Abstract: A battery (6) includes a first end (61) and an opposite second end (63). A first mechanical connecting member (611) and a second mechanical connecting member (631) are provided on the first and second ends respectively. The first mechanical connecting member is engagable with the second mechanical connecting member of another similar battery. The second mechanical connecting member is engagable with the first mechanical connecting member of another similar battery. Thus the battery provides stabilized electrical connection with another similar battery. Preferably, the first mechanical connecting member includes two protrusion, and the second mechanical connecting member includes two receptacle engagingly receiving the protrusions of another similar battery. Each protrusion may for example be cylindrical, conical, annular, or parallelepiped-shaped. The battery may for example be cylindrical, parallelepiped-shaped, or coin-shaped. A battery assembly (600) using two or more such batteries is also provided.