Flexoelectric Effect in Solid-state Polymer Electrolyte Membrane during Mechanical Deformation*

Ion diffusion is a chemical driving force for electrical power generation and signal transmission in neuron cells. There are two types of ion diffusion; passive and active. Passive diffusion is due to ion movement driven by ion concentration gradient across the membrane, which is the energy restoration process of the solid-state Li-ion batteries. During battery resting, after being fully discharged, only ~8% of energy was recovered. Alternatively, active diffusion of ions may be sought, which occurs when subjected a pressure gradient, i.e., ion pumping. In this work, the active ion diffusion process has been investigated under pressure (stress or strain) gradients across the solid polymer electrolyte membrane (PEM). Under an applied electric field, the solid PEM undergoes bending deformation and vice versa, an electric field is produced when the PEM is bent, which may be attributed to ion polarization. Of particular interest is that the flexoelectric coefficients of several PEMs, as determined under static experiment were found to be orders of magnitude greater than its counter parts - ferroelectric ceramic crystals and bent-core liquid crystals.