Zur Stromverteilung in por�sen Elektroden des Bleiakkumulators

The discharge and recharge of the PbO2 electrode was followed by optical microscopy. During discharge the PbO2 dissolved with simultaneous growth of relatively large PbSO4 crystals. PbSO4 nucleated at preferred sites on the PbO2 and did not form a passivating film over other parts of the PbO2 surface. The PbO2 remaining at the end of discharge, however, had been encapsulated within PbSO4 crystals grown during the discharge. During recharge these PbO2 particles within the PbSO4 crystals offered a conductive path through the highly resistive PbSO4 , and the formation of PbO2 began within the encapsulating PbSO4 crystals at the surface of these residual PbO2 particles. PbO2 thus formed grew rapidly toward the surface of the PbSO4 crystals and, when reaching the surface, appeared to spread to surround the PbSO4 crystals, encapsulating them in turn and leaving hollow shells as the PbSO4 crystals dissolved.

Section: Discussionmentioning

confidence: 99%

Morphological Changes in the Lead Dioxide Electrode During Its Reduction and Reoxidation

Simon¹,

Wales²,

Caulder³

1970

“…High rate discharges showed less difference between antimonial and pure lead cells, and this may be attributed to the relatively small amount of active material required to take part in such cycles (14,18). High rate discharges showed less difference between antimonial and pure lead cells, and this may be attributed to the relatively small amount of active material required to take part in such cycles (14,18).…”

Section: Resultsmentioning

confidence: 99%

“…The cells with pure lead grids usually had somewhat lower capacities than the corresponding antimonial cells, and lost approximately 80% of their initial capacity between 5 and 10 cycles. High rate discharges showed less difference between antimonial and pure lead cells, and this may be attributed to the relatively small amount of active material required to take part in such cycles (14,18). It has also been suggested (12) that in the pure lead cells a barrier layer may form between the grid and active material and may offer less resistance at high than at low discharge rates.…”

Section: Resultsmentioning

confidence: 99%

PbO[sub 2] in the Lead-Acid Cell

Ritchie¹,

Burbank²

1970

Three representative lead oxides were used in fabricating lead-acid cells with pure and antimonial lead grids. The cells were cycled and overcharged. Positive plates were removed at intervals and the active material was examined by x-ray diffraction, electron microscopy, and by spectroscopy. Bulk densities of the active materials were also determined. The cells with pure lead grids usually had somewhat lower capacities than the corresponding antimonial cells, and lost approximately 80% of their initial capacity between 5 and 10 cycles. None of the antimonial cells suffered major capacity loss during the 21 cycles comprising the test. The rate of loss in bulk density of the PbO2 was higher in the pure lead cells. This and the loss in capacity have been attributed to the grain growth and anhedralization that take place more rapidly when antimony is absent. Antimony appears to act as a nucleating catalyst for the PbO2 and inhibits crystal growth.The fully charged positive electrode of the lead-acid cell is a porous polycrystalline aggregate of PbO2. The individual crystallites are usually of submicroscopic dimensions (1), and the aggregate must retain its * Electrochemical Society Active Member. mechanical strength and electrical continuity under stringent requirements: percolation of H2SO4 throughout the mass, cyclic volume changes between PbO2 and PbSO4 during electrode operation, and vigorous O2 gas evolution during overcharging. The ability of ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.102.42.98 Downloaded on 2014-10-11 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.102.42.98 Downloaded on 2014-10-11 to IP

“…By comparing the behaviour of a lead-acid battery with static electrolyte to a battery under flow, the effect of local electrolyte concentrations can be investigated. Prior to this study, there have been two different lead-acid cells designed to force electrolyte flow through an electrode, one developed by Bode et al 17 and another z E-mail: pmahon@swin.edu.au developed by Hullmeine et al 18 Both studies showed that forcedflow through an electrode during discharge significantly increased its high-rate performance. They also showed that forced-flow led to a relatively uniform distribution of PbSO 4 compared to an electrode discharged without flow.…”

mentioning

confidence: 99%

Flow Cell for Simultaneous In Situ Analysis of Local Electrolyte Distribution and Porous Morphology within the Negative Electrode in a Lead-Acid Battery

Stone

Hollenkamp

Mahon

et al. 2023

While lead-acid is without doubt the oldest battery technology still in use and despite continuous research over many years, mystery still surrounds certain key aspects of its operation. A complex relationship exists between the characteristics of the electrolyte and those of the solid lead sulfate that is alternately deposited and removed during discharge-charge. A premature mode of failure is the often-cited ‘plate sulfation’ that affects the negative electrode and this was investigated by forcing electrolyte flow through the electrode to probe structural changes. A new design of flow cell that measures flow through the porous electrode has been developed. Under forced electrolyte flow, the discharge capacity and recharge efficiency both increased significantly confirming that local sulfuric acid concentration has a strong effect. Also contributing to decreased electrolyte flow was the production of hydrogen gas during charging, which may make this technique useful in studies of fast-charging. Beyond this, the flow cell can be used to investigate types of duty where the deposition of lead sulfate triggers catastrophic loss of performance. The ability to monitor electrolyte flow accurately provides an important additional operating parameter that will help characterize modes of electrode failure that until now have remained opaque.