Effects of Ti and Mg Codoping on the Electrochemical Performance of Li₃V₂(PO₄)₃ Cathode Material for Lithium Ion Batteries

Abstract

Ti and Mg codoped Li 3 V 2À2x Ti x Mg x (PO 4 ) 3 (x = 0, 0.05, 0.10, 0.20, and 0.25) samples were prepared by a solÀgel method. The effects of Ti and Mg codoping on the physical and electrochemical characteristics of Li 3 V 2 (PO 4 ) 3 were investigated. Compared with the XRD pattern of the undoped sample, those of the Ti and Mg codoped samples have no extra reflections, which indicates that Ti and Mg enter the structure of Li 3 V 2 (PO 4 ) 3 . According to the results of chargeÀdischarge measurements, the initial capacity of Li 3 V 2À2x Ti x Mg x (PO 4 ) 3 at a low current density (0.2 C) decreases with increasing x. However, the discharge capacities at higher current densities (1 and 2 C) and the cycling stability are improved by a low amount of Ti and Mg codoping (x = 0.05), and moreover, EIS measurements indicate the lower charge transfer resistance of Li 3 V 1.9 Ti 0.05 Mg 0.05 (PO 4 ) 3 . The improved electrochemical performance of Li 3 V 1.9 Ti 0.05 Mg 0.05 (PO 4 ) 3 can be attributed to its higher structural stability and smaller particle size. When x is higher than 0.05, the charge transfer resistance increases with increasing x, which leads to their poor electrochemical performance.

Lithium diffusion in Li3V2(PO4)3-based electrodes: a joint analysis of electrochemical impedance, cyclic voltammetry, pulse chronoamperometry, and chronopotentiometry data

“…A considerable number of articles are devoted to issues of ion transport in Li 3 V 2 (PO 4 ) 3 electrode [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25], which engage for this purpose impedance spectroscopy method. However, the analysis of impedance data in these studies is quite superficial.…”

Improvement of High Rate Performances for Ti-Doped Li₃V₂(PO₄)₃ Cathode Materials

“…However, it is difficult to bring out the proper performance of Li 3 V 2 (PO 4 ) 3 because of its low electronic conductivity with the order of 10 ¹7 S cm ¹1 . 3,4 Our group has so far prepared the Li 3¹2x (V 1¹x Zr x ) 2 -(PO 4 ) 3 materials (0¯x¯0.2) by a solid state reaction and also showed that monoclinic Li 3 V 2 (PO 4 ) 3 is stabilized by substituting Zr for V sites; Li 3 V 2 (PO 4 ) 3 changed from ¡-phase to ¢-phase at about 120°C and from ¢-phase to £-phase at about 180°C. 5 Furthermore, the Li 3¹2x (V 1¹x Zr x ) 2 (PO 4 ) 3 materials have been reported to indicate a high charge/discharge performance.…”

Nd3+-doped Li3V2(PO4)3 cathode material with high rate capability for Li-ion batteries

“…Despite the fact that several metallic ion-doped Li 3 M x V 2Àx (PO 4 ) 3 /C (M = Cr 3+ , Mn 2+ , Mg 2+ , Al 3+ , Na + , etc.) [8][9][10][11][12] have been studied, the electrochemical performance of the nominal Li 3 M x V 2Àx (PO 4 ) 3 /C has not reached a satisfactory level. In this paper, Nd 3+ is selected to dope into Li 3 V 2 (PO 4 ) 3 , and Li 3 Nd x V 2Àx (PO 4 ) 3 , which has good electrochemical performance in high discharge rate and long cycle, is synthesized.…”