Crosslinkable Nitroxide Radical Polymer for Energy Storage Applications

Due to the amount of waste generated by lithium-ion batteries disposal, a more environmentally friendly option such as organic batteries is desired to fulfill the need of this large market. Redox-active radical polymers such as poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) are popularly studied as electrode materials for organic batteries. However, linear PTMA may dissolve in the electrolyte and thus degrade the battery‘s capacity over time. Therefore, crosslinked PTMA is gaining interest as one solution to this challenge.

Here, we present a simple, post-synthetic route to crosslink PTMA while maintaining a relatively high discharge capacity. PTMA monomer is randomly copolymerized with glycidyl methacrylate (GMA). Upon thermal treatment or UV radiation, PTMA is immobilized in a network. The swelling ratio of the crosslinked electrode is calculated from the dry and swelled thickness measured by electrochemical quartz crystal microbalance with dissipation (EQCM-D). The electrochemical properties of the P(TMA-co-GMA) electrodes are obtained using cyclic voltammetry and galvanostatic cycling to evaluate whether crosslinking improves cell performance. Our general finding is that PTMA dissolution was prevented by this crosslinking approach.