Secondary battery and method of manufacturing secondary battery

A method of manufacturing a secondary battery, the method comprising:

• forming a battery device having an elongated shape, by stacking a positive electrode and a negative electrode on each other with a separator interposed therebetween, the positive electrode and the negative electrode each being a sheet having a substantially rectangular shape;
• compression-bonding the positive electrode, the negative electrode, and the separator to each other in compression-bonding regions to thereby allow the battery device to include the compression-bonding regions and a non-compression-bonding region other than the compression-bonding regions, the compression-bonding regions being provided at least at two respective positions opposed to each other in a peripheral edge part of the substantially rectangular shape of the battery device;
• placing the battery device inside an outer package member and partly sealing the outer package member to leave an opening to thereby provide the outer package member with a pouch shape, the outer package member having flexibility;
• injecting an electrolytic solution into the outer package member through the opening;
• and
• sealing the opening.