An electrode core assembly is provided, which includes an encapsulation film (11), an electrode core (12) and an spacer ring (13). The electrode core (12) and the spacer ring (13) are both arranged in an accommodating cavity defined by the encapsulation film (11). The electrode core (12) includes an electrode core body (121) and two electrode lead-out members of opposite polarities that are electrically connected to the electrode core body. The length of the electrode core body (121) extends along a first direction. Two opposite ends of the electrode core body (121) in the first direction include a V-shaped end face (1211) with a tip and protruding outward from the electrode core body (121), and the positions where the two electrode lead-out members are connected to the electrode core body (121) are respectively located at the tips of the two V-shaped end faces (1211). The spacer ring (13) includes an inclined portion (131) on the V-shaped end face (1211), and the inclined portion (131) is provided with an electrode lead-out hole (1310) penetrating through the spacer ring (13) and configured to lead out the electrode lead-out member.