Chemical activation of nanocrystalline LiNbO3 anode for improved storage capacity in lithium-ion batteries

Abstract

It has become imperative to move forward towards developing and engineering highly active electrode materials with high electrochemical performance for rechargeable lithium-ion batteries. In this perspective, a highly efficient LiNbO3 (LNO) perovskite anode material has been successfully prepared from tartarate precursor via simple combustion route and chemically activated via acid treatment with 35% HClO4 acid for the first time. The synthesis process was systematically monitored by thermal gravimetric/differential thermal analyses (TGA/DTA) and X-ray diffraction (XRD). The chemical activation of the as-prepared LNO leads to a significant expansion in the lattice parameters and cell volumes as well as a noticeable reduction in the crystallite size as a result of Li-deficiency and O-vacancies creation. The surface characterization was sufficiently performed by field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS) techniques. XPS results for LNO-activated sample elucidated the presence of Nb4+/Nb5+ ions and revealed the existence of oxygen vacancies. The reduced band gap energy (Eg ∼ 3.95 eV) and low value of activation energy of conduction (Ea ∼ 0.35 eV) for LNO-activated sample confirmed the improved electronic connectivity for the bulk electrode material after chemical activation process. Galvanostatic cycling of LNO-activated anode material revealed an eminent enhancement in the initial specific discharge capacity of about 17.7% upon cycling at 100 mA.g−1 and high capacity retention of about 92 mAhg−1 after 200 cycles. The cyclic performance tests at different current densities 50, 150, 300 and 50 mAg−1 for the activated LNO anode showed excellent rate capability and high capacity retention of about 88.5% of the original capacity after returning to 50 mA.g−1 over 60 cycles. Electrochemical impedance spectroscopy (EIS) measurements confirmed the reduced charge transfer resistance and improved Li+ ions conductivity of the LNO anode after chemical activation.