To demonstrate the concept of rechargeable polymer electrolyte bipolar lithium batteries, laboratory-type bipoIar Li/pyrite 3-cell batteries were fabricated and tested. The unoptimized 5 V, 10 cm(2) 3-cell battery had a capacity of 30-40 mAh with 100% Faradaic efficiency. The long-term projection for a prototype sealed bipolar Li/composite polymer electrolyte/pyrite (Li/CPE/FeS2) battery, with a 45 mum-thick cathode is 250 Wh/kg specific energy. The performances of monopolar and bipolar battery designs are compared.