Effects of polymeric binders on electrochemical performances of spinel lithium manganese oxide cathodes in lithium ion batteries

Effects of polymeric binders on both the dissolution of manganese (Mn) and electrochemical properties of spinel LiMn2O4 (LMO) electrodes are investigated in detail. Three promising polymers, polyvinyl alcohol (PVA), polyacrylic acid (PAA), and polyacrylonitrile (PAN) are chosen as binders for the LMO electrodes and compared to currently popular polyvinylidene fluoride (PVdF). For LMO electrodes fabricated with the selected binders, physicochemical properties including surface coverage, adhesion strength, and electrolyte uptake are examined. Also, electrochemical performance factors such as Mn dissolution behavior, rate capability, cycle performance, and thermal stability are investigated. 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. This can be ascribed to an appropriate amount of electrolyte uptake and low impedance of the PAN despite the relatively large surface coverage of the LMO that leads to lower Mn dissolution.