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

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. NPG Asia Materials (2016) 8, e287; doi:10.1038/am.2016.95; published online 22 July 2016