The invention provides an electrical insulator and a battery applying the electrical insulator. The electrical insulator comprises a separation region and a support region, wherein the support regionis provided with a circumferential edge covering the surface and at least local side surface of the separation region. The battery comprises the electrical insulator, which contacts the active material layers of the battery, wherein the electrical insulator covers at least one of the active material layers in the forward projection direction, such that the positive electrode active material layerand the negative electrode active material layer can be completely separated s as to avoid the occurrence of the internal short circuit.