Battery, battery module, battery pack and electric vehicle

The application provides a battery, a battery module, a battery pack and an electric vehicle. The battery comprises a shell and a pole core assembly arranged in the shell, wherein the pole core assembly comprises a plurality of pole core groups and an accommodating space for accommodating the pole core groups, the pole core groups are connected in series, and each pole core group comprises at least one pole core; a partition board is arranged between at least two adjacent pole core groups, the partition board divides the accommodating space into a plurality of accommodating cavities, each accommodating cavity accommodates the pole core group, and the cavity wall of each accommodating cavity comprises the partition board and an isolating membrane connected with the partition board; the battery also comprises a liquid injection channel in a sealed state, and the liquid injection channel is arranged on the isolating membrane and/or the partition plate. The electrolyte injection process of the battery is simple, the sealing performance is good, and the battery capacity of the battery is improved.