Glass corrosion in ambient temperature lithium battery headers
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RodK. Quinn Los Alamos National Laboratories, Los Alamos, New Mexico 87544 (Received 12 August 1986; accepted 2 February 1987) During high-temperature storage, glass corrosion in glass-to-metal feedthroughs can limit the lifetimes of lithium batteries designed to operate at ambient temperatures. Ampule tests have been conducted to simulate glass corrosion for Li/So 2 , Li/SOCl 2 , and Li/SOCl 2 + BrCl batteries. In all lithium battery systems tested, lithium metal has been identified as the source of glass corrosion. On the basis of thermodynamic and kinetic stability, glass compositions have been developed that minimize the corrosion problem in all lithium battery systems tested.
I. INTRODUCTION Ambient temperature lithium batteries are among the most advanced commerical batteries for high-power, low-temperature applications. A schematic of a Li/ SO2 D-cell battery is shown in Fig. 1. A key component of the battery is the glass-to-metal feedthrough, or battery header, which is shown in the Fig. 1 insert. The header consists of an inner and outer conductor for internal attachment of the anode and cathode and external attachment of battery leads. The conductors are electrically isolated from each other by a glass insulator, which also functions as part of the hermetic battery seal required to contain volatile battery components. Studies of Li/SO 2 batteries1 have shown that header glass corrosion can limit battery lifetimes to 6 months or less at 70 °C.2'3 Failure modes that have been observed include (1) electrical shorting through conductive corrosion products and (2) cracking of the glass resulting in the loss of volatile components of battery electrolytes. The latter failure has been shown to be the result of changes in the stress distribution in header glass resulting from glass corrosion.2'4 The kinetics and mechanisms of glass corrosion have been studied in a controlled manner using ampule experiments to simulate battery environments. Tests have been conducted to study glass corrosion in the Li/ SO2, Li/SOCl 2 , and Li/SOCl 2 + BrCl (BCX) battery environments, and a model has been proposed to describe corrosion in all ambient temperature lithium batteries. The model has been used at Sandia National Laboratories (SNL) to develop corrosion-resistant glass compositions such as TA-23 (see Ref. 2), which have largely eliminated glass corrosion as a process that limits battery lifetimes. The rate-determining step in the model is the corrosion of glass by lithium metal deposited next to the header anode. Therefore understanding the kinetics and mechanisms of reactions between alkali metals and glass is essential to understanding glass cor182
J. Mater. Res. 2 (2), Mar/Apr 1987
http://journals.cambridge.org
rosion for ambient temperature lithium batteries and developing corrosion resistant glass compositions.
II. EXPERIMENTAL The glass ampule configuration used to simulate battery environments for the majority of the glass corrosion tests is depicted in Fig. 1. Four glass compositions used in battery headers are
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