Isolating membrane, secondary battery, battery module, battery pack and electric device

The invention provides an isolating membrane, a secondary battery, a battery module, a battery pack and an electric device, the isolating membrane sequentially comprises a first area, a main body area and a second area along a first direction, at least one surface of the first area and/or at least one surface of the second area is provided with a fluorescent coating, and the fluorescent coating is used for identifying whether the isolating membrane is folded or not. The isolating membrane can be recognized in time after being folded, the situation that the folded isolating membrane is made into the lithium ion battery is avoided, and improvement of the yield of the lithium ion battery is facilitated. 本申请提供了一种隔离膜、二次电池、电池模块、电池包和用电装置，沿第一方向，隔离膜依次包括第一区、主体区和第二区，第一区的至少一个表面和/或第二区的至少一个表面设置有荧光涂层，荧光涂层用于标识隔离膜是否出现翻折。本申请的隔离膜能够在发生翻折后被及时识别出，避免发生翻折的隔离膜被制成锂离子电池，有利于锂离子电池良率的提高。