Lithium ion battery is composed of positive and negative electrode sheets, adhesive, electrolyte and separator. In industry, manufacturers mainly use lithium cobalate, lithium manganate, lithium nickel cobalt manganate ternary materials and lithium ferrous phosphate as cathode materials of lithium ion batteries, and natural graphite and artificial graphite as cathode active materials. Polyvinylidene fluoride (PVDF) is a widely used positive electrode binder with high viscosity, good chemical stability and physical