Poly(vinylferrocene)–Reduced Graphene Oxide as a High Power/High Capacity Cathodic Battery Material

Abstract

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.

Why is Ferrocene so Exceptional?

“…Polymers with ferrocene-containing side chains show useful properties including air stability, fast electrochemical kinetics, and stable voltage plateaux for the development of cathodic battery materials. [215][216][217][218][219][220] Such polymers are electrically insulating, however, which limits their use as energy storage materials to small thicknesses, because fast charging/discharging kinetics are required. The electronic conductivity can be enhanced, however, by introduction of conductive polymers.…”

“…[216] Ferrocene polymers have also been used as battery materials after carbon fillers were loaded into the polymer matrixes. [217][218][219][220] Walder's group recently reported a way to disperse negatively charged graphene oxide (GO) single sheets with partially oxidized poly(vinylferrocene) through electrostatic interactions with use of polymer/GO weight ratios of up to 10:1. Remarkably, these authors found that a film of (PVFc@rGO)@CC (current collector) with a specific capacity of 5.8 mC cm -2 was >98 % charged/discharged in less than 3 s, and that increasing the layer thickness up to ca.…”

Recent Trends in Metallopolymer Design: Redox‐Controlled Surfaces, Porous Membranes, and Switchable Optical Materials Using Ferrocene‐Containing Polymers

“…The changesi np olarity prior to and after oxidation of PVFc was used to achieve molecularly tightly connected graphene sheets-metallopolymer strands. [72] For this purpose, the nega-tively charged graphene oxide and partially oxidized, positively chargedP VFc was used. Mesoporousc omposite structures featuring ion percolating properties were accessible for the preparation of metallopolymer battery applications.…”

Synthesis of Breathing Metallopolymer Hollow Spheres for Redox-Controlled Release

“…In the recent past, the interesting ferrocene/ferrocenium redox couple in metallopolymers has attracted significant interest due to the unique ability to (electro)chemically switch between hydrophobic ferrocene and comparably hydrophilic ferrocenium moieties . Moreover, such types of metallopolymers revealed an excellent combination of (switchable) redox, mechanical, semi‐conductive, photo‐physical, optoelectronic, magnetic, and catalytic properties . A very recent review highlighting the progress of metallopolymers in the field of biomedical applications is given by Tang and co‐workers .…”

“…[12][13][14][15] Moreover, such types of metallopolymers revealed an excellent combination of (switchable) redox, mechanical, semi-conductive, photo-physical, optoelectronic, magnetic, and catalytic properties. [16][17][18][19][20][21] A very recent review highlighting the progress of metallopolymers in the fi eld of biomedical applications is given by Tang and co-workers. [ 22 ] Since A convenient synthetic approach for the preparation of uniform metallopolymer-containing hollow spheres based on 2-(methacryloyloxy)ethyl ferrocenecarboxylate (FcMA) as mono mer by sequential starved feed emulsion polymerization is described.…”