Cell with an outer layer of intumescent material

A battery assembly, comprising:

• a battery, said battery comprising:
• a cell case comprising an outer sidewall surface, a first end portion and a second end portion, wherein said first end portion is comprised of a cell case bottom with an outer bottom surface, and wherein said second end portion is comprised of a central open portion;
• an electrode assembly contained within said cell case, wherein a first electrode of said electrode assembly is electrically connected to said cell case;
• and
• a cap assembly mounted to said cell case, said cap assembly closing said central open portion of said second end portion, wherein said cap assembly further comprises a battery terminal electrically isolated from said cell case and electrically connected to a second electrode of said electrode assembly;
• and
• a layer of an intumescent material coating said outer bottom surface and said outer sidewall surface except for a case contact region of said outer sidewall surface of said cell case, wherein said case contact region is located within said second end portion of said outer sidewall surface of said cell case, wherein said case contact region is proximate to an end surface of said second end portion of said cell case.