Electronic device comprising battery

An electronic device, comprising:

• a housing including a plate;
• a base member disposed in the housing and disposed substantially parallel to the plate;
• and
• a battery disposed in an area of the base member, and configured to supply power to the electronic device, wherein the battery includes:
• an electrode assembly including a first portion and a second portion having different sizes;
• and
• a battery case including a receiving space that houses the electrode assembly, and a sealing portion disposed along an outer periphery of the electrode assembly,
• wherein the first portion and the second portion meet at a stepped corner portion, without a formation of a space recessed inward of the electrode assembly,
• wherein the sealing portion comprises:
• a first elongated structure adjacent to the stepped corner portion and formed to be elongated when sealing the battery case;
• a first outer periphery portion extending from the first elongated structure along a side surface of the first portion and facing the side surface of the first portion;
• and
• a second outer periphery portion extending from the first elongated structure along a side surface of the second portion facing to be perpendicular to the first outer periphery portion and facing the side surface of the second portion,
• wherein the first elongated structure smoothly connects the first outer periphery portion and the second outer periphery portion, and is formed concavely toward the stepped corner portion,
• wherein an elongated length of the first elongated structure is greater than a width which is defined in a direction perpendicular to the side surface of the first portion of the first outer periphery portion, and a width which is defined in a direction perpendicular to the side surface of the second portion, of the second outer periphery portion.