The open‐circuit voltages of the cell normalLifalse(1false)/normalLiI‐KI‐normalLiCl/LixnormalAlfalse(normalsfalse) were measured over the composition range of 6.9–50 a/o (atom per cent) Li in LixnormalAl alloy in the temperature range 282°–389°C. The composition of the LixnormalAl alloy was varied by coulometrically charging and discharging the cell. The emf values of the cell are independent of the composition up to 47 a/o lithium in the alloy and their temperature dependence follows the relationship E=451.07−0.2202T false(σ=0.3false) , where E is in millivolts, T normalin°K , and σ is the standard deviation. The constant potential exhibited by the alloy is ascribed to the formation of β‐normalLiAl phase on the alloy surface. The standard free energies of formation for β‐normalLiAl are estimated to be −7.49, −7.24, and − 7.09 kcal/mole at 300°, 350°, and 380°C, respectively. The standard enthalpy and entropy of formation are constant, −10.40 kcal/mole and −5.08 cal/mole · deg, respectively, in this temperature range. Since the electrochemically prepared lithium‐aluminum alloy has a constant potential over a wide composition range and exhibits good electrochemical behavior, it can serve as a good reference electrode as well as a high energy density anode in molten salt systems containing lithium.

of the zincate ion. 82 Furthermore, this calculated diffusion rate is too high because in making the calculation it was assumed that the concentration of zincate ions at the electrode was determined by the total number of zincate ions produced during the entire discharge process. These calculations show that the zincate ions do not diffuse away from the electrode surface as fast as they are formed. As a result, l~he concentration of zincate ions at the electrode surface builds up. The well-known ability of aqueous KOH to become supersaturated with zincate ions allows these accumulated zincate ions to remain in solution rather than precipitate, A similar calculation can be made with respect to the experimental discharge cited above. In that discharge 0.064 tool of zincate ions was formed at the electrode surface. The rate of diffusion needed to clear the electrode surface of these zincate ions was 4.3 X 10 -7 tool cm-~ sec -i while the calculated maximum rate of diffusion was 4.8 X 10 .9 mol cm-2 sec-1. Thus the diffusion of zincate ions away from the electrode surface was about 0.01 of what was needed to clear the electrode surface so that OH-ions could have access to the zinc for continuing the discharge reaction.One conclusion of all this is that while passivation of the zinc electrode in many cases may be due to the formation of Type I or Type II ZnO on or at the electrode surface, there are also situations in which passivation occurs without the formation of such a film. 38 This probably corresponds to ta in the paper and is due to the fact that the reaction products accumulate at the electrode surface and prevent access of OHions to the electrode surface.No one of these mechanisms will describe the passivation of the zinc electrode. This passivation is determined by local conditions that vary from place to place on the electrode surface and that may be quite different from average values that are used in analyses such as these.M:-B. Liu, G. M. Cook, and N. P. Yao: 34 Much of what Dirkse discusses is in complete agreement with the thinking that went into the development of our proposed scheme for the processes leading to the formation of the passivation film on zinc anodes. His primary concerns seem to be (i) our apparent specification of the film composition as Type I or Type II ZnO, and (if) the possibility that the passivation process is related to a limited rate of OH-diffusion across a boundary layer.We had hoped to avoid the apparent specification of film composition through our statements, in the second paragraph of the paper, that the composition was indeed unknown. In our scheme, the term ZnO was used only for simplicity. The logic of the scheme depends upon (i) the formation of soluble zincate species from the combination of zinc atoms with excess OH-, (ii) the precipitation of a zinc oxide-hydroxide with the release of the excess OH-, and finally (iii) the direct formation of insoluble zinc oxide-hydroxide species from the combination of zinc atoms with stoichiometric amounts of OH-. In practice, t...

Passivation times of horizontally upward‐facing and downward‐facing zinc microanodes in KOH electrolytes of five concentrations are reported. These measurements extend passivation data into a low current‐density region for evaluating conflicting interpretations of published work. To interpret our data, a new mechanism for anodic passivation is proposed. In high current‐density regions, passivation occurs when compact normalZnO covers the electrode surface; in low current‐density regions, passivation occurs when the mass transfer of hydroxide ions across a porous normalZnO layer is less than that required for anodization. This work also discusses passivation in porous zinc battery electrodes.

A generic three‐dimensional thermal model was developed for analyzing the thermal behavior of electric vehicle batteries. The model calculates temperature distribution and excursion of a battery during discharge, charge, and open circuit. The model takes into account the effects of heat generation, internal conduction and convection, and external heat dissipation on the temperature distribution in a battery. The three‐dimensional feature of the model permits incorporation of various asymmetric boundary conditions; thus, the effects of cell orientation and packaging on thermal behavior can be analyzed for a multiple‐cell battery pack. Various modes of boundary heat transfer such as radiation, insulation, and natural and forced convections were also included in the model. Model predictions agreed well with the temperature distributions measured in nickel/iron batteries. Application of the thermal model to a closely packed 330 Ah module of five cells indicated that excessive temperature rise will occur upon discharge. Forced air convection is not effective for cooling the module.

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.