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Wearable strain transducers are poised to transform the field of healthcare owing to the promise of personalized devices capable of real‐time collection of human physiological health indicators. For instance, monitoring patients' progress following injury and/or surgery during physiotherapy is crucial but rarely performed outside clinics. Herein, multifunctional liquid‐free ionic elastomers are designed through the volume effect and the formation of dynamic hydrogen bond networks between polyvinyl alcohol (PVA) and weak acids (phosphoric acid, phytic acid, formic acid, citric acid). An ultra‐stretchable (4600% strain), highly conducting (10 mS cm−1), self‐repairable (77% of initial strain), and adhesive ionic elastomer is obtained at high loadings of phytic acid (4:1 weight to PVA). Moreover, the elastomer displayed durable performances, with intact mechanical properties after a year of storage. The elastomer is used as a transducer to monitor human motions in a device comprising an ESP32‐based development board. The device detected walking and/or running biomechanics and communicated motion‐sensing data (i.e., amplitude, frequency) wirelessly. The reported technology can also be applied to other body parts to monitor recovery after injury and/or surgery and inform practitioners of motion biomechanics remotely and in real time to increase convalescence effectiveness, reduce clinic appointments, and prevent injuries. [ABSTRACT FROM AUTHOR]

The formation of an electric double‐layer (EDL) is an important phenomenon for many research areas, including energy storage technology. Although EDL is well‐known in electrochemistry, most of the studies involve the characterization of liquid electrolyte/electrode interfaces, and only a limited number of studies in solid‐solid contacts, such as solid electrolyte/electrode interface are available. This paper employed electrochemical impedance spectroscopy (EIS) to systematically investigate the influence of experimental factors in the interfacial capacitance arising from the electrode polarization in a lithium disilicate glass/gold electrode interface. It analyzed the influence of a.c. input voltage amplitude, samples' roughness (mechanical and chemomechanical polishing) and thickness, range of applied frequency and temperature, and the number of impedance cycles. In short, it was found that an input voltage range of 15–60 mV is indicated to minimize potential electrochemical processes during electrode polarization, where the data is reproducible from the second measurement cycle onward. Smoother surfaces closely approximated ideal electrode spike behavior, with surface treatment exhibiting influence on interfacial capacitance values. Moreover, as expected, we observed an increase in relative permittivity values with increasing thickness, accompanied by decreased capacitance values. Finally, by employing optimal experimental conditions and analyzing the inflection frequency (finflection${{f}_{inflection}}$) of the ε′$\varepsilon ^{\prime}$ versus log(f$f$) curve, we determined that the ratio between effective charge carriers (ne${{n}_e}$) and the total number of charge carriers (nt${{n}_t}$) nent$\frac{{{{n}_e}}}{{{{n}_t}}}$ falls within the range of 5–12% between 130°C and 280°C. [ABSTRACT FROM AUTHOR]

Inspired by human skin, soft sensors that are capable of sensing various external signals have been an active area of research. However, the vast majority of the developed soft sensors still lag far behind human skin in terms of multimodal sensing capability. Herein, this work reports on a multimodal soft sensor that can decouple thermal and mechanical signals. The sensor is made of poly(ethylene glycol) gel (PEGgel) containing ionic liquid, which is stretchable and transparent and shows decent strain and temperature sensing performances. Importantly, analysis of the ion relaxation dynamics shows that the charge relaxation time and capacitance change of the sensor are independently sensitive to the variations of temperature and mechanical deformation, respectively. By measuring the charge relaxation time and capacitance, the thermal and mechanical signals detected by the PEGgel sensor can be nicely decoupled without signal interference. Such a multimodal soft sensor may serve as a starting point for the development of lifelike soft sensors for high‐tech applications in a variety of fields such as soft robotics, the internet of things, and human–machine interaction. [ABSTRACT FROM AUTHOR]

Microstructure control of composite electrodes comprising active materials and solid electrolytes is imperative to achieve sufficient ion‐ and electron‐conductive pathways for the development of all‐solid‐state Li ion batteries. Here, we synthesized Li10GeP2S12 solid electrolytes with various particle size distributions by milling and filtering. Impedance spectroscopy revealed that the ionic conductivities in the bulk were hardly changed by the synthetic processes. This enabled us to investigate only the microstructure effects on the electrochemical properties of the composite electrodes. Microscopic and electrochemical tests of the LiCoO2‐Li10GeP2S12 composite cathodes clarified that the size distributions of the Li10GeP2S12 drastically affected the microstructures in the composite cathodes, such as contacts at interfaces and voids between particles. The size distributions also contributed to the appropriate ratio of LiCoO2 to Li10GeP2S12 for superior charge/discharge properties. The (de)intercalation reversibly proceeded in the composite cathode using the filtered Li10GeP2S12 even though the ratio of Li10GeP2S12 decreased from 50 % to 30 % in volume. This study demonstrated the possibility of high‐energy‐density composite cathodes for all‐solid‐state batteries by control of microstructures in composite electrodes. [ABSTRACT FROM AUTHOR]

Low‐grade heat is ubiquitous in the environment and its thermoelectric conversion by the ionic conductors remains a challenge because of the low efficiency and poor sustainability. Here we demonstrate that the thermoelectric performances can be boosted by combining the Soret effect of protons and proton‐coupled electron transfer (PCET) reaction of benzoquinone and hydroquinone in hydrogels. An overall enhancement of thermopower (25.9 mV K−1), power factor (5 mW m−1 K−2), figure of merit (>2.4) and continuity of power output is achieved. Moreover, an energy‐storage function can be achieved by the redox couple, and a retained power output of 27.7 %, or 14 mW m−2 for more than 3 hours is obtained by the re‐balance of PCET reactants in the hydrogel after the removal of the temperature gradient. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: With the rapid growth of soft electronic and ionotronic devices such as artificial tissues, soft luminescent devices, soft robotics, and human‐machine interfaces, there is a demanding need to accelerate the development of soft ionic conductive materials. To date, the first‐generation ionotronic devices are mainly based on hydrogels or ionogels. However, due to their intrinsic drawbacks, such as freezing or volatilization at extreme temperatures, and the leakage problem under external mechanical forces, the reliability of ionotronic devices under harsh conditions remains a great challenge. The advent of liquid‐free ionic conductive elastomers (ICEs) has the potentials to solve the issues related to the gel‐type soft conductive materials. The free ions shuttling within the ion‐dissolvable polymer network enable liquid‐free ICEs to exhibit unparalleled ionic conductivity and elasticity. Moreover, by tuning the composition and structure of the polymeric network, it is also feasible to integrate other desirable properties, such as self‐healing ability, transparency, biocompatibility, and stimulus responsiveness, into liquid‐free ICE materials. In this review, we summarize the design strategies of recently reported liquid‐free ICEs, and further explore the methods to introduce multifunctionality, which originate from the rational molecular design and/or the synergy with other materials. Moreover, we highlight the representative applications of liquid‐free ICEs in soft ionotronics. It is believed that liquid‐free ICEs might provide a unique material platform for the next‐generation ionotronics. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: With the rapid growth of soft electronic and ionotronic devices such as artificial tissues, soft luminescent devices, soft robotics, and human‐machine interfaces, there is a demanding need to accelerate the development of soft ionic conductive materials. To date, the first‐generation ionotronic devices are mainly based on hydrogels or ionogels. However, due to their intrinsic drawbacks, such as freezing or volatilization at extreme temperatures, and the leakage problem under external mechanical forces, the reliability of ionotronic devices under harsh conditions remains a great challenge. The advent of liquid‐free ionic conductive elastomers (ICEs) has the potentials to solve the issues related to the gel‐type soft conductive materials. The free ions shuttling within the ion‐dissolvable polymer network enable liquid‐free ICEs to exhibit unparalleled ionic conductivity and elasticity. Moreover, by tuning the composition and structure of the polymeric network, it is also feasible to integrate other desirable properties, such as self‐healing ability, transparency, biocompatibility, and stimulus responsiveness, into liquid‐free ICE materials. In this review, we summarize the design strategies of recently reported liquid‐free ICEs, and further explore the methods to introduce multifunctionality, which originate from the rational molecular design and/or the synergy with other materials. Moreover, we highlight the representative applications of liquid‐free ICEs in soft ionotronics. It is believed that liquid‐free ICEs might provide a unique material platform for the next‐generation ionotronics. [ABSTRACT FROM AUTHOR]

Recently, eutectogels have gained significant attention as promising materials for wearable devices. However, developing eutectogels with integrated stretchability, good toughness, self‐healing, and self‐adhesive properties through non‐covalent scaffold assembly is a major challenge. In this study, a fully physically crosslinked double‐network (DN) eutectogel was fabricated by exploiting the high solubility and gelation of gellan gum in a deep eutectic solvent (DES) to form the first physically crosslinked network and combining it with supramolecular poly (2‐hydroxyethyl acrylate‐choline chloride, HEA‐ChCl). The resulting gel showed high stretchability (1835 %), toughness (7.65 MJ m−3), desirable ionic conductivity (0.41 mS cm−1), adhesion, and high transparency. Assembling the gel into strain sensors allows precise monitoring of human motion (finger, wrist, elbow, and knee). The results of this study suggest that gellan gum/poly (ChCl‐HEA) DN eutectogels have significant potential as highly sensitive and reliable strain sensors for wearable technology applications. [ABSTRACT FROM AUTHOR]

Owing to the advantages of temperature resistance, low cost, and biocompatibility, deep eutectic solvent (DES)‐based ionic conductive gels have attracted increasing research interest for flexible devices in recent years. However, current DES gels are all based on hydrophilic DES, which tend to absorb a large amount of environmental moisture, resulting in gel softening and adversely affecting the durability of the device. In this work, we highlight for the first time that N,N‐dimethylacrylamide monomer, and the obtained polymer can form hydrogen‐bonding networks with hydrophobic DES, methyl trioctyl ammonium chloride/ethyl 4‐hydroxybenzoate (1:2), thereby obtaining a hydrophobic DES‐based gel through photo‐polymerization. The resultant DES gel displays high stretchability (~900%), toughness (341.14 kJ m−3), anti‐fatigue property (recovery after 500 compression cycles), desirable conductivity (0.12 mS cm−1), adhesiveness and high transparency (>90% visible light transmittance). Notably, the hydrophobic DES‐based gel absorbs only 2 wt% water but exhibits significant water‐induced stiffening after exposing in ambient air for 1 week. These properties lead to the successful realization of the DES gels as wearable sensors to precisely monitor human motion. This work may open new avenues for the development of hydrophobic DES‐based gel ionotronics with functional performance. [ABSTRACT FROM AUTHOR]

Single crystal specimens of apatite‐type compounds Ca5(VO4)3Cl and Ca4.78 (1)Na0.22(PO4)3Cl0.78 were prepared with a flux‐growth technique and their structures were examined with single‐crystal X‐ray diffraction. The anion channel is defined by a face‐sharing array of nearly regular Ca octahedra, which run along c, together with flat O3 trigonal antiprisms that are concentric with the Ca octahedra and highly oblate in [001]. The position of the channel anion in Ca5(VO4)3Cl is split into two at [0, 0, ±0.1691 (6)] with half occupancies. Dynamic disorder among these two positions is suggested from a saddle‐shaped electron density distribution through the Ca regular triangle, i.e. the shared face of the Ca octahedra at z = ¼. The position of Cl− was too close to Ca2+ under bond‐valence consideration. This is due to repulsion on Cl− from the flat O3 trigonal antiprism which is located at z = 0, namely, in between pairs of split Cl site positions. Ca4.78 (1)Na0.22(PO4)3Cl0.78 crystallizes as a disordered hexagonal structure in which the crystallographic pattern is not an intermediate state but a projection of two distinct halves of the monoclinic pattern [doubled in b; Mackie, Elliot & Young (1972). Acta Cryst. B28, 1840–1848] in one hexagonal cell. In spite of quite different environments, the bond‐valence sums for Cl− in these structures are large and similar to each other. The repulsion between O2− and Cl− and a demand for keeping Ca2+ and Cl− apart are balanced at the positions where bond‐valence sums for Cl− are around 1.2. [ABSTRACT FROM AUTHOR]

Lithium metal is regarded as the most promising electrode material for the next generation of energy storage devices. However, low coulombic efficiency and short cycle lifespan caused by the unstable electrode interface have hindered its practical application. Constructing artificial coatings on the anode is one of the most effective approaches for remedying this, but the practical effects are still limited due to their poor regulation of Li+ ions transport and complex construction engineering. Herein, an "inverse concentration gradient" concept is put forward to improve the lithium metal anode, especially at high current density. A Li4Ti5O12 artificial coating layer is fabricated on copper foil by a simple droplet coating method and a concentrated Li+ ions region near the electrode interface in the coating layer is formed in situ after the initial activation process, which alleviates the effects of space charge regions generated by ion depletion on the growth of lithium dendrites. Coupled with high ionic conductivity and "zero strain" characteristics, stable dendrite‐free cycling of lithium metal anodes is achieved even at 5 mA cm−2 in Li/Cu half cell. The unique concentration gradient design provides a new perspective for the interface regulation of advanced lithium metal anodes. [ABSTRACT FROM AUTHOR]

Gel polymer electrolytes (GPEs) are preferable in energy storage devices, owing to their high ionic conductivity and excellent compatibility with electrodes. In the current work, sodium‐conductive Na2Zn2TeO6 filler modified GPE membranes are fabricated, and their application performances in sodium‐ions batteries (SIBs) are demonstrated. With the modification of Na2Zn2TeO6 filler, the ionic conductivity of the GPEs is enhanced significantly, due to the decreased crystallinity and enlarged porosity of polymer membranes induced by Na2Zn2TeO6 modifier, which itself is a high ionic conductor. The modified GPE membranes exhibit enhanced ionic conductivity as high as 2.52×10−3 S/cm with a low activation energy of approximately 0.040 eV. The assembled Na3V2(PO4)3/C|GPE|Na battery delivers a high first discharge capacity of 93.3 mAh ⋅ g−1 at 0.5 C and promising capacity retention capability (98.4 % after 100 cycles) as well as excellent rate performance (83.5 mAh ⋅ g−1 at 5 C). This work proves that the performances of GPEs can be enhanced with the modification of ionic conductors similar to Na2Zn2TeO6, promoting the application of GPEs in energy storage devices. [ABSTRACT FROM AUTHOR]

Na2FeP2O7 (NFP) ceramics show potential application as the active material for sodium ion batteries. In this study, NFP ceramics were irradiated with infrared laser light with a wavelength of 1 µm. Fe2+ ions allowing local heating and resulting in instantaneous melting and rapid cooling for glass formation. The results of differential thermal analysis and X‐ray diffraction suggest that the laser‐irradiated part is vitrified and that rapid cooling is achieved to prevent recrystallization. It was possible to form a molten pattern withan output of 0.22 W and a scanning rate of up to 3mm/s of laser light. Irradiation of laser light on NFP powder on NASICON‐type Na3Zr2Si2PO12 solid electrolyte ceramic enabled the formation of a dense glassy NFP phase of several tenth‐micrometer depths on solid electrolyte ceramic. This technique is a promising process mainly for developing an oxide‐based all‐solid‐state battery because the contact interface can form instantaneously without external mechanical pressure. [ABSTRACT FROM AUTHOR]

To date, ionic conducting hydrogel attracts tremendous attention as an alternative to the conventional rigid metallic conductors in fabricating flexible devices, owing to their intrinsic characteristics. However, simultaneous realization of high stiffness, toughness, ionic conductivity, and freezing tolerance through a simple approach is still a challenge. Here, a novel highly stretchable (up to 660%), strong (up to 2.1 MPa), tough (5.25 MJ m−3), and transparent (up to 90%) ionic conductive (3.2 S m−1) organohydrogel is facilely fabricated, through sol–gel transition of polyvinyl alcohol and cellulose nanofibrils (CNFs) in dimethyl sulfoxide‐water solvent system. The ionic conductive organohydrogel presents superior freezing tolerance, remaining flexible and conductive (1.1 S m−1) even at −70 °C, as compared to the other reported anti‐freezing ionic conductive (organo)hydrogel. Notably, this material design demonstrates synergistic effect of CNFs in boosting both mechanical properties and ionic conductivity, tackling a long‐standing dilemma among strength, toughness, and ionic conductivity for the ionic conducting hydrogel. In addition, the organohydrogel displays high sensitivity toward both tensile and compressive deformation and based on which multi‐functional sensors are assembled to detect human body movement with high sensitivity, stability, and durability. This novel organohydrogel is envisioned to function as a versatile platform for multi‐functional sensors in the future. [ABSTRACT FROM AUTHOR]

DC electrical degradation as a form of dielectric and resistance breakdown is common in thin‐film devices including resistance‐switching memory. To obtain design data and to probe the degradation mechanism, highly accelerated lifetime tests (HALT) are often conducted at higher temperatures with thicker samples. While the mechanism is well established in semiconducting oxides such as perovskite titanates, it is not in stabilized zirconia and other fast oxygen‐ion conductors that have little electronic conductivity. Here we model the mechanism by an oxygen‐driven, transport‐limited, metal‐insulator transition, which finds support in rich experimental observations—including in situ videos and variable temperature studies—of yttria‐stabilized zirconia. This demonstrates that although (electro) reduction does not appreciably alter oxygen stoichiometry in stabilized zirconia, which is fixed by the dopant concentration, it can still raise the chemical potential of electrons enough to eventually reach the conduction‐band level, thereby triggering the insulator‐to‐metal transition and resistance degradation. These results are contrasted with the findings in semiconducting titanates and resistance memory, and to provide new insight into ceramic processing with extremely rapid heating and cooling such as flash sintering and melt processing. [ABSTRACT FROM AUTHOR]

Limited by the sluggish kinetics of conversion‐type anodes from huge diffusion‐controlled phase transformation and unsatisfactory capacities of intercalation/alloy‐type anodes, the performances of lithium‐based dual ion batteries (LDIBs) remain to be promoted. Herein, for the first time, ultra‐small manganese silicate (MS) nanosheets anchored on reduced graphene oxides (MSR) with enhanced diffusion kinetics are constructed, realizing the construction of high performance LDIBs on the basis of conversion‐type anodes. The ion diffusion rate of MSR is promoted by in situ coating Li4SiO4 ionic conductor on the electrode surface during lithiation process. Simultaneously, the ion diffusion pathways are shortened by partially converting the diffusion‐controlled bulk reaction to surface reaction with massive pseudocapacitive contribution. Consequently, the MSR‐based LDIB exhibits superior electrochemical performances with discharge capacities of 191 mA h g−1 at 0.5 C and 128 mA h g−1 at 2 C after 150 cycles, exceeding to those of reported LDIBs and benefiting the future electrode design of LDIBs. Conversion‐type ultra‐small Mn7O8(SiO4) nanosheet/reduced graphene oxide anodes with enhanced diffusion kinetics are constructed for Li‐dual ion batteries (LDIBs) for the first time. The in situ formed Li4SiO4 ionic conductor and the pseudocapacitive contribution endow them with 191 mA h g−1 at 0.5 C and 128 mA h g−1 at 2 C after 150 cycles, realizing the construction of high‐performance LDIBs. [ABSTRACT FROM AUTHOR]

Ni‐rich layered compounds are very promising cathodes for lithium ion batteries whose surface modifications are normally required. As excellent lithium‐conducting solid electrolytes lithium aluminates such as LiAlO2 are expected to have an important role to play as a candidate for surface modifications. Here, Ni‐rich layered LiNi0.8Co0.1Mn0.1O2 (NCM) coated by lithium aluminates with different nominal weight percentages was prepared using a sol‐gel method. Lithium aluminates are found to be a mixture of major LiAlO2 and minor Li5AlO4. The coatings almost have no influence on the size and morphology of NCM particles, and however favor the order degree of structure and change the surface states. The electrical conductivity and charge transfer resistance can be optimized by controlling the amount of lithium aluminates. The cycling stability at low rates such as 1 C tends to increase with the amount of lithium aluminates whereas the rate capability can be achieved at certain amount, which is probably related to the enhancement of electrical conductivity and the improved surface protection against the erosion by electrolyte. This study reveals that the performances of NCM can be significantly improved and tailored by controlling the amount of lithium aluminates. Both rate capability and cycling performance of Layered LiNi0.8 Co0.1Mn0.1O2 compounds are improved by coating ionically conducting Lithium aluminates composed of LiAlO2 and Li5AlO4 nanocrystals. Surface modifications cause the changes of the structure related parameters rather than the size and morphology of LiNi0.8Co0.1Mn0.1O2 particles which lead to the enhancement of electrical conductivity and the reduction of charge transfer resistance. [ABSTRACT FROM AUTHOR]

Lithium garnet-type oxides Li7−2 xLa3Zr2− xMo xO12 ( x=0, 0.1, 0.2, 0.3) ceramics were prepared by a sol-gel method. The influence of molybdenum on the structure, microstructure and conductivity of Li7La3Zr2O12 were investigated by X-ray diffraction, scanning electron microscopy, and impedance spectroscopy. The cubic phase Li7La3Zr2O12 has been stabilized by partial substitution of Mo for Zr at low temperature. The introduction of Mo ( x≥0.1) can accelerate densification. Li6.6La3Zr1.8Mo0.2O12 sintered at lower temperature 1100°C for 3 hours exhibits highest total ionic conductivity of 5.09 × 10−4 S/cm. Results indicate that the Mo doping LLZO synthesized by sol-gel method effectively lowers its sintering temperature and improves the ionic conductivity. [ABSTRACT FROM AUTHOR]

New ionic conducting materials for electrolytes for electrochemical devices have been attracting the interest of researchers in energy materials. Here, for the first time, we report a conductive composite with high ionic conductivity derived from an electronic conductor α-LiFeO2 and an insulator γ-LiAlO2. High conductivity was observed in the α-LiFeO2-γ-LiAlO2 composite when prepared by a solid state reaction method. However, the conductivity enhancement in α-LiFeO2-γ-LiAlO2 composite was not observed when the two oxides were mechanically mixed. The α-LiFeO2-γ-LiAlO2 composite also exhibits O2− or/and H+ ionic conduction which was confirmed through H2/air fuel cell measurements. An exceptionally high conductivity of 0.50 S cm−1 at 650 °C was observed under H2/air fuel cell conditions. This provides a new approach to discover novel ionic conductors from composite materials derived from electronic conductors. [ABSTRACT FROM AUTHOR]

ABSTRACT A soft ionic conductor can serve as an artificial nerve in an artificial muscle. A polyacrylamide hydrogel is synthesized containing a hygroscopic salt, lithium chloride. Two layers of the hydrogel are used as ionic conductors to sandwich a dielectric elastomer and fabricate a highly stretchable and transparent actuator. When the two layers of the hydrogels are subject to a voltage, the actuator reduces its thickness and expands. An areal strain of 134% is demonstrated. The voltage-strain curves are calculated by using a model that accounts for the elastic constraint of the hydrogel and the inhomogeneous deformation of the actuator. For actuators fabricated with the hydrogel of various thicknesses and with the dielectric elastomer of various prestretches, excellent agreements are found between experimental data and theoretical predictions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1055-1060 [ABSTRACT FROM AUTHOR]

A structural investigation of Ag x(Ge0.25Se0.75)100 − x glasses with x = 5, 15, and 25 at.% has been carried out by neutron diffraction and ab initio molecular dynamics (AIMD) simulation. A structural model for the glasses has been proposed: the Ge(Se1/2)4 tetrahedra would remain the fundamental structural units in all samples. The introduction of Ag in the Ge0.25Se0.75 network would lead to a decrease in homopolar SeSe bonds and appearance of GeGe bonds. A strong evolution in the AgAg correlations upon introduction of Ag was observed with the AgAg correlation distances changing from 4.4 Å for the Ag-poor glass to 3.0 Å for the Ag-rich ones. Such information was used to discuss the evolution of conductivity with Ag content in these glasses. [ABSTRACT FROM AUTHOR]

Probability density functions (PDFs) of mobile ions in one-dimensional ionic conductors of hollandite A xMg x/2Ti8 − x/2O16 ( A = K, Rb) were examined by single-crystal X-ray diffraction. A conventional structure model was modified by imposing an additional constraint condition, which is based on microscopic description for the possible displacement of mobile ions adjacent to a vacancy in the tunnel. Joint PDFs and one-particle potentials for mobile ions were obtained from the structure models applying harmonic and anharmonic atomic displacement parameters (ADPs). Potential curves of the ion hopping between neighboring cavities were calculated from the joint PDF of the specific ions of the process. Energy barriers of the ion hopping were estimated at 52–60 meV from anharmonic ADP models of K-hollandite, while the values varied from 140 to 250 meV for Rb-hollandite. [ABSTRACT FROM AUTHOR]

To date, various stretchable conductors have been fabricated, but simultaneous realization of the transparency, high stretchability, electrical conductivity, self‐healing capability, and sensing property through a simple, fast, cost‐efficient approach is still challenging. Here, α‐lipoic acid (LA), a naturally small biological molecule found in humans and animals, is used to fabricate transparent (>85%), electrical conductivity, highly stretchable (strain up to 1100%), and rehealable (mechanical healing efficiency of 86%, electrical healing efficiency of 96%) ionic conductor by solvent‐free one‐step polymerization. Furthermore, the ionic conductors with appealing sensitivity can be served as strain sensors to detect and distinguish various human activities. Notably, this ionic conductor can be fully recycled and reprocessed into new ionic conductors or adhesives by a direct heating process, which offers a promising prospect in great reduction of electronic wastes that have brought acute environmental pollution. In consideration of the extremely facile preparation process, biological available materials, satisfactory functionalities, and full recyclability, the emergence of LA‐based ionic conductors is believed to open up a new avenue for developing sustainable and wearable electronic devices in the future. [ABSTRACT FROM AUTHOR]

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 P63mc 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. A super ionic conductor Li4(BH4)3I@SBA‐15 for all‐solid‐state Li batteries is reported. It shows a Li‐ion conductivity of 2.4 × 10−4 S cm−1 at 35 °C and exhibits excellent electrochemical stability and electrode compatibility in the potential window of 0 to 5 V, as it can work well in Li–Li4Ti5O12, Li–S, and Li–LiCoO2 all‐solid‐state cells at 55 °C. [ABSTRACT FROM AUTHOR]

Hydrogel-based ionic devices represent an alternative approach to stretchable electronics through use of soft ionic conductors that are both highly stretchable and transparent. However, these devices require the integration of dissimilar materials, dielectric elastomers and hydrogels, into a single system; a process thus far achieved primarily via the combination of several different manufacturing techniques. We have developed a 3D extrusion printing technique capable of fabricating an entire ionic circuit that integrates a LiCl-doped poly(acrylamide) (PAAm) hydrogel with a poly(dimethylsiloxane) (PDMS) dielectric elastomer. By incorporating hygroscopic salts such as LiCl into the hydrogel, we are able to prepare an ionically conductive hydrogel with excellent water-retaining properties. For printing reliability, we have optimized the rheological properties of a high ionic-strength hydrogel precursor and the interfacial energy between PDMS and hydrogel. Printed ionic devices that consist of PAAm and PDMS exhibit outstanding mechanical and electrical stability when tested with up to 1000 cycles of uniaxial tension. Moreover, we successfully demonstrate functionality in terms of signal transmission and as a soft sensor by fabricating and characterizing an ionic cable and several strain gauges., Engineering and Applied Sciences