Effects of high surface energy on lithium-ion intercalation properties of Ni-doped Li3VO4

Abstract

Nickel was doped into Li3VO4 (Ni-LVO) successfully via a facile room temperature reaction, and the resulting Ni-LVO nanocrystallites showed excellent lithium-ion storage properties with a capacity of 650 mAh g−1 at 50 mAh g−1 and excellent capacity stability as an anode in lithium-ion batteries, maintaining nearly 100% of the initial reversible capacity after 800 cycles at 1 A g−1. The superior electrochemical properties arose largely from the nickel doping in the Ni-LVO. The surface energy of the electrode material was analyzed by an inverse gas chromatography method, and the Ni-LVO surface energy, 43.91 mJ m−2, was much higher than the 30.74 mJ m−2 of Li3VO4. X-ray photoelectron spectra results demonstrated that nickel doping promoted the formation of tetravalent vanadium ions, V4+, as well as a more amorphous surface of Li3VO4, thus probably resulting in more nucleation sites for the phase transformation and reduced activation energy of the redox reactions and phase transition during the lithium-ion intercalation/extraction processes. Using nickel-doped nanocrystals boosts the stability and charge storage of rechargeable lithium-ion batteries, find scientists in China. Lithium and vanadium containing oxides, such as lithium vanadate (Li3VO4), could replace graphite anodes used in commercial lithium-ion batteries because they possess more stable crystal structure and offer greater energy storage. Guozhong Cao and colleagues at the National Center for Nanoscience and Technology have found how to make the switch to Li3VO4 anodes feasible by improving this materials' poor electrical conductivity. The researchers used a simple mixing procedure to introduce nickel atoms into the Li3VO4 framework and found that the resulting nanocrystals significantly enhanced battery performance. Characterization experiments revealed that these improvements arose from nickel's electrochemical and surface-disrupting effects: amorphous surface regions induced by the dopants likely resulted in additional nucleation sites for lithium-ion extraction and intercalation processes. Nickel doped Li3VO4 nanocrystallites with high surface energy showed excellent lithium ion storage property with a capacity of 650 mAh g−1 at 50 mAh g−1 and excellent capacity stability as anode in lithium ion batteries. The nickel doping promoted the formation of V4+ and more amorphous in the surface of Li3VO4, probably resulting in higher surface energy, more nucleation sites for the phase transformation and reducing the activation energy of the redox reactions and phase transition during the Li+ intercalation/extraction processes.