The lithium-ion battery is the most preferred choice for energy storage, for example, in electric vehicle batteries and electronic devices. These commonly utilized transition metal-based cathodes and graphite anodes. However, replacing the active materials with organic, redox-active materials is of great interest since these organic batteries are excelling in charging speed and cycling stability. Therefore, in the present thesis, the synthesis and characterization of potential organic electroactive materials, mainly polymers, are investigated. Concerning the structure of the polymers, linear polymers, three-dimensional / crosslinked polymers, as well as dendrimers, were chosen. The electroactive subunits include viologen, imide, triphenylamine, porphyrin, and ferrocene, either as homopolymer or copolymer, as well as active materials like graphene oxide (GO) or electrolytes. The characterization of the structures was performed by means of NMR, FTIR spectroscopy, and elemental analysis. The electrochemical properties of products were investigated by the cyclic voltammetry (CV) technique. Electrodes were prepared by drop-casting a solution of the polymers onto a current collector, and the (dis)charge performance was investigated. To enhance the conductivity of the layers, composites of the polymers with GO were prepared. Since the performance depends on the electrolyte composition, different types of solvents and salts were used and compared. The capacities in a thin film of pure polymers and dendrimers were much smaller than in the composite film with rGO. These performances are based on the molecular self-assembly of polymers and dendrimers on individual GO sheets yielding colloidal polymer/dendrimer@GO and efficient GO/rGO transformation electrocatalyzed by polymers and dendrimers. However, the stability and capacity of some polymers and dendrimers such as P2, P5, P6 and G2 were not optimal in this type of composite film. Moreover, the peak potential in the positive charge range assigned to the nitrogen centre of triphenylamine and porphyrin was found to decrease after the first scan, which is probably due to a dissolution of the film. Therefore different methods were used to composite polymer or dendrimer with GO such as reducing GO before mixing. As noticed that the redox behaviour of amine and ferrocene are reversible, but the stability of radical cation species is not stable in organic solvent after oxidation. Besides the preparation of electrodes by drop-casting, the layer-by-layer process was used by alternate dipping between cationic polymer solution and anionic GO or Poly(sodium p-styerenesulfonate) (PSS) solution. PSS acts as a counter ion for the polymer, which changes the moving species in the electrolyte from anion to cation. As noted that a large cation (TBA+) shows lower capacity compared to small cations (Li+, K+). Apart from the CV, quartz crystal microbalance (QCM) was used to monitor layer growth.

With an increasing share of intermittent electricity production in the energy system, there is an increased need for energy storage. Because of electrochemical batteries’ ability of modularization, fast response and flexibility, grid connected energy storage will enable load balance and dispatching stored energy to optimize grid operations. Grid operation applications such as frequency regulations, peak- and time-shifting will enable saving otherwise curtailed renewable energy. The extraction of materials and the manufacturing of batteries are though energy intense processes themselves. Ligna Energy develops an organic battery, based on organic electronic polymers and biopolymers from the forest. These organic batteries are less energy dense, but do not contain conflicts material, require any strict, energy consuming production environment and can be burned as biofuels in the end of life. Standardize methods for life cycle assessment is a useful tool to determine the cumulative energy demand from extraction of material to end of life thermal conversion. Operation applications such as increase of self-consumption, energy time shift and frequency regulation show that the Ligna Energy organic battery deliver more energy to the grid through the specific operation, than demanded for manufacturing after 15, 9 respectively 1 year.

Organic electrode materials are finding increasing use in energy storage devices due to their attractive properties that allow building of flexible and low weight devices in an environmentally friendlier manner than traditional alternatives. Among these organic electrode materials, conducting redox polymers (CRPs), consisting of conducing polymer (CP) with covalently attached redox active pendant groups (PG), have attracted our interests. This is due to the advantageous synergy between CP and PG, e.g. electronic conductivity, high stability and large charge storage capacity. In this thesis polypyrrole has been selected as CP and quinones as PGs. A series of quinone-pyrrole dyad polymers has been synthesized with a variety of quinone substituents, demonstrating the adjustability of quinone formal potentials by choice of substituents. Importantly, in this series we show that the CP-PG redox match, i.e. that the formal potential of the PG is within the conducting region of the CP, is a requirement for fast charge transfer from the electrode to the PGs. Moreover, a series of quinone-pyrrole dyad polymers with various linkers was synthesized, showing that the choice of linker has a pronounced impact on the interactions between the PG and CP. In addition, the temperature dependence of conductance during doping of the polymers reveals the charge transport mechanism. To summarize, the adjustability of the quinone formal potential as well as the fast charge transport in the bulk material ensures the applicability of the CRPs as electrode materials in organic batteries.

A small report on modelling an electrolyte flow-battery using the software COMSOL.