A method for manufacturing folding electric core of an electrode composite unit, comprising steps of: a, providing a strip-shaped electrode composite unit, the electrode composite unit comprising multiple electrode layers, a separator layer being provided between two adjacent electrode layers having opposite polarities, a top electrode layer located on a top of the electrode composite unit comprising multiple top electrode units arranged in a row, a bottom electrode layer located on a bottom of the electrode composite unit comprising multiple bottom electrode units arranged in a row, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent top electrode units, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent bottom electrode units, and a blank region greater than or equal to a length of one electrode unit being formed on at least the top electrode layer and the bottom electrode layer at a head end and/or a tail end of the electrode composite unit; and b, folding the head end of the electrode composite unit up and down alternatively, with the length of one electrode unit as a unit of folding each time, to form an electric core of battery; in the electric core of battery, two adjacent electrode units having opposite polarities, the electrode units at a top and a bottom of the electric core of battery being both negative electrodes and covered by the separator layer; characterized in that, the number of the separator layers is odd, the top electrode layer located on the top of the electrode composite unit and the bottom electrode layer located on the bottom of the electrode composite unit have opposite polarities; the electrode composite unit comprises the top electrode layer, a first separator layer, a first electrode layer, a second separator layer, a second electrode layer, a third separator layer and the bottom electrode layer, from top to bottom; the first electrode layer comprises multiple first electrode units spaced apart from each other and arranged in rows, the second electrode layer comprises multiple second electrode units spaced apart from each other and arranged in rows, the first electrode units are aligned with the second electrode units in a vertical direction, the top electrode units are aligned with the first electrode units, and the bottom electrode units are aligned with the second electrode units. a, providing a strip-shaped electrode composite unit, the electrode composite unit comprising multiple electrode layers, a separator layer being provided between two adjacent electrode layers having opposite polarities, a top electrode layer located on a top of the electrode composite unit comprising multiple top electrode units arranged in a row, a bottom electrode layer located on a bottom of the electrode composite unit comprising multiple bottom electrode units arranged in a row, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent top electrode units, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent bottom electrode units, and a blank region greater than or equal to a length of one electrode unit being formed on at least the top electrode layer and the bottom electrode layer at a head end and/or a tail end of the electrode composite unit; and b, folding the head end of the electrode composite unit up and down alternatively, with the length of one electrode unit as a unit of folding each time, to form an electric core of battery; in the electric core of battery, two adjacent electrode units having opposite polarities, the electrode units at a top and a bottom of the electric core of battery being both negative electrodes and covered by the separator layer; characterized in that, the number of the separator layers is odd, the top electrode layer located on the top of the electrode composite unit and the bottom electrode layer located on the bottom of the electrode composite unit have opposite polarities; the electrode composite unit comprises the top electrode layer, a first separator layer, a first electrode layer, a second separator layer, a second electrode layer, a third separator layer and the bottom electrode layer, from top to bottom; the first electrode layer comprises multiple first electrode units spaced apart from each other and arranged in rows, the second electrode layer comprises multiple second electrode units spaced apart from each other and arranged in rows, the first electrode units are aligned with the second electrode units in a vertical direction, the top electrode units are aligned with the first electrode units, and the bottom electrode units are aligned with the second electrode units.