Perylenetetracarboxylic Diimide as Diffusion‐Less Electrode Material for High‐Rate Organic Na‐Ion Batteries

Abstract

In this work 3,4,9,10-perylenetetracarboxylic diimide (PTCDI)i si nvestigated as electrode material for organic Na-ion batteries. Since PTCDI is aw idely used industrial pigment, it may turn out to be ac ost-effective, abundant, and environmentally benign cathode materialf or secondary Na-ion batteries. Among other carbonyl pigments, PTCDI is especially interesting due to its high Na-storage capacity in combination with remarkable high rate capabilities.T he detailed analysiso fc yclic voltammetry measurements reveals a diffusion-less mechanism,s uggesting that Na-ion storagei n the PTCDI film allows for exceptionally fast charging/dischargingr ates. This finding is furtherc orroborated by galvanostatics odiation measurements at high rates of 17 C (2.3 Ag À1), showing that 57 %o ft he theoretically possible capacityo fP TCDI,o r7 8mAh g À1 ,a re attained in only 3.5 min charging time.

Substrate Dependent Charge Transfer Kinetics at the Solid/Liquid Interface of Carbon‐Based Electrodes with Potential Application for Organic Na‐Ion Batteries

“…A small current signal around 1.6 V for the Cp electrode and around 1.3 V for the CuC electrode has already been previously reported and is attributed to some side reaction of the substrate with the electrolyte (1 M NaFSI in EC/DMC, see Experimental Section). [37] As previously reported, [39] the PTCDI coated Cp electrodes (Figure 4c) are characterized by two broad reduction peaks at 1.99 V, with a current density of 2.82 mA cm À 2 , and 1.86 V, with a current density of 2.97 mA cm À 2 (at 200 mV s À 1 ), corresponding to two one electron reductions of the PTCDI molecule, and one intense back-oxidation peak at 2.20 V, having a current density of 6.97 mA cm À 2 (at 200 mV s À 1 ).…”

“…The reason for this behavior has been studied in detail in our previous work, where we were able to show that the charge transfer is governed by a diffusion-less mechanism, where the transport of the Na counter ion is apparently not a limiting factor. [39] Consequently, exceptionally high charge transfer rates are possible. Since the PTCDI film is best described by a multilayer surface confined electrode, the kinetic limitation of the electrode is expected to be governed by the electron exchange reaction throughout the stacked PTCDI layers.…”

“…This tailing at small scan rates has been previously explained by kinetic limitations of the electron exchange reaction throughout the film. [39] Laviron et al revealed in a theoretical study that for a multilayer surface confined electrode, the kinetic limitation of the charge transfer throughout the organic layers is at the beginning visible for slow scan rates, whereas the kinetic limitation of the electrochemical reaction of the first layer with the carrier substrate, here Cp, follows for faster scan rates. [74] Physically this can be interpreted as the PCTDI molecules in different layers need a slightly different energy (potential) to be reduced /oxidized, hence the broadening of the peaks.…”

“…[27] Carbon materials derived from biomass are widely applied in bioelectrochemical systems, [28][29][30] biosensing applications, [31] and ITO electrode replacement. [32] Additionally, their high electrical conductivity and overall stability during cycling, makes carbon based materials suitable for rechargeable electrochemical power sources, such as batteries, including stationary and large-scale systems, [10,33,34] supercapacitors, [35,36] Na-ion batteries, [37][38][39] and Na-ion capacitors. [40] For all these applications, an efficient charge transfer at the materials interfaces (solid/solid or solid/liquid) is crucial and found to be ideal for applications in combination with organic semiconductors (OSCs).…”

“…[52] In recent years PDIs have also shown potential to be used in Na-ion batteries. [39,53] Our group has shown that an industriallyrelevant pigment, perylene tetracarboxylic diimide (PTCDI, Scheme 1), is capable of delivering high sodiation rates (2.3 A g À 1 ) with a capacity of 78 mAh g À 1 under 5 minutes charging time. [39] In this work we investigate the role of two different conductive carbon substrates, graphite/copper (CuC) and carbon paper (Cp), towards their charge transfer kinetics at the solid/solid and solid/liquid interface.…”