Ni(II) and Cu(II) coordination polymers with rubeanic acid ligands as promising electrode materials for lithium and potassium batteries

Abstract

We report the synthesis of Ni(II) and Cu(II) coordination polymers with rubeanic acid ligands and their application as electrode materials in lithium and potassium batteries. Both designed polymers delivered specific discharge capacity of ∼100–106 mAh g−1 and demonstrate stable charge-discharge cycling at 1 A g−1 for at least 300 cycles. Furthermore, Ni-based coordination polymer showed decent performance in potassium batteries providing the specific discharge capacity of 138 mAh g−1 after 400 cycles at 0.5 A g−1. The electrode degradation pathways during the battery cycling were investigated using ex-situ FTIR and XPS spectroscopy.