Cathode Characteristics of Organic Electron Acceptors for Lithium Batteries

Discharge and charge characteristics of cathode‐active materials for lithium batteries were studied. Electron acceptors of charge transfer complex with high electron affinity were examined as cathode‐active materials because they were expected to have high cell voltage. These electron acceptors are 2,4,7‐trinitro‐9‐fluorenone (TNF), 2,4,5,7‐tetranitro‐9‐fluorenone, 7,7,8,8‐tetracyanoquinodimethane, 9,10‐phenanthrenequinone, and 13 other compounds. Among these compounds, TNF showed the highest discharge capacity (1050 A‐hr/kg) and the highest energy density (2030 W‐hr/kg). Cycle lives of TNF were 400 and 54 times at charge‐discharge capacity of 100 of A‐hr/kg (1.2 electron transfer per 1 mol TNF) and 200 A‐hr/kg (2.4 electron transfer per 1 mol TNF), respectively. The cycle tests indicate reversibility of TNF up to two‐electron transfer.