Highly dispersed silver nanoparticles for performance-enhanced lithium oxygen batteries

Aprotic lithium-oxygen batteries possess ultrahigh energy density but suffer from the sluggish decomposition of discharge product,quick depletion of Li anode and cleavage of electrolyte,in close association with oxygen reduction reaction at the cathode.Herein,highly dispersed silver nanoparticles are used to enhance the lithium-oxygen battery with 1.0 M lithium perchlorate in dimethyl sulfoxide.It is observed that film-like amorphous lithium peroxide is formed through surface pathway instead of bulk crystals,due to the incorporation of silver nanoparticles dispersed in the electrolyte,which subsequently accelerates the decomposition of the discharge product by offering more active sites and improved conductivity.The released silver nanoparticles after battery charging can be re-used in the following cycles.Experiments and theoretical calculation further indicate that the suspended silver nanoparticles can adsorb the soluble oxygen reduction intermediates,which are responsible for the alleviation of oxidative cleavage of electrolyte and corrosion of lithium anode.The lifespan of lithium oxygen batteries is therefore significantly extended from 55 to 390 cycles,and the rate performance and full-discharge capacity are also largely enhanced.The battery failure is attributed to the coalescence and growth of silver nanoparticles in the electrolyte,and further improvement on colloid stability is underway.

Sodium-Ion Storage Properties of Thermally Stable Anatase

Anatase titanium dioxide(TiO_(2))is a potential anode material for sodium-ion batteries(NIBs).However,the low electronic conductivity and sluggish ion diffusion kinetics at high rate hamper its practical applications.Herein,we demonstrate a sol-gel approach to the synthesis of thermally stable anatase nanoparticles with a carbon shell as anode materials for NIBs.A sample calcined at 750℃(designated as H-750TiO_(2)@C)exhibits high-rate capability and excellent stability against cycling with no capacity loss after 2000 cycles at 1 A g^(-1).In situ X-ray diffraction and Raman spectroscopy characterization results reveal a nearly zero-strain characteristic of the anatase phase during charge/discharge processes.In situ transmission electron microscopy,ex situ X-ray photoelectron spectroscopy,and scanning electron microscope characterization results of samples collected at different charged and discharged states suggest that the anatase phase undergoes an irreversible sodiationactivation during the initial discharge process to form a sodiated-TiO_(2)phase.A full cell assembled with H-750TiO_(2)@C as the anode and Na_(3)V_(2)(PO_(4))_(3)as the cathode delivers an energy density of 220Whkg^(-1),demonstrating H-750TiO_(2)@C is a potential anode material for NIBs.