Effect of Zwitterionic Additive on Electrode Protection through Electrochemical Performances of Anatase TiO2 Nanotube Array Electrode in Ionic Liquid Electrolyte.

In this work, a functionalized zwitterionic (ZI) compound 1-butylsulfonate-3-methylimidazole (C1C4imSO3) was synthesized and tested as an additive to LiTFSI/C2C2imTFSI ionic liquid-based electrolytes for lithium-ion batteries. The structure and purity of C1C4imSO3 were confirmed by NMR and FTIR spectroscopy. The thermal stability of the pure C1C4imSO3 was examined by simultaneous thermogravimetric-mass spectrometric (TG-MS) measurements and differential scanning calorimetry (DSC). The LiTFSI/C2C2imTFSI/C1C4imSO3 system was tested as a potential electrolyte for lithium-ion batteries by using anatase TiO2 nanotube array electrode as the anode material. This electrolyte with 3% C1C4imSO3 showed significant improvement of lithium-ion intercalation/deintercalation properties, such as capacity retention and Coulombic efficiency compared to electrolyte without additive.

Crystal Structure and Electrical Properties of Ruthenium-Substituted Calcium Copper Titanate.

This paper reports a detailed study of crystal structure and dielectric properties of ruthenium-substituted calcium-copper titanates (CaCu3Ti4-xRuxO12, CCTRO). A series of three samples with different stoichiometry was prepared: CaCu3Ti4-xRuxO12, x = 0, 1 and 4, abbreviated as CCTO, CCT3RO and CCRO, respectively. A detailed structural analysis of CCTRO samples was done by the Rietveld refinement of XRPD data. The results show that, regardless of whether Ti4+ or Ru4+ ions are placed in B crystallographic position in AA'3B4O12 (CaCu3Ti4-xRuxO12) unit cell, the crystal structure remains cubic with Im3¯ symmetry. Slight increases in the unit cell parameters, cell volume and interatomic distances indicate that Ru4+ ions with larger ionic radii (0.62 Å) than Ti4+ (0.605 Å) are incorporated in the CaCu3Ti4-xRuxO12 crystal lattice. The structural investigations were confirmed using TEM, HRTEM and ADF/STEM analyses, including EDXS elemental mapping. The effect of Ru atoms share in CaCu3Ti4-xRuxO12 samples on their electrical properties was determined by impedance and dielectric measurements. Results of dielectric measurements indicate that one atom of ruthenium per CaCu3Ti4-xRuxO12 unit cell transforms dielectric CCTO into conductive CCT3RO while preserving cubic crystal structure. Our findings about CCTO and CCT3RO ceramics promote them as ideal tandem to overcome the problem of stress on dielectric-electrode interfaces in capacitors.