The lithium battery is wound into the shell and the bottom welding roll groove follows the principle that the negative electrode covers the positive electrode and has the following control points:
(1) At the end of the winding head, the negative electrode exceeds the positive electrode by more than 5mm;
(2) The negative pole at the edge of the pole piece wraps the positive pole (X-ray detection).
(3) Spot welding meets the process requirements-welding tension, no false welding, but welding.
(4) The rolling groove conforms to the process size, and there is no appearance problem such as coating drop, and no warped gasket phenomenon.
Diagram of internal short circuit phenomenon of lithium battery:
1. Metal particles can enter the battery, and the triangular area rarely appears during the electrolyte injection process.
2. After the electrolyte is charged and discharged, the particles are dissolved and deposited on the negative electrode.
3. Lithium metal dendrites grow on the nickel negative electrode. It reaches the positive electrode through the separator. Finally, a short-circuit path is created between the negative electrode and the positive electrode and causes a fire.
Since the aluminum foil directly acts on the positive substrate, the presence of thermally active metal lithium and low short-circuit resistance can assist in the occurrence of fire.