Helical Poly(isocyanide anthraquinones)-Based Cathodes for Long-Cycling Lithium Metal Batteries

Thanks to the unique rigid conformation and designable side-chain structure, helical polymers are starting to be more widely considered as ideal electrode materials in secondary batteries. In this study, a series of helical poly(isocyanide anthraquinones) (PIC-AQs), including PIC-1AQ_n and PIC-2AQ_n, were designed and synthesized via living polymerization using a palladium catalyst (Pd-II). The polymers feature a helical polyisocyanide main chain and anthraquinone (AQ) pendants, offer high yields (approximately 90%), controlled number-average molecular weight (M_n), and a low polymer dispersity index (PDI). Attributed to a narrow energy band gap, low unoccupied molecular orbitals, and high spatial freedom of PIC-2AQ, it exhibits excellent long-term stability in lithium metal batteries (LMBs), maintaining 141 mAh g^-1 after 2000 cycles at 1 A g^-1. Additionally, an in situ polymerized poly(ionic liquid) electrolyte was prepared for assembling a PIC-2AQ all-solid-state soft-pouch battery. And it remained stable under extreme operations like bending or cutting. Such a battery significantly broadens the application scope of organic LMBs and offers great potential for their use in flexible electronic devices.