Kinetic Study of the Lithium Electroinsertion in  V 2 O 5 by Impedance Spectroscopy

Abstract

The kinetics of the lithium electroinsertion in vanadium pentoxide was studied vs. Li=V=O5 composition bronzes formed during the two first processes (0 < x < 1), by means of complex impedance spectroscopy between 104 and 10 -3 Hz at 20 ~ and 50~ in 1M LiC104/propylene carbonate solutions. The interfacial charge transfer process is found to be independent ofx. At 20~ the exchange current density is equal to 1.3 _+ 0.5 10 -4 A/cm 2 and the chemical coefficient diffusion, DLi , varies between 10 -9 and 10 -11 cm 2 s -1, with a minimum value for x ~ 0.25. The partial conductivity CrLi of lithium in V205 is found to vary betwee_n 10 -6 and 10 -7 ~-1 cm-~. The E)5i and r values at 50~ are five to six times greater than those at 20~ The dependence of D~ on the composition of the Li=V205 bronzes composition was correlated with structural and thermodynamic data already reported in the literature.

Determination of Li+ Diffusion Coefficients in the LixV2O5 (x = 0 − 1) Nanocrystals of Composite Film Cathodes

“…This value is more accurate than those previously reported in the literature, [5][6][7][8][16][17][18] since the BET area is used for the electrode specific area. In addition, the DLi+ values for the ε-LixV2O5 and δ-LixV2O5 phases (8.0 ± 0.4 × 10 -15 and 8.5 ± 0.3 × 10 -15 ) were precisely calculated in the 0.3 < x < 0.4 and 0.9 < x < 1.0 ranges, respectively.…”

“…The severe loss of capacity usually observed for the V2O5 powder cathodes during repeated discharging/charging processes is considered to be correlated with several steps of irreversible structural modification induced by extensive Li insertion into/extraction from the LixV2O5 lattice (1 << x). [3][4][5][6][7][8][9][10][11][12][13][14] For the nanobeam-V2O5/PEDOT composite film cathode, there appears to be a voltage deflection at about 2.2 V, in addition to the voltage plateaus and deflections above 3 V. This particular contribution from the redox reaction of PEDOT in the V2O5/ PEDOT composite-film-cathode, was confirmed by a discharge/ charge cycling experiment of a Li battery assembled with a PEDOT-only film cathode (Fig. 3).…”

“…The diffusion properties of the Li ions determine some of the key battery-performances, including the charge and discharge rates, practical capacity, and cycling stability. [5][6][7][8][9][10][16][17][18][21][22][23][24][25][26][27] GITT combines transient and steady-state electrochemical measurements, which have been widely applied for the characterization of the diffusion kinetics of Li ions into various electrode materials including graphite anodes and transition-metal-oxide cathodes. [21][22][23][24][25][26][27] Although the intercalation diffusion kinetics are complicated by first-order phase transitions, GITT provides valuable information on the chemical diffusion coefficient, even at the starting point of the two-phase coexistence region (i.e., at the very beginning and the very end of a two-phase domain).…”

“…1,2 Layered V2O5 demonstrates a high capacity and structural flexibility for the reversible insertion and release of Li ions as a novel cathode material. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The crystallinity and morphology of V2O5 can play a key role in determining the electrochemical properties of this material. [3][4][5][6][7][8][9][10][11][12][13][14][15] Elongated-rectangular-plate-shape (beam-shaped) V2O5 crystals were prepared by a hydrothermal method and the plate-like morphology reflects the intrinsic properties of layered structure.…”

Determination of lithium diffusion coefficient in LiFePO4 electrode by galvanostatic and potentiostatic intermittent titration techniques

“…In most of the works dealing with lithium transport processes in the intercalated electrode material, it is considered as a solid solution with continuous concentration distribution along the diffusion thickness (see, for example, [14][15][16][17]). However, many compounds undergo phase transition during lithium intercalation (see, for example, [18][19][20]). The transport processes in such materials are discussed as well [6,16,21,22].…”