Intrinsic Stress-strain in Barium Titanate Piezocatalysts Enabling Lithium−Oxygen Batteries with Low Overpotential and Long Life

Rechargeable lithium−oxygen (Li−O₂) batteries with high theoretical energy density are considered as promising candidates for portable electronic devices and electric vehicles, whereas their commercial application is hindered due to poor cyclic stability caused by the sluggish kinetics and cathode passivation. Herein, the intrinsic stress originated from the growth and decomposition of the discharge product (lithium peroxide, Li₂O₂) is employed as a microscopic pressure resource to induce the built-in electric field, further improving the reaction kinetics and interfacial Lithium ion (Li⁺) transport during cycling. Piezopotential caused by the intrinsic stress-strain of solid Li₂O₂ is capable of providing the driving force for the separation and transport of carriers, enhancing the Li⁺ transfer, and thus improving the redox reaction kinetics of Li−O₂ batteries. Combined with a variety of in situ characterizations, the catalytic mechanism of barium titanate (BTO), a typical piezoelectric material, was systematically investigated, and the effect of stress-strain transformation on the electrochemical reaction kinetics and Li⁺ interface transport for the Li−O₂ batteries is clearly established. The findings provide deep insight into the surface coupling strategy between intrinsic stress and electric fields to regulate the electrochemical reaction kinetics behavior and enhance the interfacial Li⁺ transport for battery system.     

Synthesis and Crystal Structure of Blue Luminescent Cadmium(II) Coordination Networks with 4,4′-Bis(imidazol-1-ylmethyl)biphenyl from Different Solvent Systems

Two supramolecular complexes, [Cd(bimb)²Cl²] (1) and [Cd(bimb)(DMF)Cl²]·DMF (2) [bimb=4,4′-bis(imidazol-1-ylmethyl)biphenyl], were synthesized by reactions of CdCl²·2.5H²O with bimb ligand in ethanol and N,N′-dimethylformamide (DMF), respectively, and their structures were determined by X-ray crystallography. Complex 1 is an infinite 2D grid network bridged by bimb ligands, and the 2D sheets were further linked by C–H ?Cl hydrogen bonds to form a polycatenated 3D framework. Complex 2 has dicadmium(II) di-μ-chloride units which are connected by bimb bridging ligands to form an infinite non-interpenetrating 2D network. The results provide a nice example of the solvent system exerting a great effect on the construction of supramolecular frameworks.     

Coordination modes of N-2-(4-amino-1-methyl-5-nitroso-6-oxo-1,6-dihydropyrimidinyl) potassium L-alaninate toward Ag(I), Cd(II) and Pd(II). Crystal structure of {Ag((η4-μ3-L)]·3H2O}n,first example of a silver 3D-polymer with a pyrimidine-derivative ligand

The acid-base behaviour of the N-2-(4-amino-1-methyl-5-nitroso-6-oxo-1,6-dihydropyrimidinyl) potassium L-alaninate (KL) and its reactivity with Ag(I), Cd(II) and Pd(II) metal ions have been studied. Three solid species with formulae AgL·3H₂O, CdL₂·6H₂O and PdClL·H₂O have been obtained and characterized by IR, ¹H and ¹³C NMR spectroscopic methods and thermal, conductivity and magnetic measurements. The structure of {Ag((η⁴-μ₃-L)]·3H₂O}_n has been established by single-crystal X-ray diffraction and consists in a 3D-polymer. Within the polymer each Ag(I) ion is tetrahedrally coordinated to three differents L anions, while each ligand is coordinated in a rather unusual η⁴-μ₃ coordination mode. Spectroscopic data show a similar coordination mode for the Cd(II) complex, while for the Pd(II) one a different coordination mode is proposed.