Effect of Lithium 4-Styrene Sulfonate-Based Self-Doped Polymer Electrolyte on LiMn2O4 Electrodes in Lithium-Ion Secondary Batteries

摘要

In this study, the synthesized poly(lithium 4-styrene sulfonate)-based self-doped solid polymer electrolytes were incorporated into LiMn2O4 (LMO) electrodes by two processes. In the first process, the prepared LMO electrode was coated with a polymer electrolyte at an appropriate thickness, whereas in the second, the electrolyte was used as a binder in the fabrication of the LMO electrode. Among the electrodes coated with various thicknesses, the best discharge-capacity characteristics were obtained for the one with the thinnest coating. In particular, the capacity improved by 19% than that of the uncoated electrode at a thickness of less than 1 mu m in a discharge capacity test at 60 degrees C. In contrast, when the polymer electrolyte was used as 50 wt% of the binder, the discharge capacity over 50 cycles increased by 4.5%. This increase is attributed to a decrease in charge transfer resistance owing to the presence of the polymer electrolyte in the LMO electrodes. However, the discharge capacity decreased when 75 wt% of the polymer electrolyte was included in the binder. Therefore, excellent discharge-capacity characteristics can be expected when an appropriate amount of self-doped polymer electrolyte is used as a coating or binder material for LMO electrodes.