Synthesis of Poly(1,4-anthraquinone) Using Catalytic Amounts of Nickel.

Multivalent metal batteries are attractive options to diversify energy storage options offering higher sustainability, but the high charge density of multivalent ions poses challenges to electrode materials. Organic electrode materials are currently the best-performing candidates, and among them, poly(1,4-anthraquinone) (P14AQ) shows excellent electrochemical properties. This holds in particular for magnesium-ion batteries, where the polymer displays reversible insertion of Mg²⁺ ions with high cycling stability. The conventional synthesis of P14AQ, however, employs stoichiometric amounts of bis(cycloocta-1,5-diene)nickel(0) (Ni(COD)₂), which is an air- and light-sensitive and expensive chemical, and therefore lacks sustainability. Herein a synthetic route to P14AQ is presented that uses only catalytic amounts of dibromobis(triphenylphosphine)nickel(II) (NiBr₂(PPh₃)₂). This route - in addition to being more cost-efficient and less toxic - results in higher yields and polymer molecular weights. A life-cycle assessment (LCA) comparing the new and conventional polymerization methods shows that regarding the environmental impact categories climate change, human toxicity, and cumulative energy demand, the new method brings significant improvement.