ИСТИНА

Search and study of the materials for reversible intercalation of Li+ is an actual problem. Wadsley-Roth phase LixNb9PO25 has been studied as a potential candidate for anode material of Li-ion batteries. Its crystal structure, which consists of ReO3-type blocks of NbO6 octahedra connected with PO4 tetrahedra, provides a good stability and performance during Li+ insertion/removal [1, 2]. The purpose of this work was investigation of the intercalation kinetics of lithium ions in complex niobium phosphate Nb9PO25 with crystallographic shear structure. Method of sintering of Nb9PO25 was optimized for obtaining the monodisperse material suitable for electrochemical experiments. Its particle size (appr. 1 μm) was defined by means of scanning electron microscopy. An electrode material with reversible capacity about 170 mAh/g (≈0.8 Li:Nb) at potential range of 1.2-2.5 V was prepared. Li-ion chemical diffusion coefficient (Dchem) in LixNb9PO25 was determined by means of potentiostatic intermittent titration technique and electrochemical impedance spectroscopy. Dchem changes with the Li-ion doping degree, x, in LixNb9PO25 and has a sharp minimum near the two-phase region at appr. 1.7 V vs. Li+/Li. These values of Dchem in LixNb9PO25 (~ 10-9-10-11 cm2 s-1) were found to be in average noticeably higher than in the widely studied anode material, Li4Ti5O12. Comparison of electrochemical properties of different inorganic anode materials for Li-ion batteries is discussed in the work [3]. The work was supported with Contract with the Ministry of Education and Science of Russian Federation (No. 16.526.11.6011), Russian Foundation for Basic Research (13-03-00495 А) and M.V. Lomonosov Moscow State University Program of Development.