Copper-Coordinated Organometallic Polymers for Stable Lithium-Ion Storage

Lithium-ion capacitors (LICs) combine the high energy density of batteries with the high power density and long-term stability of capacitors, but are hindered by the limited performance of conventional carbon-based anodes. Herein, we report a Cu²⁺-p-phenylenediamine coordination polymer (Cu-PPD) with a flower-like morphology as a new anode material for LICs. Local Cu─N coordination interactions are proposed to enhance electronic conductivity through charge transfer between metal ions and organic ligands, while the rigid framework is expected to suppress active material dissolution. Kinetic analysis indicates a pseudocapacitance-dominated mechanism (85% capacitive contribution at 1.0 mV s^-1), and ex-situ XPS confirms the synergistic contribution of Cu²⁺/Cu⁺ redox centers and C═N active sites. The Cu-PPD anode retains 88% capacity after 200 cycles at 2 A g^-1. When paired with activated carbon, the pre-lithiated Cu-PPD//AC LIC operates stably within 0.01-4.4 V, delivering a maximum energy density of 92.7 Wh kg^-1 at 141.9 W kg^-1 and retaining 87% capacitance after 1000 cycles at 1 A g^-1. This work provides a molecular engineering blueprint for converting soluble organic ligands into robust, high-rate, and long-life coordination-polymer anodes, demonstrating the feasibility for organic materials in high-performance LICs.