Lithium ion battery, battery module, battery pack and automobile

The invention provides a lithium ion battery which comprises: a shell and partition plates located in the shell, wherein the partition plates divide the interior of the shell into a plurality of containing cavities, pole core groups are arranged in the containing cavities, each pole core group comprises at least one pole core, the pole core groups are connected in series, a liquid injection hole is formed in at least one partition plate, and the liquid injection hole is used for communicating two adjacent containing cavities on the two sides of the partition plate; and a blocking mechanism which is located in the shell, wherein the blocking mechanism can enable the liquid injection hole to be in a preset state, and the preset state comprises an opening state and a closing state. According to the battery provided by the invention, liquid injection can be facilitated, and meanwhile, isolation and safety of the pole core groups can be ensured. Meanwhile, the invention also provides a battery module, a battery pack and an automobile based on the battery provided by the invention.