Hierarchical Encapsulation of Nitroxide Radical Polymers in Yarn-Ball-Like CNT Clusters for Advanced Organic Polymer Battery Cathodes

Poly(4-vinyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl) (PTVE), a nitroxide radical polymer, represents a highly promising cathode material for next-generation sustainable, high-performance rechargeable batteries. However, its practical application is hindered by intrinsic challenges, including limited electronic conductivity, high solubility in organic electrolytes, suboptimal active-material utilization, and elevated self-discharge rates. To address these limitations, a PTVE-carbon nanotube (CNT) composite with a high active-material content of 80 wt % is synthesized using a facile dissolving-diffusion technique. The resulting composite exhibits significantly enhanced electroactivity, enabling a stable and highly reversible one-electron redox process involving nitroxide radicals and oxoammonium cations within a potential window of 3.0–4.0 V. A specific capacity of 134 mAh g–1, approaching the theoretical capacity of 135 mAh g–1 for PTVE, is achieved. Additionally, the composite demonstrates superior rate performance and an extended cycle life, ensuring long-term operational stability. The remarkable electrochemical performance of the PTVE-CNT composite is attributable to the following synergistic factors: rapid redox kinetics of nitroxide radical moieties, seamless electron transport pathways enabled by the interconnected three-dimensional yarn-ball-like CNT cluster, and optimal integration and uniform dispersion of PTVE within the CNT matrix. This work highlights the potential of hybrid composites combining organic radical polymers with advanced carbonaceous architectures as transformative cathode materials for environmentally sustainable and high-performance energy-storage systems.