Unfortunately the problem is likely to get worse.
Most cell phones and PEDs today have Lithium-ion technology batteries. Already there is Lithium Polymer which is a higher power/weight ratio and soon there will be Lithium Sulfur.
Failures will be either faulty cells or faulty charging. If you have ever seen a Li-Po fire they have somewhat worrying tendancy to spray burning Lithium
I think we will see even more 'dodgy' aftermarket batteries as the market is just so big.