Tu.114,
Unfortunately, moving the battery to an unpressurized position is not possible - I had the same thoughts until I read the spec. for the cells: min. operating temp. is minus 18 degrees C.
See this link:
http://www.s399157097.onlinehome.us/...s/LVP10-65.pdf
I fully agree with you that the avionics compartment is not the most "pleasant" battery location in case of fire, explosions or other problems.