Bioderived Ionic Liquids with Alkaline Metal Ions for Transient Ionics

Choline lactate, an ionic liquid composed of bioderived materials, offers an opportunity to develop biodegradable electrochemical devices. Although ionic liquids possess large potential windows, high conductivity, and are nonvolatile, they do not exhibit electrochemical characteristics such as intercalation pseudocapacitance, redox pseudocapacitance, and electrochromism. Herein, bioderived ionic liquids are developed, including metal ions, Li, Na, and Ca, to yield ionic liquid with electrochemical behavior. Differential scanning calorimetry results reveal that the ionic liquids remained in liquid state from 230.42 to 373.15 K. The conductivities of the ionic liquids with metal are lower than those of the pristine ionic liquid, whereas the capacitance change negligibly. A protocol of the Organization for Economic Co-operation and Development 301C modified MITI test (I) confirms that the pristine ionic liquid and ionic liquids with metal are readily biodegradable. Additionally, an ionic gel comprising the ionic liquid and poly(vinyl alcohol) is biodegradable. An electrochromic device is developed using an ionic liquid containing Li ions. The device successfully changes color at −2.5 V, demonstrating the intercalation of Li ions into the WO₃ crystal. The results suggest that the electrochemically active ionic liquids have potential for the development of environmentally benign devices, sustainable electronics, and bioresorbable/implantable devices.     

A Water Dissolvable Electrolyte with an Ionic Liquid for Eco‐Friendly Electronics

A water‐dissolvable electrolyte is developed by combining an ionic liquid (IL) with poly(vinyl alcohol) (PVA), which decays over time by contact with water. An IL generally consists of two species of ions (anion and cation), and forms an electrical double layer (EDL) of a large electrostatic capacitance due to the ions accumulated in the vicinity of a conductive electrode when voltage is applied. In a similar manner, the ionic gel developed in this work forms an EDL due to the ions suspended in the conjugated polymer network while maintaining the gel form. Test measurements show a large capacitance of 13 µF cm⁻² within the potential window of the IL. The ionic gel shows an electrical conductance of 20 µS cm⁻¹ due to the ionic conduction, which depends on the weight ratio of the IL with respect to the polymer. The developed ionic gel dissolves into water in 16 h. Potential application includes the electrolyte in disposable electronics such as distributed sensors and energy harvesters that are supposed to be harmless to environment.     

Soft Elastomers with Ionic Liquid‐Filled Cavities as Strain Isolating Substrates for Wearable Electronics

Managing the mechanical mismatch between hard semiconductor components and soft biological tissues represents a key challenge in the development of advanced forms of wearable electronic devices. An ultralow modulus material or a liquid that surrounds the electronics and resides in a thin elastomeric shell provides a strain‐isolation effect that enhances not only the wearability but also the range of stretchability in suitably designed devices. The results presented here build on these concepts by (1) replacing traditional liquids explored in the past, which have some nonnegligible vapor pressure and finite permeability through the encapsulating elastomers, with ionic liquids to eliminate any possibility for leakage or evaporation, and (2) positioning the liquid between the electronics and the skin, within an enclosed, elastomeric microfluidic space, but not in direct contact with the active elements of the system, to avoid any negative consequences on electronic performance. Combined experimental and theoretical results establish the strain‐isolating effects of this system, and the considerations that dictate mechanical collapse of the fluid‐filled cavity. Examples in skin‐mounted wearable include wireless sensors for measuring temperature and wired systems for recording mechano‐acoustic responses.     

Graphene‐Analogues Boron Nitride Nanosheets Confining Ionic Liquids: A High‐Performance Quasi‐Liquid Solid Electrolyte

Solid electrolytes are one of the most promising electrolyte systems for safe lithium batteries, but the low ionic conductivity of these electrolytes seriously hinders the development of efficient lithium batteries. Here, a novel class of graphene‐analogues boron nitride (g‐BN) nanosheets confining an ultrahigh concentration of ionic liquids (ILs) in an interlayer and out‐of‐layer chamber to give rise to a quasi‐liquid solid electrolyte (QLSE) is reported. The electron‐insulated g‐BN nanosheet host with a large specific surface area can confine ILs as much as 10 times of the host's weight to afford high ionic conductivity (3.85 × 10^?3 S cm^?1 at 25 °C, even 2.32 × 10^?4 S cm^?1 at ?20 °C), which is close to that of the corresponding bulk IL electrolytes. The high ionic conductivity of QLSE is attributed to the enormous absorption for ILs and the confining effect of g‐BN to form the ordered lithium ion transport channels in an interlayer and out‐of‐layer of g‐BN. Furthermore, the electrolyte displays outstanding electrochemical properties and battery performance. In principle, this work enables a wider tunability, further opening up a new field for the fabrication of the next‐generation QLSE based on layered nanomaterials in energy conversion devices.     

羟基离子液体中单晶金纳米片的制备与表征(英文)

羟基功能化离子液体氯化1-(3-羟丙基)-3-甲基咪唑中,微波加热还原HAuCl4.4H2O制备了多边形单晶金纳米片,制备过程不需要额外添加包覆剂。产物用扫描电镜、透射电镜、选区电子衍射、能谱、X射线衍射和紫外可见分光光度计等进行了表征。产物的形状和大小可以通过控制反应条件如反应温度、反应物浓度等进行控制。50毫克HAuCl4.4H2O溶解于1毫升羟基功能化离子液体中,在140℃进行还原反应时,得到平面尺寸达16微米,厚度约为35纳米的单晶金纳米片。在单晶金纳米片的制备反应中,离子液体氯化1-(3-羟丙基-)3-甲基咪唑同时起到了反应介质、还原剂和包覆剂的作用。     

Borohydride‐Scaffolded Li/Na/Mg Fast Ionic Conductors for Promising Solid‐State Electrolytes

Borohydride solid‐state electrolytes with room‐temperature ionic conductivity up to ≈70 mS cm^?1 have achieved impressive progress and quickly taken their place among the superionic conductive solid‐state electrolytes. Here, the focus is on state‐of‐the‐art developments in borohydride solid‐state electrolytes, including their competitive ionic‐conductive performance, current limitations for practical applications in solid‐state batteries, and the strategies to address their problems. To open, fast Li/Na/Mg ionic conductivity in electrolytes with BH₄ ^? groups, approaches to engineering borohydrides with enhanced ionic conductivity, and later on the superionic conductivity of polyhedral borohydrides, their correlated conductive kinetics/thermodynamics, and the theoretically predicted high conductive derivatives are discussed. Furthermore, the validity of borohydride pairing with coated oxides, sulfur, organic electrodes, MgH₂, TiS₂, Li₄Ti₅O₁₂, electrode materials, etc., is surveyed in solid‐state batteries. From the viewpoint of compatible cathodes, the stable electrochemical windows of borohydride solid‐state electrolytes, the electrode/electrolyte interface behavior and battery device design, and the performance optimization of borohydride‐based solid‐state batteries are also discussed in detail. A comprehensive coverage of emerging trends in borohydride solid‐state electrolytes is provided and future maps to promote better performance of borohydride SSEs are sketched out, which will pave the way for their further development in the field of energy storage.     

A Fully Biodegradable Battery for Self‐Powered Transient Implants

Biodegradable transient devices represent an emerging type of electronics that could play an essential role in medical therapeutic/diagnostic processes, such as wound healing and tissue regeneration. The associated biodegradable power sources, however, remain as a major challenge toward future clinical applications, as the demonstrated electrical stimulation and sensing functions are limited by wired external power or wireless energy harvesters via near‐field coupling. Here, materials' strategies and fabrication schemes that enable a high‐performance fully biodegradable magnesium–molybdenum trioxide battery as an alternative approach for an in vivo on‐board power supply are reported. The battery can deliver a stable high output voltage as well as prolonged lifetime that could satisfy requirements of representative implantable electronics. The battery is fully biodegradable and demonstrates desirable biocompatibility. The battery system provides a promising solution to advanced energy harvesters for self‐powered transient bioresorbable implants as well as eco‐friendly electronics.     

DSC and conductivity studies on PVA based proton conducting gel electrolytes

An attempt has been made in the present work to prepare polyvinyl alcohol (PVA) based proton conducting gel electrolytes in ammonium thiocyanate (NH₄SCN) solution and characterize them. DSC studies affirm the formation of gels along with the presence of partial complexes. The cole-cole plots exhibit maximum ionic conductivity (2.58 × 10⁻³ S cm⁻¹) for gel samples containing 6 wt% of PVA. The conductivity of gel electrolytes exhibit liquid like nature at low polymer concentrations while the behaviour is seen to be affected by the formation of PVA-NH₄SCN complexes upon increase in polymer content beyond 5 wt%. Temperature dependence of ionic conductivity exhibits VTF behaviour.     

磷酸酯基离子液体对木质素的溶解性能

合成表征了5种磷酸酯类离子液体,并将其用于溶解木质素。结果表明,离子液体1,3-二甲基咪唑磷酸甲酯盐[Mmim]DMP对木质素的溶解性能最佳,在70℃搅拌120 min,木质素溶解度可达45%。扫描电镜(SEM)、X射线衍射(XRD)和红外光谱(FT-IR)表征结果显示离子液体在木质素溶解过程中并未使木质素发生衍生化反应,但经离子液体溶解再生后,木质素的形貌均发生了显著变化,离子液体溶解性能越强,所得再生木质素颗粒越均匀、分散性越好且弥散衍射特征越强烈。此外,回收所得离子液体重复使用5次后,对木质素仍有较好的溶解性能。     

Biosafe,Eco‐Friendly Levan Polysaccharide toward Transient Electronics

New options in the material context of transient electronics are essential to create or expand potential applications and to progress in the face of technological challenges. A soft, transparent, and cost‐effective polymer of levan polysaccharide that is capable of complete, programmable dissolution is described when immersed in water and implanted in an animal model. The results include chemical analysis, the kinetics of hydrolysis, and adjustable dissolution rates of levan, and a simple theoretical model of reactive diffusion governed by temperature. In vivo experiments of the levan represent nontoxicity and biocompatibility without any adverse reactions. On‐demand, selective control of dissolution behaviors with an animal model demonstrates an effective triggering strategy to program the system's lifetime, providing the possibility of potential applications in envisioned areas such as bioresorbable electronic implants and drug release systems.     

强吸水性离子液体-水工质对吸收式制冷循环性能分析

离子液体的出现,为吸收式制冷循环工质的改进开辟了新途径。以离子液体-水为工质对的吸收式制冷循环性能与离子液体的吸湿性能密切相关,因此筛选两种对水有极强吸收性能的离子液体：1-乙基-3-甲基咪唑醋酸盐（[EMIm]Ac）、1-己基-3-甲基咪唑氯盐（[HMIm]Cl）,对其水溶液吸收式制冷循环进行研究。首先对离子液体水溶液热力学特性（蒸汽压、比热、比焓等）进行了研究,然后分析吸收式制冷循环的性能系数。研究结果表明这两种离子液体-水工质对单效吸收循环可工作于较高温度条件下,其性能系数大大优于现今国内外学者所研究的离子液体,其中[EMIm]Ac水溶液优于[HMIm]Cl水溶液。与传统工质溴化锂-水比较,[EMIm]Ac-水工质对在发生温度为100℃时具有相当的循环性能系数,且在较高温度条件下优于传统溴化锂-水的性能系数。然而该离子液体水溶液优势只在较高发生温度时才能体现,要实现技术上的进一步突破,应着重筛选低温区蒸汽压特性优良的水溶性离子液体。