A lithium-ion battery, comprising: a housing and at least one separator located inside the housing, wherein the separator separates an internal space of the housing into a plurality of receiving cavities; at least two or more battery core groups disposed inside corresponding receiving cavities and connected in series, wherein the battery core groups each comprise at least one pole shank; at least one separator including a liquid injection hole for electrolyte passage, and connecting two adjacent receiving cavities on two opposite sides of the separator; and a block mechanism inside the housing, wherein the block mechanism for opening and closing the liquid injection hole, wherein when the block mechanism is in a first situation, the liquid injection hole is open, when the block mechanism is in a second situation, the liquid injection hole is closed, and the block mechanism switches between the first situation and the second situation, wherein in the first situation, the block mechanism is located at a first position in the housing; and in the second situation, the block mechanism is located at a second position in the housing; wherein the separator is provided with a block mechanism placement space, the block mechanism is located inside the block mechanism placement space, the first position and the second position are formed in the block mechanism placement space, and the block mechanism moves between the first position and the second position under an external force; when the block mechanism is located at the first position, the liquid injection hole is open, the two adjacent receiving cavities are connected through the liquid injection hole; and when the block mechanism is located at the second position, the block mechanism closes the liquid injection hole, the liquid injection hole is closed, and connection between the two adjacent receiving cavities through the liquid injection hole is blocked. a housing and at least one separator located inside the housing, wherein the separator separates an internal space of the housing into a plurality of receiving cavities; at least two or more battery core groups disposed inside corresponding receiving cavities and connected in series, wherein the battery core groups each comprise at least one pole shank; at least one separator including a liquid injection hole for electrolyte passage, and connecting two adjacent receiving cavities on two opposite sides of the separator; and a block mechanism inside the housing, wherein the block mechanism for opening and closing the liquid injection hole, wherein when the block mechanism is in a first situation, the liquid injection hole is open, when the block mechanism is in a second situation, the liquid injection hole is closed, and the block mechanism switches between the first situation and the second situation, wherein in the first situation, the block mechanism is located at a first position in the housing; and in the second situation, the block mechanism is located at a second position in the housing; wherein the separator is provided with a block mechanism placement space, the block mechanism is located inside the block mechanism placement space, the first position and the second position are formed in the block mechanism placement space, and the block mechanism moves between the first position and the second position under an external force; when the block mechanism is located at the first position, the liquid injection hole is open, the two adjacent receiving cavities are connected through the liquid injection hole; and when the block mechanism is located at the second position, the block mechanism closes the liquid injection hole, the liquid injection hole is closed, and connection between the two adjacent receiving cavities through the liquid injection hole is blocked.