Lead Deficiency and Hydrogen Content in Battery Electrode β ‐ PbO2

Abstract

Neutron powder diffraction data have been collected for β‐PbO2 obtained from lead‐acid battery plates cycled in H2SO4 and D2SO4 . A comparison of total scattering cross sections for the hydrogenated sample vs. the deuterated sample indicates a bulk hydrogen concentration of 0.21 H atoms per PbO2 unit. Rietveld refinements of the data yield the expected tetragonal β‐PbO2 structure, P42/normalmnm , with a 3–5% vacancy concentration on the lead sites. These results suggest that at least part of the hydrogen is incorporated into the β‐PbO2 crystalline lattice.

Inelastic Neutron Scattering and Transmission Electron Microscope Studies of Lead Dioxide

“…Table III also shows the percentage difference between the analyses for total Pb and for Pb TM and it will be seen that, in most cases, these correlate qualitatively with the values calculated for x in PbO2-x(H20)x from the transmission experiment. The ratio of hydrogen to lead atoms for electrochemically prepared ~-PbO2 (0.16) is similar to that deduced for active fl-PbO2 (0.20) by Jorgenson et al (9).…”

“…Complexes with PPh3 also exist for monovalent nickel. Solid (PPh~)3NiC1 has been prepared and is paramagnetic (9,10). Cryoscopic studies in benzene indicate some dissociation into (PPh3)2NiX and no significant Ni-Ni interaction.…”

Nature of the Band Gap and Origin of the Conductivity ofPbO2Revealed by Theory and Experiment

“…PbO 2 has a small but finite band gap defects in PbO 2 has also been a cause for much debate and a light electron effective mass. The calculated charge [14,15]. PbO 2 typically displays degenerate n-type neutrality level lies deep in the conduction band, which is conductivity, with undoped samples possessing carrier consistent with high levels of electrical conductivity.…”

“…In the lead-acid battery, it has been reported that PbO 2 levels of conductivity are well established, the electronic electrodes are substoichiometric on the cation sublattice, structure of PbO 2 has been a source of controversy in the and not on the anion sublattice, based on neutron diffrac literature, and to date remains uncertain. It has been postu-tion experiments [14,15,19]. Even recent studies refer to lated that PbO 2 is intrinsically metallic [4][5][6][7][8][9], but con-the fact that the oxygen sublattice is ''complete'' [2].…”

“…Based on previous reports of PbO 2 electrodes being lead deficient [14,15,19], one would expect the formation en ergy of the positively charged defects to be lower than, or equivalent to those of the negatively charged defects. Upon examining Fig.…”