A Systematic Study Aiming Toward Voltage Noise Elimination in Viscoelastic Poly(methyl methacrylate)–Poly(ethylene oxide) Polymer Blend Electrolytes in Li Metal Battery Cells

Abstract

AbstractRandom appearance of micro short circuits and voltage noise is observed, until now, on initial cycles of solid polymer electrolyte high voltage cathode cells with lithium metal anodes. However, this phenomenon also takes place in lower operation voltages such as those in LiFePO4 cathode cells. Approaching the direct/indirect effect of the cathode, the polymer electrolyte, and the anode parts on this initial dendritic bridging between the electrodes separately, a systematic study is carried out toward determining potential causes of voltage noise and ways of prevention. Electrolytes based on the blend of PMMA–PEO show that relying only on the viscoelastic nature cannot prevent the appearance of voltage noise. Liquid polymers are used for the wetting of the cathode active material that lead to a complete pore infiltration. Having ensured the optimization of the interfacial area between the solid electrolyte and the cathode, studies along the directions of the lithium surface pretreatment and polymer ionic conductivity are examined as a means of dendrite growth suppression and cell cycling capabilities improvement, leading to the observation that methylated PEO chains work in favor of both of these directions.