BATTERY CASE, BATTERY, BATTERY PACK, BATTERY MODULE, AND VEHICLE

A battery case is provided, including a plurality of side plates. A first side plate has the largest area among the plurality of side plates, and at least one first side plate includes a first portion and a second portion. The first portion is a curved surface concave toward inside of the battery case. A three-dimensional coordinate system is established in a first direction, a second direction, and a third direction, and the second direction is perpendicular to the first side plate. A curvature of the first portion is less than a curvature of an ellipsoid, the curvature of the ellipsoid is obtained from an ellipsoid function, and the ellipsoid function is: ((x−a)/i)2+((y−b)/j)2+((z−c)/k)2=1, where, a, b, c, i, j, and k are determined according to coordinates of at least four points that are different from each other, and x, y, and z are coordinates of the three directions of the ellipsoid function.