The invention provides a flexible
lithium secondary battery, comprising a
flexible battery shell, a battery main body and an
electrolyte, wherein the battery main body is arranged in the
flexible battery shell and comprises one or more sequentially stacked
electrode units; each
electrode unit comprises a positive plate, a flexible diaphragm and a negative plate, the positive plate, the flexible diaphragm and the negative plate are sequentially stacked, the positive plate comprises a
positive current collector and a plurality of positive active material
layers arranged on the
positive current collector in an array type, the negative plate comprises a negative
current collector and a plurality of negative active material
layers arranged on the negative
current collector in the array type, the positive plate and the negative plate have correspondingly arranged array interstitial vacancies, the correspondingly arranged array interstitial vacancies are applied to bending of a flexible
lithium secondary battery in a plane two-dimensional direction, and the width of each array interstitial vacancy is 5-50mm. The flexible
lithium secondary battery has the advantages that the integral flexibility is excellent, the
energy density is high, the battery thickness, volume and
mass are small, and the battery is suitable for flexible electronic products. The invention further provides a preparation method of the flexible lithium secondary battery.