A process for producing a boric acid ester compound which comprises esterifying
a compound represented by the formula (1):
X—[O(AO)n—H]a (1)
wherein X represents a group independently selected from a residue of a compound
having 1 to 6 hydroxyl groups, an acryloyl group and a methacryloyl group with
a boron-containing compound represented by the formula (2):
(RO)3—B (2)
wherein R represents an alkyl group having 1 to 4 carbon atoms. The present
invention can provide a boric acid ester compound which has a high ion conductivity,
which is useful as a material for an electrochemical device, such as a secondary
battery or a capacitor, having excellent safety and which is low in water and impurity
contents, a polymer electrolyte containing the boric acid ester compound, and a
secondary battery using the polymer electrolyte.
