A battery assembly comprising: a first housing shell having a first perimeter side wall, a first housing bottom, and a first contact area on said first housing bottom; a second housing shell having a second perimeter side wall, a second housing bottom, and a second contact area on said second housing bottom, said second housing shell being disposed in said first housing shell with said second contact area opposing said first contact area; an insulator interposed between said first housing shell and said second housing shell to effect electrical insulation between said first housing shell and said second housing shell; and battery components comprising: an anode electrode electrically communicated to one of said first contact area or said second contact area; a cathode electrode electrically communicated to another one of said first contact area or said second contact area; and a separator interposed between said cathode electrode and said anode electrode, said separator including an electrolyte; wherein said first housing bottom of said first housing shell opposes said second housing bottom of said second housing shell to define a battery component cavity in conjunction with said first perimeter side wall of said first housing shell, and said anode electrode, said separator, and said cathode electrode are disposed in said battery component cavity; characterized in that said second perimeter side wall includes a U-fold extending from a junction with said second housing bottom toward said first housing bottom and defines at least a portion of said battery components cavity; wherein said U-fold has first and second opposite outer surfaces and said insulator is disposed on said first and second opposite outer surfaces. a first housing shell having a first perimeter side wall, a first housing bottom, and a first contact area on said first housing bottom; a second housing shell having a second perimeter side wall, a second housing bottom, and a second contact area on said second housing bottom, said second housing shell being disposed in said first housing shell with said second contact area opposing said first contact area; an insulator interposed between said first housing shell and said second housing shell to effect electrical insulation between said first housing shell and said second housing shell; and battery components comprising: an anode electrode electrically communicated to one of said first contact area or said second contact area; a cathode electrode electrically communicated to another one of said first contact area or said second contact area; and a separator interposed between said cathode electrode and said anode electrode, said separator including an electrolyte; wherein said first housing bottom of said first housing shell opposes said second housing bottom of said second housing shell to define a battery component cavity in conjunction with said first perimeter side wall of said first housing shell, and said anode electrode, said separator, and said cathode electrode are disposed in said battery component cavity; characterized in that said second perimeter side wall includes a U-fold extending from a junction with said second housing bottom toward said first housing bottom and defines at least a portion of said battery components cavity; wherein said U-fold has first and second opposite outer surfaces and said insulator is disposed on said first and second opposite outer surfaces.