Patent ID: 8530068

Claim:
A square battery comprising: a wound body in which a positive electrode sheet coated with a positive electrode active material and a negative electrode sheet coated with a negative electrode active material are wound together with a separator therebetween into a flat shape; a container in which the wound body is contained; a cover to seal the container; a positive electrode external terminal and a negative electrode external terminal provided on the cover; a positive electrode current collector to electrically connect a positive electrode connection part of the positive electrode sheet to the positive electrode external terminal; a negative electrode current collector to electrically connect a negative electrode connection part of the negative electrode sheet to the negative electrode external terminal; spreading members to push and extend a laminate of the positive electrode connection part of the positive electrode sheet and a laminate of the negative electrode connection part of the negative electrode sheet from inside at both end surfaces of the wound body; a shaft core around which the positive electrode sheet, the negative electrode sheet and the separator are wound is further provided, and the spreading members are provided on the shaft core; wherein: a slit is formed in the shaft core, and the spreading member is inserted in the slit.