Optimizing hydrogen ad/desorption of Mg-based hydrides for energy-storage applications

Hydrogen energy is expected to be an“ideal fuel”in the era of decarbonization.The discovery,de-velopment,and modification of high-performance hydrogen storage materials are the keys to the fu-ture development of solid-state hydrogen storage and hydrogen energy utilization.Magnesium hydride(MgH_(2)),with its high hydrogen storage capacity,abundant natural reserves,and environmental friend-liness,has been extensively researched.Herein,we briefly summarize the typical structure and hy-drogenation/dehydrogenation reaction mechanism of MgH_(2)and provide a comprehensive overview of strategies to effectively tune the thermodynamics and kinetics of Mg-based materials,such as alloy-ing,nanosizing,the introduction of additives,and composite modification.With substantial efforts,great achievements have been achieved,such as lower absorption/desorption temperatures and better cy-cling stability.Nonetheless,some pivotal issues remain to be addressed,such as unfavorable hydro-genation/dehydrogenation factors,harsh conditions,slow kinetics,incomplete dehydrogenation,low hy-drogen purity,expensive catalysts,and a lack of valid exploration of mechanisms in the hydrogena-tion/dehydrogenation process.Lastly,some future development prospects of MgH_(2)in energy-efficient conversion and storage have been presented,including advanced manufacturing ways,stabilization of nanostructures,the introduction of additives combined with structural modification,and utilization of advanced characterization techniques.

Wide-temperature rechargeable Li metal batteries enabled by an in-situ fabricated composite gel electrolyte with a hierarchical structure

Lithium metal bateries(LMBs)are well recognized as promising next-generation high energy density batteries,but the uncontrollable Li dendrites growth and the volatilization/gas production of electrolytes,which become extremely worse at low and high temperatures,restrict their practical utilizations.In this work,a hierarchically structured polymerized gel electrolyte(HGE),which was composed of an inorganic(Li_(x)Ga_(86) In_(14) alloy and Licl salt)/organic(polymerized tetrahydrofuran(THF)hybrid layer and the bulk polymerized THF electrolyte,was proposed to achieve a steady performance of LMBs over a wide temperature range of-20-55℃.The HGE fabrication can be completed within ssembled ells with a simultaneously occurring replacement-polymerizationalloying reaction,which helps decrease the interfacial resistance and enhance the stability and ion diffusion under both low and high temperatures.The use of THF with low polarity also ensures high ion conductivity under low temperatures.With such HGE,the Li symmetric cell showed low overpotential under 10 mA/cm^(2) with a capac.ity of 10 mAh/cm^(2) over a 1200 h cycling,and the fullcell coupled with Li_(4)Ti_(5)O_(12) demonstrated high capacity retention over 5000 cycles at room temperature.Besides,the symmetric cells showed low overpotentials of 12 mV at 55℃ and 80 mV at-20℃ at 2 mA/cm^(2) after a 1000 h cyeling,and the full cell revealed the high capacity retention of 93.5%at 55℃ and 88.8%at-20℃ after 1500 cycles under a high current density of 1000 mA/g.This work shows a hierarchically structured polymerized electrolyte design for advanced Li batteries workable under broad temperatures.