Effects of Electrolyte Composition on Mn( II) dissolution Behavior ofLiMn204 Cathode for Li-ion Battery

Abstract

LiMn204 (LMO) is a promising cathode for Lithium ion battery due to its low cost and environmental inertness. However, LMO suffers from Mn dissolution followed by cell degradation. Mn-dissolution is electrode/electrolyte interfacial phenomenon, thus it is heavily affected by electrode surface and electrolyte. However, more methodical research about the relationship between the electrolyte property and Mn-dissolution has not been carried out so far. This study investigates the dependence of the Mn-dissolution on electrolyte composition and binders at high temperature (60 °C ) . The Mn2+ ion concentration in the electrolyte after high temperature (60 °C ) storage was analyzed by using atomic absorption spectroscopy (AAS). It was revealed that increasing EC content and storage duration accelerates Mn-dissolution. When different solvents are used instead of EC, Mn-dissolution behavior becomes severe in the same order of the solvation energy of the solvent. It was also found that proper additives can be very effective in suppressing Mn-dissolution. P2, the most effective additive to suppress the dissolution behavior, has advantage to improve the cell performance of the LMO/Graphite cell. Furthermore, PAN is revealed to be an outstanding binder for LMO electrodes based on its excellent rate capability, superior cycle performance, and high thermal stability when compared to the other three binders. ⓒ 2014 DGIST