BINDER AND PREPARATION METHOD THEREFOR, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK AND POWERED DEVICE

The present application provides a binder and a preparation method thereof. The binder comprises a copolymer comprising a building block (I) and a building block (II), wherein the building block (I) is formed by copolymerizing a building block (i) and a building block (ii). The binder of the present application is a multifunctional binder with excellent binding, dispersing and thickening properties. An electrode sheet prepared from the binder of the present application has a relatively low electrode sheet resistance. A secondary battery prepared from the binder of the present application also has excellent cycling performance.