Molecular Engineering Enables Hydrogel Electrolyte with Ionic Hopping Migration and Self-Healability toward Dendrite-Free Zinc-Metal Anodes.

Hydrogel electrolytes (HEs), characterized by intrinsic safety, mechanical stability, and biocompatibility, can promote the development of flexible aqueous zinc-ion batteries (FAZIBs). However, current FAZIB technology is severely restricted by the uncontrollable dendrite growth arising from undesirable reactions between the HEs with sluggish ionic conductivity and Zn metal. To overcome this challenge, this work proposes a molecular engineering strategy, which involves the introduction of oxygen-rich poly(urea-urethane) (OR-PUU) into polyacrylamide (PAM)-based HEs. The OR-PUU/PAM HEs facilitate rapid ion transfer through their ionic hopping migration mechanism, resulting in uniform and orderly Zn2+ deposition. The abundant polar groups on the OR-PUU molecules in OR-PUU/PAM HEs break the inherent H-bond network, tune the solvation structure of hydrated Zn2+, and inhibit the occurrence of side reactions. Moreover, the interaction of hierarchical H-bonds in the OR-PUU/PAM HEs endows them with self-healability, enabling in situ repair of cracks induced by plating/stripping. Consequently, Zn symmetric cells incorporating the novel OR-PUU/PAM HEs exhibit a long cycling life of 2000 h. The resulting Zn-MnO2 battery displays a low capacity decay rate of 0.009% over 2000 cycles at 2000 mA g-1. Overall, this work provides valuable insights to facilitate the realization of dendrite-free Zn-metal anodes through the molecular engineering of HEs.

Activating Selenium Cathode Chemistry for Aqueous Zinc-Ion Batteries.

Aqueous rechargeable zinc-ion batteries (ARZIBs) are a promising next-generation energy-storage device by virtue of the superior safety and low cost of both the aqueous electrolyte and zinc-metal anode. However, their development is hindered by the lack of suitable cathodes with high volumetric capacity that can provide both lightweight and compact size. Herein, a novel cathode chemistry based on amorphous Se doped with transition metal Ru that mitigates the resistive surface layer produced by the side reactions between the Se cathode and aqueous electrolyte is reported. This improvement can permit high volumetric capacity in this system. Distinct from the conventional conversion mechanisms between Se and ZnSe in Se||Zn cells, this strategy realizes synchronous proton and Zn2+ intercalation/deintercalation in the Ru-doped amorphous Se||Zn half cells. Moreover, an unanticipated Zn2+ deposition/stripping process in this system further contributes to the superior electrochemical performance of this new cathode chemistry. Consequently, the Ru-doped amorphous Se||Zn half cells are found to deliver a record-high capacity of 721 mAh g-1 /3472 mAh cm-3 , and superior cycling stability of over 800 cycles with only 0.015% capacity decay per cycle. This reported work opens the door for new chemistries that can further improve the gravimetric and volumetric capacity of ARZIBs.

Electrochemical conversion of methane to ethylene in a solid oxide electrolyzer.

Conversion of methane to ethylene with high yield remains a fundamental challenge due to the low ethylene selectivity, severe carbon deposition and instability of catalysts. Here we demonstrate a conceptually different process of in situ electrochemical oxidation of methane to ethylene in a solid oxide electrolyzer under ambient pressure at 850 °C. The porous electrode scaffold with an in situ-grown metal/oxide interface enhances coking resistance and catalyst stability at high temperatures. The highest C2 product selectivity of 81.2% together with the highest C2 product concentration of 16.7% in output gas (12.1% ethylene and 4.6% ethane) is achieved while the methane conversion reaches as high as 41% in the initial pass. This strategy provides an optimal performance with no obvious degradation being observed after 100 h of high temperature operation and 10 redox cycles, suggesting a reliable electrochemical process for conversion of methane into valuable chemicals.

Fabrication of porous starch microspheres by electrostatic spray and supercritical CO2 and its hemostatic performance.

Effective control of bleeding is critical to saving lives whether on the battle field or in civilian life. Microporous starch (MS) is a promising hemostat for its extensive sources, huge surface area and good biocompatibility. However, the hemostatic performance of MS is limited because of its complex preparation process and lack of effective component to activate coagulation factors. Herein, porous starch microspheres modified by calcium (Ca-PSM) with dense shell and honeycomb micro-porous core were prepared by electrostatic spray and supercritical CO2 for the first time. The topological morphology of Ca-PSM changed with the increase of Tween-80 content within 0.5%. Ca-PSM possessed excellent water absorbability due to high specific surface area, and what's more, it showed good hemostatic performance because of the synergistic effects of physical adsorption and chemical activation mechanisms. The results of thrombelastograph (TEG) showed that the initial clotting time (R) and coagulation time (R + K) of Ca-PSM-1 were shortened by 47.1%, 53.3% than that of control group. The maximum blood clot strength (MA) of Ca-PSM-1 was also significantly raised. Furthermore, it was noteworthy that Ca-PSM could activate clotting cascade and induce erythrocyte adsorption. In summary, Ca-PSM as a hemostat will be a promising and alternative candidate for clinical application.