The refinement results showed that the substitution of Ni decreased the lattice constant and Mn–O distance, while increased Li–O bond length and 16c octahedral volume. The EIS results confirmed the decrease of conductivity with increasing Ni substitution content. Based on XRD and EIS results, the relationship between the crystal structure and electrochemical behavior of the materials was discussed and explained. | Communications in Physics, Vol. 26, No. 4 (2016), pp. 361-368 DOI: STRUCTURE AND ELECTROCHEMICAL IMPEDANCE OF LiNix Mn2−x O4 TA ANH TAN1,4 , NGUYEN SI HIEU1 , LE HA CHI1 , DANG TRAN CHIEN2 LE DINH TRONG3 AND PHAM DUY LONG1,† 1 Institute of Materials Science, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam 2 Hanoi University of Natural Resources and Environment, 41A-Phu Dien, Bac Tu Liem, Hanoi, Vietnam 3 Hanoi Pedagogical University No. 2, 32-Nguyen Van Linh, Xuan Hoa, Phuc Yen, Vinh Phuc, Vietnam 4 Hanoi Metropolitan University, 98-Duong Quang Ham, Cau Giay, Hanoi, Vietnam † E-mail: longphd@ Received 01 December 2016 Accepted for publication 27 February 2017 Abstract. Ni-substitution spinel LiNix Mn2−x O4 (x = 0, , ) materials were synthesized by the sol–gel method. The structure and morphology of the samples were characterized by the X-ray diffraction (XRD) and the scanning electron microscopy. The ac conduction of the materials was investigated by electrochemical impedance spectroscopy (EIS) measurements. The refinement results showed that the substitution of Ni decreased the lattice constant and Mn–O distance, while increased Li–O bond length and 16c octahedral volume. The EIS results confirmed the decrease of conductivity with increasing Ni substitution content. Based on XRD and EIS results, the relationship between the crystal structure and electrochemical behavior of the materials was discussed and explained. Keywords: lithium ion battery, spinel manganate cathode material, Rietveld refinement, Electrochemical impedance. Classification numbers: , , . I. INTRODUCTION The efforts for the development of energy storage systems have been forced rapidly due to the increase in the demand of clean and renewable energy sources. Lithium ion batteries have been considered as the most attractive energy storage system due to its advantages including .
