An electronic device having a semi-rigid battery pack is disclosed. The semi-rigid battery pack offers an internal power supply with relatively high energy density (energy per volume) with a stiff cover covering the battery pack to shield other internal components from the battery pack. The cover may also be formed with a larger dimension than that of the battery pack such that when the battery pack undergoes a swelling event, the battery pack increases its volume while still be contained by the cover. In this manner, other internal components may be positioned proximate to the cover without being affected by the battery pack. In another embodiment, a mold member covers an outer peripheral portion and supports the battery pack while allowing the battery pack to undergo a swelling event.