both deterministic and random fractal structures. Values of critical exponents describing the structure of SAWs in different environments are updated whenever available. The case of random fractal structures is modeled by percolation clusters at criticality, and the issue of multifractality, which is typical of these complex systems, is illustrated. Applications of these models are suggested, and references to known results in the literature are provided. A detailed discussion of the reptation method and its many interesting applications are provided. The problem of protein folding and protein evolution are also considered, and the key issues and open questions are highlighted. We include an experimental section on polymers which introduces the most relevant aspects of linear polymers relevant to this work. The last two sections are dedicated to applications, one in materials science, such as fractal features of plasma-treated polymeric materials surfaces and the growth of polymer thin films, and a second one in biology, by considering among others long linear polymers, such as DNA, confined within a finite domain.

High-Stability Composite Solid Polymer Electrolyte Composed of PAEPU/PP Nonwoven Fabric for Lithium-Ion Batteries

Solid polymer electrolytes have attracted considerable attention, owing to their flexibility and safety. At present, poly(ethylene oxide) is the most widely studied polymer electrolyte matrix. It exhibits higher safety than the polyolefin diaphragm used in traditional lithium-ion batteries. However, it readily crystallizes at room temperature, resulting in low ionic conductivity, and the preparation process involves organic solvents. In this study, from the perspective of molecular design, solvent-free polyaspartate polyurea (PAEPU) and the cheap and easily available polypropylene (PP) nonwoven fabric were used as support materials for the PAEPU/PP composite solid polymer electrolyte (PAEPU/PP m -CPE). This CPE has good thermal stability, dimensional stability, flexibility, and mechanical properties. Among the different CPEs that were analyzed, PAEPU/PP10-CPE@20 had the highest ionic conductivity, which was reinforced with 10 g/m2 PP nonwoven fabric and the content of lithium salt was 20 wt %. Furthermore, PAEPU/PP10-CPE@20 exhibited the highest electrochemical stability with an electrochemical window value of 5.53 V. Moreover, the capacity retention rate of the Li//PAEPU/PP10-CPE@20//LiFePO4 half-cell was 96.82% after 150 cycles at 0.05 C and 60 °C, and the capacity recovery rate in the rate test reached 98.81%.

State-of-the-Art Advances and Current Applications of Gel-Based Membranes

Gel-based membranes, a fusion of polymer networks and liquid components, have emerged as versatile tools in a variety of technological domains thanks to their unique structural and functional attributes. Historically rooted in basic filtration tasks, recent advancements in synthetic strategies have increased the mechanical strength, selectivity, and longevity of these membranes. This review summarizes their evolution, emphasizing breakthroughs that have positioned them at the forefront of cutting-edge applications. They have the potential for desalination and pollutant removal in water treatment processes, delivering efficiency that often surpasses conventional counterparts. The biomedical field has embraced them for drug delivery and tissue engineering, capitalizing on their biocompatibility and tunable properties. Additionally, their pivotal role in energy storage as gel electrolytes in batteries and fuel cells underscores their adaptability. However, despite monumental progress in gel-based membrane research, challenges persist, particularly in scalability and long-term stability. This synthesis provides an overview of the state-of-the-art applications of gel-based membranes and discusses potential strategies to overcome current limitations, laying the foundation for future innovations in this dynamic field.