The invention relates to a core component and a battery. The core component comprises a protective box and a core main body comprising a diaphragm, wherein the core main body is disposed in the protective box to surround the diaphragm with the protective box; the core component is used to be placed in a shell, and the protective box is used to be arranged between the main body and the shell to separate the diaphragm from the shell. In the core component, when the core component is put in the shell and after an electrolyte is injected into the protective box and the protective box is vacuumed,the diaphragm adsorbs part of the electrolyte, and the free electrolyte is extracted; the core is arranged in the protective box to surround the diaphragm with the protective box to avoid the contactof the diaphragm and the shell so as to reduce the phenomenon that the adsorbed electrolyte in the diaphragm corrodes the shell. Besides, in the core component, since the core is disposed in the protective box and the protective box surrounds the diaphragm, the protective box can be prevented from being scratched by contact of the diaphragm and the shell when the core component is arranged into the shell.