A power storage cell comprising: an electrode assembly; a cell case that houses the electrode assembly; and an electrolytic solution contained in the cell case, wherein the electrode assembly includes: a plurality of electrodes (110, 120) arranged side by side in one direction; and a separator formed in a zigzag shape and configured to insulate the plurality of electrodes from each other, the separator includes: a plurality of intervening portions, each of which is interposed between a pair of electrodes adjacent to each other in the one direction; an upper folded portion which connects an upper end of one intervening portion of the plurality of intervening portions and an upper end of another intervening portion of the plurality of intervening portions which is adjacent to the one intervening portion on one side of the one direction; and a lower folded portion which connects a lower end of the one intervening portion of the plurality of intervening portions and a lower end of another intervening portion of the plurality of intervening portions which is adjacent to the one intervening portion on the other side of the one direction, the plurality of electrodes include a plurality of positive electrodes and a plurality of negative electrodes, the negative electrode is disposed above the lower folded portion, and the porosity of the lower folded portion is smaller than that of the intervening portion, characterized in that: the separator further includes a side covering portion which faces both ends of the plurality of electrodes in a width direction orthogonal to both the one direction and a vertical direction and is connected to the lower folded portion, the side covering portion and the lower folded portion form a storage space for storing the electrolytic solution below the negative electrode, and the side covering portion is provided with a void filling material that fills voids in the separator. an electrode assembly; a cell case that houses the electrode assembly; and an electrolytic solution contained in the cell case, wherein the electrode assembly includes: a plurality of electrodes (110, 120) arranged side by side in one direction; and a separator formed in a zigzag shape and configured to insulate the plurality of electrodes from each other, a plurality of electrodes (110, 120) arranged side by side in one direction; and a separator formed in a zigzag shape and configured to insulate the plurality of electrodes from each other, the separator includes: a plurality of intervening portions, each of which is interposed between a pair of electrodes adjacent to each other in the one direction; an upper folded portion which connects an upper end of one intervening portion of the plurality of intervening portions and an upper end of another intervening portion of the plurality of intervening portions which is adjacent to the one intervening portion on one side of the one direction; and a lower folded portion which connects a lower end of the one intervening portion of the plurality of intervening portions and a lower end of another intervening portion of the plurality of intervening portions which is adjacent to the one intervening portion on the other side of the one direction, a plurality of intervening portions, each of which is interposed between a pair of electrodes adjacent to each other in the one direction; an upper folded portion which connects an upper end of one intervening portion of the plurality of intervening portions and an upper end of another intervening portion of the plurality of intervening portions which is adjacent to the one intervening portion on one side of the one direction; and a lower folded portion which connects a lower end of the one intervening portion of the plurality of intervening portions and a lower end of another intervening portion of the plurality of intervening portions which is adjacent to the one intervening portion on the other side of the one direction, the plurality of electrodes include a plurality of positive electrodes and a plurality of negative electrodes, the negative electrode is disposed above the lower folded portion, and the porosity of the lower folded portion is smaller than that of the intervening portion, characterized in that: the separator further includes a side covering portion which faces both ends of the plurality of electrodes in a width direction orthogonal to both the one direction and a vertical direction and is connected to the lower folded portion, the side covering portion and the lower folded portion form a storage space for storing the electrolytic solution below the negative electrode, and the side covering portion is provided with a void filling material that fills voids in the separator. the separator further includes a side covering portion which faces both ends of the plurality of electrodes in a width direction orthogonal to both the one direction and a vertical direction and is connected to the lower folded portion, the side covering portion and the lower folded portion form a storage space for storing the electrolytic solution below the negative electrode, and the side covering portion is provided with a void filling material that fills voids in the separator.