Nanostructure-forming polymers have tremendous potential to enhance the performance and safety of lithium-ion batteries (LiBs) as a result of their ability to simultaneously optimize often contradictory properties, such as ionic conductivity and mechanical stability, in a single material. These macromolecules can be harnessed in both LiB electrolyte and electrode components. With respect to electrolytes, advances in salt-doped and single-ion systems are highlighted herein with a focus on strategies that improve conductivities to rival that found in gel and liquid electrolytes, while also permitting further enhancements in electrochemical and mechanical stability. In the arena of electrodes, three major functions are considered: binders to maximize active material efficiency, polymer electrodes to enable fully organic LiBs, and sacrificial constructs that template high surface area, well-ordered metal oxide or metallic electrodes to improve electrode capacity. Additionally, the application of theory and simulation to streamline the development of key structure–property−processing relationships in ion-conducting nanomaterials is discussed. Finally, several next steps and future directions are suggested to accelerate the fabrication of next-generation LiBs.