Fig. 5 shows that the cycle life of

Fig. 5 shows that the cycle life of the cell withMMAGM
membrane is 400 cycles, against 300 cycles for the MPVP and 330
cycles for the MPVS cells, respectively. These results illustrate the
important role of the membrane layer on the cycle life performance
of batteries (cells) with three-layered AGM separators. The
composition of the polymeric emulsion used to process the AGM
membrane needs to be optimized so as to keep up high cell/battery
capacity on cycling. A juxtaposition of the data in Fig. 5 with those
in Figs. 2–4 shows that the cells with small H2SO4 concentration
difference between the two electrolyte spaces of the plates have
longer cycle life than the cells with greater concentration difference.
Hence, the difference between the H2SO4 concentrations in the two electrode spaces is an important parameter limiting the
cycle life of the cells.
On comparing the capacity curves for the cells with the three
types of polymer-modified membranes it can be seen that the cell
withMMAGMmembrane has the longest cycle life of all cells under
test, but the cell withMPVSmembrane sustains the highest capacity
on cycling. The properties of the polymer-treated separator membranes
affect both the cycle life and the capacity performance of the
cells.
In an attempt to verify the reproducibility of the influence of
the three-layered membrane separator on the capacity of leadacid
batteries on cycling we set two identical 34 Ah batteries with
three-layered MMAGM membrane separators to cycling tests. The
obtained results are presented in Fig. 6.
The data in the figure evidence almost equal changes in capacity
with cycling for the two batteries. To follow the effect of temperature
on battery capacity the batteries were heated to 50 ◦C for
5 cycles (between cycles 35 and 40), but no changes in capacity
were observed on further cycling at room temperature. It can be
concluded that both batteries have undergone identical structural
changes since the beginning of the cycling test and the changed separator
structure is sustained on further cycling. Hence, the changes
in capacity of batteries assembled with the same membrane separator
follow the same profile. These results prove experimentally
that three-layered AGMseparators with identical membranes exert
the same influence on the energetic and cycle life performance of
the batteries.