Patent ID: 8168331

Claim:
An electrochemical device comprising a cathode, an anode and an electrolyte arranged between the cathode and anode, wherein the electrolyte comprises an ionic liquid comprising an anion and a cation, which cation has the formula N-methyl-N-hexyl-pyrrolidinium, wherein the active material of the cathode comprises as its major constituent by mass an intercalation material having an upper reversible-potential-limit of at most 4 V versus Li/Li + and comprising any of the following compounds: Li 4 Ti 5 O 12 , LiTi 2 O 4 , Li 4-y Mg y Ti 5 O 12 (0≦y≦1), V 2 O 5 , Li 4 Mn 5 O 12 , or Li 4-y Mg y Mn 5 O 12 (0≦y≦1).