Packaging housing, battery, and electric device

A cell includes an electrode assembly and a tab electrically connected to the electrode assembly, the packaging housing includes a housing body, a cover, and a polymer layer. The housing body is provided with an accommodating portion, where the accommodating portion is configured to accommodate the electrode assembly, the tab extends from the accommodating portion to the outside of the housing body, and the housing body is further provided with a first sealing portion extending from an edge of an opening of the accommodating portion to the outside of the housing body along a first direction. The cover is provided with a second sealing portion extending along the first direction. The cover covers the opening of the accommodating portion, and the first sealing portion and the second sealing portion are disposed opposite to each other. The polymer layer is disposed between the first sealing portion and the second sealing portion.