Lead-acid cells positive electrodes

The lead-acid cell can be represented schematically as having a negative electrode of porous lead (lead sponge) and a positive electrode of lead dioxide, Pb02, both immersed in an aqueous solution of sulphuric acid ... 

Fig. 5.7 Interleaving of positive and negative electrode groups (elements) to form a lead-acid cell...

The potential/pH diagram in Fig. 2.1 shows that the lead—acid cell is thermodynamically unstable on open circuit. Processes of self-discharge proceed on the two electrodes as a result of which water decomposes to H2 and O2, and discharge reactions commence at the positive and negative plates as follows ... 

A one-dimensional model describing the transient discharge behavior of a lead-acid cell was presented by Tiedemann and Newman [56] in 1979 (Figure 9.22), considering Reaction 9.142 at the positive electrode and... 

Three years later, Nguyen and White presented a model of a hermetically sealed lead-acid cell [63]. They studied the effect of having an excess negative electrode and the transport rate of oxygen across the separator on the oxygen evolution at the positive electrode... 

FIGURE 24,5 Exploded view of typical thin, flat sealed lead-acid cell. Metal plates, each approximately 0.3 mm thick, are laminated with special resin films to negative and positive electrode plates, both physically and electrically. They are then fused to a resin frame by a pressurized thermal bonding process. ( Courtesy of Panasonic Industrial Co.)... 

Element The negative and positive electrodes together with the separators of a single cell. It is used almost exclusively in describing lead-acid cells and batteries. 

As current is drawn from the cell, the positive electrode voltage is depressed due to concentration polarization as sulphuric acid within the pores is consumed. This effect is more marked for partially discharged cells. Formation of lead sulphate decreases the pore volume and produces a microporous film on the Pb02 matrix. 

The characteristic of the lead-acid battery is that both electrodes are based on the chemistry of lead. The discharge-charge process is known as the double sulfate reaction, with the positive and negative electrodes being the seats of a dissolving-precipitating (and not some kind of solid-state ion transport or film formation) mechanism of the lead sulfate. The cell, the electrode reactions and the cell reaction are ... 

The mercurous sulfate [7783-36-0j/, Hg2S04, mercury reference electrode, (Pt)H2 H2S04(/ ) H S04(Hg), is used to accurately measure the half-cell potentials of the lead—acid battery. The standard potential of the mercury reference electrode is 0.6125 V (14). The potentials of the lead dioxide, lead sulfate, and mercurous sulfate, mercury electrodes versus a hydrogen electrode have been measured (24,25). These data may be used to calculate accurate half-cell potentials for the lead dioxide, lead sulfate positive electrode from temperatures of 0 to 55°C and acid concentrations of from 0.1 to 8m. 

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