Limitations of Polyacrylic Acid Binders When Employed in Thick LNMO Li-ion Battery Electrodes

Abstract

Polyacrylic acid (PAA) was studied as a binder material for LiNi0.5Mn1.5O4 (LNMO) cathodes for lithium-ion batteries. When the LNMO electrodes weare fabricated with an active mass loading of ~10 mg cm-2 (~1.5 mA h cm-2), poor discharge capacity and short cycle life was obtained in full-cells with graphite electrodes. The electrochemical results with PAA were compared with a commonly used water-based binder, sodium carboxymethyl cellulose (CMC), which showed better electrochemical performance. The main cause for these problems in PAA based cells was identified to be the high internal resistance in the initial cycles, caused by factors such as contact resistance, inhomogeneous binder distribution, and poor electrolyte wetting of the active material.