Synthesis and solvent-free polymerisation of vinyl terephthalate for application as an anode material in organic batteries

Abstract

The synthesis and polymerisation of dimethyl 2-vinylterephthalate M1 for possible applications as an anode material in organic secondary batteries are reported. M1 exhibits a vinyl group as a polymerisable unit while the carboxylate moieties serve as cation (Li⁺, Na⁺) coordinating sites. The gram-scale synthesis of M1 is described via three different routes in order to evaluate the route with the highest overall yield. Furthermore, different conditions for free radical polymerisation are investigated for obtaining polymer P1 with high molecular weights in order to study the impact of immobilising the carboxylate redox-active centres in a polymer on the charge/discharge cycling stability when used in an organic battery. In order to synthesis suitable materials for battery investigations, P1 was post-functionalised to the corresponding lithium salt P1-Li, which was further electrochemically investigated. Cyclic voltammetry measurements showed for P1-Li redox activity in the range of 0.5–1.2 V vs. Li⁺/Li which assigns it as a candidate for the anode. Under the present experimental conditions, the galvanostatic measurements of P1-Li exhibited a specific capacity of 64 mA h g⁻¹. It is further demonstrated that P1-Li shows an improved cycling stability of 83% discharge capacity remaining after 100 cycles compared to the parent monomer (44%).