X-ray diffractometry applied to the comparative study of processes of formation of automotive batteries

X-RAY DIFFRACTOMETRY APPLIED TO THE COMPARATIVE STUDY OF PROCESSES OF FORMATION OF AUTOMOTIVE BATTERIES

LUCILA E. P. BORGES

Departamento de Engenharia de Minas, CTG-UFPE, Recife, PE, Brazil.

Presented by VALDEREZ P. FERREIRA

X ray diffraction was applied to the investigation of the main steps in lead acid battery production (mixing, soaking and formation) in order to improve manufacturing conditions and to contribute with a theoretical understanding of these processes.

In the first step, mixing, the following results were obtained: (a) liquid nitrogen freezing of the paste was effective; (b) the reaction was instantaneous; (c) it is directly related to the amount of acid added.

In the soaking step, plates with a high content of total sulfate display a final monobasic lead sulfate content bigger than those displayed by plates with low content of total sulfate. In order to explain this behavior, two hypotheses are proposed: (a) 3BS could lead to monobasic sulfate crystallization; and (b) 1BS initially present in the plates could act as seeds for further crystallization. Crystal sizes were also followed as a function of time during the soaking period, demonstrating the possibility of extending the use of X-ray diffraction in the observation of crystal sizes in this and any other step of battery production.

In continuous current formation it was observed that higher temperatures (60^oC) are favorable, affected by an increase in current and especially by the interaction: increase in current vs. increase in density. The best results of plate formation were obtained with plates rich in tribasic lead sulfate. It was found that the total charge used in the industry is too high and a reduction of up to 43% of the charge yields excellent results, with PbO₂ contents as high as 92% with an average of 80%.

A laboratory test of pulsed formation showed that longer time is the main factor in order to achieve better results, moreover longer pulses in experiments with short times also yield higher contents of PbO₂.

In a comparison of both formation schemes it was observed that pulsed formation was more efficient, with respect to total PbO₂ obtained, with plates richer in tetrabasic sulfate. In continuous formation, under the same experimental conditions, no tetrabasic sulfate remains unformed. — (May 24, 2002) .

Publication Dates

• Publication in this collection
  09 Oct 2002
• Date of issue
  Sept 2002