Sandwich-like Structure of Carbon Fluoride/Graphene Oxide/Polyacrylonitrile Cathode for Lithium and Sodium Batteries.

Carbon fluoride/graphene oxide/polyacrylonitrile (CF _x/GO/PAN, denoted as CGP) electrodes are prepared for lithium primary and sodium secondary batteries. The introduction of GO sheets and PAN built a sandwich-like structure. The rate performances of Li/CGP batteries verify that PAN and GO materials have negligible effects on the electrochemical properties of lithium primary batteries. In Na/CGP batteries, GO sheets have more defects to facilitate sodium ions transfer and offer more active sites for NaF deposition and decomposition. Meanwhile, the GO network coating of the CF _x particles confines active fluorine during the cycles. Cubic and nanoscale discharge products of NaF form both on the surface of CF _x particles and the GO sheets, respectively. Na/CGF batteries achieve an initial discharge capacity of 507.0 mAh g⁻¹ and a voltage polarization of 0.75 V, except in the first cycle. These results demonstrate that CGP electrodes with a sandwich-like structure have favorable electrochemical properties, resulting in the synergetic effect of GO sheets and PAN. [ABSTRACT FROM AUTHOR]