Bio-Derivative Galactomannan Gum Binders for Li 4 Ti 5 O 12 Negative Electrodes in Lithium-Ion Batteries

Abstract

Two types of galactomannan gum derived from plant seeds, guar gum (GG) and tara gum (TG), were used for the first time as the binders for Li4Ti5O12 (LTO) negative electrodes in lithium-ion batteries; they were thoroughly compared to typical carboxymethyl cellulose (CMC) binder using various characterization techniques. The galactomannan gums, branched polysaccharides, better facilitate the transport of lithium ions in LTO electrodes than CMC binder, a cellulose (linear polysaccharide) derivative, even though their binding capability is not as strong as CMC. This is attributed to a large extent of electrolyte uptake and a large LTO surface exposed to electrolyte when the gum binders are used. In particular, the GG-containing LTO electrode exhibits a high reversible capacity of 160.0 mAh g-1 at the 100th cycle with 1 C current rate, whereas the CMC-containing LTO electrode has a reversible capacity of 150.1 mAh g-1. The difference in capacity between the GG and CMC electrodes increased at higher current rates and was approximately 25 mAh g-1 at 10 C current rate.