Microelectrodes lithium deposition

A microelectrode has been used by Uchida et al. to study lithium deposition in order to minimize the effect of solution resistance [41], They used a Pt electrode (10-30 jum in diameter) to measure the lithium-ion diffusion coefficient in 1 mol L 1 LiC104/PC electrolyte. The diffusion coefficient was 4.7 x 10-6 cm2 s at 25 °C. 

An example of this latter application is that of Pletcher and his coworkers [29] into the deposition of lithium in ether solvents. This system is of particular interest in view of its relevance to lithium battery studies. At conventional electrodes, it is difficult to study transient behaviour because the electrode solution is so resistive but, as shown, in Fig. 16 studies at microelectrodes are very effective. This figure shows a series of current-time transients for the deposition of lithium on 40 /zm radius copper disc electrodes and no problems were encountered from either iRu drop or charging currents. Some might question the relevance of microelectrode studies at very low currents to technological systems such as batteries but it must be remembered that, whilst the currents are small, the current densities involved are, in fact, quite large. 

Fig. 16. A series of current-time transients for the deposition of lithium on a copper microelectrode (radius 40pm) from a solution of LiAsF6 (0.37mol dm 3) in tetrahydrofuran. The base potential for all pulses was 0.0 V the potentials stepped to are given on the figure, (After Genders et al. [29].)...

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