Piperazine derivative, process for producing the same, polymeric solid electrolyte and secondary battery

A novel piperazine derivative which is suitable for use as a hardener or crosslinking agent; a polymeric solid electrolyte which is obtained with the piperazine derivative and has high ionic conductivity and electrochemical stability; and a secondary battery employing the polymeric solid electrolyte. The piperazine derivative is novel piperazine derivative having per molecule two or more groups represented by the following formula: wherein R1 to R6 each is hydrogen or lower alkyl; and X is oxygen, sulfur, or NR6.