Through TEM observations it was established that
PbO2
particles of the positive active mass are heterogeneous in mass distribution. Using electron micro‐micro‐diffraction it was found that
PbO2
particles are built up of zones of
α‐normaland/normalorβ‐PbO2
crystal structure with various orientation, and of amorphous zones. The latter are more transparent for the electron beam and are assumed to be hydrated. It was determined, through XPS (x‐ray photoelectron spectroscopy), that at least 30% of the
PbO2
surface is hydrated. The changes in the crystal part of the active mass particles are followed during charge, discharge, open circuit, and overcharge. It was established that
H2SO4
adsorption on the surface of the particles brings about an increase in their amorphous part. When the positive active mass is washed, its crystal part increases. It was also found that
O2
causes amorphization of the particles, too. Oxygen atoms are sorbed by the
PbO2
particles and increase their zones of disorder. A mechanism of formation of
PbO2
particles during battery charge is proposed taking into account the processes of dehydration. OH− ions are assigned a considerable role in the interaction of the particles with the solution or with the neighboring particles.
Through TEM observations it was established that the lead acid battery
PbO2
active mass crystals have a nonhomogeneous mass distribution and contain some defects in their crystal lattice. By electron diffraction analysis of the active mass agglomerates and individual crystals it was determined that
β‐PbO2
is formed in the long and needle‐like crystals, while
α‐PbO2
is formed in the short and slab‐like crystals often with a nonuniform shape. During plate discharge, besides the
PbSO4
crystals, fine orthorhombic
normalPbO false(normalort‐normalPbOfalse)
crystals are formed as well. This fact is explained by the proton‐electron mechanism of
PbO2
reduction. The difficult penetration of
SO42−
ions into the agglomerates' micropores causes alkalization of the solution in them and creates conditions for the formation of
normalort‐normalPbO
. Since the molar volumes of
normalort‐normalPbO
and
PbO2
are almost equal, the transport of H+ ions and of water along the agglomerates' micropores is not impeded by the reduction
PbO2→normalPbO
. This reaction allows the
PbO2
crystals in the agglomerates' interior to take part in the discharge process, thus a high coefficient of active mass utilization is achieved. When the discharge is stopped,
normalort‐normalPbO
reacts with
H2SO4
forming
PbSO4
.
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