Encapsulation of Iodine in Nitrogen-Containing Porous Carbon Plate Arrays on Carbon Fiber Cloth as a Freestanding Cathode for Lithium-Iodine Batteries

Rechargeable lithium-iodine (Li-I2) batteries are a promising energy storage technology because of their cost-effectiveness and nature abundance of iodine. However, the low electron conductivity, slow diffusion kinetics, and poor stability of iodine are the big hindrances to the technology development. We report here an approach to improving iodine cathode performance by stabilizing iodine with polyvinylpyrrolidone (PVP) and porous nitrogen-containing carbon plate arrays (PNCA) grown on carbon fiber cloth. This freestanding composite electrode exhibits a charge storage capacity of 132 mA h g–1 at 5C and stable cycling stability (150 mA h g–1 after 1000 cycles at 1C). The cycling stability of the electrode is due to the confinement effect of PNCA and PVP via both physical and chemical forces. In situ Raman spectroscopy results suggest that the I3–/I– redox couple is highly reversible during galvanostatic charge/discharge cycling. The pseudocapacitive lithium storage behavior of the composite electrode enables its high rate performance in Li-I2 batteries. This work provides a facile approach to designing freestanding cathode materials for high-rate and stable Li-I2 batteries.