Search

Nb-doped cathode materials with the formula Li(Ni0.7Mn0.3)1−xNbxO2 (x = 0, 0.01, 0.02, 0.03, 0.04) have been prepared successfully by calcining the mixtures of LiOH·H2O, Nb2O5, and Ni0.7Mn0.3(OH)2 precursor formed through a simple continuous co-precipitation method. The effects of Nb substitution on the crystal structure and electrochemical properties of LiNi0.7Mn0.3O2 were studied systematically by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and various electrochemical measurements. The results show that the lattice parameters of the Nb substitution LiNi0.7Mn0.3O2 samples are slightly larger than that of pure LiNi0.7Mn0.3O2, and the basic α-NaFeO2 layered structure does not change with the Nb doping. What’s more, better morphology, lower resistance, and good cycle stability were obtained after Nb substitution. In addition, CV test exhibits that Nb doping results in lower electrode polarization and XPS results indicate that the valence of Mn kept constant but the component of Ni3+ decreased after doping. All the results indicate that Nb doping in LiNi0.7Mn0.3O2 is a promising method to improve the properties of Ni-rich lithium-ion batteries positive-electrode materials. [ABSTRACT FROM AUTHOR]

Tetra-β-nitro-substituted nickel phthalocyanine (TN-NiPc) and hollow phthalocyanine (TN-HPc) were synthesized and investigated as novel organic electrode materials for rechargeable lithium batteries. After the two H atoms in the center of TN-HPc were replaced with Ni atoms, the interactive force between the phthalocyanine rings was reduced, which resulted in a fluffy morphology for the TN-NiPc that was beneficial to the transition of Li. As a result, better electrochemical properties and reversibility were observed in the TN-NiPc electrodes compared to the TN-HPc electrode. The capacity of TN-NiPc electrode was stable at about 280 mAh g at 0.2 C after 250 cycles at several different current rates of 0.1, 0.2, 0.5, and 1 C. The TN-NiPc based cathode materials may provide new opportunities for organic, flexible, and stable secondary lithium batteries. [ABSTRACT FROM AUTHOR]