PHOTOANODIC CHARACTERISTICS OF LAYER-STRUCTURED n-InSe IN POLYSULFIDE SOLUTION

The photoanodic characteristics of layer-structured n-InSe were investigated in polysulfide solution as a solid-liquid junction photoelectro- chemical cell(PEC).A quantum yield approaching about 90% and a photocurrent density as high as 30 mA/cm^2 were obtained.But the stabilization experiment demonstrates that about 8% of the photocurrent is attributed to a photoanodic corrosion ceaction.

Two positive effects with one arrow:Modulating crystal and interfacial decoration towards high-potential cathode material

As the primary suppliers of cyclable sodium ions,O3-type layer-structured manganese-based oxides are recognized as highly competitive cathode candidates for sodium-ion batteries.To advance the development of high-energy sodium-ion batteries,it is crucial to explore cathode materials operating at high voltages while maintaining a stable cycling behavior.The orbital and electronic structure of the octahedral center metal element plays a crucial role in maintaining the octahedra structural integrity and improving Na^(+)ion diffusion by introducing heterogeneous chemical bonding.Inspired by the abundant configuration of extra nuclear electrons and large ion radius,we employed trace amounts of tungsten in this study.The obtained cathode material can promote the reversibility of oxygen redox reactions in the high-voltage region and inhibit the loss of lattice oxygen.Additionally,the formation of a Na_(2)WO_(4) coating on the material surface can improve the interfacial stability and interface ions diffusion.It demonstrates an initial Coulombic efficiency(ICE)of 94.6%along with 168.5 mA h g^(-1 )discharge capacity within the voltage range of 1.9-4.35 V.These findings contribute to the advancement of high-energy sodium-ion batteries by providing insights into the benefits of tungsten doping and Na_(2)WO_(4) coating on cathode materials.

Ion Exchange of Layer-Structured Titanate Cs_xTi₂-<i>_x</i>/₂Mg<i>_x</i>/₂O₄(<i>x</i>= 0.70) and Applications as Cathode Materials for Both Lithium- and Sodium-Ion Batteries

Cathode materials for rechargeable batteries have been extensively investigated. Sodium-ion batteries are emerging as alternatives to lithium-ion batteries. In this study, a novel cathode material for both lithium- and sodium-ion batteries has been derived from a layered crystal. Layer-structured titanate CsxTi2-x/2Mgx/2O4 (x = 0.70) with lepidocrocite (γ-FeOOH)-type structure has been prepared in a solid-state reaction from Cs2CO3, anatase-type TiO2, and MgO at 800°C. Ion-exchange reactions of Cs+ in the interlayer space were studied in aqueous solutions. The single phases of Li+, Na+, and H+ exchange products were obtained, and these were found to contain interlayer water. The interlayer water in the lithium ion-exchange product was removed by heating at 180°C in vacuum. The resulting titanate Li0.53H0.13Cs0.14Ti1.65Mg0.30O4 was evaluated for use as cathodes in both rechargeable lithium and sodium batteries. The Li+ intercalation-deintercalation capacities were found to be 151 mAh/g and 114 mAh/g, respectively, for the first cycle in the voltage range 1.0 - 3.5 V. The amounts of Li+ corresponded to 0.98 and 0.74 of the formula unit, respectively. The Na+ intercalation-deintercalation capacities were 91 mAh/g and 77 mAh/g, respectively, for the first cycle in the voltage range 0.70 - 3.5 V. The amounts of Na+ corresponded to 0.59 and 0.50 of the formula unit, respectively. The new cathode material derived from the layer-structured titanate is non-toxic, inexpensive, and environmentally benign.

Boosting energy storage performance of low-temperature sputtered CaBi_(2)Nb_(2)O_(9) thin film capacitors via rapid thermal annealing

CaBi_(2)Nb_(2)O_(9) thin film capacitors were fabricated on SrRuO_(3)-buffered Pt(111)/Ti/Si(100)substrates by adopting a two-step fabrication process.This process combines a low-temperature sputtering deposition with a rapid thermal annealing(RTA)to inhibit the grain growth,for the purposes of delaying the polarization saturation and reducing the ferroelectric hysteresis.By using this method,CaBi_(2)Nb_(2)O_(9) thin films with uniformly distributed nanograins were obtained,which display a large recyclable energy density Wrec≈69 J/cm^(3) and a high energy efficiencyη≈82.4%.A superior fatigue-resistance(negligible energy performance degradation after 10^(9) charge-discharge cycles)and a good thermal stability(from-170 to 150℃)have also been achieved.This two-step method can be used to prepare other bismuth layer-structured ferroelectric film capacitors with enhanced energy storage performances.

A REVIEW ON LEAD-FREE PIEZOELECTRIC CERAMICS STUDIES IN CHINA

There are a large number of research publications on the hot topic of environmental friendly leadfree piezoelectric materials worldwide in the last decade.The number of researchers and institutions involved from China is much larger than other countries or regions.The publications by Chinese researchers cover a broad spectrum on the preparations,structures,properties and applications of lead-free piezoelectric ceramics.This has motivated us to come out with a review on recent advances in development of lead-free piezoelectric ceramics in China.The emphases are especially on the preparation and electric properties of barium titanate-based materials,bismuth sodium titanate and related materials,alkaline niobate and related materials,bismuth layerstructured materials,as well as texture engineering of ceramics and some of their single crystals.Hopefully,this could give further impetus to the researchers to continue their e®orts in this promising area and also draw the attentions from legislature,research o±ce,industrial and publics.