US Patent 10115535 Electric storage device

In an embodiment, an electric storage device 1 includes: an electric storage element 50 having a positive electrode and a negative electrode; a non-aqueous electrolytic solution constituted by a non-aqueous solvent primarily containing cyclic ester and cyclic carbonate ester, in which an electrolyte containing lithium salt is dissolved and to which a sulfonate ester derivative whose reduction potential is higher than that of the cyclic ester and cyclic carbonate ester is added; and an outer container 70 that stores the electric storage element 50 and non-aqueous electrolytic solution. The electric storage device can offer both good low-temperature characteristics and good high-temperature reliability.