Increasing ionic conductivity in polymer electrodes using oxanorbornene

Pendant polymer-based organic electrodes consisting of redox-active quinones are promising for the next generation of rechargeable batteries owing to their fast redox kinetics and the structural diversity of their design. Many commercially available norbornene monomers have been popular choices for preparing pendant polymer electrodes, since these monomers enable numerous synthetic routes for attaching redox-active pendant groups. However, these electrodes often suffer from sluggish lithium-ion mobility at both the electrode-electrolyte interface and within the bulk of the electrode because of their poor ionic conductivity. This can lead to low cycling stability and rate capability. In this study, we design and compare the performance of redox-active poly(norbornene) and poly(oxanorbornene) pendant polymer electrodes. The additional oxygen in the repeat unit of poly(oxanorbornene) facilitates conduction of Li-ions, resulting in improved performance relative to their poly(norbornene) counterparts. Specifically, higher reversible capacities are achieved at high current densities and initial capacity is better retained during prolonged cycling tests. Unlike previous strategies to increase the ionic conductivity of polymer electrodes, our design involves minimal synthetic steps and only contributes to a small increase in additional redox-inactive mass, offering a versatile platform for high-performance organic electrode materials.