When Daimler unveils its electric car strategy tomorrow, one of the things to really focus on is the battery chemistry.

Is the company adopting lithium-cobalt batteries? lithium phosphates? lithium nickel manganese?

It's a crucial question. Ever since a few Dell laptops blew up in spectacular fashion in 2006, a big question for electric car makers has been how to insulate drivers from a "thermal runaway reaction," otherwise known as an explosion.

Tesla Motors makes its battery pack out of lithium cobalt cells, the chemistry that's used inside notebook batteries. To prevent explosions and passenger injury, Tesla created a somewhat elegant battery pack that insulates the cells from each other. It also came up with software and monitoring systems to take potentially errant batteries out of commission.

It's a great idea, but it also, arguably, could become something of an anachronism some day. Tesla devised its battery pack with lithium cobalts in part because that is what existed when it first started designing its car. Since then, the alternative chemistries have been honed and other battery makers are gravitating toward them. These batteries can withstand higher operating temperatures and thus don't need the same ornate battery pack. (The second element – cobalt, manganese, etc. – refers to the chemical composition of the components, such as the cathode, in the battery.).

Nissan, for instance, has a lithium manganese polymer battery it devised with NEC. GM went with a manganese battery from LG Chem for the Volt. Fisker Automotive has said it will use batteries from Ener1, another manganese company. Miles EV wouldn't tell me precisely what it is using, but said it won't be cobalt. Chrysler will use A123 Systems batteries, which are lithium phosphates. Aptera won't say what battery they are using, but sources say it isn't cobalt. Think, I think, continues to work with Ener1.

So far, Tesla is the only automaker I know actively plugging cobalt.

Some of these batteries don't perform as well as cobalts in certain circumstances. Lithium phosphates, which can withstand higher temperatures, don't have the same energy density, so a car packed with them can't drive as far. These new types of lithium batteries also aren't being made in as large of volumes. Thus, cobalt will be around for a while. Daimler has already said that it will use Tesla battery packs in some cars, so cobalt will get a boost there, and if the deal between two expands tomorrow, all the better for cobalt. If Daimler goes with another battery company, and another chemistry, it may be another strong indication that the chemistries are indeed changing.

Tesla could one day even switch. Who knows what will happen. But this is an issue to keep an eye on.