Patent ID: 9577268
Date: 2017-02-21
CPC Classifications: H01G,H01M,Y02E,Y02P,Y10T

Claim:
1. A power storage device comprising a plurality of stacks which are stacked, wherein the plurality of stacks comprise; a positive electrode current collector; a positive electrode active material layer over the positive electrode current collector; a negative electrode active material layer over the positive electrode active material layer; a negative electrode current collector over the negative electrode active material layer; and an electrolyte layer between the positive electrode active material layer and the negative electrode active material layer, wherein the negative electrode active material layer comprises a low density layer, the negative electrode active material layer is a silicon film, and the low density layer is part of the silicon film, wherein the low density layer is in contact with the negative electrode current collector; wherein the low density layer comprises a void, wherein a density of silicon of the low density layer is lower than a density of silicon of the negative electrode active material layer, wherein the positive electrode current collector has a thickness of more than or equal to 10 nm and less than or equal to 1 μm, and wherein the negative electrode current collector has a thickness of more than or equal to 10 nm and less than or equal to 1 μm.