Movement of the deposit segment in thin layer electrochemical cell - A conjugate dissolution/deposition behavior

Article abstract of DOI:10.1016/j.electacta.2004.08.002

In this paper we report a novel phenomenon taking place in the thin layer electrodeposition of Pb. A segment of dendrite deposit, which was segregated from the cathode, moved and shortened spontaneously in the electrochemical cell. We find that this behavior arises from the concurrent electrodissolution and electrodeposition reactions taking place at two ends of the isolated segment of the deposits. A mechanism inducing this phenomenon is suggested.

Full text of DOI:10.1016/j.electacta.2004.08.002

Electrochimica Acta 50 (2004) 1031–1037
Movement of the deposit segment in thin layer electrochemical
cell – a conjugate dissolution/deposition behavior
Bin Sun, Xian-Wu Zou∗, Zhun-Zhi Jin
Department of Physics, Wuhan University, Wuhan 430072, PR China
Received 18 May 2004; received in revised form 8 August 2004; accepted 8 August 2004
Available online 13 September 2004
Abstract
In this paper we report a novel phenomenon taking place in the thin layer electrodeposition of Pb. A segment of dendrite deposit, which
was segregated from the cathode, moved and shortened spontaneously in the electrochemical cell. We find that this behavior arises from the
concurrent electrodissolution and electrodeposition reactions taking place at two ends of the isolated segment of the deposits. A mechanism
inducing this phenomenon is suggested.
© 2004 Published by Elsevier Ltd.
Keywords: Pb; Electrodeposition; Electrodissolution; Thin layer cell; Kinetics
to spontaneous alternate accumulation of Cu and Cu2+ on the
growing interface. The reason was that in the thin electrolyte
layer the concentration of ions before the reaction interface
may oscillate periodically, since the diffusion of ions was
limited and the rate of electrode reaction is a mismatch for
the velocity of ion transport. In addition, lots of models
and equations have been formulated to describe the electro-
chemical process occurring in the thin layer electrochemical
system, such as thin film electrodeposition, atmospheric
corrosion, polymer electrolyte fuel cell and so on [14–17].
In this paper, we investigated a novel phenomenon taking
place in the thin layer electrodeposition of lead. A segment
of dendrite deposit, which was segregated from the cathode,
could move and shorten spontaneously in the electrochem-
ical cell. We suggested the mechanism resulting in these
phenomena.
1. Introduction
Investigation on the electrochemical behavior in a thin
layer electrochemical cell is interested from fundamental and
practical points of view [1–3]. During the past decades, a
large number of theories and experiments have been directed
to study the transport mechanisms and reaction kinetics in
thin layer electrochemical cells [4–12].
Generally, when the electrolyte is confined to the quasi-
two-dimensional space with the thickness from a few ␮m to
100 ␮m, the convection effect is eliminate, and the diffusion
and electromigration of ion possess the different character-
istics from that in bulk electrolyte cell [6,8]. For instance,
the resistance of solution becomes extremely high when
the thickness of the electrolyte layer is very thin. In such a
condition, a very high ohmic drop and nonuniform current
distribution over the working electrode cause many novel
phenomena such as nonlinear effect, etc. Wang et al. [13] had
studied the electrodeposition of copper in the ultrathin elec-
trolyte layer. It was indicated that the nanostructure copper
filaments with the periodic chemical composition formed due
2. Experimental
2.1. Electrodeposition setup
∗
The electrochemical deposition of Pb was carried out in
the electrolyte layer sandwiched by two glass plates made
Corresponding author. Tel.: +86 2787682969; fax: +86 2787654569.
E-mail address: xwzou@whu.edu.cn (X.-W. Zou).
0013-4686/$ – see front matter © 2004 Published by Elsevier Ltd.
doi:10.1016/j.electacta.2004.08.002

1032
B. Sun et al. / Electrochimica Acta 50 (2004) 1031–1037
Fig. 1. Schematic diagrams of the experiment setup: (a) side view, (b) top
view.
of microscope slide. The experimental device is shown in
Fig. 1. The size of the upper glass plate was 7 cm in length
and 2 cm in width. The thickness of the electrolyte layer was
50 ␮m in the present experiment. The cathode was made of
a platinum foil, which was polished by diamond paste and
rinsed by acetone before use. The anode was lead plate with
purity 99.9%. The electrolyte solution was 0.5 M Pb(BF4)2
with reagent grade. The electrodeposition was performed at
a constant applied voltage −10 V.
Fig. 2. Schematic diagrams of the measurement setup. (a) The setup mea-
suring the conductivity of the thin solution layer. (b) The setup measuring
the electrode potential at the two ends of the metal band sandwiched in the
thin electrochemical cell.
of lead foil substituted for the irregular disengaged deposits.
The thickness of the band was 50 ␮m and the width 0.5 mm.
The measurement method was illustrated in Fig. 2(b). A cop-
per wire, 30 ␮m in diameter, was welded on the band, and it
extended from the band to the cell. The surface of the copper
wire was coated with a layer of insulating paint to prevent
distorting the distribution of electric field in the cell. A plat-
inum microprobe was used to detect the electrode potential
around the ends of the metal band. Since the microprobe was
very thin (30 ␮m in diameter) and soft, it was welded on a
steel plate to firm up. In this way, we could operate the mi-
croprobe conveniently. Similarly, the surface of the platinum
microprobe and the steel plate were protected by insulating
paint except the tip of the probe. A digital potentiometer was
used to measure the electrode potential.
Polarization curves for the different electrode reactions
were obtained by linear voltage scanning (LVS) technology.
The experiments were conducted on electrochemical anal-
yser (CHI 6200, Shanghai, China). The measurement was
performed in a 3D electrochemical bath. The working elec-
trode was lead with the surface area of 1 mm2. The auxil-
iary electrode was platinum plate and the reference electrode
was a saturated calomel electrode (SCE). The sweep rate was
10 mV s−1. Our measurement consisted of these electrode re-
actions: dissolution of Pb, deposition of Pb and electrolysis
of water. For the electrode reaction of Pb, the measurement
was carried out in Pb(BF4)2 solution with the concentration
of 0.5, 0.1 and 0.02 M, respectively. For the anodic and ca-
thodic reaction of the electrolysis of water, considering these
reactions mainly depend on the pH value of the water, we
The process of electrodeposition growth was viewed by
an optical microscope equipped with a charge-coupled device
(CCD) video camera, as shown in Fig. 1. The CCD device
connected with a personal computer. With this optical system,
we can make a real-time observation on the growth of deposit
and simultaneously save the video image for analysis later.
2.2. Measurement methods
Kinetic measurements in the present experiment involved
three aspects: conductivity of the electrolyte solution, elec-
trode potential and I–V properties for different electrode re-
actions.
Conductivity of the electrolyte solutions was determined
by a conductivity meter (DDSJ-308A, Shanghai, China). The
frequency was 1 kHz. Considering that the glass plate might
have an impact on the transport of ions in the thin layer elec-
trochemical cell, we designed a setup to measure the con-
ductivity of electrolyte solution confined in a very thin cell.
The measurement setup is shown in Fig. 2(a). The length
and width of the glass plate were 4 and 2 cm, respectively.
Two thin platinum wire electrodes (50 ␮m in diameter) were
placed at the two ends of the cell.
To investigate the change in the overpotential at the two
ends of a disengaged dendrite, the electrode potential was
measured. In our experiments, a regular metal band made

B. Sun et al. / Electrochimica Acta 50 (2004) 1031–1037
1033
first measured the pH values of the Pb(BF4)2 solution with
the concentration of 0.5, 0.1 and 0.02 M by a pH-meter, which
are 2.5, 3.8 and 5.5, respectively. Then, H2(BF4)2 solutions
with the same pH values were used to survey the polarization
properties of the electrolysis of water.
local electrolyte solution? Both appear incorrect. Further in-
vestigations revealed that the ‘movement’ of the segment was
caused by concurrent dissolution and deposition reactions oc-
curring at the two ends of the dendrite segment. At the end
toward to the anode, electrodeposition took place, which al-
lowed the deposit to grow forward. At the end toward to the
cathode, the electrodissolution took place, which consumed
the deposit continuously. These concurrent dissolution and
deposition reactions caused the dendrite segment to move
in the cell. In addition, we also found that under different
experimental condition, the behavior of the disengaged den-
drite segment in the cell was varied. When the concentration
of the solution was low (e.g. 0.02 M), the dendrite segment
shortened gradually rather than moved. When the length of
the disengaged segment along the line of the field was very
short, the disengaged dendrite segment neither moved nor
shortened, did not change. In these experiments, we never
observed the disengaged segment to grow up. In the view of
the competition between the dissolution and deposition reac-
tions taking place at two ends of the deposit segment, we can
expect that if the amount of dissolving lead was larger than
the deposited lead, the segment appeared to shorten gradu-
ally; if the dissolution and deposition reactions did not occur,
the disengaged deposit remained stationary.
In electrochemistry, the conjugate dissolution–deposition
reactions have been reported [19–23]. When a metal rod is
placed in an electric field, the field will induce polarization.
Anodic and cathodic polarization at the two sides of the metal
rod will give rise to appropriate anodic and cathodic over-
potentials. Once the overpotential is beyond a critical value,
electrochemical reaction will take place at the two ends of the
metal rod. The amount of dissolution and that of deposition
should meet the charge conservation principle. Because the
two ends of the metal rod serve as the anode and cathode, the
3. Results and discussion
When an external voltage is exerted on at the electrodes,
Pb began to deposit on the platinum cathode and formed
dendrite deposit [18]. Because the cell was thin, the den-
drite deposit was thin and brittle. During the course of the
growth, one could find small bubble of hydrogen gas gener-
ating by the electrolysis of water. Generation of the bubble
disturbed the growth of the Pb dendrites and even made the
deposit break down. In general, electrodeposits grow out of
the electrodes; once a part of the deposit separates from the
deposit and becomes an isolated segment, the segment will
stop growing. However, in the present experiment we found
that the segment moved toward the anode in the thin cell after
it broke away from the dendrite deposit linked to the cathode.
Fig. 3 illustrates this interesting process with in situ obser-
vations. Fig. 3(a) and (b) show the growth of the dendrite
deposit without any disturbance from hydrogen gas bubbles.
After a few seconds, the deposit began to break, as shown in
Fig. 3(c). Then this disengaged dendrite segment began move
[see Fig. 3 (d), (e) and (f)]. The movement velocity was about
0.5 mm s−1 and the direction was toward the anode.
This novel observation aroused our interest to investigate
the mechanism inducing the movement of the isolated de-
posit segment in the two-dimensional (2D) electrochemical
cell. Did the deposit move by the driving force of the elec-
tric field? Or was this movement caused by the flow of the
Fig. 3. The movement of the disengaged segment of the dendrite deposit in the 2D electrochemical cell. The photographs were obtained with an in situ
observation setup (t = 0, 2, 4, 6, 8, 10 s from (a) to (f)).

1034
B. Sun et al. / Electrochimica Acta 50 (2004) 1031–1037
process is referred as bipolar electrochemistry. This kind of
phenomenon has been investigated using fluidized or packed
bed electrode for industrial applications in metal recovery
[20,21] and electrosynthesis [22–23]. However, in published
studies the phenomenon shown in Fig. 3 has not been ob-
served. The reason, we suppose, is that the rates of the elec-
trode reactions are very slow, and the species dissolving and
those deposition are generally not the same in those investiga-
tions. In the present experimental system, the rate of electrode
reaction is large enough and the dissolving mater and de-
posited product are the same metal lead. In addition, 2D thin
layer systems have the advantage that the change of the den-
drite segments resulting from a small amount of dissolving
mater or deposited product can be observed clearly. There-
fore, the movement of the dendrite segment can be viewed
in the present electrochemical deposition experiment. In or-
der to verify this conclusion, an experiment was performed
in a 3D bath under the same experimental conditions. It was
found that in the 3D bath the dissolution–deposition behav-
ior still occurred, but the rates of electrode reactions were
very low and the movement of the disengaged deposit was
not observed.
According to electrochemical principles [24], the rate of
an electrode reaction depends on the overpotential on the re-
action interface for a charge transfer controlled process. If
the overpotentialη is low, the rate of reaction is small. Con-
trarily, ifη is high, the rate of reaction is large. Why are there
large overpotentials at the two ends of the isolated metal band
in the 2D electrochemical cell? To answer this question the
equivalent resistance model was used [25,26]. Fig. 4 shows
the equivalent resistance model describing the 2D electro-
chemical cell with an isolated metal band sandwiched in the
cell. As shown in Fig. 4, the total current It flowing through
the cell can be written as
η and current Ip can be expressed by the Tafel equation [24]
ꢀ
ꢁ
Ip
S
η = a + b log
,
(2)
where a and b are reaction constants and s the area of the side
surface of the metal band. Eq. (2) indicates that the overpo-
tential at the end of the metal band increases with the current
Ip. It can be seen from Eq. (1) and Fig. 4 that for a constant
total current It the current Ip depends on the proportion of the
resistance of metal to that of the electrolyte solution. If the
resistance of the solution is very large, nearly all current flows
through the metal band and the current Ip becomes large.
Based on above analysis, it can be inferred that the occur-
rence of the phenomenon shown in Fig. 3 was related to the
resistance of the solution in the 2D electrochemical cell. In
ordertoinvestigate the resistance ofthe solutioninthe present
system, the setup shown in Fig. 2(a) was used. The experi-
ments showed that the conductivity of the Pb(BF4)2 solution
(0.5 M, 20 ◦C) sandwiched in the 50 ␮m cell was 0.6 S cm−1
.
In the present experiment, the conductivity of metal lead was
50,000 S cm−1 [27] and the width of the deposit segment was
about 0.5 mm. Thus, in terms of the ohmic model of the resis-
tance of electrolyte solutions, the ratio of the resistance of the
deposit segment Rp to that of the solution Rb was calculated
to be about 1800:1. In this condition, it can be concluded that
nearly all current It flowed through the deposit segment and
the polarization overpotentials at the two ends of the segment
was very large. The large overpotential caused the high rates
of the electrode reactions and the movement of the dendrite
segment in the 2D cell.
As mentioned above, the phenomenon shown in Fig. 3 was
not observed in the 3D system. The reasons, we propose, lie
in two aspects: the first is that in 3D electrochemical cell, the
distribution of electric field is not limited within the space
between the electrodes, but nearly the full electrochemical
cell [24]. Thus, the bypass current Ib was still large since the
area of the current section in solution was very large in com-
parison with that in the metal band. The second reason was
that in the 3D bath the conductivity of the solution was higher
than that in the 2D cell. We measured the conductivity of the
solution in the 3D bath. Under the same conditions (concen-
tration and temperature), the conductivity of the Pb(BF4)2
solution was 1.1 S cm−1. This result indicates that in the thin
electrochemical cell, the boundary of the cell indeed made
an impact on the transport of ions. The transport process in
the 2D electrochemical cell has been investigated in previous
studies [18,28]. It has been shown that when the thickness
of the cell was very small (<100 ␮m), the convection effect
is strongly inhibited. Convection is an important mode in
transporting ions. Once the convection is eliminated in the
transport process, the movement of ions is impeded and the
conductivity of the solution would decreases drastically.
In the present thin layer electrochemical experiment, the
resistance of the solution was much larger than that of the
metal band. So nearly all current It flowed through the metal
It = Ip + Ib,
(1)
where Ip is the current flowing through the metal band and
Ib the bypass current flowing through the solution. When the
current Ip comes through the metal band placed in the elec-
trolyte solution, polarization overpotential will be induced at
the two ends of the band. The relation between overpotential
Fig. 4. Equivalent resistance model for current pathways in bipolar elec-
trochemical system. It: total current; Ib: current flowing through the metal
band; Ip: current flowing through the solution; Rb: equivalent resistance of
the metal band; Rp: equivalent resistance of the solution.

B. Sun et al. / Electrochimica Acta 50 (2004) 1031–1037
1035
(7)
(8)
(9)
ꢀ
ꢀ
ꢀ
ꢁ
ꢁ
ꢁ
band, as analysis above. Thus, Eq. (1) becomes
It ≈ Ip.
It
ηc1 = E1 − E0 = ac + bc log
,
,
Wd
(3)
It
ηa2 = E2 − E0 = aa + ba log
ηc2 = E2 − E0 = ac + bclog
Eq. (3) offers us the possibility to estimate the overpotential at
the two ends of the metal band placed in 2D electrochemical
cell. Let L, W and d denote the length, width and the thickness
of the cell, and l, w and d denote corresponding parameters
of the metal band. When a voltage Vappl is applied across the
electrodes of the cell, it can be partitioned as follows:
Wd
It
,
Wd
In Eqs. (6)–(9), the equilibrium potential E0 can be mea-
sured by the electrochemical analyser; the reaction constants
of lead dissolution aa, ba and the reaction constants of lead
deposition ac and bc can be obtained by fitting of the polar-
ization curves [see Fig. 6(a) and (c)]. For the experiments
with the concentration of 0.5 M, we obtained the values of
E0, aa, ba, ac and bc were −0.39, 0.18, 0.20, 0.10 and 0.34 V,
respectively. Substituting Eqs. (5)–(9) into Eq. (4), we obtain
Vappl = E1 + E1 + E2 + E2 + IRsol1 + IRsol2
,
(4)
where E1aed and E1ced are anodic and cathodic electrode po-
tentials, E2 and E2 are electrode potentials at the two
aed
ced
ends of the metal band, and IRsol1 + IRsol2 are the potential
drops in the solutions. The calculated model is described in
Fig. 5(a). Letσdenotes the conductivity of the solution, so the
potential drop of the solution can be written as
ꢂ
ꢃ
It2
Wwd
Vappl = 4E0 + 2(aa + ac) + (ba + bc) log
It(L − l)
It(L − l)
IRsol1 + IRsol2
=
.
(5)
σdW
+
.
(10)
sdW
Under the condition of low current density, the electrode re-
action can be considered as a charge transfer controlled pro-
cess. In this case, the relation between the overpotentialη and
the current Ip meets Eq. (2). Thus, the overpotentials can be
expressed as
For an experimental system, the parameters E0, aa, ac, ba, bc,
W, w, d, L, l andσare fixed, so we can calculate the value of
the total current It when the applied voltage Vappl is given.
Then, the overpotential at the ends of the metal band can be
determined by using Eqs. (8) and (9). Similarly, fixed the
parameters Vappl, W, w, d and L, the relation between the
overpotentialη and the length of the metal band l can be ob-
tained.
ꢀ
ꢁ
It
ηa1 = E1 − E0 = aa + ba log
,
(6)
Wd
Fig. 5(b) is the calculated relationship of the overpotential
at the cathodic end of the metal band on the length of the band
when the applied voltage Vappl = −10 V, in company with the
experimental value measured by the platinum microprobe. It
can be seen from Fig. 5(b) that the experimental value is little
less than the calculated value for a certain length of the metal
band. The reason is that the microprobe could not be placed
close to the end of the band in the experiment, thus causing a
small potential different between the microprobe and the end
of the band. Fig. 5(b) shows that as the length of the metal
band decreased, the overpotential became small. This result
presents an interpretation of another phenomenon observed
in the present studies that the disengaged deposit segment did
not change when the size of the segment was very small. As
thelengthofthesegmentdecreased, theoverpotentialbecame
small. Once the overpotential was below the critical value,
the deposit segment could not grow and kept its stationary
status. In the present experiments, we measured the critical
length of the metal band lc ≈ 1 mm, and the corresponding
critical overpotential was about 50 mV. When the length of
deposit segment was less than 1 mm, the separate deposit
remained stationary, and neither deposition nor dissolution
occurred.
Besides the movement of the disengaged dendrite seg-
ment in the 2D electrochemical cell, another phenomenon
observed was the shortening of the segment when the con-
Fig. 5. Calculation of the overpotential at the ends of the metal band. (a)
A schematic diagram of the calculation model. (b) The overpotential at the
ends of the metal band as a function of the length of the metal band.

1036
B. Sun et al. / Electrochimica Acta 50 (2004) 1031–1037
Fig. 6. Polarization curves of four electrode reactions. (a) Pb2+ + 2e → Pb; (b) H2O + 2e → H2 + O2−; (c) Pb → Pb2+ + 2e; (d) 2H2O → O2 + 4H+ + 4e.
The concentration of the electrolyte solution is 0.02, 0.1 and 0.5 M, respectively. Corresponding values of pH are 5.5, 3.8 and 2.5. The working electrode was
made of lead plate with the area 1 mm2. The sweep rate was 10 mV s−1. A saturated calomel electrode (SCE) was used as a reference electrode.
−0.50 V1 and the reduction potential of H+ is about −1.0 V.
centration of the solution was low. The mechanism inducing
this phenomenon can be understood as follows. In the present
Moreover, at the same voltage the current for Pb deposition
is much larger than that for H+ reduction. This fact indicates
that when the concentration of the solution is high, cathodic
reaction is dominated by lead deposition, i.e. Eq. (11) is suf-
ficient to describe the cathodic reaction. However, when the
concentration of the solution decreases to 0.02 M, the depo-
sition potential of Pb becomes about −1.5 V and the reduc-
tion potential of H+ is about −1.3 V. They are very close.
Thus, the cathodic reactions include the deposition of lead
and the release of hydrogen gas described by Eqs. (11) and
(12), respectively. As for the anodic reaction, Fig. 6(c) and
(d) show that the current for the dissolution of Pb is always
larger than that for the generation of O2 over the ranges of
concentration and voltage used. Thus, the dissolution of lead
(Eq. (13)), no matter whether the concentration of the solu-
tion is high or low, is the principle anodic reaction. To sum
up, in the case of low concentrations, the anodic reaction is
experiments, there are two kinds of electrode reactions. They
are
cathode reaction:
Pb2+ + 2e → Pb,
(11)
(12)
H2O + 2e → H2 + O2−
and anode reaction:
Pb → Pb2+ + 2e,
,
(13)
(14)
2H2O → O2 + 4H+ + 4e.
To find the difference between the reactions in the case of low
concentrations and those in the case of high concentrations,
we made the measurements on the polarization curves for
the four reactions at the concentration 0.02, 0.1 and 0.5 M by
using linear voltage scanning (LVS). The results are shown
in Fig. 6. The cathodic polarization curves of lead and hy-
drogen are shown in Fig. 6(a) and (b), respectively. It can
be seen from these figures that when the concentration of
the solution is 0.5 M, the deposition potential of Pb is about
1
The polarization curve of Pb electrodeposition [Fig. 6(a)] indicates that
when the electrode potential is between −0.50 and −0.39 V (the equilibrium
potential), the deposition reaction meets the linear polarization relation, and
current is very small (approximately 1 mA). In this case, the deposit cannot
grow into a dendrite structure. Thus, in the present experiment we consider
the −0.50 V as the deposition potential.

B. Sun et al. / Electrochimica Acta 50 (2004) 1031–1037
1037
only the dissolution of lead and the cathodic reactions are
References
both the deposition of lead and the generation of hydrogen
gas. Conjugate dissolution–deposition reactions require that
the charges in the anodic reactions should be equal to those
in the cathodic reactions. Thus, the consumption of lead due
to the dissolution is more than that for the deposition of lead,
and the disengaged deposit segment would shorten gradually.
[1] C.R. Martin, Science (1994) 266.
[2] G.J. Snyder, J.R. Lim, C.K. Huang, J.P. Fleurial, Nature Mater. 2
(2003) 528.
[3] G.L. Che, B.B. Lakshmi, E.R. Fisher, C.R. Martin, Nature 393
(1998) 346.
[4] J.E. Devibiss, J.X. Wang, B.M. Ocko, K. Tamura, R.R. Adzic, I.A.
Vartanyants, I.K. Robinson, Electrochim. Acta 47 (2002) 3057.
[5] A.C. Finnefrock, K.L. Ringland, J.D. Brock, Phys. Rev. Lett. 81
(1998) 3459.
4. Conclusion
[6] G. Marshall, E. Mocskos, F.V. Molina, S. Dengra, Phys. Rev. E 68
(2003) 021607.
[7] H. Wang, Electrochim. Acta 40 (1995) 1707.
[8] Y.W. Xie, T. Chen, S.J. Dong, Electrochim. Acta 40 (1995) 1177.
[9] S.N. Atchison, R.P. Burford, C.P. Whitby, D.B. Hibbert, J. Elec-
troanal. Chem. 399 (1995) 71.
[10] C.F. Wallgren, F.H. Bark, B.J. Andersson, Electrochim. Acta 41
(1996) 2909.
[11] B. Sun, X.W. Zou, Z.Z. Jin, Phys. Rev. E 69 (2004) 067202.
[12] B. Sun, X.W. Zou, Z.Z. Jin, Mater. Phys. Chem. (2004) 144.
[13] M. Wang, S. Zhong, X.B. Yin, J.M. Zhu, R.W. Peng, Y. Wang, K.Q.
Zhang, N.B. Ming, Phys. Rev. Lett. 86 (2001) 3827.
[14] P. Futerko, I.M. Hsing, Electrochim. Acta 45 (2000) 1741.
[15] P.G. Bruce, C.A. Vincent, J. Electroanal. Chem. 225 (1987) 1.
[16] J.R. Maccallum, C.A. Vincent, Polymer Electrolyte Reviews 1, El-
sevier, London, 1987.
[17] C.A. Vincent, F. Bonino, M. lazzari, B. Scrosati, Modern Batteries,
Edward Arnold, London, 1984.
[18] F. Sagues, M.Q. Lopez-Salvans, P. Claret, Phys. Reports 337 (2000)
97.
[19] J.C. Bradley, et al., Nature 389 (1997) 268.
[20] J.K. Lee, L.W. Shemilt, H.S. Chun, J. Appl. Electrochem. 19 (1989)
877.
[21] R.E. Plimley, A.R. Wright, Chem. Eng. Sci. 39 (1984) 395.
[22] M. Sudoh, T. Kodera, T. Ichino, J. Chem. Eng. Jpn. 24 (1991) 165.
[23] H.J. Kim, K. Kusakabe, S. Hokazono, S. Morooka, Y. Kato, J. Appl.
Electrochem. 17 (1987) 1213.
A conjugate electrodissolution–electrodeposition phe-
nomenon was investigated in a 2D electrodeposition cell.
Because of the lower conductivity and low thickness of the
solution layer, the ohmic resistance of the electrolyte solution
became very large, which led to higher polarization overpo-
tentials at the ends of disengaged deposit segments. As a
result, the higher overpotential gave rise to the larger rates
of the electrode reactions and caused the movement of the
disengaged deposit segment. Moreover, we discuss the con-
ditions inducing this novel phenomenon based on a calcula-
tion model. It is shown that whether or not the movement of
the disengaged deposit segment takes place depends on the
polarization overpotential at the ends of the segment. Higher
concentrations of the electrolyte and longer length of disen-
gaged segments are necessary for the movement of the seg-
ment. When the concentration of the solution is low enough,
the disengaged segment will shorten gradually. When the
length of the disengaged deposit segment is small, the seg-
ment will neither move nor shorten, but keeps a stationary
state.
[24] A.J. Bard, L.R. Faulkner, Electrochemical Methods: Fundamentals
And Applications, Wiley, New York, 1980.
[25] K. Kusakabe, T. Kimura, S. Morooka, Y. Koto, J. Appl. Electrochem.
17 (1987) 724.
Acknowledgments
[26] K. Kusakabe, S. Morooka, Y. Koto, J. Appl. Electrochem. 19 (1986)
43.
[27] C.J. Smithells, Metal Reference Book, 5th ed., Butterworths, London,
1976.
[28] G. Gonzalez, G. Marshall, F. Molina, S. Dengra, Phys. Rev. E 65
(2002) 051607.
This work was supported by the National Nature Sci-
ence Foundation of China No. 10374072 (XWZ) and
No. 10274056 (ZZJ), and by the Specialized Research
Fund for the Doctoral Program of Higher Education No.
20020486009.