IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 1, January 2015.
www.ijiset.com
ISSN 2348 – 7968
164
Effect of anhydrous Magnesium Sulphate on eutectic mixture of
Magnesium thermal cell
Samaa Saadi Mahmood and Abbas A-Ali Drea*
Babylon University - College of Science - Chemistry Department
Hilla -Iraq
*E-mail: aadreab22@yahoo.com
Abstract
Effect of additive salt on eutectic mixture of
Magnesium thermal cell (Lithium Chloride -
Potassium Chloride) upon the performance of
voltage production using anhydrous magnesium
sulphate have been done by the mechanism of
open thermodynamic system. Different weights
of anhydrous magnesium sulphate have been
used within eutectic mixture in presence
constant amount of vanadium pent oxide.
Different ratios of new eutectic mixtures have
been examined relatively to the ambient
operating temperatures and the activity of
producing voltage of electrochemical systems in
new system of thermal cells. Optimized ratio of
eutectic mixture for voltage production have
been choice relative to minimum ambient
temperatures, and its operating temperature.
Optimized weight of depolarizer in eutectic
mixture of new Magnesium thermal cell have
been studied.
High effect have been found due
anhydrous magnesium Sluphate additions, as
well as the thermodynamic and conductivity
activity for eutectic mixture of Magnesium
thermal cell, since the optimized weight ratio of
new eutectic mixture Lithium Chloride :
Potassium Chloride : anhydrous magnesium
Sluphate is consisted from 5.5 :4.5 : 1. ratio
.Operating temperature is 400 ? C, Open system
cell produced 1.5 volte in presence 0.5 optimized
weight ratio of depolarizer relative to weight
ratios of new eutectic mixture components. The
new thermal cell is sensitive to ambient
temperatures and produce electrical energy when
ambient temperature raise to 35 into 350 ? C by
voltage range from 0.3 into 1.5 volte
respectively. Electrical discharge of open circuit
occurs in 400 ? C as ambient operating
temperature by 13 mints of elapsed time.
Key Words: - Magnesium thermal cell, Eutectic mixture,
Open Cup cell, Anhydrous magnesium Sulphate.
1. Introduction
Thermal battery is provided with solid
electrolyte and non-active at ordinary
temperature, which is divided into two class, the
primary battery and secondary battery. The
electrolyte becomes molten by using a
pyrotechnic heat source which is essential of the
battery cell stack [2-3]. Thermal batteries are
used for high power applications that requiring
fast runtimes from a few seconds to a few hours,
and these batteries are used for multifunctional
propose to provide power for electronic systems
devices and guidance systems [4]. All batteries
are composed of some thermal cells provided
with two electrodes connected by an ionically
conductive material as electrolyte. The two
electrodes have different chemical potential.
When these electrodes are connected by means
of an external device, electrons spontaneously
flow from the more negative to the more positive
potential. Ions are transported through the
electrolyte, and electrical energy can be tapped
by the external circuit. In secondary, or
rechargeable batteries, a larger voltage applied in
the opposite direction can cause the battery to
recharge [5]. Magnesium batteries is the luckiest
IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 1, January 2015.
www.ijiset.com
ISSN 2348 – 7968
165
technology in order to achieve substantially
greater energy density than Li-ion due the
divalent nature of Mg2+. Magnesium batteries
can obtain higher energy density (energy per unit
volume) and specific energy (energy per unit
weight) than state of the art lithium batteries.
Magnesium metal anode has a greater volumetric
capacity than graphite or lithium metal, it’s
inexpensive, environmentally friendly and safe
to handle [6-8].
2. Experimental
The study of salt effect needed some
evaluation experiments to estimate the optimum
conditions of newest thermal cell according to
the ratio of anhydrous Magnesium Sulphate salt
additive to the composition of original eutectic
mixture of magnesium cell.
2.1 Preparation of molten salts
The new eutectic of cell were prepared
by mixing different percentages of anhydrous
magnesium sulfate with the original fixed
percentage of potassium chloride and lithium
chloride that includes ( LiCl:KCl:45:55) [9].
Constant weight of depolarizer V2O5 has been
used for each experiments, to get the optimal
weight for the anhydrous magnesium sulfate salt.
In each experiments the mixture was crushed to
a powder and then moved to the furnace whose
temperature had been raised from 35 to 600 ?C
till get melted the powder. The furnace get turn
off and leave it until gets cool down to 100 ?C.
the mixture moves to a dry box and leave it there
until it gets cool down to solidifies then grind to
a powder again and get used for electrical
measurements.
2.2 Determination the weight percent of
depolarizer
Choose the best of weight ratio for
(anhydrous magnesium sulfate) that it was added
to the molten salts that it has formed from the
two salts (potassium chloride and lithium
chloride) with the fixed ratio of depolarizer
V2O5. Different weight ratio have been added of
depolarizer substance V2O5 .Observations are
recorded about the molten salts and choose the
best ratio for this substance, that’s gives the
highest voltage for the mixture.
2.3 Operation of the thermal cell
Newest eutectic mixture has transferred to
the pottery basin inside the electric muffle
furnace and connected the two electrodes of this
cell to the multi electronic voltmeter. Operating
temperature has been recorded for the cell
operation, through raising the temperature from
35 to 600 ?C.
2.4 Optimum temperature of thermal cell
operation.
The optimum temperature was determined
by taken the pottery basin that contained the best
ratios of molten salts, that’s putted it inside the
furnace and connected to the voltmeter, the
temperature was gradually raised from 35 to
600 ?C with recorded the temperatures rather than
resulted voltage.
2.5 Effect of Temperature
Effect of temperature on the voltage of
thermal cell has been showed by setting the
pottery basin of best ratio of molten salts and
putted inside the furnace, that’s connected to the
voltmeter. Temperature been raised from 35 to
400 ?C, when reach the temperature to 400 ?C,
starts running the stopwatch and monitoring the
voltages resulting with time up to the low
voltage to zero.
3. Results and Discussion
3.1 Components of thermal cell
Magnesium thermal cell is consisted from
Mg-metal as anode with thickness 0.15-0.2 mm
and width 3mm. Surface impurities of
magnesium has been removed by washing with
diluted nitric acid (1M) and later, washed up
with distilled water for several times then drying
[10,11] . Cathode is composed from depolarizer
(V2O5), that’s provided with local metal clip
IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 1, January 2015.
www.ijiset.com
ISSN 2348 – 7968
166
alloy is consisted from nickel, iron and
chromium, that’s available with very low cost
and been used as positive current collector.
Eutectic mixture is consisted from the LiCl salt
KCl salt by 45:55 ratio respectively. This
eutectic is common used as electrolyte in
thermal cells [12]. The purpose of anhydrous
magnesium sulfate addition to original eutectic
mixture to improving a new properties and
accelerate voltage production at lower
temperature than ordinary operating temperature
of thermal cell. The components of the thermal
battery (electrodes and eutectic mixture) are
putted in the pottery basin that using for all
experiments according to the open
thermodynamic system.
Table 1 and fig 1 shows that weight ratios of
anhydrous magnesium sulfate were added to the
original molten salt with the constant weight of
the depolarizer (1.5 gm. for all these
experiments) and they found the best ratio of
anhydrous magnesium sulfate was 1gm. that
given the maximum voltage 1.5 volt for the
mixture in the 350 ?C .
Table 1: Optimize weight ratio investigation of
anhydrous magnesium sulfate of new eutectic
mixture.
Temp.
C?
wt. /0.25
gm.
Wt. 2
/0.5gm.
wt. 3
/o.75
gm.
wt. 4
/1 gm.
50 0.1 0.2 0.3 0.52
100 0.3 0.25 0.35 0.58
150 0.3 0.3 0.4 0.65
200 0.35 0.35 0.45 0.7
250 0.4 0.41 0.6 0.9
300 0.48 0.5 0.7 1.3
350 0.55 0.7 0.88 1.5
400 0.6 0.85 1 1.1
450 0.5 0.7 0.65 0.99
500 0.5 0.5 0.4 0.75
550 0.4 0.15 0.3 0.3
600 0.25 0.1 0.2 0.1

Temp.
C?
wt. 5
/1.25
gm.
wt. 6
/1.5 gm.
wt. 7
/1.75
gm.
wt. 8
/2 gm.
50 0.4 0.3 0.3 0.1
100 0.5 0.45 0.4 0.11
150 0.55 0.5 0.5 0.15
200 0.7 0.65 0.55 0.2
250 0.75 0.73 0.6 0.28
300 0.82 0.8 0.72 0.35
350 1 1.2 0.8 0.5
400 0.95 0.98 0.9 0.75
450 0.91 0.6 0.7 0.5
500 0.4 0.55 0.35 0.21
550 0.25 0.4 0.3 0.1
600 0.2 0.2 0.25 0.1
Fig. 1 Effect of anhydrous magnesium sulfate on voltages
production of magnesium thermal cell.
After determined the optimize weight of
anhydrous magnesium sulfate, Effect of the
depolarizer V2O5 has been studied on the voltage
production of magnesium thermal cell by
different weight ratio to the molten salts that has
been weighted from anhydrous magnesium
sulfate. Vanadium pentoxid been choiced as
depolarizer that used in magnesium thermal cell.
Table 2. and Fig 2. Shows that weight ratios of
V2O5 were added to the molten salts (LiCl: KCl:
IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 1, January 2015.
www.ijiset.com
ISSN 2348 – 7968
167
MgSO4:45:55:1). They found the best weight of
V2O5 was 0.5 gm., that given the higher voltage
1.6 volt for the eutectic mixture in 400 C?
.
Table 2.Optimize weight of V2O5 of eutectic effecting on
voltage of the electrochemical system.
Temp.
?C
0.1gm
V2O5
0.2gm
V2O5
0.3gm
V2O5
0.4gm
V2O5
0.5gm
V2O5
50 0.1 0.15 0.1 0.1 0.1
100 0.11 0.2 0.2 0.1 0.2
150 0.2 0.35 0.25 0.15 0.25
200 0.33 0.4 0.3 0.25 0.3
250 0.51 0.5 0.41 0.42 0.35
300 0.65 0.85 0.5 0.5 0.6
350 0.75 0.95 0.65 0.8 1.2
400 0.7 0.8 0.88 1.1 1.6
450 0.45 0.65 0.6 0.8 1
500 0.4 0.3 0.2 0.6 0.65
550 0.3 0.29 0.1 0.4 0.2
600 0.25 0.25 0.1 0.24 0.12
Fig2. Effect of depolarizer on voltage production
of magnesium thermal cell.
3.2 Operating Temperature
Fig 3. Shows the operating temperature of
thermal cell with maximum efficiency at 400 ?C,
where the voltage is 1.5 volt. The temperature
degrees were raised from 35 to 600 ?C and the
rising in the voltage was noticed from 0.3 volt at
50 ?C and continue to raise until reach the voltage
to 1.5 volt at 400 ?C, this demonstrates the
effectiveness of these thermal cell at the ambient
temperature, after that observed the rapid
dropping in voltage, due consumption of the
reactants in the thermal cell.
Fig 3. The operating temperature of the laboratory thermal
cell.
3.3 Effect of temperature on voltage
production.
Fig 4. Shows effect of ambient temperature on
the thermal cell and that explain the regularly
electric discharge in the 400 ?C, with the lifetime
equal to 13 minutes.
Fig4.Voltage consumption of magnesium thermal cell.

IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 1, January 2015.
www.ijiset.com
ISSN 2348 – 7968
168
4. Conclusions
Anhydrous magnesium sulfate has
significant effect on the specifications of the
eutectic mixture of magnesium thermal cell,
since the maximum voltage production is 1.5
volt with activation ambient temperature equal
to 35? C. Operating temperature of magnesium
cell equal to 400?C and the half lifetime of
maximum voltage production equal to 13
minutes.
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