The present disclosure provides a battery core assembly, a battery, a battery pack, and a vehicle. The battery core assembly includes an encapsulation film and an electrode core assembly. The electrode core assembly is arranged in an accommodating cavity defined by the encapsulation film, and the electrode core assembly includes at least one electrode core. The electrode core assembly includes a first electrode lead-out member and a second electrode lead-out member for current output, and a cap is arranged in the accommodating cavity at a first end portion of the electrode core assembly. The first end portion of the electrode core assembly has the first electrode lead-out member, and the cap includes an electrode lead-out hole, where the first electrode lead-out member passes through the electrode lead-out hole.