Armoring the cathode with starch gel enables Shuttle-Free Zinc-Iodine batteries.

Zinc-iodine batteries (ZIBs) have been recognized as a promising energy storage device due to their high energy density, low cost and environmental friendliness. However, the development of ZIBs is hindered by the shuttle effect of polyiodides which results in capacity degradation and poor cycling performance. Inspired by the ability of starch to form inclusion compounds with iodine, we propose to use a starch gel on the cathode to suppress the shuttle of polyiodides. Herein, porous carbon is utilized as a host for iodine species and provides an excellent conductive network, while starch gel is used as another host to suppress polyiodides shuttle, resulting in improved battery performance. The test results demonstrate that the conversion between I-/I2/I3- in the cathode and the effective inclusion role of starch suppress the shuttle of polyiodides during the charging process. Meanwhile, based on the electrochemical tests and theoretical DFT calculations, it is found that starch has a stronger ability to adsorb polyiodides compared to carbon materials, which enables effective confinement of polyiodides. The ZIBs used the cathode with starch gel exhibit high coulombic efficiency (>95 % at 0.2 A/g) and low self-discharge (86.8 % after resting for 24 h). This strategy is characterized by its simplicity, low cost and high applicability, making it significant for the advancement of high-performance ZIBs.

Unveiling Superior Capacitive Behaviors of One-Pot Molten Salt-Engineered B, N Co-Doped Porous Carbon Sheets.

Heteroatom-doped porous carbon materials with distinctive surface properties and capacitive behavior have been accepted as promising candidates for supercapacitor electrodes. Currently, the researches mainly focus on developing facile synthetic method and unveiling the structure-activity relationship to further elevate their capacitive performance. Here, the B, N co-doped porous carbon sheet (BN-PCS) is constructed by one-pot pyrolysis of agar in KCl/KHCO3 molten salt system. In this process, the urea acts as directing agent to guide the formation of 2D sheet morphology, and the decomposition of KHCO3 and boric acid creates rich micro- and mesopores in the carbon framework. The specific capacitance of optimized BN-PCS reaches 361.1 F g-1 at a current density of 0.5 A g-1 in an aqueous KOH electrolyte. Impressively, the fabricated symmetrical supercapacitor affords a maximum energy density of 43.5 Wh kg-1 at the power density of 375.0 W kg-1 in 1.0 mol L-1 TEABF4 /AN electrolyte. It also achieves excellent long-term stability with capacitance retention of 91.1% and Columbic efficiency of 100% over 10 000 cycles. This study indicates one-pot molten salt method is effective in engineering advanced carbon materials for high-performance energy storage devices.

In situ lead oxysalt passivation layer for stable and efficient perovskite solar cells.

A Rb2SO4 additive is employed to passivate the Pb2+ defects in a perovskite film by forming PbSO4in situ, which can cover the surface and grain boundaries of the perovskite to ensure that the film is not decomposed by moisture. Finally, a device based on the Rb2SO4 modification achieved an enhanced power conversion efficiency (22.25%) and long-term stability.

High-Sensitivity and Extreme Environment-Resistant Sensors Based on PEDOT:PSS@PVA Hydrogel Fibers for Physiological Monitoring.

The rapid development of flexible electronic devices has caused a boom in researching flexible sensors based on hydrogels, but most of the flexible sensors can only work at room temperature, and they are difficult to adapt to extremely cold or dry environments. Here, the flexible hydrogel fibers (PEDOT:PSS@PVA) with excellent resistance to extreme environments have been prepared by adding glycerin (GL) to the mixture of poly(vinyl alcohol) (PVA) and poly 3,4-dioxyethylene thiophene:polystyrene sulfonic acid (PEDOT:PSS) because GL molecules can form dynamic hydrogen bonds with an elastic matrix of PVA molecules. It is found that the prepared sensor exhibits very good flexibility and mechanical strength, and the ultimate tensile strength can reach up to 13.76 MPa when the elongation at break is 519.9%. Furthermore, the hydrogel fibers possess excellent water retention performance and low-temperature resistance. After being placed in the atmospheric environment for 1 year, the sensor still shows good flexibility. At a low temperature of -60 °C, the sensor can stably endure 1000 repeated stretches and shrinks (10% elongation). In addition to the response to a large strain, this fiber sensor can also detect extremely small strains as low as 0.01%. It is proved that complex human movements such as knuckle bending, vocalization, pulse, and others can be monitored perfectly by this fiber sensor. The above results mean that the PEDOT:PSS@PVA fiber sensor has great application prospects in physiological monitoring.

Using Stretchable PPy@PVA Composites as a High-Sensitivity Strain Sensor To Monitor Minute Motion.

With the rapid development of flexible and wearable electronic devices, research on high-sensitivity strain sensors has been attracting much attention. Here, glutaraldehyde is used as a cross-linking reagent to precross-link poly(vinyl alcohol); then FeCl3·6H2O is added into the precross-linked poly(vinyl alcohol) to obtain composite films of FeCl3@PVA after gelatinization and freeze drying. Elastic conductive films of polypyrrole@poly(vinyl alcohol) (PPy@PVA) are prepared by immersing FeCl3@PVA into a solution of pyrrole in acetonitrile and water to complete the polymerization in situ. The effects of the concentrations of glutaraldehyde and FeCl3·6H2O on the film's structure and properties have been studied in detail; the results show that the strain sensor prepared from the optimized film has excellent stretchability (strain up to 309.5%), mechanical property (tensile strength of 32.8 MPa), and relatively high sensitivity (gauge factor can reach 5.07 under 1.0% strain). It can be used to detect various tiny physiological signals, for example, detecting the number of pulse beats, bending of the knuckles at different frequencies, and recognizing the pronunciation of different words by vocal cord vibration. These good properties mean that this kind of PPy@PVA strain sensor has great application prospects in physiological monitoring.