Power storage device and method for manufacturing the same

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 active material comprises a first active material and a second active material,
• wherein the first active material has a composition of LieFefPgOh 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 LiaFebPcOd satisfying relations 3.5≦d/c≦4.5, 0.6≦c/b≦1.8, and 0.7≦a/b≦2.8.

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;
• a first film over the collector, the first film containing a first active material;
• and
• a second film over the first film and in contact with the electrolyte, the second film containing a second active material,
• wherein the first active material is lithium iron phosphate containing Fe(II), and
• wherein the second active material is lithium iron phosphate containing Fe(III).

A method for manufacturing a power storage device, the method comprising the steps of:

• forming a first active film over and in contact with a collector;
• and
• forming a second active film over the first active film,
• wherein the first active film comprises a first active material,
• wherein the second active film comprises a second active material,
• wherein the first active material is lithium iron phosphate containing Fe(II), and
• wherein the second active material is lithium iron phosphate containing Fe(III).