Molecular Design of New Classes of Electrofunctional Metallo-organic Polymers with Multi-electron Redox Properties and Application Studies in Organic Battery and Organic Memory Devices

The search for new battery materials and chemistry with high-power and high density energy storage is an important topic for tomorrow’s energy storage needs. Development of high-performance organic batteries is one of the key technologies necessary for an extensive market of energy storage systems. Rechargeable secondary lithium-ion batteries are currently the systems of choice, offering high energy density, flexible and lightweight design, and longer lifespan than comparable battery technologies. They are key components of the portable, computing and telecommunication electronic equipment required by today’s information-rich, mobile society. As a rising star in electrochemical energy-storage systems, new-generation organic batteries are expected to complement or replace traditional batteries in certain applications. Organic batteries are considered attractive alternatives to conventional inorganic energy-storage analogues for applications that demand low-cost, low-temperature fabrication, solution-phase device processing and mechanical flexibility. As the core element of an organic battery, electroactive organic polymers with high performance and excellent redox stability are necessary for practical applications. To date, many redox-active organic polymers have been developed, and among these, radical polymers have become the benchmark for this field. Yet, the way to promote the multi-electron redox reactions in battery systems remains a big challenge for scientists. In a related context, information technology has become an essential part of our lives. As the complexity of the mobile gadgets increases, miniaturization and data storage become important issues. To cope with the demand for storing ever more information, scientists are turning their attention to data storage systems based on organic materials. Because of the similar merits as for organic batteries, organic electronic memory devices that can be configured to two or more stable states have been extensively explored as new information storage media. However, examples of organic battery and memory systems exploiting electrofunctional metallo-organic polymers as active materials are very scarce indeed, despite their several advantages such as the immense structural diversity, range of redox properties and intermolecular/supramolecular interactions made possible by the metallic elements.

The proposed research here seeks a versatile solution to developing electroactive metallated polymers that combine well-defined organometallic structures and tunable multi-electron redox properties. The project will establish effective synthetic routes to a large variety of new metal-containing macromolecules with novel structures, advanced functionalities, and practical applications for both energy and data storage. Such products with multi-electron redox chemistry will potentially offer a good avenue towards high-performance organometallic batteries and complement the properties of the traditional inorganic systems. The incorporation of redox-active transition-metal centers would be expected to facilitate charge/discharge processes and enhance the energy densities favorable for high-performance devices. In this way, a new type of organic powering system can be developed. Apart from the wet-type energy storage, the work can also be extended to explore the battery-inspired and resistor-type organic memory devices for data storage application. It is anticipated that a similar charge-storage configuration should develop for a dry system in the absence of the electrolyte layer, by sandwiching a dielectric material with the new polymers, leading to electroconductive bistability essential for memory devices rather than power storage. With our strengths in synthetic chemistry, polymer and metal complex chemistry, the performance of both new types of organometallic battery and memory devices can be fine-tuned through chemical modifications of the organometallic structures with various redox functionalities. The present work fills in a relatively under-investigated area of organic batteries and memories and would provide a new impetus to the creation of some technologically useful materials and systems for both energy and information storage.