Safety of Lithium Batteries

It is remarkable that C&EN would publish an article on the safety issues of lithium-ion batteries without referring to the nature of the polymers (membrane separator) (Dec. 17, 2007, page 26). If, as speculated, the problem is related to possible foreign contamination affecting the separator, how could the nature of the separator membrane not be mentioned and noted, no less addressed and discussed?

That the nature is indeed relevant is admitted later in the article where it is stated that "manufacturers are developing new types of separators made from polymers that are more likely than conventional separators to remain intact at high temperatures." Does this imply that present membranes do not remain intact at high temperatures?

This article raises the question of a correlation between the issue of the burning of batteries and the nature of the polymer membrane separator. Yet this does not seem to have been considered, no less discussed. Changing electrodes is only half the story.

Bruce Bernstein
Rockville, Md.