In Situ Formation of Lithium Polyacrylate Binder for Aqueous Manufacturing and Recycling of Ni-Rich Cathodes

Abstract

Water has now become the standard process solvent for graphite-based anodes, eliminating the use of toxic and costly N-Methyl-pyrrolidone (NMP) in anode manufacturing. Ideally, water could also become the standard for cathodes; however, water-based processing of NMC cathode materials induces lithium leaching, which reduces their specific capacity and leads to capacity fade. Here, we demonstrate that leached lithium ions can be exploited during aqueous slurry preparation to create a Li-containing polymer binder that enables cathode performance comparable to those fabricated using NMP. Specifically, we show that leached lithium ions from LiNi0.8Mn0.1Co0.1O2 (NMC 811) particles react with polyacrylic acid (PAA) to form a lithium polyacrylate (LPA) surface coating and binder. Because the resulting LPA binder is water soluble, aqueous-based recycling of the cathode particles is feasible and over 90% capacity retention is shown in recycled material after 100 cycles.