| CPC H01M 50/538 (2021.01) [H01M 10/0431 (2013.01); H01M 10/0525 (2013.01); H01M 50/107 (2021.01); H01M 50/152 (2021.01); H01M 50/169 (2021.01); H01M 50/186 (2021.01); H01M 50/474 (2021.01)] | 10 Claims |

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1. A cylindrical lithium-ion battery, comprising a negative cap, a case, a jellyroll, and a negative current collector, wherein the case is cylindrical;
the jellyroll and the negative current collector are arranged inside the case, a sidewall of a bottom of the case is provided with an annular inwardly-concaved groove, the annular inwardly-concaved groove is arranged circumferentially around a central axis of the case, and the annular inwardly-concaved groove forms an annular protrusion inside the case, the negative current collector is connected to a negative electrode of the jellyroll, a portion of the case located below the annular inwardly-concaved groove is bent to form an annular engaging groove, an opening of the annular engaging groove faces towards the interior of the case, a periphery of the negative cap is arranged in the annular engaging groove, and a bottom surface of the negative cap and the annular engaging groove are connected in a sealed manner by laser welding.
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