The WSJ reports that Boeing has a new battery design that it will be testing once the FAA lets them fly test flights. That is why BA requested that the FAA let them fly.
It is still the lithium ion battery but with more space between cells to further isolate them from each other. It said sources say BA hopes to have the 787's back in service by March.
Time will tell.
In looking at events over the past month, it appears the NTSB still has no clue as to the cause of the battery events. They only know that there was thermal runaway. The NTSB chair went out of her way to say that the investigation was NOT thinking that the lithium battaries are unsafe for use in aircraft. So it is possible that the battery redesign is only adressing the thermall runaway and the new design will allow the 787 (assuming it works) to start flying again while the NTSB continues the investigation into the root cause of the initial incidents.
The root of the problem is still to be discovered. The battery redesign is not a solution.
It is only a bandade to the problem.
Knowing well before takeoff what the battery condition is will be the most important factor to aircraft systems integrity and to the pilots knowlege of what is happening.
Once again I feel the charging systems and their fault warnings systems are at fault.