A battery core assembly includes an encapsulation film and multiple electrode core assemblies disposed in the encapsulation film. The electrode core assemblies are connected to form an electrode core string, and each of the electrode core assemblies includes at least one electrode core. A spacer is disposed between two adjacent electrode core assemblies, the first spacer divides an accommodating space inside the encapsulation film into multiple accommodating cavities, cavity walls of the accommodating cavities includes the first spacer and the encapsulation film connected to the first spacer, and the electrode core assemblies are respectively accommodated in the accommodating cavities. The first spacer includes at least one first liquid reservoir, and the at least one first liquid reservoir communicates with one of accommodating cavities on both sides of the first spacer.