Electrochemical Properties of Powdery LiNi1/3Mn1/3Co1/3O2 Electrodes with Styrene-Acrylic-Rubber-Based Latex Binders at High Voltage.

Efforts to improve the energy density and cycling stability of lithium-ion batteries have focused on replacing LiCoO2 in cathodes with LiNixMnyCo1-x-yO2. However, reliance on polyvinylidene fluoride (PVdF) as the binder limits the application of the LiNixMnyCo1-x-yO2 composite electrode for lithium-ion batteries. Here, we evaluate the electrochemical properties of a LiNi1/3Mn1/3Co1/3O2 (NMC111) powder electrode formed using a waterborne-styrene-acrylic-rubber (SAR) latex binder combined with sodium carboxymethylcellulose. The composite electrodes prepared with the SAR-based binder copolymerized with the butyl acrylate monomer and styrene exhibited high adhesive strength and excellent cyclability and rate capability. The results of surface analysis via X-ray photoelectron spectroscopy suggested that the electrode with the SAR-based binder is more resistant to electrolyte decomposition during charge and discharge cycling compared with the NMC111 electrode comprising the conventional PVdF binder. The SAR-derived passivation resulted in enhanced capacity retention during long-term cycling tests of both half- and full-cells (NMC111//graphite). An electrode with a higher Ni content, LiNi0.6Mn0.2Co0.2O2 (NMC622), fabricated using the SAR-based binder, retained 87.1% of its capacity after 50 cycles at 4.6 V and exhibited excellent cycling stability.