Metal-Organic Frameworks based membranes for gas separation in Li-air batteries

Modern lithium-ion (Li-ion) batteries are rapidly reaching their own limits in terms of performance, and many doubts have been raised regarding their sustainability due to required resources including transition metals such as cobalt for the cathodes. More than 60% of the world's cobalt supply comes from the Democratic Republic of Congo (DRC), and a series of reports have shown that cobalt mining comes along with human rights abuses, unsafe mining, and several other risks. For a renewable energy transition, we need to minimize the social and environmental cost of batteries, therefore there is a real incentive to develop advanced sustainable battery types that exceed the energy storage performance of present Li-ion batteries.

Li-air batteries, a novel type of next-generation technology, can address the issues above-mentioned. Unlike Li-ion, Li-air batteries are not based on the mechanism of ion insertion of Co-based cathodes, as the electrode is lithium metal and air acts as the cathode material. Additionally, in Li-air batteries O2 acts as the active material storing electric charge, so in principle the battery has a higher energy density, lower cost and potentially less toxicity compared with Li-ion technologies.

In practice, however, designing a viable rechargeable Li-air device has proven extremely challenging. One of the greatest challenges is to avoid carbon dioxide entry into the cell as this can be detrimental to cell performance, due to the formation of insoluble by-products, such as Li2CO3.

Proposed solution and methodology

A novel solution proposed in this project involves using Mixed Matrix Membranes (MMMs) constructed from polymers and metal-organic framework (MOF) fillers to capture CO2 from air, preventing it from entering the cell.

MMMs have the potential to achieve higher selectivity and permeability relative to the pure polymeric membranes, resulting from the addition of MOFs thanks to their inherent superior gas separation characteristics. At the same time, the fragility inherent of inorganic membranes may be avoided by using a flexible polymer as the continuous matrix.

The final membranes will be composed of a highly oxygen permeability polymer phase, that ensures a proper oxygen flow inside the battery, and dispersed MOF particles (up to 50% weight of the final membrane) with high carbon dioxide selectivity and adsorption capacity. Structure-property-performance relationships will be used to optimize gas separation.





































Modern lithium-ion (Li ion) batteries are rapidly reaching their own limits in terms of performance, and many doubts have been raised regarding their sustainability due to required resources including transition metals such as cobalt for the cathodes. More than 60% of the world's cobalt supply comes from the Democratic Republic of Congo (DRC), and a series of reports have shown that cobalt mining comes along with human rights abuses, unsafe mining, and several other risks. For a renewable energy transition, we need to minimize the social and environmental cost of batteries, therefore there is a real incentive to develop advanced sustainable battery types that exceed the energy storage performance of present Li ion batteries.

Li-air batteries, a novel type of next generation technology, can address the issues above-mentioned. Unlike Li ion, Li air batteries are not based on the mechanism of ion insertion of Co based cathodes, as the electrode is lithium metal and air acts as the cathode material. Additionally, in Li-air batteries O2 acts as the active material storing electric charge, so in principle the battery has a higher energy density, lower cost and potentially less toxicity compared with Li-ion technologies.

In practice, however, designing a viable rechargeable Li air device has proven extremely challenging. One of the greatest challenges is to avoid carbon

This CDT will deliver impact aligned to the following agendas:

People
A2P will provide over 60 PhD graduates with the skill sets required to deliver innovative sustainable products and processes into the UK chemicals manufacturing industry. A2P will inspire and develop leaders who will:
- understand the needs of industrial end-users;
- embed sustainability across a range of sectors; and
- catalyse the transition to a more productive and resilient UK economy.

Economy
A2P will promote a step change towards a circular economy that embraces resilience and efficiency in terms of atoms and energy. The benefits of adopting more sustainable design principles and smarter production are clear. For example, the global production of active pharmaceutical ingredients (APIs) has been estimated at 65,000-100,000 tonnes per annum. The scale of associated waste is > 10 million tonnes per annum with a disposal cost of more than £15 billion. Consequently, even a modest efficiency increase by applying new, more sustainable chemical processes would deliver substantial economic savings and environmental wins. A2P will seek and deliver systematic gains across all sectors of the chemicals manufacturing industry. Our goals of providing cross-scale training in chemical sciences with economic and life- cycle awareness will drive uptake of sustainable best practice in UK industry, leading to improved economic competitiveness.

Knowledge
This CDT will deliver significant new knowledge in the development of more sustainable processes and products. It will integrate the philosophy of sustainability with catalysis, synthetic methodology, process engineering, and scale-up. Critical concepts such as energy/resource efficiency, life cycle analysis, recycling, and sustainability metrics will become seamlessly joined to what is considered a 'normal' approach to new molecular products. This knowledge and experience will be shared through publications, conferences and other engagement activities. A2P partners will provide efficient routes to market ensuring the efficient translation and transferal of new technologies is realised, ensuring impact is achieved.

Society
The chemistry-using industries manufacture a rich portfolio of products that are critical in maintaining a high quality of life in the UK. A2P will provide highly trained people and new knowledge to develop smarter, better products, whilst increasing the efficiency and sustainability of chemicals manufacture.
To amplify the impacts of our CDT, effective public engagement and technology transfer will become crucially important. As a general comment, 'sustainability' styled research is often regarded in a positive light by society, however, the science that underpins its effective implementation is often poorly appreciated. The University of Nottingham has developed an effective communication portfolio (with dedicated outreach staff) to tackle this issue. In addition to more traditional routes of scientific communication and dissemination, A2P will develop a portfolio of engagement and outreach activities including blogs, webpages, public outreach events, and contribution of material to our award-winning YouTube channel, www.periodicvideos.com.

A2P will build on our successful Sustainable Chemicals and Processes Industry Forum (SCIF), which will provide entry to networks with a wide range of chemical science end-users (spanning multinationals through to speciality SMEs), policy makers and regulators. We will share new scientific developments and best practice with leaders in these areas, to help realise the full impact of our CDT. Annual showcase events will provide a forum where knowledge may be disseminated to partners, we will broaden these events to include participants from thematically linked CDTs from across the UK, we will build on our track record of delivering hi-impact inter-CDT events with complementary centres hosted by the Universities of Bath and Bristol.