Single Ti atoms coupled with Ti-O clusters enable low temperature hydrogen cycling by sodium alanate

Ti-based catalysts are known to improve the hydrogen storage performance of NaAlH4by facilitating the dissociation/recombination of H-H and Al-H bonds.The catalytic activity of metallic Ti species strongly depends on its particle size and dispersity.Ti clusters and even single atoms are therefore highly desirable,but their controllable fabrication has been highly challenging.He rein,we demonstrate a novel facile sonochemical synthesis of a Ti-O clusters featuring single Ti atom catalyst at room temperature.Through reducing TiCl_(4)by MgBu_(2)with ultrasound instead of heating as driving force,numerous single Ti atoms coupled with Ti-O clusters with Ti loading on graphene(Ti_(1)/Ti-O@G)up to 22.6 wt%have been successfully obtained.The prepared Ti_(1)/Ti-O@G contributes high reactivity and superior catalytic activity,therefore enabling full dehydrogenation of NaAlH_(4)at 80℃in thermogravimetric mode and re-hydrogenation at 30℃and 10 MPa with 4.9 wt% H_(2).This fact indicates for the first time that single Ti atom catalyst with high loading is highly effective in catalyzing hydrogen cycling of NaAlH4at remarkably reduced temperatures.

Recently developed strategies to restrain dendrite growth of Li metal anodes for rechargeable batteries

Lithium metal has been regarded as one of the most promising anode materials for high-energy-density batteries due to its extremely high theoretical gravimetric capacity of 3860 mAh·g^-1 along with its low electrochemical potential of-3.04 V.Unfortunately,uncontrollable Li dendrite growth and repetitive destruction/formation of the solid electrolyte interphase layer lead to poor safety and low Coulombic efficiencies(CEs)for long-term utilization,which largely restricts the practical applications of lithium metal anode.In this review,we comprehensively summarized important progresses achieved to date in suppressing Li dendrite growth.Strategies for protection of Li metal anodes include designing porous structured hosts,fabricating artificial solid electrolyte interface(SEI)layers,introducing electrolyte additives,using solid-state electrolytes and applying external fields.The protection of Li metal anodes can be achieved by regulating the stripping and deposition behaviours of Li ions.Finally,the challenges remaining for lithium metal battery systems and future perspectives for Li metal anodes in practical applications are outlined,which are expected to shed light on future research in this field.