Journal of Science and Technology 55 (1B) (2017) 276–283 ENHANCEMENT OF Li–ION BATTERY CAPACITY USING NICKEL DOPED LiFePO 4 AS CATHODE MATERIAL La Thi Hang 1, 2, 3, * , Le My Loan Phung 4 , Nguyen Thi My Anh 5 , Hoang Xuan Tung 5 , Doan Phuc Luan 5 , Nguyen Nhi Tru 5 1 Vinh Long University of Technology Education (VLUTE) 73 Nguyen Hue Street, Vinh Long City, Vinh Long Province, Vietnam 2 Institute of Applied Materials Science – VAST 1 Mac Dinh Chi Street, Ben Nghe Ward,, District 1, Ho Chi Minh City, Vietnam 3 Graduate University of Science & Technology – VAST 18 Hoang Quoc Viet Street, Nghia Do Ward, Cau Giay District, Hanoi, Vietnam 4 Applied Physical Chemistry Lab, University of Science – VNU HCM 227 Nguyen Van Cu Street, Ward 4, District 5, Ho Chi Minh City, Vietnam 5 Faculty of Materials Technology, University of Technology – VNU HCM 268 Ly Thuong Kiet Street, Ward 14, District 10, Ho Chi Minh City, Vietnam * Email: hanglt@vlute.edu.vn Received: 30 December 2016; Accepted for Publication: … ABSTRACT Selective supervalent cations (M = Ni, Mn, La etc.) doped LiFePO 4 (LFP) is an effective route to enhance its electrical conductivity, thereby improving electrochemical performances of lithium–ion batteries. For this purpose, nickel doped LiFePO 4 based cathode material was investigated at different substitution amounts (x Ni = 0.05, 0.10). LiFe 1–x Ni x PO 4 (LFNP) was synthesized from Ni(NO 3 ) 2 .6H 2 O, LiOH.H 2 O, FeSO 4 .7H 2 O, H 3 PO 4 , and ascorbic acid precursors via solvothermal technique, followed by calcination in nitrogen atmosphere at 550 °C for 5 h. The structure and morphology of synthesized materials were examined by X–ray diffraction, Scanning electronic microscopy and Raman vibrational micro–spectroscopy. The electrochemical performances of doped materials were studied in Swagelok–type cell using LiPF 6 /EC–DMC (1:1) as electrolyte. LiFe 1–x Ni x PO 4 was shown to exhibit homogenous particles size of 50 ÷ 150 nm. The doped materials were titrated to quantify iron and nickel contents in samples. As anticipated, the electrochemical performances of LiFe 1–x Ni x PO 4 were significantly enhanced compared to those of undoped LiFePO 4 . Keywords: LiFe 1–x Ni x PO 4 (LFNP), solvothermal, lithium–ion, conductivity, capacity. 1. INTRODUCTION LiFePO 4 (LFP) is a promising cathode material for manufacturing lithium–ion batteries with prolonged life time, good cycle stability, environmental friendliness, and relatively low cost.