Highly stretchable graphene-nanocellulose composite nanopaper is fabricated for strain-sensor applications. Three-dimensional macroporous nanopaper from crumpled graphene and nanocellulose is embedded in elastomer matrix to achieve stretchability up to 100%. The stretchable graphene nanopaper is demonstrated for efficient human-motion detection applications.

Beyond state-of-the-art lithium-ion battery (LIB) technology with metallic lithium anodes to replace conventional ion intercalation anode materials is highly desirable because of lithium's highest specific capacity (3,860 mA/g) and lowest negative electrochemical potential (∼3.040 V vs. the standard hydrogen electrode). In this work, we report for the first time, to our knowledge, a 3D lithium-ion-conducting ceramic network based on garnet-type Li 6.4 La 3 Zr 2 Al 0.2 O 12 (LLZO) lithium-ion conductor to provide continuous Li + transfer channels in a polyethylene oxide (PEO)-based composite. This composite structure further provides structural reinforcement to enhance the mechanical properties of the polymer matrix. The flexible solid-state electrolyte composite membrane exhibited an ionic conductivity of 2.5 × 10 −4 S/cm at room temperature. The membrane can effectively block dendrites in a symmetric Li j electrolyte j Li cell during repeated lithium stripping/plating at room temperature, with a current density of 0.2 mA/cm 2 for around 500 h and a current density of 0.5 mA/cm 2 for over 300 h. These results provide an all solid ion-conducting membrane that can be applied to flexible LIBs and other electrochemical energy storage systems, such as lithium-sulfur batteries.solid-state electrolyte | 3D garnet nanofibers | polyethylene oxide | ionic conductor | flexible membrane H igh capacity, high safety, and long lifespan are three of the most important key factors to developing rechargeable lithium batteries for applications in portable electronics, transportation (e.g., electrical vehicles), and large-scale energy storage systems (1-5). Based on state-of-the-art lithium-ion battery (LIB) technology, metallic lithium anode is preferable to replace conventional ion intercalation anode materials because of the highest specific capacity (3,860 mAh/g) of lithium and the lowest negative electrochemical potential (∼3.040 V vs. the standard hydrogen electrode), which can maximize the capacity density and voltage window for increased battery energy density (1). Moreover, the success of beyond LIBs, such as lithium-sulfur and lithium-oxygen, will strongly rely on lithium metal anode designs with good stability to achieve their targeted goals of high energy density and long cycle life.Using lithium metal in organic liquid electrolyte systems faces many challenges in terms of battery performance and safety. For example, lithium-sulfur batteries suffer from the dissolution of intermediate polysulfides in the organic electrolyte that causes severe parasitic reactions on lithium metal surfaces, leading to lithium metal degradation and low lithium cycling efficiency (6). Lithium-oxygen batteries have the challenge of chemically instable liquid electrolytes on the oxygen electrode that cause limited battery cycling (7). All of these challenges are associated with the use of lithium metal in liquid electrolyte battery systems. Another major associated challenge is lithium dendrite growth on lithium metal anodes, which causes int...

All-component 3D-printed lithium-ion batteries are fabricated by printing graphene-oxide-based composite inks and solid-state gel polymer electrolyte. An entirely 3D-printed full cell features a high electrode mass loading of 18 mg cm(-2) , which is normalized to the overall area of the battery. This all-component printing can be extended to the fabrication of multidimensional/multiscale complex-structures of more energy-storage devices.

Searching the long-life MnO-based materials for lithium ion batteries (LIBs) is still a great challenge because of the issue related to the volumetric expansion of MnO nanoparticles (NPs) or nanowires (NWs) during lithiation. Herein, we demonstrate an unexpected result that a peapod-like MnO/C heterostructure with internal void space can be facilely prepared by annealing the MnO precursor (MnO-P) NW/polydopamine core/shell nanostructure in an inert gas, which is very different from the preparation of typical MnO/C core/shell NWs through annealing MnO NW/C precursor nanostructure. Such peapod-like MnO/C heterostructure with internal void space is highly particular for high-performance LIBs, which can address all the issues related to MnO dissolution, conversion, aggregation and volumetric expansion during the Li(+) insertion/extraction. They are highly stable anode material for LIBs with a very high reversible capacity (as high as 1119 mAh g(-1) at even 500 mA g(-1)) and fast charge and discharge capability (463 mAh g(-1) at 5000 mA g(-1)), which is much better than MnO NWs (38 mAh g(-1) at 5000 mA g(-1)) and MnO/C core/shell NWs (289 mAh g(-1) at 5000 mA g(-1)). Such nanopeapods also show excellent rate capability (charged to 91.6% in 10.6 min using the constant current mode). Most importantly, we found that MnO/C nanopeapods show no capacity fading even after 1000 cycles at a high current density of 2000 mA g(-1), and no morphology change. The present MnO/C nanopeapods are the most efficient MnO-based anode materials ever reported for LIBs.

The development of mechanically "robust" EL devices that can confront different demanding mechanical deformations, such as fl exing, folding, twisting, and stretching without incurring damage, is the primary requirement for fabricating selfdeformable EL devices. Reported attempts have demonstrated polymer light-emitting materials for intrinsically stretchable EL devices. [3][4][5][6][7]12 ] Different strategies have also been employed by engineering stretchable structures with assembled rigid inorganic light-emitting elements. [ 1,2,13,14 ] The substrates and electrodes of devices can be stretched while the light-emitting elements are kept intact during stretching. Here, a different method has been developed to fabricate an intrinsically stretchable inorganic EL device with both stretchable conductors and light-emitting layers. The elastic EL device could sustain its performance at stretching strains as large as 100% (close to the mechanical failure of the host elastomer). The simplicity of the device fabrication together with its excellent stretchability enabled the integration with actuators, which could drive the elastic EL devices into dynamic shapes. Dielectric elastomer actuators (DEAs) are emerging "smart materials" that can generate mechanical motions with applied electrical fi elds. DEAs have demonstrated extraordinary mechanical actuation performance with area strain reaching beyond 200% on prestrained elastomers; [15][16][17] this exceeds most actuators based on other working mechanisms, such as piezoelectric actuators (≈5%), [ 18 ] ionic gel actuators (≈40%), [ 19 ] and natural muscle (≈100%). [ 20 ] With their intrinsic stretchability, ease of minimization, high power density, and low-cost fabrication, DEAs have been applied in many applications such as wearable tactile display devices, [ 21,22 ] highspeed electromechanical transducers, [ 23,24 ] and smart artifi cial muscles [ 20,25 ] etc. In this report, DEAs are demonstrated to be ideal shape display components to integrate with stretchable EL devices. An unprecedented self-deformable EL device is fabricated by the innovative method in this work.A schematic drawing of the stretchable EL device is represented in Figure 1 a. The stretchable EL device was fabricated with a simple all-solution processable method. In brief, AgNW networks were fi rstly spray-coated onto the polydimethylsiloxane (PDMS) substrate, forming the bottom electrode. ZnS:Cu microparticles mixed with liquid PDMS were then spun onto the bottom electrode. ACEL devices have been developed for display or lighting applications for a few decades and have attracted persistent interest for their simple device architecture and low production cost. [26][27][28] ZnS:Cu is a widely available ACEL material with well-studied and understood emission behavior. [ 29,30 ] Its emission colors can be easily tuned by using different active dopants or adjusting the dopant concentrations. After crosslinking, the ZnS:Cu/PDMS composite layer harvests the excellent stretchability from the PDMS matrix with...

in order to restrict the loss of material. Furthermore, due to their scalability and flexibility, 3D flexible electronics (see Supporting Information (SI), where Table S1 contains a list) were considered revolutionary materials and were used in many fields such as imperceptible electronic devices, wearable electronic devices, and bionic technology. [11][12][13] Recently studies have shown the encapsulation of sulfur in the pores of carbon materials, such as meso-/microporous carbons, [11] cable-shaped carbon, [12] and carbon nanotubes/fibers, [13] can reduce the capacity fading. However, such nonpolar flexible carbon materials have a destructive disadvantage; they only have physical van der Waals (vdW) adsorption for polar Li 2 S n , which leads to the facile detachment of Li 2 S n from the carbon surface. [14] This proves that carbon-based materials alone cannot serve as the perfect host. In light of this new insight, various types of polar functional groups on carbon-based materials have been demonstrated to increase the interaction between Li 2 S n species and the electrode; these materials can generally be categorized into three types: polymers (polyaniline, polypyrrole, poly(3,4ethylenedioxythiophene) (PEDOT)), [15] metal oxides

Stretchable and wearable WO3 electrochromic devices on silver nanowire (AgNW) elastic conductors are reported. The stretchable devices are mechanically robust and can be stretched, twisted, folded, and crumpled without performance failure. Fast coloration (1 s) and bleaching (4 s) time and good cyclic stability (81% retention after 100 cycles) were achieved at relaxed state. Proper functioning at stretched state (50% strain) was also demonstrated. The electrochromic devices were successfully implanted onto textile substrates for potential wearable applications. As most existing electrochromic devices are based on rigid technologies, the innovative devices in their soft form hold the promise for next-generation electronics such as stretchable, wearable, and implantable display applications.

Stretchable graphene thermistors with intrinsic high stretchability were fabricated through a lithographic filtration method. Three-dimensional crumpled graphene was used as the thermal detection channels, and silver nanowires were used as electrodes. Both the detection channel and electrodes were fully embedded in an elastomer matrix to achieve excellent stretchability. Detailed temperature sensing properties were characterized at different strains up to 50%. It is evident that the devices can maintain their functionalities even at high stretched states. The devices demonstrated strain-dependent thermal indices, and the sensitivity of the thermistors can be effectively tuned using strain. The unique tunable thermal index is advantageous over conventional rigid ceramic thermistors for diverse and adaptive applications in wearable electronics.