Electrochemical lithium insertion in sol-gel crystalline vanadium pentoxide thin films

Li diffusion and electrochromism in amorphous and crystalline vanadium oxide thin film electrodes

“…In the literature, 16,17,[24][25][26] measurements of DC as a function of the Li-inserted charge in crystalline Li x V 2 O 5 electrode films confirm our results of a dependence between the Li-diffusion coefficient and the crystalline phases of this compound. Figure 5 shows the electrochromic effect measured by the optical transmittance at 632.8 nm as a function of the charge, for one galvanostatic charge-discharge cycle and the concurrent electrode potential curves.…”

“…23 Figure 4 shows that the dependence of DC on the crystalline phases for sample E is very similar to that obtained for sample D, for which the DC increases with the inserted charge in the δ single-phase region and with the effective DC decreasing in the δ+γ two-phase region. The absence of the two peaks in the DC curve of sample E, one at the region comprising the ε single-phase and ε+δ two-phase, and the other at the middle of the δ phase, can be assigned to the low resolution in the experimental data of this sample, as it can be seen by the scarceness of points on its DC and potential curves, when compared to the experimental data points of sample D.On this supposition, we inquire also if the peak and the shoulder observed in the DC curve of the film treated at 300 o C (sample C), around 2.7 and 2.4 V in the corresponding V e curve, would not be due to the presence of micro or nanocrystallites phases in the film composition.In the literature, 16,17,[24][25][26] measurements of DC as a function of the Li-inserted charge in crystalline Li x V 2 O 5 electrode films confirm our results of a dependence between the Li-diffusion coefficient and the crystalline phases of this compound. Figure 5 shows the electrochromic effect measured by the optical transmittance at 632.8 nm as a function of the charge, for one galvanostatic charge-discharge cycle and the concurrent electrode potential curves.…”

Electrochemical behavior and structural changes of V2O5 xerogel

“…Moreover, the structural changes during the charge injection also modify the flux of Li + . In fact, Vivier et al 19 and McGraw et al 48 showed a dependence of D Li + with the formation of new phases in crystalline V 2 O 5 . Because of this, it is very important to investigate the diffusion process in different structural arrangements, as those observed in the V 2 O 5 xerogel.…”

“…In fact, electrical, optical and mass transport properties are a function of the structural order. 7,[17][18][19] Thus, considering the amorphization of V 2 O 5 during the discharge step, it is important to analyze its structure in more detail. This work shows results about different aspects of V 2 O 5 xerogel in the form of thin films.…”

Cathodes for lithium ion batteries: the benefits of using nanostructured materials

“…31,32 The Li + diffusion distances will be significantly reduced and Li + diffusion within the particle to compensate reduction of non-surface cation sites. For example, for a 10 nm particle and a bulk diffusion coefficient of Li + in typical insertion materials of approximately 10 -10 cm 2 s -1 , 33 the time required for Li + to diffuse a distance equal to the particle radius is 2.5 × 10 -3 s. Thus, Li + diffusion within the particle to compensate reduction of non-surface Mn sites is not a significant kinetic barrier during cycling. At high discharge rate, high Li + ion insertion flux density and slow Li + transport result in concentration polarization of lithium ion within the electrode material.…”