Here is another link from Ars technica on this issue:
Boeing’s Dreamliner batteries “inherently unsafe”
The issue to stress is that these batteries are impossible to put out because they generate oxygen when in thermal runaway. Hence the spectacular roman candle video of what they can do. The safe technology based on LiFePO4 is unfortunately going to result in an approximate doubling of battery weight according to a battery specialist I talked to about this. How much do the batteries of the 787 weigh, so what would be the 'added weight of the solution?