Effect of gel electrolytes on the performance of a minimized flexible micro-supercapacitor based on graphene/PEDOT composite using pen lithography

A Biomimetic Cement-Based Solid-State Electrolyte with Both High Strength and Ionic Conductivity for Self-Energy-Storage Buildings

Cement-based materials are the foundation of modern buildings but suffer from intensive energy consumption. Utilizing cement-based materials for efficient energy storage is one of the most promising strategies for realizing zero-energy buildings. However, cement-based materials encounter challenges in achieving excellent electrochemical performance without compromising mechanical properties. Here, we introduce a biomimetic cement-based solid-state electrolyte (labeled as l-CPSSE) with artificially organized layered microstructures by proposing an in situ ice-templating strategy upon the cement hydration, in which the layered micropores are further filled with fast-ion-conducting hydrogels and serve as ion diffusion highways. With these merits, the obtained l-CPSSE not only presents marked specific bending and compressive strength (2.2 and 1.2 times that of traditional cement, respectively) but also exhibits excellent ionic conductivity (27.8 mS·cm-1), overwhelming most previously reported cement-based and hydrogel-based electrolytes. As a proof-of-concept demonstration, we assemble the l-CPSSE electrolytes with cement-based electrodes to achieve all-cement-based solid-state energy storage devices, delivering an outstanding full-cell specific capacity of 72.2 mF·cm-2. More importantly, a 5 × 5 cm2 sized building model is successfully fabricated and operated by connecting 4 l-CPSSE-based full cells in series, showcasing its great potential in self-energy-storage buildings. This work provides a general methodology for preparing revolutionary cement-based electrolytes and may pave the way for achieving zero-carbon buildings.

Ti3 C2 TX MXene Ink Direct Writing Flexible Sensors for Disposable Paper Toys

Flexible electronics have gained great attention in recent years owing to their promising applications in biomedicine, sustainable energy, human-machine interaction, and toys for children. Paper mainly produced from cellulose fibers is attractive substrate for flexible electronics because it is biodegradable, foldable, tailorable, and light-weight. Inspired by daily handwriting, the rapid prototyping of sensing devices with arbitrary patterns can be achieved by directly drawing conductive inks on flat or curved paper surfaces; this provides huge freedom for children to design and integrate "do-it-yourself (DIY)" electronic toys. Herein, viscous and additive-free ink made from Ti3 C2 TX MXene sediment is employed to prepare disposable paper electronics through a simple ball pen drawing. The as-drawn paper sensors possess hierarchical microstructures with interweaving nanosheets, nanoflakes, and nanoparticles, therefore exhibiting superior mechanosensing performances to those based on single/fewer-layer MXene nanosheets. As proof-of-concept applications, several popular children's games are implemented by the MXene-based paper sensors, including "You say, I guess," "Emotional expression," "Rock-Paper-Scissors," "Arm wrestling," "Throwing game," "Carrot squat," and "Grab the cup," as well as a DIY smart whisker for a cartoon mouse. Moreover, MXene-based paper sensors are safe and disposable, free from producing any e-waste and hazard to the environment.

Functionalized Metallic 2D Transition Metal Dichalcogenide-Based Solid-State Electrolyte for Flexible All-Solid-State Supercapacitors

Highly efficient and durable flexible solid-state supercapacitors (FSSSCs) are emerging as low-cost devices for portable and wearable electronics due to the elimination of leakage of toxic/corrosive liquid electrolytes and their capability to withstand elevated mechanical stresses. Nevertheless, the spread of FSSSCs requires the development of durable and highly conductive solid-state electrolytes, whose electrochemical characteristics must be competitive with those of traditional liquid electrolytes. Here, we propose an innovative composite solid-state electrolyte prepared by incorporating metallic two-dimensional group-5 transition metal dichalcogenides, namely, liquid-phase exfoliated functionalized niobium disulfide (f-NbS₂) nanoflakes, into a sulfonated poly(ether ether ketone) (SPEEK) polymeric matrix. The terminal sulfonate groups in f-NbS₂ nanoflakes interact with the sulfonic acid groups of SPEEK by forming a robust hydrogen bonding network. Consequently, the composite solid-state electrolyte is mechanically/dimensionally stable even at a degree of sulfonation of SPEEK as high as 70.2%. At this degree of sulfonation, the mechanical strength is 38.3 MPa, and thanks to an efficient proton transport through the Grotthuss mechanism, the proton conductivity is as high as 94.4 mS cm^-1 at room temperature. To elucidate the importance of the interaction between the electrode materials (including active materials and binders) and the solid-state electrolyte, solid-state supercapacitors were produced using SPEEK and poly(vinylidene fluoride) as proton conducting and nonconducting binders, respectively. The use of our solid-state electrolyte in combination with proton-conducting SPEEK binder and carbonaceous electrode materials (mixture of activated carbon, single/few-layer graphene, and carbon black) results in a solid-state supercapacitor with a specific capacitance of 116 F g^-1 at 0.02 A g^-1, optimal rate capability (76 F g^-1 at 10 A g^-1), and electrochemical stability during galvanostatic charge/discharge cycling and folding/bending stresses.

A Review of Fabrication Technologies for Carbon Electrode-Based Micro-Supercapacitors

The very fast evolution in wearable electronics drives the need for energy storage micro-devices, which have to be flexible. Micro-supercapacitors are of high interest because of their high power density, long cycle lifetime and fast charge and discharge. Recent developments on micro-supercapacitors focus on improving the energy density, overall electrochemical performance, and mechanical properties. In this review, the different types of micro-supercapacitors and configurations are briefly introduced. Then, the advances in carbon electrode materials are presented, including activated carbon, carbon nanotubes, graphene, onion-like carbon, and carbide-derived carbon. The different types of electrolytes used in studies on micro-supercapacitors are also treated, including aqueous, organic, ionic liquid, solid-state, and quasi-solid-state electrolytes. Furthermore, the latest developments in fabrication techniques for micro-supercapacitors, such as different deposition, coating, etching, and printing technologies, are discussed in this review on carbon electrode-based micro-supercapacitors.

Mechanically exfoliated graphite paper with layered microstructures for enhancing flexible electrochemical energy storage

This work fabricates mechanically exfoliated graphite paper with layered microstructures, which not only ensures the high flexibility of the resulting electrochemical capacitor, but substantially boosts its electrochemical properties.

Enhanced In-Vitro Hemozoin Polymerization by Optimized Process using Histidine-Rich Protein II (HRPII)

Conductive biopolymers, an important class of functional materials, have received attention in various fields because of their unique electrical, optical, and physical properties. In this study, the polymerization of heme into hemozoin was carried out in an in vitro system by the newly developed heme polymerase (histidine-rich protein 2 (HRP-II)). The HRP-II was produced by recombinant E. coli BL21 from the Plasmodium falciparum gene. To improve the hemozoin production, the reaction conditions on the polymerization were investigated and the maximum production was achieved after about 790 μM at 34 °C with 200 rpm for 24 h. As a result, the production was improved about two-fold according to the stepwise optimization in an in vitro system. The produced hemozoin was qualitatively analyzed using the Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). Finally, it was confirmed that the enzymatically polymerized hemozoin had similar physical properties to chemically synthesized hemozoin. These results could represent a significant potential for nano-biotechnology applications, and also provide guidance in research related to hemozoin utilization.