Single‐Atom Active Sites in Polymeric Phthalocyanine Hybrid Electrocatalysis for High‐Efficiency Lithium–Carbon Dioxide Batteries

ABSTRACT Lithium–carbon dioxide (Li–CO 2 ) batteries represent a compelling dual‐function technology that simultaneously enables electrochemical energy storage and CO 2 capture for carbon neutrality. However, the inherent insulating nature and high thermodynamic stability of lithium carbonate (Li 2 CO 3 ) discharged product impose excessive charge overpotentials and rapid capacity fade that limit practical deployment. Here, we demonstrate polymerized copper phthalocyanine immobilized on carbon nanotubes (CuPPc@CNT) as a noble‐metal‐free cathode electrocatalyst that harnesses atomically dispersed Cu–N 4 single‐atom active sites to overcome these limitations. The in situ polymerization of copper phthalocyanine units through triethylene glycol linkers enables conformal, non‐aggregated coating on the CNT surface via strong π–π interactions, ensuring efficient charge transfer and long‐term interfacial stability. The CuPPc@CNT cathode delivers a markedly reduced overpotential of 1.06 V and sustains capacity‐limited cycling up to 120 cycles, outperforming both pristine CNT and lithium polyphthalocyanine‐based counterparts. Ex situ surface characterization and in situ differential electrochemical mass spectrometry confirm highly reversible Li 2 CO 3 formation and decomposition, while theoretical calculations reveal that the Cu–N 4 coordination center provides a moderate binding strength for Li 2 CO 3 and reduces the discharge–charge potential gap to 1.43 V. These findings establish polymeric metal phthalocyanine–carbon nanotube hybrids as an advanced electrocatalyst platform for next‐generation Li–CO 2 battery technologies.