Ultrahigh Elastic Polymer Electrolytes for Solid-State Lithium Batteries with Robust Interfaces

The multi-scale dissipation mechanism of composite solid electrolyte based on nanofiber elastomer for all-solid-state lithium metal batteries

Developing next generation batteries necessitates a paradigm shift in the way to engineering solutions for materials challenges. In comparison to traditional organic liquid batteries, all-solid-state batteries exhibit some significant advantages such as high safety and energy density, yet solid electrolytes face challenges in responding dimensional changes of electrodes driven by mass transport. Herein, the critical mechanical parameters affecting battery cycling duration are evaluated based on Spearman rank correlation coefficient, decoupling them into strength, ductility, stiffness, toughness, elasticity, etc. Inspired by the statistical results to apply the materials with stress-relief mechanisms, we propose an elastic solid electrolyte based on the multi-scale mechanical dissipation mechanism. The Li6.4La3Zr1.4Ta0.6O12/thermoplastic polyurethanes curled fibrous framework is designed and prepared by side-by-side electrospinning technique, serving as elastic source and ion-transport pathways for the composite with poly(ethylene oxide) matrix. Dominated sequentially by electrolyte deformation, network orientation, extendable fibers and molecular chain unfolding, the prepared elastic electrolyte exhibits excellent resilience, compression and puncture resistance. Meanwhile, the curled fast ion conductor fibers can also provide the transport pathways along the component of transmembrane direction, endowing the composite electrolyte with an ionic conductivity of 1.46 × 10-4 S cm-1 at 30 °C. A low capacity decay of 0.011 % per cycle at 2 C in assembled LiFePO4/Li battery and an excellent lifespan of 1000 cycles at 50 °C in LiNi0.8Mn0.1Co0.1O2/Li battery can be achieved. The elastic electrolyte system presents a promising strategy for enabling stable operation of high-energy all-solid-state lithium batteries.

The Intercorrelations of Mechanical Properties in Composite Solid Electrolytes and Their Decisive Role in Cells' Cycling Life

With deepening research on solid electrolytes, mechanical properties have been recognized to impact significantly on cells' performances and need to be intentionally enhanced. However, the intercorrelation of mechanical parameters and their modifications is still poorly understood. In this study, comprehensive mechanical characterizations are conducted on a series of typical PEO/LLZTO composite electrolytes. Each mechanical parameter under different deformation processes is obtained, including tensile, fracture, puncture, lap-shear, adhesion, and indentation. For the first time, change trends of these parameters are observed to reveal their intercorrelations. Interestingly, the mechanical resistances (elastic modulus, hardness, fracture energy, and puncturing force) could be adjusted toward the same direction, whereas the adhesive behaviors (shear strength and adhesion force) show an opposite trend. The mechanical resistance parameters show a decisive effect on the cell's cycling time, when they have a contradictory tendency with ionic conductivity. Also, different influences of synthesis conditions on mechanical properties are investigated systematically.

Kinetic and stability studies of amino acid metal-organic frameworks for encapsulating of amino acid dehydrogenase

Zr-MOFs was applied for the immobilization of hyperthermophilic and halophilic amino acid dehydrogenase (Zr-MOFs-NTAaDH) by physical adsorption for the biosynthesis of L-homophenylalanine. Activity of Zr-MOFs-NTAaDH was enhanced by 3.3-fold of the free enzyme at 70°C. And the enzyme activity of Zr-MOFs-NTAaDH was maintained at 4.16 U/mg at pH 11, which was 7.8 folds of that of NTAaDH. Kinetic parameters indicated catalytic efficiency of Zr-MOFs-NTAaDH was increased compared to the free enzyme as kcat of Zr-MOFs-NTAaDH was 12.3-fold of that of free enzyme. After 7 recycles, the activity of Zr-MOFs-NTAaDH remained 68 %. And Zr-MOFs-NTAaDH exhibited high ionic liquid tolerance which indicated the great potential for industrial application.

Composite Ionogel Electrodes for Polymeric Solid-State Li-Ion Batteries

Realizing rechargeable cells with practical energy and power density requires electrodes with high active material loading, a remaining challenge for solid-state batteries. Here, we present a new strategy based on ionogel-derived solid-state electrolytes (SSEs) to form composite electrodes that enable high active material loading (>10 mg/cm2, ~9 mA/cm2 at 1C) in a scalable approach for fabricating Li-ion cells. By tuning the precursor and active materials composition incorporated into the composite lithium titanate electrodes, we achieve near-theoretical capacity utilization at C/5 rates and cells capable of stable cycling at 5.85 mA/cm2 (11.70 A/g) with over 99% average Coulombic efficiency at room temperature. Finally, we demonstrate a complete polymeric solid-state cell with a composite anode and a composite lithium iron phosphate cathode with ionogel SSEs, which is capable of stable cycling at a 1C rate.

Epoxy-based multifunctional solid polymer electrolytes for structural batteries and supercapacitors. a short review

The potential applications of epoxy-based solid polymer electrolytes are continually expanding because of their versatile characteristics. These characteristics include mechanical rigidity, nonvolatility, nonflammability, and electrochemical stability. However, it is worth noting that pure epoxy-based solid polymer electrolytes inherently exhibit lower ion transport capabilities when compared to traditional liquid electrolytes. Striking a balance between high mechanical integrity and superior ionic conductivity at room temperature poses a significant challenge. In light of this challenge, this review is dedicated to elucidating the fundamental concepts of epoxy-based solid polymer electrolytes. It will explore various preparation techniques, the incorporation of different nanomaterials into epoxy-based solid polymer electrolytes, and an evaluation of their multifunctional properties. This comprehensive evaluation will cover both mechanical and electrical properties with a specific focus on their potential applications in batteries and structural supercapacitors.

Chemistry Aspects and Designing Strategies of Flexible Materials for High-Performance Flexible Lithium-Ion Batteries

In recent years, flexible and wearable electronics such as smart cards, smart fabrics, bio-sensors, soft robotics, and internet-linked electronics have impacted our lives. In order to meet the requirements of more flexible and adaptable paradigm shifts, wearable products may need to be seamlessly integrated. A great deal of effort has been made in the last two decades to develop flexible lithium-ion batteries (FLIBs). The selection of suitable flexible materials is important for the development of flexible electrolytes self-supported and supported electrodes. This review is focused on the critical discussion of the factors that evaluate the flexibility of the materials and their potential path toward achieving the FLIBs. Following this analysis, we present how to evaluate the flexibility of the battery materials and FLIBs. We describe the chemistry of carbon-based materials, covalent-organic frameworks (COFs), metal-organic frameworks (MOFs), and MXene-based materials and their flexible cell design that represented excellent electrochemical performances during bending. Furthermore, the application of state-of-the-art solid polymer and solid electrolytes to accelerate the development of FLIBs is introduced. Analyzing the contributions and developments of different countries has also been highlighted in the past decade. In addition, the prospects and potential of flexible materials and their engineering are also discussed, providing the roadmap for further developments in this fast-evolving field of FLIB research.

Laponite-Supported Gel Polymer Electrolyte with Multiple Lithium-Ion Transport Channels for Stable Lithium Metal Batteries

Lithium metal batteries have emerged as a promising candidate for next-generation power systems. However, the high reactivity of lithium metal with liquid electrolytes has resulted in decreased battery safety and stability, which poses a significant challenge. Herein, we present a modified laponite-supported gel polymer electrolyte (LAP@PDOL GPE) that was fabricated using in situ polymerization initiated by a redox-initiating system at ambient temperature. The LAP@PDOL GPE effectively facilitates the dissociation of lithium salts via electrostatic interaction and simultaneously constructs multiple lithium-ion transport channels within the gel polymer network. This hierarchical GPE demonstrates a remarkable ionic conductivity of 5.16 × 10^-4 S cm^-1 at 30 °C. Furthermore, the robust laponite component of the LAP@PDOL GPE forms a barrier against Li dendrite growth while also participating in the establishment of a stable electrode/electrolyte interface with Si-rich components. The in situ polymerization process further improves the interfacial contact, enabling the LiFePO₄/LAP@PDOL GPE/Li cell to exhibit an impressive capacity of 137 mAh g^-1 at 1C, with a capacity retention of 98.5% even after 400 cycles. In summary, the developed LAP@PDOL GPE shows great potential in addressing the critical issues of safety and stability associated with lithium metal batteries while also delivering improved electrochemical performance.

Abundant Hydrogen Bonds Formed in a Urea-Based Gel Polymer Electrolyte Improve Interfacial Stability in Lithium Metal Batteries

As an emerging and potential replacement system for liquid electrolytes, polymer electrolytes (PEs) exhibit unique capacity in suppressing metal dendrite formation and leakage risks. However, the most used polymer matrix, including polyether, polyester, and polysiloxane, still cannot meet the practical demands for metal electrode compatibility and long lifespan. In this study, gel polymer electrolytes consisting of a polyurea network with abundant hydrogen bonds and deep eutectic electrolyte (DEE) are designed and prepared in-situ. The hydrogen bonding between polyurea chains and polyurea-DEE provides good interfacial stability between PEs and lithium metal. As a result, the assembled Li/LiFePO₄ cells based on this electrolyte deliver a long cycle life with 90 % retention after 500 cycles and 76.5 % retention after 1000 cycles at 1 C. In addition, the flexible design characteristics of polyurea structure permit easy operation for performance optimization by modulating the composition of hard and soft segments, and enhanced ionic conductivity and self-healing efficiency are obtained. This study provides a novel method for preparing advanced polymer electrolytes for lithium metal batteries.