Periodic conductivity trends are placed in the scope of lithium-ion batteries, where increases in the ionic radii of salt components affect the conductivity of a poly(ethyleneoxide)-based polymer electrolyte. Numerous electrolytes containing varying concentrations and types of metal salts are prepared and evaluated in either one or two laboratory sessions, requiring cooperation between all students in the classroom. The experiment is suitable for either high school students with a general chemistry background or undergraduate students in introductory general chemistry courses, as a number of fundamental topics can be discussed with this simple, inexpensive, and real-world-oriented project. (Contains 4 figures.)