Gelation mechanisms of gel polymer electrolytes for zinc-based batteries

Zinc-based batteries(ZBs)have been deemed as a potential substitute for lithium-ion batteries due to its unique advantages of abundant resources,low cost and acceptable energy density.Despite great progress in designing electrode materials has been made,the development of high-performance ZBs still remain challenges,such as the dendrite growth of zinc anode,hydrogen evolution reaction,limited electrochemical stability window,water evaporation and liquid leakage.Gel polymer electrolytes(GPEs),including hydrous GPEs with low content of active water and anhydrous GPEs without the presence of water,are proposed to avoid these problems.Furthermore,employing GPEs is conductive to fabricate flexible devices owing to the good mechanical strength.To date,most of researches focus on discovering new GPEs and exploring its application on flexible or wearable devices.Recent reviews also have outlined the polymer matrixes and advances of GPEs in various battery systems.Given this,herein,we seek to summarize the gelation mechanisms of GPEs,involving physical gel of polymer,chemical crosslinking of polymer and chemical polymerization of monomers.Peculiarly,the preparation methods are also classified.In addition,not only the features and central conundrum of GPEs are analyzed but also the corresponding strategies are discussed,contributing to design GPEs with ideal properties for high-performance ZBs.

Ultralight Magnetic and Dielectric Aerogels Achieved by Metal-Organic Framework Initiated Gelation of Graphene Oxide for Enhanced Microwave Absorption

The development of a convenient methodology for synthesizing the hierarchically porous aerogels comprising metal–organic frameworks(MOFs)and graphene oxide(GO)building blocks that exhibit an ultralow density and uniformly distributed MOFs on GO sheets is important for various applications.Herein,we report a facile route for synthesizing MOF/reduced GO(rGO)aerogels based on the gelation of GO,which is directly initiated using MOF crystals.Free metal ions exposed on the surface of MIL-88A nanorods act as linkers that bind GO nanosheets to a three-dimensional porous network via metal–oxygen covalent or electrostatic interactions.The MOF/rGOderived magnetic and dielectric aerogels Fe_(3)O_(4)@C/rGO and Ni-doped Fe_(3)O_(4)@C/rGO show notable microwave absorption(MA)performance,simultaneously achieving strong absorption and broad bandwidth at low thickness of 2.5(-58.1 dB and 6.48 GHz)and 2.8 mm(-46.2 dB and 7.92 GHz)with ultralow filling contents of 0.7 and 0.6 wt%,respectively.The microwave attenuation ability of the prepared aerogels is further confirmed via a radar cross-sectional simulation,which is attributed to the synergistic effects of their hierarchically porous structures and heterointerface engineering.This work provides an effective pathway for fabricating hierarchically porous MOF/rGO hybrid aerogels and offers magnetic and dielectric aerogels for ultralight MA.