Lithium salt of carboxymethyl cellulose as an aqueous binder for thick graphite electrode in lithium ion batteries

Abstract

The increase in a graphite electrode thickness is an inevitable to achieve the high energy density of lithium ion batteries (LIBs). However, the increment of electrode thickness results in a significant degradation of the electrochemical performances due to a poor kinetic associated with lithium ion caused by a long lithium ion diffusion length and large polarization. To improve the kinetic associated with lithium ion, the lithium salt of carboxymethyl cellulose (Li-CMC) is introduced as a binder. The Li-CMC is synthesized from sodium salt of carboxymethyl cellulose (Na-CMC) via simple two-step method. The thick graphite electrode prepared with Li-CMC exhibits much improved electrochemical performances, including a specific capacity and a cycle performance, compared to that with Na-CMC. The voltage profiles, electrochemical impedance spectroscopy (EIS), and rate capabilities results indicate that these improvements are attributed to improved lithium ion kinetics and low polarization by employing Li-CMC binder.