Solid‐State Plastic Crystal Electrolytes: Effective Protection Interlayers for Sulfide‐Based All‐Solid‐State Lithium Metal Batteries

All‐solid‐state lithium metal batteries (ASSLMBs) have attracted significant attention due to their superior safety and high energy density. However, little success has been made in adopting Li metal anodes in sulfide electrolyte (SE)‐based ASSLMBs. The main challenges are the remarkable interfacial reactions and Li dendrite formation between Li metal and SEs. In this work, a solid‐state plastic crystal electrolyte (PCE) is engineered as an interlayer in SE‐based ASSLMBs. It is demonstrated that the PCE interlayer can prevent the interfacial reactions and lithium dendrite formation between SEs and Li metal. As a result, ASSLMBs with LiFePO₄ exhibit a high initial capacity of 148 mAh g^?1 at 0.1 C and 131 mAh g^?1 at 0.5 C (1 C = 170 mA g^?1), which remains at 122 mAh g^?1 after 120 cycles at 0.5 C. All‐solid‐state Li‐S batteries based on the polyacrylonitrile‐sulfur composite are also demonstrated, showing an initial capacity of 1682 mAh g^?1. The second discharge capacity of 890 mAh g^?1 keeps at 775 mAh g^?1 after 100 cycles. This work provides a new avenue to address the interfacial challenges between Li metal and SEs, enabling the successful adoption of Li metal in SE‐based ASSLMBs with high energy density.     

High Energy Density All‐Solid‐State Batteries: A Challenging Concept Towards 3D Integration

Rechargeable all‐solid‐state batteries will play a key role in many autonomous devices. Planar solid‐state thin film batteries are rapidly emerging but reveal several drawbacks, such as a relatively low energy density and the use of highly reactive metallic lithium. In order to overcome these limitations a new 3D‐integrated all‐solid‐state battery concept with significantly increased surface area is presented. By depositing the active battery materials into high‐aspect ratio structures etched in, for example silicon, 3D‐integrated all‐solid‐state batteries are calculated to reach a much higher energy density. Additionally, by adopting novel high‐energy dense Li‐intercalation materials the use of metallic Lithium can be avoided. Sputtered Ta, TaN and TiN films have been investigated as potential Li‐diffusion barrier materials. TiN combines a very low response towards ionic Lithium and a high electronic conductivity. Additionally, thin film poly‐Si anodes have been electrochemically characterized with respect to their thermodynamic and kinetic Li‐intercalation properties and cycle life. The Butler‐Vollmer relationship was successfully applied, indicating favorable electrochemical charge transfer kinetics and solid‐state diffusion. Advantageously, these new Li‐intercalation anode materials were found to combine an extremely high energy density with fast rate capability, enabling future 3D‐integrated all‐solid‐state batteries.     

Intercalated Electrolyte with High Transference Number for Dendrite‐Free Solid‐State Lithium Batteries

Solid‐state lithium (Li) batteries using solid electrolytes and Li anodes are highly desirable because of their high energy densities and intrinsic safety. However, low ambient‐temperature conductivity and poor interface compatibility of solid electrolytes as well as Li dendrite formation cause large polarization and poor cycling stability. Herein, a high transference number intercalated composite solid electrolyte (CSE) is prepared by the combination of a solution‐casting and hot‐pressing method using layered lithium montmorillonite, poly(ethylene carbonate), lithium bis(fluorosulfonyl)imide, high‐voltage fluoroethylene carbonate additive, and poly(tetrafluoroethylene) binder. The electrolyte presents high ionic conductivity (3.5 × 10^?4 S cm^?1), a wide electrochemical window (4.6 V vs Li⁺/Li), and high ionic transference number (0.83) at 25 °C. In addition, a 3D Li anode is also fabricated via a facile thermal infusion strategy. The synergistic effect of high transference number intercalated electrolyte and 3D Li anode is more favorable to suppress Li dendrites in a working battery. The solid‐state batteries based on LiFePO₄ (Al₂O₃ @ LiNi_0.5Co_0.2Mn_0.3O₂), CSE, and 3D Li deliver admirable cycling stability with discharge capacity 145.9 mAh g^?1 (150.7 mAh g^?1) and capacity retention 91.9% after 200 cycles at 0.5 C (92.0% after 100 cycles at 0.2 C) at 25 °C. This work affords a splendid strategy for high‐performance solid‐state battery.     

A High‐Performance Graphene Oxide‐Doped Ion Gel as Gel Polymer Electrolyte for All‐Solid‐State Supercapacitor Applications

A high‐performance graphene oxide (GO)‐doped ion gel (P(VDF‐HFP)‐EMIMBF₄‐GO gel) is prepared by exploiting copolymer (poly(vinylidene fluoride‐hexafluoro propylene), P(VDF‐HFP)) as the polymer matrix, ionic liquid (1‐ethyl‐3‐methylimidazolium tetrafluoroborate, EMIMBF₄) as the supporting electrolyte, and GO as the ionic conducting promoter. This GO‐doped ion gel demonstrates significantly improved ionic conductivity compared with that of pure ion gel without the addition of GO, due to the homogeneously distributed GO as a 3D network throughout the GO‐doped ion gel by acting like a ion “highway” to facilitate the ion transport. With the incorporation of only a small amount of GO (1 wt%) in ion gel, there has been a dramatic improvement in ionic conductivity of about 260% compared with that of pure ion gel. In addition, the all‐solid‐state supercapacitor is fabricated and measured at room temperature using the GO‐doped ion gel as gel polymer electrolyte, which demonstrates more superior electrochemical performance than the all‐solid‐state supercapacitor with pure ion gel and the conventional supercapacitor with neat EMIMBF₄, in the aspect of smaller internal resistance, higher capacitance performance, and better cycle stability. These excellent performances are due to the high ionic conductivity, excellent compatibility with carbon electrodes, and long‐term stability of the GO‐doped ion gel.     

Synthetic Strategies for Hybrid Materials to Improve Properties for Optoelectronic Applications

We report, for the first time to the best of our knowledge, a systematic study to relate the laser action from BODIPY dyes, doped into monolithic hybrid matrices, with the synthetic protocols of the final materials prepared via sol‐gel. To this aim, the influence of both the hydrolysis time, increased in a controlled way, and the nature of the neutralization agent (pyridine, 3‐amino‐propyltriethoxy‐silane (APS), N‐[3‐(trimethoxysilyl)propyl]‐ethylene diamine (TSPDA), and N¹‐[3‐(trimethoxysilyl)propyl]‐ diethylene triamine (TSPTA) on the laser action of PM567, incorporated into hybrid matrices based on copolymers of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA), with methyltriethoxysilane (TRIEOS) as inorganic precursor, was analyzed. The presence of the amine‐modified silane TSPDA as neutralization agent, which is able at the same time to be anchored to the inorganic network enhancing the inorganic‐organic compatibility through the matrix interphase, and utilization of hydrolysis times lower than 10 minutes, increased significantly the lasing efficiency and photostability of dye. The extension of this study to the laser behavior of BODIPY dyes embedded in other different hybrid materials based on hydrolyzed‐condensed copolymers of MMA with 3‐(trimethoxysilyl)propyl methacrylate (TMSPMA) in a 1/1 volumetric proportion, validates the generalization of the above conclusions, which provide guides for the optimization of the synthesis of organic‐inorganic hybrid materials with optoelectronic innovative applications independently of their composition.     

Foldable All‐Solid‐State Supercapacitors Integrated with Photodetectors

Recent development in flexible electronics has promoted the increasing demand for their energy storage systems that will be lightweight, thin, flexible, and even foldable. Although various flexible supercapacitors recently have been successfully developed, the design and assembly of highly foldable supercapacitors have received less attention. Furthermore, foldable supercapacitors are in general operated independently with other electronics, resulting in some space and energy consumption from the external connection system. Therefore, the authors fabricate the foldable all‐solid‐state integrated devices with supercapacitor and photodetector functions in a simplified and compact configuration based on single‐walled carbon nanotube films and TiO₂ nanoparticles. The integrated devices not only retain the intrinsic capacitance behavior but also show excellent sensitivity of detecting white light. More importantly, the capacitance behavior of integrated devices remains almost unchanged and the photodetector behavior is quite stable even folded by 180° due to their unique integrated configuration. Such rational design of all‐solid‐state integrated devices will pave the way for assembling energy storage devices and other electronics into highly flexible and foldable integrated devices.     

A High‐Performance Li–B–H Electrolyte for All‐Solid‐State Li Batteries

Highly Li‐ion conductive Li₄(BH₄)₃I@SBA‐15 is synthesized by confining the LiI doped LiBH₄ into mesoporous silica SBA‐15. Uniform nanoconfinement of P6₃ mc phase Li₄(BH₄)₃I in SBA‐15 mesopores leads to a significantly enhanced conductivity of 2.5 × 10^?4 S cm^?1 with a Li‐ion transference number of 0.97 at 35 °C. The super Li‐ion mobility in the interface layer with a thickness of 1.2 nm between Li₄(BH₄)₃I and SBA‐15 is believed to be responsible for the fast Li‐ion conduction in Li₄(BH₄)₃I@SBA‐15. Additionally, Li₄(BH₄)₃I@SBA‐15 also exhibits a wide apparent electrochemical stability window (0 to 5 V vs Li/Li⁺) and a superior Li dendrite suppression capability (critical current density 2.6 mA cm^?2 at 55 °C) due to the formation of stable interphases. More importantly, Li₄(BH₄)₃I@SBA‐15‐based Li batteries using either high‐capacity sulfur cathode or high‐voltage oxide cathode show excellent electrochemical performances, making Li₄(BH₄)₃I@SBA‐15 a very attractive electrolyte for next‐generation all‐solid‐state Li batteries.     

Materials for a Reliable Solid‐State Dye Laser at the Red Spectral Edge

In the search to extend the tuning range of solid‐state dye lasers (SSDLs) to the red‐edge spectral region, new photosensitive materials have been designed and synthesized based on six commercial dyes (sulforhodamine B, perylene red, rhodamine 640, LDS698, LDS722, and LDS730) incorporated into different linear, crosslinked, fluorinated, and sililated polymeric matrices. Under transversal pumping at 532 nm, these materials exhibit highly efficient, stable, as well as wavelength‐tunable laser action from the visible‐to‐NIR spectral region (575–750 nm). The lasing performance of the materials doped with perylene and xanthene dyes is, to the best of our knowledge, the highest achieved to date for these chromophores when incorporated into organic, inorganic, or hybrid matrices. Regarding the LDS derivatives, this is the first time that laser action from these dyes in solid‐state media is reported. These particular characteristics have impelled the building of the first prototype SSDL that is compact, versatile, and easy to handle.     

Wood‐Derived Materials for Advanced Electrochemical Energy Storage Devices

Over the past decade, wood‐derived materials have attracted enormous interest for both fundamental research and practical applications in various functional devices. In addition to being renewable, environmentally benign, naturally abundant, and biodegradable, wood‐derived materials have several unique advantages, including hierarchically porous structures, excellent mechanical flexibility and integrity, and tunable multifunctionality, making them ideally suited for efficient energy storage and conversion. In this article, the latest advances in the development of wood‐derived materials are discussed for electrochemical energy storage systems and devices (e.g., supercapacitors and rechargeable batteries), highlighting their micro/nanostructures, strategies for tailoring the structures and morphologies, as well as their impact on electrochemical performance (energy and power density and long‐term durability). Furthermore, the scientific and technical challenges, together with new directions of future research in this exciting field, are also outlined for electrochemical energy storage applications.     

Operando Differential Electrochemical Pressiometry for Probing Electrochemo‐Mechanics in All‐Solid‐State Batteries

Owing to an absence or lack of soft (and/or liquid) components, electrochemo‐mechanical effects are imperative for all‐solid‐state batteries (ASBs) based on inorganic solid electrolytes (SEs). As this aspect has been overlooked, relevant investigation has remained scarce. In this work, the development of a new operando differential electrochemical pressiometry (DEP) for ASBs is reported. The time‐ (or capacity‐) derivative differential pressure signals (dP/dt or dP/dQ) reflecting corresponding differential volume changes of electrode active materials feature the specific state of charges (SOCs). This finding leads to a precise estimation of the SOCs of graphite (Gr) electrodes in LiNi_0.70Co_0.15Mn_0.15O₂ (NCM)/Gr all‐solid‐state full cells using sulfide SEs with varying capacity ratios of negative to positive electrodes (n/p ratios); this is corroborated by complementary analysis using a three‐electrode electrochemical cell and ex situ X‐ray diffraction measurements. Furthermore, electrochemo‐mechanical behaviors of NCM/Gr full cells with Gr electrodes employing SEs excluding or including reductively unstable Li₁₀GeP₂S₁₂ are investigated. Notable volume changes caused by lithiation of Li₁₀GeP₂S₁₂ are detected. Importantly, significantly delayed SOC for Gr caused by a severe side reaction with Li₁₀GeP₂S₁₂ is disclosed by the operando DEP result.     

Biocompatible and Biodegradable Organic Transistors Using a Solid‐State Electrolyte Incorporated with Choline‐Based Ionic Liquid and Polysaccharide

Biocompatible, biodegradable, and solid‐state electrolyte‐based organic transistors are demonstrated. As the electrolyte is composed of all edible materials, which are levan polysaccharide and choline‐based ionic liquid, the organic transistor fabricated on the electrolyte can be biocompatible and biodegrable. Compared to the other ion gel based electrolytes, it has superior electrical and mechanical properties, large specific capacitance (≈40 µF cm^?2), non‐volatility, flexibility, and high transparency. Thus, it shows mechanical reliability by maintaining electrical performances under up to 1.11% of effective bending strain, 5% of stretching, and have low operation voltage range when it is utilized in organic transistors. Moreover, the biodegradable electrolyte‐based organic transistors can be applied to bio‐integrated devices, such as electrocardiogram (ECG) recordings on human skin and the heart of a rat. The measured ECG signals from the transistors, compared to signals from electrode‐based sensors, has a superior signal‐to‐noise ratio. The biocompatible and biodegradable materials and devices can contribute to the development of many bioelectronics.     

Gradiently Sodiated Alucone as an Interfacial Stabilizing Strategy for Solid‐State Na Metal Batteries

All‐solid‐state metal batteries (ASSMBs) are attracting much attention due to their cost effectiveness, enhanced safety, room‐temperature performance and high theoretical specific capacity. However, the alkali metal anodes (such as Li and Na) are active enough to react with most solid‐state electrolytes (SSEs), leading to detrimental reactions at the metal–SSE interface. In this work, a molecular layer deposition (MLD) alucone film is employed to stabilize the active Na anode/electrolyte interface in the ASSMBs, limiting the decomposition of the sulfide‐based electrolytes (Na₃SbS₄ and Na₃PS₄) and Na dendrite growth. Such a strategy effectively improves the room‐temperature full battery performance as well as cycling stability for over 475 h in Na–Na symmetric cells. The modified interface is further characterized by X‐ray photoelectron spectroscopy (XPS) depth profiling, which provides spatially resolved evidence of the synergistic effect between the dendrite‐suppressed sodiated alucone and the insulating unsodiated alucone. The coupled layers reinforce the protection of the Na metal/electrolyte interface. Therefore, alucone is identified as an effective and bifunctional coating material for the enhancement of the metal/electrolyte interfacial stability, paving the way for rapid development and wide application of high‐energy ASSMBs.     

Capacitive Enhancement Mechanisms and Design Principles of High‐Performance Graphene Oxide‐Based All‐Solid‐State Supercapacitors

Graphene oxide (GO)‐based all‐solid‐state supercapacitors (GO‐A3Ss) are superior over liquid electrolyte‐based supercapacitors and capable of being integrated on a single chip in various geometry shapes for the use of future smart wearable electronics field as a fast energy storage device, but their capacitance need to be improved. Here, a new approach has been developed for enhancing the capacitive capability of the supercapacitors through molecular dynamics simulations with the first‐principle input. A theoretical model of charge storage is developed to understand the unique capacitive enhancement mechanism and to predict the capacitance of the GO‐A3Ss, which agrees well with the experimental observations. A novel supercapacitor with GO and reduced graphene oxide (rGO) alternatively layered structures is designed based on the model, and its energy density is the highest among conventional supercapacitors using liquid electrolytes and all‐solid‐state supercapacitors using aerogels or hydrogels as the solid‐state electrolyte. Based on the predictions, two new types of high‐performance GO/rGO multilayered capacitors are proposed to meet different practical applications. The results of this work provide an approach for the design of high‐performance all‐solid‐state supercapacitors based on GO and rGO materials.     

A Flexible Dual‐Ion Battery Based on Sodium‐Ion Quasi‐Solid‐State Electrolyte with Long Cycling Life

Sodium‐based dual‐ion batteries (SDIBs) have attracted much attention for their advantages of high operating voltage, environmental friendliness, and especially low cost. However, the electrochemical performances of the reported SDIBs are still unsatisfied due to the decomposition problem of traditional liquid electrolyte under high working voltage. Development of quasi‐solid‐state electrolytes (QSSEs) with excellent electrochemical stability at high voltage is a possible means to improve their properties. In this work, a flexible SDIB based on a QSSE, consisting of poly(vinylidene ?uoride‐co‐hexa?uoropropylene) (PVDF‐HFP) three‐dimensionally cross‐linked with Al₂O₃ nanoparticles, which exhibits a porous 3D structure with dramatically enhanced ionic conductivity up to ≈1.3 × 10^?3 S cm^?1, facilitating fast ionic migration of both anions and cations, is reported. This quasi‐state SDIB exhibits a high specific capacity of 96.8 mAh g^?1 at a current rate of 5 C and excellent cycling stability with a capacity retention of 97.5% after 600 cycles at 5 C, which is the best performance of the SDIBs. Moreover, excellent flexibility and a wide working temperature range (?20 to 70 °C) have been realized for this battery, suggesting its potential for high‐performance flexible energy storage applications.     

Self‐Healing Materials for Energy‐Storage Devices

The booming development of electronics, electric vehicles, and grid storage stations has led to a high demand for advanced energy‐storage devices (ESDs) and accompanied attention to their reliability under various circumstances. Self‐healing is the ability of an organism to repair damage and restore function through its own internal vitality. Inspired by this, brilliant designs have emerged in recent years using self‐healing materials to significantly improve the lifespan, durability, and safety of ESDs. Extrinsic and intrinsic self‐healing materials and their working principles are first introduced. Then, the application of self‐healing materials in ESDs according to their self‐healing chemistry, including hydrogen bonds, electrostatic interactions, and borate ester bonds, are described in detail. Based on these, critical challenges and important future directions of self‐healing ESDs are discussed.     

Shaping the Contact between Li Metal Anode and Solid‐State Electrolytes

Scientific and technological interest in solid‐state Li metal batteries (SSLMBs) arises from their excellent safety and promising high energy density. However, the practical application of SSLMBs is hindered by poor contact between the Li metal anode (LMA) and solid‐state electrolytes (SSEs). To circumvent this limitation, a pattern‐guided approach that shapes the LMA/SSE contact is disclosed to offer fast Li ion conduction in the interface. A thermally‐treated copper foam is used as the lithophilic pattern to confine and guide Li for forming a tight contact with garnet‐type SSE. The contact can be easily manipulated according to the shape of lithiophilic pattern, facilitating cell assembly. The resulting Li|patterned garnet|Li symmetric cell exhibits an interfacial resistance of 9.8 Ω cm², which is dramatically lower than that of 998 Ω cm² for Li|pristine garnet|Li symmetric cell. Being used in Li–sulfur batteries, the patterned garnet effectively eliminates the polysulfide shuttle and enables stable cycling performance, showing a low capacity decay of 0.035% per cycle over 1000 cycles. The fundamental contact process of metallic anodes/SSEs is carefully investigated. This contact strategy provides a new design concept to improve the interface wettability via a lithiophilic pattern for a variety of SSEs that cannot wet with metallic anodes.     

Molecularly Coupled Two‐Dimensional Titanium Oxide and Carbide Sheets for Wearable and High‐Rate Quasi‐Solid‐State Rechargeable Batteries

High‐performance, flexible, and lightweight powering electrodes are urgently needed to meet the increasing interest in deformable electronic devices, particularly those utilizing solid‐state electrolytes and performing at high charging rates, which unfortunately have remained a formidable challenge. Here, by regularly stacking two‐dimensional (2D) titanium oxide and carbide sheets, in which the two kinds of sheets are coupled at the molecular level, a self‐standing electrode is achieved with ideal mechanical durability and excellent electrochemical performance, including superb rate performance (delivering a capacity of 114 mAh g^?1 in 3.4 min) and good cycling stability (remaining >93% after 1000 cycles at 1000 mA g^?1). Profiting from these advantages, a flexible and safe full lithium‐ion battery, employing a poly(ethylene glycol) diamine‐based gel polymer as the electrolyte, possesses an excellent power density of 1412 W kg^?1 while maintaining a high energy density of 59 Wh kg^?1, which outperforms most documented flexible batteries that utilize liquid electrolytes and is even comparable with some cells using coin configurations. Importantly, the performance was well maintained under mechanical deformation and after multiple breaking and self‐healing cycles, demonstrating the feasibility for practical application in wearable powering devices. The results highlight the numerous possibilities for utilizing sheet materials to fabricate wearable electrode materials.     

Merging Biology and Solid‐State Lighting: Recent Advances in Light‐Emitting Diodes Based on Biological Materials

Solid‐state lighting (SSL) is one of the biggest achievements of the 20^th century. It has completely changed our modern life with respect to general illumination (light‐emitting diodes), flat devices and displays (organic light‐emitting diodes), and small labeling systems (light‐emitting electrochemical cells). Nowadays, it is however mandatory to make a transition toward green, sustainable, and equally performing lighting systems. In this regard, several groups have realized that the actual SSL technologies can easily and efficiently be improved by getting inspiration from how natural systems that manipulate light have been optimized over millennia. In addition, various natural and biocompatible materials with suitable properties for lighting applications have been used to replace expensive and unsustainable components of current lighting devices. Finally, SSL has also started to revolutionize the biomedical field with the achievement of efficient implantable lighting systems. Herein, the‐state‐of‐art of (i) biological materials for lighting devices, (ii) bioinspired concepts for device designs, and (iii) implantable SSL technologies is summarized, highlighting the perspectives of these emerging fields.