Ultra-thin Solid-State Li-Ion Electrolyte Membrane Facilitated by a Self-Healing Polymer Matrix

Fusion Bonding Technique for Solvent-Free Fabrication of All-Solid-State Battery with Ultrathin Sulfide Electrolyte

For preparing next-generation sulfide all-solid-state batteries (ASSBs), the solvent-free manufacturing process has huge potential for the advantages of economic, thick electrode, and avoidance of organic solvents. However, the dominating solvent-free process is based on the fibrillation of polytetrafluoroethylene, suffering from poor mechanical property and electrochemical instability. Herein, a continuously solvent-free paradigm of fusion bonding technique is developed. A percolation network of thermoplastic polyamide (TPA) binder with low viscosity in viscous state is constructed with Li6PS5Cl (LPSC) by thermocompression (≤5 MPa), facilitating the formation of ultrathin LPSC film (≤25 µm). This composite sulfide film (CSF) exhibits excellent mechanical properties, ionic conductivity (2.1 mS cm-1), and unique stress-dissipation to promote interface stabilization. Thick LiNi0.83Co0.11Mn0.06O2 cathode can be prepared by this solvent-free method and tightly adhered to CSF by interfacial fusion of TPA for integrated battery. This integrated ASSB shows high-energy-density feasibility (>2.5 mAh cm-2 after 1400 cycles of 9200 h and run for more than 10 000 h), and energy density of 390 Wh kg-1 and 1020 Wh L-1. More specially, high-voltage bipolar cell (≥8.5 V) and bulk-type pouch cell (326 Wh kg-1) are facilely assembled with good cycling performance. This work inspires commercialization of ASSBs by a solvent-free method and provides beneficial guiding for stable batteries.

Dynamic Covalent Amphiphilic Polymer Conetworks Based on End-Linked Pluronic F108: Preparation, Characterization, and Evaluation as Matrices for Gel Polymer Electrolytes

We present the development of a platform of well-defined, dynamic covalent amphiphilic polymer conetworks (APCN) based on an α,ω-dibenzaldehyde end-functionalized linear amphiphilic poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) (PEG-b-PPG-b-PEG, Pluronic) copolymer end-linked with a triacylhydrazide oligo(ethylene glycol) triarmed star cross-linker. The developed APCNs were characterized in terms of their rheological (increase in the storage modulus by a factor of 2 with increase in temperature from 10 to 50 °C), self-healing, self-assembling, and mechanical properties and evaluated as a matrix for gel polymer electrolytes (GPEs) in both the stretched and unstretched states. Our results show that water-loaded APCNs almost completely self-mend, self-organize at room temperature into a body-centered cubic structure with long-range order exhibiting an aggregation number of around 80, and display an exceptional room temperature stretchability of ∼2400%. Furthermore, ionic liquid-loaded APCNs could serve as gel polymer electrolytes (GPEs), displaying a substantial ion conductivity in the unstretched state, which was gradually reduced upon elongation up to a strain of 4, above which it gradually increased. Finally, it was found that recycled (dissolved and re-formed) ionic liquid-loaded APCNs could be reused as GPEs preserving 50-70% of their original ion conductivity.

External Stimuli-Induced Welding of Dynamic Cross-Linked Polymer Networks

Thermosets have been crucial in modern engineering for decades, finding applications in various industries. Welding cross-linked components are essential in the processing of thermosets for repairing damaged areas or fabricating complex structures. However, the inherent insolubility and infusibility of thermoset materials, attributed to their three-dimensional network structure, pose challenges to welding development. Incorporating dynamic chemical bonds into highly cross-linked networks bridges the gap between thermosets and thermoplastics presenting a promising avenue for innovative welding techniques. External stimuli, including thermal, light, solvent, pH, electric, and magnetic fields, induce dynamic bonds' breakage and reformation, rendering the cross-linked network malleable. This plasticity facilitates the seamless linkage of two parts to an integral whole, attracting significant attention for potential applications in soft actuators, smart devices, solid batteries, and more. This review provides a comprehensive overview of dynamic bonds employed in welding dynamic cross-linked networks (DCNs). It extensively discusses the classification and fabrication of common epoxy DCNs and acrylate DCNs. Notably, recent advancements in welding processes based on DCNs under external stimuli are detailed, focusing on the welding dynamics among covalent adaptable networks (CANs).

Self-healing polymers through hydrogen-bond cross-linking: synthesis and electronic applications

Recently, polymers capable of repeatedly self-healing physical damage and restoring mechanical properties have attracted extensive attention. Among the various supramolecular chemistry, hydrogen-bonding (H-bonding) featuring reversibility, directionality and high per-volume concentration has become one of the most attractive directions for the development of self-healing polymers (SHPs). Herein, we review the recent advances in the design of high-performance SHPs based on different H-bonding types, for example, H-bonding motifs and excessive H-bonding. In particular, the effects of the structural design of SHPs on their mechanical performance and healing efficiency are discussed in detail. Moreover, we also summarize how to employ H-bonding-based SHPs for the preparation of self-healable electronic devices, focusing on promising topics, including energy harvesting devices, energy storage devices, and flexible sensing devices. Finally, the current challenges and possible strategies for the development of H-bonding-based SHPs and their smart electronic applications are highlighted.

Liquid-Phase Approach to Glass-Microfiber-Reinforced Sulfide Solid Electrolytes for All-Solid-State Batteries

Deformable, fast-ion conducting sulfides enable the construction of bulk-type solid-state batteries that can compete with current Li-ion batteries in terms of energy density and scalability. One approach to optimizing the energy density of these cells is to minimize the size of the electrolyte layer by integrating the solid electrolyte in thin membranes. However, additive-free thin membranes, as well as many membranes based on preprepared scaffolds, are difficult to prepare or integrate in solid cells on a large scale. Here, we propose a scalable solution-based approach to produce bulk-type glass-microfiber-reinforced composites that restore the deformability of sulfide electrolytes and can easily be shaped into thin membranes by cold pressing. This approach supports both the ease of preparation and enhancement of the energy density of sulfide-based solid-state batteries.

Elucidating Ion Transport Phenomena in Sulfide/Polymer Composite Electrolytes for Practical Solid-State Batteries

Despite the enormous interest in inorganic/polymer composite solid-state electrolytes (CSEs) for solid-state batteries (SSBs), the underlying ion transport phenomena in CSEs have not yet been elucidated. Here, we address this issue by formulating a mechanistic understanding of bi-percolating ion channels formation and ion conduction across inorganic-polymer electrolyte interfaces in CSEs. A model CSE is composed of argyrodite-type Li6PS5Cl (LPSCl) and gel polymer electrolyte (GPE, including Li+-glyme complex as an ion-conducting medium). The percolation threshold of the LPSCl phase in the CSE strongly depends on the elasticity of the GPE phase. Additionally, manipulating the solvation/desolvation behavior of the Li+-glyme complex in the GPE facilitates ion conduction across the LPSCl-GPE interface. The resulting scalable CSE (area = 8 × 6 (cm × cm), thickness ~ 40 μm) can be assembled with a high-mass-loading LiNi0.7Co0.15Mn0.15O2 cathode (areal-mass-loading = 39 mg cm-2) and a graphite anode (negative (N)/positive (P) capacity ratio = 1.1) in order to fabricate an SSB full cell with bi-cell configuration. Under this constrained cell condition, the SSB full cell exhibits high volumetric energy density (480 Wh Lcell-1) and stable cyclability at 25 °C, far exceeding the values reported by previous CSE-based SSBs.

Recent Configurational Advances for Solid-State Lithium Batteries Featuring Conversion-Type Cathodes

Solid-state lithium metal batteries offer superior energy density, longer lifespan, and enhanced safety compared to traditional liquid-electrolyte batteries. Their development has the potential to revolutionize battery technology, including the creation of electric vehicles with extended ranges and smaller more efficient portable devices. The employment of metallic lithium as the negative electrode allows the use of Li-free positive electrode materials, expanding the range of cathode choices and increasing the diversity of solid-state battery design options. In this review, we present recent developments in the configuration of solid-state lithium batteries with conversion-type cathodes, which cannot be paired with conventional graphite or advanced silicon anodes due to the lack of active lithium. Recent advancements in electrode and cell configuration have resulted in significant improvements in solid-state batteries with chalcogen, chalcogenide, and halide cathodes, including improved energy density, better rate capability, longer cycle life, and other notable benefits. To fully leverage the benefits of lithium metal anodes in solid-state batteries, high-capacity conversion-type cathodes are necessary. While challenges remain in optimizing the interface between solid-state electrolytes and conversion-type cathodes, this area of research presents significant opportunities for the development of improved battery systems and will require continued efforts to overcome these challenges.

Solid-State Electrolytes in Lithium-Sulfur Batteries: Latest Progresses and Prospects

Solid-state lithium-sulfur batteries (SSLSBs) have attracted tremendous research interest due to their large theoretical energy density and high safety, which are highly important indicators for the development of next-generation energy storage devices. Particularly, safety and "shuttle effect" issues originating from volatile and flammable liquid organic electrolytes can be fully mitigated by switching to a solid-state configuration. However, their road to thecommercial application is still plagued with numerous challenges, most notably the intrinsic electrochemical instability of solid-state electrolytes (SSEs) materials and their interfacial compatibility with electrodes and electrolytes. In this review, a critical discussion on the key issues and problems of different types of SSEs as well as the corresponding optimization strategies are first highlighted. Then, the state-of-the-art preparation methods and properties of different kinds of SSE materials, and their manufacture, characterization and performance in SSLSBs are summarized in detail. Finally, a scientific outlook for the future development of SSEs and the avenue to commercial application of SSLSBs is also proposed.

Progress and Prospects of Inorganic Solid-State Electrolyte-Based All-Solid-State Pouch Cells

All-solid-state batteries have piqued global research interest because of their unprecedented safety and high energy density. Significant advances have been made in achieving high room-temperature ionic conductivity and good air stability of solid-state electrolytes (SSEs), mitigating the challenges at the electrode-electrolyte interface, and developing feasible manufacturing processes. Along with the advances in fundamental study, all-solid-state pouch cells using inorganic SSEs have been widely demonstrated, revealing their immense potential for industrialization. This review provides an overview of inorganic all-solid-state pouch cells, focusing on ultrathin SSE membranes, sheet-type thick solid-state electrodes, and bipolar stacking. Moreover, several critical parameters directly influencing the energy density of all-solid-state Li-ion and lithium-sulfur pouch cells are outlined. Finally, perspectives on all-solid-state pouch cells are provided and specific metrics to meet certain energy density targets are specified. This review looks to facilitate the development of inorganic all-solid-state pouch cells with high energy density and excellent safety.

Interface Design Enabling Stable Polymer/Thiophosphate Electrolyte Separators for Dendrite-Free Lithium Metal Batteries

Organic/inorganic interfaces greatly affect Li⁺ transport in composite solid electrolytes (SEs), while SE/electrode interfacial stability plays a critical role in the cycling performance of solid-state batteries (SSBs). However, incomplete understanding of interfacial (in)stability hinders the practical application of composite SEs in SSBs. Herein, chemical degradation between Li₆ PS₅ Cl (LPSCl) and poly(ethylene glycol) (PEG) is revealed. The high polarity of PEG changes the electronic state and structural bonding of the PS₄ ^3- tetrahedra, thus triggering a series of side reactions. A substituted terminal group of PEG not only stabilizes the inner interfaces but also extends the electrochemical window of the composite SE. Moreover, a LiF-rich layer can effectively prevent side reactions at the Li/SE interface. The results provide insights into the chemical stability of polymer/sulfide composites and demonstrate an interface design to achieve dendrite-free lithium metal batteries.

Solvent-Responsive Reversible and Controllable Conversion between a Polyimine Membrane and an Organic Molecule Cage

Adaptive bionic self-correcting behavior offers an attractive property for chemical systems. Here, based on the dynamic feature of imine formation, we propose a solvent-responsive strategy for smart switching between an amorphous ionic polyimine membrane and a crystalline organic molecule cage without the addition of other building blocks. To adapt to solvent environmental constraints, the aldehyde and amine components undergo self-correction to form a polymer network or a molecular cage. Studies have shown that the amorphous film can be switched in acetonitrile to generate a discrete cage with bright birefringence under polarized light. Conversely, the membrane from the cage crystal conversion can be regained in ethanol. Such a membrane-cage interconversion can be cycled continuously at least 5 times by switching the two solvents. This work builds a bridge between the polymer network and crystalline molecules and offers prospects for smart dynamic materials.

Preparation and Closed-Loop Recycling of Ultra-High-Filled Wood Flour/Dynamic Polyurethane Composites

The development of biomass-based composites has greatly reduced the daily consumption of plastics. However, these materials are rarely recyclable, thus, posing a severe threat to the environment. Herein, we designed and prepared novel composite materials with ultra-high biomass (i.e., wood flour) filling capacity and good closed-loop recycling properties. The dynamic polyurethane polymer was polymerized in situ on the surface of wood fiber, and then they were hot-pressed into composites. Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and dynamic thermomechanical analysis (DMA) measurements reveal good compatibility between the polyurethane and wood flour in the composites when the wood flour content is ≤80 wt%. The maximum tensile and bending strength of the composite are 37 and 33 MPa when the wood flour content is 80%. The higher wood flour content results in higher thermal expansion stability and creep resistance in the composites. Moreover, the thermal debonding of dynamic phenol–carbamate bonds facilitates the composites to undergo physical and chemical cycling. The recycled and remolded composites exhibit good mechanical property recovery rates and retain the chemical structures of the original composites.

Lithium Phosphorus Sulfide Chloride-Polymer Composite via the Solution-Precipitation Process for Improving Stability toward Dendrite Formation of Li-Ion Solid Electrolyte

Improving the mechanical strength of ceramic solid electrolytes such as lithium phosphorus sulfide families for pressure-driven dendrite blocking as well as reducing the electronic conductivity to prevent a dendrite formation inside the electrolytes are very important to extend the lifespan of all-solid-state lithium-metal batteries. Here, we propose a low-temperature solution-precipitation process to prepare polymer-solid electrolyte composites for a highly uniform polymer distribution in the electrolyte to enhance their mechanical strength and reduce their electronic conduction. The composites with up to 12 wt % of polymer are prepared, and the composites exhibit high ionic conductivities of up to 0.3 mS/cm. Furthermore, the electrochemical stability of the electrolyte composites on Li striping/plating cycles is investigated. We confirm that the proposed solution-precipitation process makes the composite much more stable than the bare solid electrolyte and causes them to outperform similar composites from the other existing preparation methods, such as mechanical mixing and solution dispersion.

Self-Healing Polymer Electrolytes for Next-Generation Lithium Batteries

The integration of polymer materials with self-healing features into advanced lithium batteries is a promising and attractive approach to mitigate degradation and, thus, improve the performance and reliability of batteries. Polymeric materials with an ability to autonomously repair themselves after damage may compensate for the mechanical rupture of an electrolyte, prevent the cracking and pulverization of electrodes or stabilize a solid electrolyte interface (SEI), thus prolonging the cycling lifetime of a battery while simultaneously tackling financial and safety issues. This paper comprehensively reviews various categories of self-healing polymer materials for application as electrolytes and adaptive coatings for electrodes in lithium-ion (LIBs) and lithium metal batteries (LMBs). We discuss the opportunities and current challenges in the development of self-healable polymeric materials for lithium batteries in terms of their synthesis, characterization and underlying self-healing mechanism, as well as performance, validation and optimization.

Self-organized hetero-nanodomains actuating super Li+ conduction in glass ceramics

Easy-to-manufacture Li₂S-P₂S₅ glass ceramics are the key to large-scale all-solid-state lithium batteries from an industrial point of view, while their commercialization is greatly hampered by the low room temperature Li⁺ conductivity, especially due to the lack of solutions. Herein, we propose a nanocrystallization strategy to fabricate super Li⁺-conductive glass ceramics. Through regulating the nucleation energy, the crystallites within glass ceramics can self-organize into hetero-nanodomains during the solid-state reaction. Cryogenic transmission electron microscope and electron holography directly demonstrate the numerous closely spaced grain boundaries with enriched charge carriers, which actuate superior Li⁺-conduction as confirmed by variable-temperature solid-state nuclear magnetic resonance. Glass ceramics with a record Li⁺ conductivity of 13.2 mS cm^-1 are prepared. The high Li⁺ conductivity ensures stable operation of a 220 μm thick LiNi_0.6Mn_0.2Co_0.2O₂ composite cathode (8 mAh cm^-2), with which the all-solid-state lithium battery reaches a high energy density of 420 Wh kg^-1 by cell mass and 834 Wh L^-1 by cell volume at room temperature. These findings bring about powerful new degrees of freedom for engineering super ionic conductors.

Toluene Tolerated Li9.88GeP1.96Sb0.04S11.88Cl0.12 Solid Electrolyte toward Ultrathin Membranes for All-Solid-State Lithium Batteries

Sulfide solid electrolyte membranes employed in all-solid-state lithium batteries generally show high thickness and poor chemical stability, which limit the cell-level energy density and cycle life. In this work, Li_9.88GeP_1.96Sb_0.04S_11.88Cl_0.12 solid electrolyte is synthesized with Sb, Cl partial substitution of P, S, possessing excellent toluene tolerance and stability to lithium. The formed SbS₄^3- group in Li_9.88GeP_1.96Sb_0.04S_11.88Cl_0.12 exhibits low adsorption energy and reactivity for toluene molecules, confirmed by first-principles density functional theory calculation. Using toluene as the solvent, ultrathin Li_9.88GeP_1.96Sb_0.04S_11.88Cl_0.12 membranes with adjustable thicknesses can be well prepared by the wet coating method, and an 8 μm thick membrane exhibits an ionic conductivity of 1.9 mS cm^-1 with ultrahigh ionic conductance of 1860 mS and ultralow areal resistance of 0.68 Ω cm^-2 at 25 °C. The obtained LiCoO₂|Li_9.88GeP_1.96Sb_0.04S_11.88Cl_0.12 membrane|Li all-solid-state lithium battery shows an initial reversible capacity of 125.6 mAh g^-1 with a capacity retention of 86.3% after 250 cycles at 0.1 C under 60 °C.

Current Self-Healing Binders for Energetic Composite Material Applications

Energetic composite materials (ECMs) are the basic materials of polymer binder explosives and composite solid propellants, which are mainly composed of explosive crystals and binders. During the manufacturing, storage and use of ECMs, the bonding surface is prone to micro/fine cracks or defects caused by external stimuli such as temperature, humidity and impact, affecting the safety and service of ECMs. Therefore, substantial efforts have been devoted to designing suitable self-healing binders aimed at repairing cracks/defects. This review describes the research progress on self-healing binders for ECMs. The structural designs of these strategies to manipulate macro-molecular and/or supramolecular polymers are discussed in detail, and then the implementation of these strategies on ECMs is discussed. However, the reasonable configuration of robust microstructures and effective dynamic exchange are still challenges. Therefore, the prospects for the development of self-healing binders for ECMs are proposed. These critical insights are emphasized to guide the research on developing novel self-healing binders for ECMs in the future.

Ultrathin Solid Polymer Electrolyte Design for High-Performance Li Metal Batteries: A Perspective of Synthetic Chemistry

Li metal batteries (LMBs) have attracted widespread attention in recent years because of their high energy densities. But traditional LMBs using liquid electrolyte have potential safety hazards, such as: leakage and flammability. Replacing liquid electrolyte with solid polymer electrolyte (SPE) can not only significantly improve the safety, but also improve the energy density of LMBs. However, till now, there is only limited success in improving the various physical and chemical properties of SPE, especially in thickness, posing great obstacles to further promoting its fundamental and applied studies. In this review, the authors mainly focus on evaluating the merits of ultrathin SPE and summarizing its existing challenges as well as fundamental requirements for designing and manufacturing advanced ultrathin SPE in the future. Meanwhile, the authors outline existing cases related to this field as much as possible and summarize them from the perspective of synthetic chemistry, hoping to provide a comprehensive understanding and serve as a strategic guidance for designing and fabricating high-performance ultrathin SPE. Challenges and opportunities regarding this burgeoning field are also critically evaluated at the end of this review.

Self-Healable Lithium-Ion Batteries: A Review

The inner constituents of lithium-ion batteries (LIBs) are easy to deform during charging and discharging processes, and the accumulation of these deformations would result in physical fractures, poor safety performances, and short lifespan of LIBs. Recent studies indicate that the introduction of self-healing (SH) materials into electrodes or electrolytes can bring about great enhancements in their mechanical strength, thus optimizing the cycle stability of the batteries. Due to the self-healing property of these special functional materials, the fractures/cracks generated during repeated cycles could be spontaneously cured. This review systematically summarizes the mechanisms of self-healing strategies and introduces the applications of SH materials in LIBs, especially from the aspects of electrodes and electrolytes. Finally, the challenges and the opportunities of the future research as well as the potential of applications are presented to promote the research of this field.

Concepts and Emerging Trends for Structural Battery Electrolytes

The structural battery is a multifunctional energy storage device that aims to address the weight and volume efficiency issues that conventional batteries face, especially in electric transportation. By combining the functions of mechanical load bearing and energy storage, structural batteries can reduce the reliance on, or even eventually replace the main power source in an electric vehicle or a drone. However, one of the key challenges to be addressed before achieving multifunctionality in structural batteries would be the design of a suitable multifunctional structural battery electrolyte. The structural battery electrolyte is the constituent that provides mechanical integrity under flexural loads or impact and hence determines the electrochemical and much of the mechanical performance of a structural battery device. This concept paper aims to cover the key considerations and challenges facing the design of structural battery electrolytes. In addition, the main approaches to surmount these challenges are highlighted, keeping design aspects like sustainability and recyclability in view.

Priority and Prospect of Sulfide-Based Solid-Electrolyte Membrane

All-solid-state lithium batteries (ASSLBs) employing sulfide solid electrolytes (SEs) promise sustainable energy storage systems with energy-dense integration and critical intrinsic safety, yet they still require cost-effective manufacturing and the integration of thin membrane-based SE separators into large-format cells to achieve scalable deployment. This review, based on an overview of sulfide SE materials, is expounded on why implementing a thin membrane-based separator is the priority for mass production of ASSLBs and critical criteria for capturing a high-quality thin sulfide SE membrane are identified. Moreover, from the aspects of material availability, membrane processing, and cell integration, the major challenges and associated strategies are described to meet these criteria throughout the whole manufacturing chain to provide a realistic assessment of the current status of sulfide SE membranes. Finally, future directions and prospects for scalable and manufacturable sulfide SE membranes for ASSLBs are presented.

Development of High-Energy Anodes for All-Solid-State Lithium Batteries Based on Sulfide Electrolytes

All-solid-state Li batteries (ASSBs) promise better performance and higher safety than the current liquid-based Li-ion batteries (LIBs). Sulfide ASSBs have been extensively studied and considerably advanced in recent decades. Research on identifying suitable cathode materials for sulfide ASSBs is currently well established, with great progress being made in the commercialization of layered cathodes in the liquid-based LIBs. Research on anode materials for sulfide ASSBs is of great importance for enhancing the battery energy density. However, it seems that little has been published that summarizes studies of anode materials for sulfide ASSBs and suggests future research directions. Thus, within this Minireview, we aim to provide an overview of previous and current research focused on anode materials for sulfide ASSBs and to suggest a future research direction for developing suitable anode systems for sulfide ASSBs.

In Situ Growth of Crystalline and Polymer-Incorporated Amorphous ZIFs in Polybenzimidazole Achieving Hierarchical Nanostructures for Carbon Capture

Mixed matrix materials (MMMs) hold great potential for membrane gas separations by merging nanofillers with unique nanostructures and polymers with excellent processability. In situ growth of the nanofillers is adapted to mitigate interfacial incompatibility to avoid the selectivity loss. Surprisingly, functional polymers have not been exploited to co-grow the nanofillers for membrane applications. Herein, in situ synergistic growth of crystalline zeolite imidazole framework-8 (ZIF-8) in polybenzimidazole (PBI), creating highly porous structures with high gas permeability, is demonstrated. More importantly, PBI contains benzimidazole groups (similar to the precursor for ZIF-8, i.e., 2-methylimidazole) and induces the formation of amorphous ZIFs, enhancing interfacial compatibility and creating highly size-discriminating bottlenecks. For instance, the formation of 15 mass% ZIF-8 in PBI improves H₂ permeability and H₂ /CO₂ selectivity by ≈100% at 35 °C, breaking the permeability/selectivity tradeoff. This work unveils a new platform of MMMs comprising functional polymer-incorporated amorphous ZIFs with hierarchical nanostructures for various applications.

Development, Retainment and Assessment of the Graphite-Electrolyte Interphase in Li-ion Batteries Regarding the Functionality of SEI-Forming Additives

Formation of a decent solid-electrolyte interphase (SEI) is recognized as an approach to improve the performance of lithium-ion batteries. SEI is a passivation layer generated on the anode during the initial cycles. Characteristics of the graphite SEI depend on the operational parameters, state of the anode, and the content of the electrolyte. Introducing reduction-type additives to the carbonate electrolytes has been one of the most practiced methods to generate an effective SEI on carbonous anodes. To track the role of additives in SEI evolution, first, we have presented a general review on what is currently understood about the SEI formation processes and the impacting parameters. In the second step, the most reported methods to study and analyze the functionality of the SEI-forming additives are classified. As the third part, different reduction-type additives are categorized, and their performances are comparatively reviewed.

Growth of lithium-indium dendrites in all-solid-state lithium-based batteries with sulfide electrolytes

All-solid-state lithium-based batteries with inorganic solid electrolytes are considered a viable option for electrochemical energy storage applications. However, the application of lithium metal is hindered by issues associated with the growth of mossy and dendritic Li morphologies upon prolonged cell cycling and undesired reactions at the electrode/solid electrolyte interface. In this context, alloy materials such as lithium-indium (Li-In) alloys are widely used at the laboratory scale because of their (electro)chemical stability, although no in-depth investigations on their morphological stability have been reported yet. In this work, we report the growth of Li-In dendritic structures when the alloy material is used in combination with a Li6PS5Cl solid electrolyte and Li(Ni0.6Co0.2Mn0.2)O2 positive electrode active material and cycled at high currents (e.g., 3.8 mA cm-2) and high cathode loading (e.g., 4 mAh cm-2). Via ex situ measurements and simulations, we demonstrate that the irregular growth of Li-In dendrites leads to cell short circuits after room-temperature long-term cycling. Furthermore, the difference between Li and Li-In dendrites is investigated and discussed to demonstrate the distinct type of dendrite morphology.

Self-Healing of a Covalently Cross-Linked Polymer Electrolyte Membrane by Diels-Alder Cycloaddition and Electrolyte Embedding for Lithium Ion Batteries

Thermally reversible self-healing polymer (SHP) electrolyte membranes are obtained by Diels-Alder cycloaddition and electrolyte embedding. The SHP electrolytes membranes are found to display high ionic conductivity, suitable flexibility, remarkable mechanical properties and self-healing ability. The decomposition potential of the SHP electrolyte membrane is about 4.8 V (vs. Li/Li⁺) and it possesses excellent electrochemical stability, better than that of the commercial PE film which is only stable up to 4.5 V (vs. Li/Li⁺). TGA results show that the SHP electrolyte membrane is thermally stable up to 280 °C in a nitrogen atmosphere. When the SHP electrolyte membrane is used as a separator in a lithium-ion battery with an LCO-based cathode, the SHP membrane achieved excellent rate capability and stable cycling for over 100 cycles, and the specific discharge capacity could be almost fully recovered after self-healing. Furthermore, the electrolyte membrane exhibits excellent electrochemical performance, suggesting its potential for application in lithium-ion batteries as separator material.

Self-Healing Functional Electronic Devices

Electronic devices with various functions bring great convenience and revolutionize the way we live. They are inevitable to degrade over time because of physical or chemical fatigue and damage during practical operation. To make these devices have the ability to autonomously heal from cracks and restore their mechanical and electrical properties, self-healing materials emerged as the time requires for constructing robust and self-healing electronic devices. Here the development of self-healing electronic devices with different functions, for example, energy harvesting, energy storage, sensing, and transmission, is reviewed. The new application scenarios and existing challenges are explored, and possible strategies and perspectives for future practical applications are discussed.

2D Silicate Materials for Composite Polymer Electrolytes

Two-dimensional (2D) silicate materials have become one of the promising candidates for constructing composite polymer electrolytes due to their advantages of low cost, high stability, good mechanical property, high ionic conductivity and potential to inhibit the growth of lithium dendrites. However, the application of 2D silicate materials in composite polymer electrolytes (CPEs) is still at the infancy stage and facing a lot of challenges. In this minireview, we summarize the structures and properties of 2D silicate materials that have been applied in CPEs, the processing methods of composite electrolytes based on 2D silicates, and the recent process of 2D silicate materials in CPEs. We hope this review could present a general overview of the 2D silicates for CPEs and promote the further study for potential applications.

Covalent Adaptable Networks Using β-Amino Esters as Thermally Reversible Building Blocks

In this study, β-amino esters, prepared by the aza-Michael addition of an amine to an acrylate moiety, are investigated as building blocks for the formation of dynamic covalent networks. While such amino esters are usually considered as thermally nondynamic adducts, the kinetic model studies presented here show that dynamic covalent exchange occurs via both dynamic aza-Michael reaction and catalyst-free transesterification. This knowledge is transferred to create β-amino ester-based covalent adaptable networks (CANs) with coexisting dissociative and associative covalent dynamic exchange reactions. The ease, robustness, and versatility of this chemistry are demonstrated by using a variety of readily available multifunctional acrylates and amines. The presented CANs are reprocessed via either a dynamic aza-Michael reaction or a catalyst-free transesterification in the presence of hydroxyl moieties. This results in reprocessable, densely cross-linked materials with a glass transition temperature (T_g) ranging from -60 to 90 °C. Moreover, even for the low T_g materials, a high creep resistance was demonstrated at elevated temperatures up to 80 °C. When additional β-hydroxyl group-containing building blocks are applied during the network design, an enhanced neighboring group participation effect allows reprocessing of materials up to 10 times at 150 °C within 30 min while maintaining their material properties.

Flexible Sulfide Electrolyte Thin Membrane with Ultrahigh Ionic Conductivity for All-Solid-State Lithium Batteries

All-solid-state lithium batteries (ASSLBs) employing Li-metal anode, sulfide solid electrolyte (SE) can deliver high energy density with high safety. The thick SE separator and its low ionic conductivity are two major challenges. Herein, a 30 μm sulfide SE membrane with ultrahigh room temperature conductivity of 8.4 mS cm^-1 is realized by mechanized manufacturing technologies using highly conductive Li_5.4PS_4.4Cl_1.6 SE powder. Moreover, a 400 nm magnetron sputtered Al₂O₃ interlayer is introduced into the SE/Li interface to improve the anodic stability, which suppresses the short circuit in Li/Li symmetric cells. Combining these merits, ASSLBs with LiNi_0.5Co_0.2Mn_0.3O₂ as the cathode exhibit a stable cyclic performance, delivering a discharge specific capacity of 135.3 mAh g^-1 (1.4 mAh cm^-2) with a retention of 80.2% after 150 cycles and an average Coulombic efficiency over 99.5%. The high ionic conductivity SE membrane and interface design principle show promising feasible strategies for practical high performance ASSLBs.

Lithium/Sulfide All-Solid-State Batteries using Sulfide Electrolytes

All-solid-state lithium batteries (ASSLBs) are considered as the next generation electrochemical energy storage devices because of their high safety and energy density, simple packaging, and wide operable temperature range. The critical component in ASSLBs is the solid-state electrolyte. Among all solid-state electrolytes, the sulfide electrolytes have the highest ionic conductivity and favorable interface compatibility with sulfur-based cathodes. The ionic conductivity of sulfide electrolytes is comparable with or even higher than that of the commercial organic liquid electrolytes. However, several critical challenges for sulfide electrolytes still remain to be solved, including their narrow electrochemical stability window, the unstable interface between the electrolyte and the electrodes, as well as lithium dendrite formation in the electrolytes. Herein, the emerging sulfide electrolytes and preparation methods are reviewed. In particular, the required properties of the sulfide electrolytes, such as the electrochemical stabilities of the electrolytes and the compatible electrode/electrolyte interfaces are highlighted. The opportunities for sulfide-based ASSLBs are also discussed.

Self-healing solid polymer electrolyte based on imine bonds for high safety and stable lithium metal batteries

Due to their low flammability, good dimensional stability and chemical stability, solid polymer electrolytes are currently attracting extensive interest for building lithium metal batteries. But severe safety issues such as cracks or breakage, resulting in short circuits will prevent their widespread application. Here, we report a new design of self-healing solid polymer electrolyte (ShSPE) based on imine bonds, fabricated from varying amounts of polyoxyethylenebis(amine) and terephthalaldehyde through a simple Schiff base reaction. Moreover, adding diglycidyl ether of bisphenol A improves the flexibility and high stretchability of the polymer electrolyte. The polymer networks exhibit good thermal stability and excellent self-healing characteristics. The ShSPE with the highest NH2-PEG-NH2 content (ShSPE-3) has an improved lithium ion transference number of 0.39, and exhibits an electrochemical stability up to 4.5 V vs. Li/Li+. ShSPE-3 shows the highest ionic conductivity of 1.67 × 10-4 S cm-1 at 60 °C. Besides, the interfacial stability of ShSPE-3 is promoted and the electrolyte membrane exhibits good cycling performance with LiFePO4, and the LiFePO4/Li cell exhibits an initial discharge capacity of 141.3 mA h g -1. These results suggest that self-healing solid polymer electrolytes are promising candidates for high safety and stable lithium metal batteries.

Heterogeneous integration of rigid, soft, and liquid materials for self-healable, recyclable, and reconfigurable wearable electronics

Wearable electronics can be integrated with the human body for monitoring physical activities and health conditions, for human-computer interfaces, and for virtual/augmented reality. We here report a multifunctional wearable electronic system that combines advances in materials, chemistry, and mechanics to enable superior stretchability, self-healability, recyclability, and reconfigurability. This electronic system heterogeneously integrates rigid, soft, and liquid materials through a low-cost fabrication method. The properties reported in this wearable electronic system can find applications in many areas, including health care, robotics, and prosthetics, and can benefit the well-being, economy, and sustainability of our society.

Recent Advances in High-Performance Microbatteries: Construction, Application, and Perspective

High-performance miniaturized energy storage devices have developed rapidly in recent years. Different from conventional energy storage devices, microbatteries assume the main responsibility for micropower supply, functionalization, and characterization platforms. Evolving from the essential goals for battery design of high power density, high energy density, and long lifetime, further practical demands for microbatteries (MBs) have been raised for the microfabrication technique and device design. Numerous studies have generally focused on specific aspects of the microelectrode structures or certain microfabrication techniques, while the connection from techniques to functional applications is rarely involved. This Review generally fills such blanks from an application-oriented perspective. First, some basic micromachining techniques with different compatible features are summarized. Afterward, device designs including diversified battery reaction types, configuration, and assembly are highlighted, as well as microbatteries serving powering resources or further complicated functional systems. Finally, through providing the overall design concept based on requirements in application, this Review offers innovative insights for further development of microbatteries.

Reprocessable Cross-Linked Polymer Networks: Are Associative Exchange Mechanisms Desirable?

Covalent adaptable networks (CANs) are covalently cross-linked polymers that may be reshaped via cross-linking and/or strand exchange at elevated temperatures. They represent an exciting and rapidly developing frontier in polymer science for their potential as stimuli-responsive materials and to make traditionally nonrecyclable thermosets more sustainable. CANs whose cross-links undergo exchange via associative intermediates rather than dissociating to separate reactive groups are termed vitrimers. Vitrimers were postulated to be an attractive subset of CANs, because associative cross-link exchange mechanisms maintain the original cross-link density of the network throughout the exchange process. As a result, associative CANs demonstrate a gradual, Arrhenius-like reduction in viscosity at elevated temperatures while maintaining mechanical integrity. In contrast, CANs reprocessed by dissociation and reformation of cross-links have been postulated to exhibit a more rapid decrease in viscosity with increasing temperature. Here, we survey the stress relaxation behavior of all dissociative CANs for which variable temperature stress relaxation or viscosity data are reported to date. All exhibit an Arrhenius relationship between temperature and viscosity, as only a small percentage of the cross-links are broken instantaneously under typical reprocessing conditions. As such, dissociative and associative CANs show nearly identical reprocessing behavior over broad temperature ranges typically used for reprocessing. Given that the term vitrimer was coined to highlight an Arrhenius relationship between viscosity and temperature, in analogy to vitreous glasses, we discourage its continued use to describe associative CANs. The realization that the cross-link exchange mechanism does not greatly influence the practical reprocessing behavior of most CANs suggests that exchange chemistries can be considered with fewer constraints, focusing instead on their activation parameters, synthetic convenience, and application-specific considerations.

Designing composite solid-state electrolytes for high performance lithium ion or lithium metal batteries

Solid-state electrolytes (SSEs) are capable of inhibiting the growth of lithium dendrites, demonstrating great potential in next-generation lithium-ion batteries (LIBs). However, poor room temperature ionic conductivity and the unstable interface between SSEs and the electrode block their large-scale applications in LIBs. Composite solid-state electrolytes (CSSEs) formed by mixing different ionic conductors lead to better performance than single SSEs, especially in terms of ionic conductivity and interfacial stability. Herein, we have systematically reviewed recent developments and investigations of CSSEs including inorganic composite and organic-inorganic composite materials, in order to provide a better understanding of designing CSSEs. The comparison of different types of CSSEs relative to their parental materials is deeply discussed in the context of ionic conductivity and interfacial design. Then, the proposed ion transfer pathways and models of lithium dendrite growth in composites are outlined to inspire future development of CSSEs.

Towards high-performance solid-state Li-S batteries: from fundamental understanding to engineering design

Solid-state lithium-sulfur batteries (SSLSBs) with high energy densities and high safety have been considered among the most promising energy storage devices to meet the demanding market requirements for electric vehicles. However, critical challenges such as lithium polysulfide shuttling effects, mismatched interfaces, Li dendrite growth, and the gap between fundamental research and practical applications still hinder the commercialization of SSLSBs. This review aims to combine the fundamental and engineering perspectives to seek rational design parameters for practical SSLSBs. The working principles, constituent components, and practical challenges of SSLSBs are reviewed. Recent progress and approaches to understand the interfacial challenges via advanced characterization techniques and density functional theory (DFT) calculations are summarized and discussed. A series of design parameters including sulfur loading, electrolyte thickness, discharge capacity, discharge voltage, and cathode sulfur content are systematically analyzed to study their influence on the gravimetric and volumetric energy densities of SSLSB pouch cells. The advantages and disadvantages of recently reported SSLSBs are discussed, and potential strategies are provided to address the shortcomings. Finally, potential future directions and prospects in SSLSB engineering are examined.

Sulfide-Based Solid-State Electrolytes: Synthesis, Stability, and Potential for All-Solid-State Batteries

Due to their high ionic conductivity and adeciduate mechanical features for lamination, sulfide composites have received increasing attention as solid electrolyte in all-solid-state batteries. Their smaller electronegativity and binding energy to Li ions and bigger atomic radius provide high ionic conductivity and make them attractive for practical applications. In recent years, noticeable efforts have been made to develop high-performance sulfide solid-state electrolytes. However, sulfide solid-state electrolytes still face numerous challenges including: 1) the need for a higher stability voltage window, 2) a better electrode-electrolyte interface and air stability, and 3) a cost-effective approach for large-scale manufacturing. Herein, a comprehensive update on the properties (structural and chemical), synthesis of sulfide solid-state electrolytes, and the development of sulfide-based all-solid-state batteries is provided, including electrochemical and chemical stability, interface stabilization, and their applications in high performance and safe energy storage.

Photothermal-Induced Self-Healable and Reconfigurable Shape Memory Bio-Based Elastomer with Recyclable Ability

Photothermal-induced self-healable and shape memory materials have drawn much attention due to the rapidly growing technical applications and environmental requirements. As epoxy natural rubber (ENR) is a kind of bio-based elastomer with good mechanical properties, weather resistance, and air impermeability, it is of great significance to incorporate ENR with recyclable, photothermal-induced self-healable and shape memory properties. In this study, we report a simple method to cross-link ENR with dodecanedioic acids (DAs) through esterification reaction, and during the cross-linking process, a little aniline trimer (ACAT, a kind of oligoaniline) was added at the same time. Then, the ENR-DA-ACAT vitrimers that were covalently cross-linked with recyclable, self-healable, and multiple responsive properties were obtained, which also possessed various functions. As a result of the transesterification reactions at elevated temperatures, the ENR-based vitrimers possess the ability to be reprocessed and self-healed, and the mechanical properties could be maintained even after three consecutive breaking/mold pressing cycles. Besides, the vitrimer is also responsive to near-infrared (NIR) light and pH with the introduction of ACAT, and we also find that ACAT can be used as a catalyst to accelerate the transesterification reaction. Moreover, it is demonstrated that the ENR-DA-ACAT vitrimer could also be used to construct the reconfigurable shape memory polymer; the shape fixing ratio and shape recovery ratio are both above 95% in the reconfiguration process, and the multistage shape memory performance can also be achieved by NIR irradiation, which will potentially lead to a wide application for ENR in the field of actuators.

Self-healing and shape-memory solid polymer electrolytes with high mechanical strength facilitated by a poly(vinyl alcohol) matrix

This article reports PVA-based electrolytes with supramolecular networks formed via quadruple hydrogen bonding for lithium-ion batteries.