Power storage device and method for manufacturing the same

A power storage device comprising:

• a positive electrode;
• a negative electrode including a negative electrode current collector and a negative electrode active material layer;
• and
• an electrolyte provided between the positive electrode and the negative electrode,
• wherein the negative electrode active material layer includes:
• a silicon layer over the negative electrode current collector, the silicon layer including a common portion and a projected portion;
• a first layer including silicon oxide, the first layer being over and in contact with the silicon layer;
• and
• graphene over and in contact with the first layer,
• wherein the common portion is in contact with an entire surface of the negative electrode current collector, and
• wherein the projected portion is extended from the common portion.

A power storage device comprising:

• a positive electrode;
• a negative electrode including a negative electrode current collector and a negative electrode active material layer;
• and
• an electrolyte provided between the positive electrode and the negative electrode,
• wherein the negative electrode active material layer includes:
• a silicon layer over the negative electrode current collector, the silicon layer including a common portion and a projected portion;
• a first layer including silicon oxide, the first layer being over and in contact with the silicon layer;
• and
• graphene over and in contact with the first layer,
• wherein the common portion is in contact with an entire surface of the negative electrode current collector,
• wherein the projected portion is extended from the common portion,
• wherein the silicon layer includes a core which is included in the common portion and the projected portion,
• wherein the core includes crystalline silicon and the silicon layer includes amorphous silicon covering the crystalline silicon.