Application of a Polyacrylate Latex to a Lithium Iron Phosphate Cathode as a Binder Material

In the manufacturing process of lithium-ion batteries, the current organic solvent-based processes will inevitably be replaced with eco-friendly water-based processes. For this purpose, the current organic-soluble binder should be replaced with a water-soluble or water-dispersed binder. In this study, a new polyacrylate latex dispersed in water was successfully applied as a binder of lithium-ion battery cathodes for the first time. One of the biggest advantages of the polyacrylate binder is that it is electrochemically stable at the working voltage of typical cathodes, unlike a conventional water-dispersed styrene-butadiene binder. This implies that the water-dispersed polyacrylate has no limitations for the usage of a cathodic binder. The performance of the polyacrylate binder for lithium iron phosphate cathodes was compared with those of a conventional organic-based polyvinylidene fluoride binder as well as a water-dispersed styrene-butadiene binder. The polyacrylate binder exhibited an electrochemical performance that was comparable to that of an existing styrene-butadiene binder and much better than that of the polyvinylidene fluoride binder. This superior performance of the polyacrylate binder is attributed to the point-to-point bonding mechanism of an emulsified binder, which leads to a strong adhesion strength as well as the low electrical and charge transfer resistances of the cathodes.