Electrochemical device, joined body, method of producing electrochemical device, and method of producing joined body

A joined body, comprising:

• a first member formed of metal containing a first metal type;
• a plurality of foils each formed of metal that contains a second metal type and is different from that of the first member, the second metal type being different from the first metal type;
• and
• a second member formed of metal containing the first metal type,
• the first member and the second member being welded with the plurality of foils being sandwiched therebetween, the first metal type and the second metal type coexisting at a welding portion thereof.

A method of producing an electrochemical device, comprising:

• preparing
• an exterior can formed of metal containing a first metal type,
• an electricity storage device that includes a positive electrode, a negative electrode, and a separator, the positive electrode and the negative electrode being stacked via the separator and wound, the electricity storage device further including a lead plate that is electrically connected to one of the positive electrode and the negative electrode, contains a second metal type different from the first metal type, and is formed of metal different from that of the exterior can, the electricity storage device being housed in the exterior can, and
• a reinforcement plate formed of metal containing the first metal type;
• sandwiching the lead plate between the exterior can and the reinforcement plate;
• bringing a first welding electrode into contact with the exterior can;
• bringing a second welding electrode into contact with the reinforcement plate;
• and
• applying a voltage between the first welding electrode and the second welding electrode to join the exterior can and the reinforcement plate by resistance welding with the lead plate being sandwiched therebetween.

A method of producing a joined body, comprising:

• preparing
• a first member formed of metal containing a first metal type,
• a plurality of foils each formed of metal that contains a second metal type and is different from that of the first member, the second metal type being different from the first metal type, and
• a second member formed of metal containing the first metal type;
• sandwiching the plurality of lead foils between the first member and the second member;
• bringing a first welding electrode into contact with the first member;
• bringing a second welding electrode into contact with the second member;
• and
• applying a voltage between the first welding electrode and the second welding electrode to join the first member and the second member by resistance welding with the plurality of lead foils being sandwiched therebetween.