High Active Material Loading in Organic Electrodes Enabled by a Multifunctional Binder

Mussel-Inspired Polymer Binders for Organic Electrodes

The development of polymer binders is necessary to meet the growing demands of modern energy storage technologies. While catechol-containing materials are proven successful in silicon anodes, their application in organic batteries remains unexplored. In this contribution, the synthesis of four polymers are described with nearly identical side chain composition but varying backbone structures. The materials are used to investigate the effect of polymer backbone structure on the binding abilities of catechol-containing materials. Comparative analysis with the commonly used polyvinylidene fluoride (PVDF) binder aims to address two critical questions: 1) Can catechol-rich polymers replace PVDF for use in organic cathodes? and 2) Does the choice of polymer backbone affect the performance of the battery?. The investigation reveals that supramolecular interactions, such as π-π stacking and coordination bonding, are pivotal features of catechol binders. Among the catechol-rich polymers, the polyacrylate binder stands out, likely attributed to its high flexibility. Additionally, introducing an oxygen atom into a catechol-rich polynorbornene enhances lithium-ion conductivity and rate performance. Overall, the findings highlight the viability of catechol-containing polymers as organic cathode binders, and that the choice of polymer backbone is a crucial factor for their use as lithium-ion battery binder materials.

Practical organic batteries: Concepts to realize high mass loading with high performance

Organic electrode materials (OEMs) have been well developed in recent years. However, the practical applications of OEMs have not been paid sufficient attention. The concept here focused on one of the essential aspects for practical applications, i. e., high mass loading of active materials. This paper summarizes the challenges posed by high-mass loading of active materials in organic batteries and discusses the possible solutions in terms of organic electrode materials, conductive additives, electrode structures, and electrolytes or battery systems. We hope this concept can stimulate more attention to practical applications of organic batteries towards industry from lab.

Sequence-Defined Conjugated Oligomers in Donor-Acceptor Dyads

Conjugated macromolecules have a rich history in chemistry, owing to their chemical arrangements that intertwine physical and electronic properties. The continuing study and application of these systems, however, necessitates the development of atomically precise models that bridge the gap between molecules, polymers, and/or their blends. One class of conjugated polymers that have facilitated the advancement of structure-property relationships is discrete, precision oligomers that have remained an outstanding synthetic challenge with only a handful of reported examples. Here we show the first synthesis of molecular dyads featuring sequence-defined oligothiophene donors covalently linked a to small-molecule acceptor. These dyads serve as a platform for probing complex photophysical interactions involving sequence-defined oligomers. This assessment is facilitated through the unprecedented control of oligothiophene length- and sequence-dependent arrangement relative to the acceptor unit, made possible by the incorporation of hydroxyl-containing side chains at precise positions along the backbone through sequence-defined oligomerizations. We show that both the oligothiophene sequence and length play complementary roles in determining the transfer efficiency of photoexcited states. Overall, the work highlights the importance of the spatial arrangement of donor-acceptor systems that are commonly studied for a range of uses, including light harvesting and photocatalysis.

Influence of Backbone on the Performance of Pendant Polymer Electrode Materials in Li-ion Batteries

Pendant polymers are a promising class of electrode materials due to their synthetic simplicity, derivation from sustainable feedstocks, and potentially benign synthesis. These materials consist of a redox-active pendant tethered to a polymer backbone, which mitigates dissolution during electrode cycling. To date, an extensive number of pendant groups have been studied within the context of metal-ion batteries. However, the choice of the polymer backbone and its impact on the electrode performance have been relatively understudied. In this work, we use a postpolymerization modification approach to synthesize a series of viologen-bearing redox-active pendant polymers with similar molecular weights but three distinct chemical backbones, namely, polyacrylamide, polymethacrylamide, and polystyryl. By evaluating the polymers in lithium-ion batteries, we show that the polymer backbone has a significant influence on electrode performance and behavior. Specifically, the polymethacrylamide displays slower kinetics than the other two polymers, resulting in lower capacities, particularly at high cycling rates. Furthermore, the charge storage mechanism is dependent on the nature of the backbone: the polyacrylamide shows a significant capacitive contribution to charge storage, while the polystyryl does not. The difference in performance between the polymer electrode materials is ascribed to a difference in chain mobility and packing within the electrode films. Overall, this work shows that the fundamental properties of the polymer backbone are critical to the design of high-performance polymer electrodes.