Separator, battery cell, battery, and electrical apparatus

A separator, comprising a polymer group, wherein the polymer group comprises at least one of a first polymer and a second polymer,

• wherein the separator satisfies:
• 1.5
• ≤
• [
• m
• 2
• -
• M
• m
• 1
• -
• M
• ]
• ×
• v
• λ
• ≤
• 1
• ⁢
• 2
• ;
• M represents mass of the separator that does not absorb an electrolyte solution, and a unit thereof is g;
• m1 represents mass of the separator weighed under an ambient pressure after same is soaked in the electrolyte solution for 2 h, and a unit thereof is g;
• m2 represents mass of the separator weighed under a pressure of 10,000 N in the ambient pressure after same is soaked in the electrolyte solution for 2 h, and a unit thereof is g;
• v represents a liquid absorption rate of the separator, and a unit thereof is mg/s;
• and
• λ represents porosity of the separator.