25. April 2016 : Poly(vinylferrocene)–Reduced Graphene Oxide as a High Power/High Capacity Cathodic Battery Material
Seyyed Mohsen Beladi-Mousavi, Shamaila Sadaf, Lorenz Walder,* Markus Gallei, Christian Rüttiger, Siegfried Eigler, and Christian E. Halbig
The preparation and performance of a new cathodic battery material consisting of a composite of poly(vinylferrocene) (PVFc) and reduced graphene oxide (rGO) is described. It shows the highest charge/discharge efficiency (at a rate of 100 A g−1) ever reported for ferrocene–polymer materials. The composite allows for specific capacities up to 0.21 mAh cm−2 (770 mC cm−2, 29 μm film thickness) at a specific capacity density of 114 mAh g−1 and less than 5% performance decay over 300 cycles. The composite material is binder free and the charge storing PVFc accounts for 88% of the total weight of the cathodic material. The superb performance is based on (i) perfect self-assembling of oxidized PVFc on graphene oxide (GO) leading to PVFc@GO, (ii) its stepwise (n steps) transfer onto a current collector (CC) (PVFc@GO)n@CC (n = drop casting steps), and (iii) the efficient electrochemical transformation of GO into rGO in the composite using viologen as homogeneous electrocatalyst. The self-assembling step is analyzed by zeta potential and atomic force microscopy (AFM) studies, demonstrating heavy ferrocene loading on GO and a mesoporous composite structure, respectively. Complete GO/rGO transition and quantitative ClO4 − ion breathing of the composite are found by electrochemical quartz crystal microbalance and by electrochemical AFM.
Advanced Energy Materials