How can they sell something that when it malfunctions, it is a Class D fire so you had better run? Because everyone else does.
Although quite entertaining to blow up, generally speaking they are fairly safe if they have overvoltage/undervoltage cut off for each cell (each one!) They also should have vents in them that rupture if the pressure inside gets too high from overcharging/over discharge or thermal runaway. The reason those Sony cells started on fire was due to an internal short as there was metal shavings in the electrolyte which would cut through the plastic after expansion/contraction from cycling the batteries. If it has an internal short, no protection devices will work (called Battery Management Systems or BMS) The cells internally short to themselves, it creates heat rapidly goes into thermal runaway and boom. They don't call it "explosion", the term is "violent venting with flame"
Much safer is Lithium-Iron Phosphate (LiFePO4) VS Lithium-Cobalt Oxide. You can shoot a hole in a LiFePO4, crush them, short the terminals together and it might vent a bit--won't blow though. The cell phone type have a flammable metal and and oxidizer mixed together--they used to call those solid fuel rockets.
The Volt used LiMn batteries, better than LiCoO but can burn if you do something stupid and use electrically conductive coolant (when dried) and give it to the government who would crush it and turn it upside down for 3 weeks. Chevy is switching to A123 Systems LiFePO4 so the LG Chems are heading to the sunset.
I like LiFePO4 batteries, I've been using the A123 versions for the last 5 years plus with my DeWalt 36V tools. They throw out the current, light weight, as long as you charged them in the past 6 months or so--they hold their charge and I've had no issues.
So if LiFePO4 batteries can take 3,000 cycles, heat does not bother them, they won't explode, nothing toxic in them, should last 7 to 10 years at least and (in bulk) cost less to make than LiMn/LiCoO/LiPo.... they should of taken over the market quickly. Not so fast...here are the downsides
They are 3.2V and not 3.6V like regular Li cells. It was easy to change from NiCd/NiMH cells since they are 3.6V for three of them. It costs money to change the design for the different voltage.
They don't have the same watt hours by weight/size as regular lithium cells, it is about 25% lower. Most consumers would rather risk blowing their body parts off than have a slightly thicker phone or a little less runtime.
The Tesla roadster used over 6,900 Sony laptop cells--heck of a battery management system to keep the pack alive. One cell goes into thermal runaway which causes the cells around it to go...and so on. The new models are going to run LiFePO4 cells, much better performance, longevity, cycle life and it won't explode.
To remember how to take care of batteries, remember it this way. Only car batteries or lead-acid likes to be trickle charged or charged to 100%. ALL other batteries should never be trickle charged or kept at 100% charge. For long term storage, lithium chemistry prefers to be kept at a 40 to 60% charge level.
One last tip, don't use regular lithium batteries in a sealed metal device--like a flashlight for instance. They make a really big mess if they ever vent violently with flame and will take chunks out of cement etc.
If you have an afternoon to blow and would like to learn more about fun with batteries, here is the site.
Basic to Advanced Battery Information from Battery University
It is owned by Cadex which makes battery chargers/conditioners/analyzers for all sorts of cells.
Low voltage detector for LIPOs
