While this is not commonly[clarification needed] known,[according to whom?] the CIA developed and created the concept of long-term, reliable battery life with the lithium-ion battery.[20] The reasoning for the interest in this technical development was to prolong the battery lifetime of many surveillance equipment used in the field. Once developers within the DS&T perfected the chemical composition in the mid 1960s, it was then declassified to allow for use in the private sector.[21]