Description: NASA has identified needs for compact high-energy-density primary and secondary batteries. Lithium and Lithium Ion cells, respectively, are meeting these needs for both manned and unmanned needs. The high power available in some of these cell chemistries can cause substantial internal heating in the event of sustained internal and external heating. At sufficiently elevated temperatures, cell components can react energetically causing cell case rupture, and in some cases, fire. The proposed will develop and demonstrate an internal means of controlling short circuit, which is chemically and electrochemically compatible with the cell's active materials. Using suitable controls, safe handling of an external short circuit will be demonstrated in small cells.