| 摘要 |
<p>An additive with which a nonaqueous-electrolyte secondary battery or nonaqueous-electrolyte electric-double-layer capacitor having excellent low-temperature properties while retaining necessary battery properties, etc. can be produced; and a nonaqueous-electrolyte secondary battery and a nonaqueous-electrolyte electric-double-layer capacitor both containing the additive. The additive is characterized by containing at least tautomers of a phosphazene derivative which are represrnted by general formulae (1) and (2), wherein R?1, R2, and R3¿ each represents a monovalent substituent or a halogen element; X represents a substituent containing at least one of carbon, silicon, germanium, tin, nitrogen, phosphorus, arsenic, antimony, bismuth, oxygen, sulfur, selenium, tellurium, and polonium; and Y?1 and Y2¿ each represents a divalent connecting group, divalent element, or single bond.</p> |
