Abstract: A lithium-ion battery includes a positive electrode piece, a negative electrode piece, a separator arranged between the positive electrode piece and the negative electrode piece, and an electrolyte. The positive electrode piece includes a positive electrode current collector, a positive diaphragm and a positive electrode tab which are attached to a surface of the positive electrode current collector. The negative electrode piece includes a negative electrode current collector, a negative electrode diaphragm and a negative electrode tab which are attached to a surface of the negative electrode current collector. The negative electrode diaphragm is provided with a first groove in which the negative electrode tab is arranged. The positive electrode piece opposite to the first groove is provided with a first insulating adhesive tape thereon, and the positive electrode diaphragm around an edge of the first insulating adhesive tape is provided with a first adhesive tape groove.