A battery has a battery case with a hole, and a micro-electro-mechanical system (MEMS) safety valve mounted to the battery case over the hole. The MEMS safety valve includes a silicon diaphragm and a silicon electrode layer with a movable electrode mounted above the diaphragm, a stationary electrode around the movable electrode, and one or more links electrically connecting the movable and the stationary electrodes. The stationary electrode, the links, and the movable electrode form part of an electrical path between one or more battery cells and a battery terminal. The links break to open the electrical path when the pressure in the battery case pushes the diaphragm and the links past a first limit. The diaphragm breaks to release fluid from the battery case when the pressure pushes the diaphragm past a second limit. The first limit may be smaller, larger, or the same as the second limit.