Mitsubishi Electric, a Japanese maker of factory robots and cell phones, along with DoCoMo, the nation's biggest mobile phone operator, have recalled 1.3 million handset batteries that may overheat. The batteries were made by Sanyo GS Soft Energy, a Kyoto based unit of Sanyo Electric. Over a dozen cases of rupture or overheating have been reported and are being investigated. Deformed electrode plates in the batteries can pierce the cell's internal insulation when subjected to strong external impact. The break may cause an electrical short during or immediately after.