Patent ID: 8795895

Claim:
A power storage device comprising: a negative electrode; and a positive electrode facing the negative electrode with an electrolyte provided therebetween, wherein the positive electrode comprises a collector and a film containing an active material formed over the collector, wherein the film is in contact with the electrolyte, wherein the film has a stacked structure including a first layer and a second layer which comprise a first active material and a second active material, respectively, wherein the first active material has a composition of Li e Fe f P g O h satisfying relations 3.5≦h/g≦4.5, 0.6≦g/f≦1.1, and 0≦e/f≦1.3, and wherein the second active material has a composition of Li a Fe b P c O d satisfying relations 3.5≦d/c≦4.5, 0.6≦c/b≦1.8, and 0.7≦a/b≦2.8.