Li-ion Battery Cathode Materials Free of Cobalt

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EPSRC
EPSRC
EPSRC
EPSRC
EPSRC

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Sept. 30, 2020

Sept. 30, 2024

As the effects of climate change become increasingly evident, the reliance of humanity on fossil fuels fails to lessen at a sufficient rate. The discovery of sustainable, safe and effective battery materials is vital for a shift in the energy-economy towards renewable energy sources. Much of this research focusses around cathode materials for lithium-ion batteries, where it is perceived the greatest improvements can be made- although electrolyte research also represents a significant contribution. Lithium-ion batteries have applications in a vast range of technologies, from mobile phones to remote-controlled drones. The UK plans to ban all-but electric car sales by 2035, a feat which will require significant further development of battery technologies.
Currently consumer-available cathode materials all present some issues, slowing down further adoption. The most widely adopted of these materials, lithium cobalt oxide has significant issues with material supply. 70% of cobalt is mined in the Democratic Republic of the Congo, of which, a portion is mined in locations linked to modern slavery and human rights abuses. There have been international calls to reduce production reliance on cobalt from these sources or remove cobalt from battery materials entirely. A global call was made by Amnesty International in 2019 to "clean up" battery supply chains, although insufficient changes have been made in many industries.
Research targeting battery materials free of cobalt focusses around 2 areas of new material synthesis- substituted, layered oxide materials and polyanionic materials. Research in this project shall focus on the latter, which expects to produce a new generation of safe, cheap cathode materials. These materials feature large polyanions on some crystal sites, resulting in a sacrifice of energy density due to the "dead weight" of the polyanions. As such, recent work has trialled the use of anion-redox to boost the voltage produced in these battery materials. These anion-redox processes free up additional electrons from the material upon discharge, increasing the voltage and energy density of the material over that provided by just cation-redox.
A further advantage of polyanion materials is provided by their chemical stability. At high voltage, oxide materials may form oxygen, which can in-turn interfere with the electrolyte. However, the oxygen atoms in polyanion materials are covalently bonded to the anion core, suppressing O2 formation and allowing for access of higher voltages.
This project shall utilise these new anion-redox methods to improve the properties of polyanion cathode materials, including boosting energy density. Target materials shall include transition metal polyanion species, such as sulfates, phosphates, oxalates, peroxodisulfates and their thio-substituted analogues. Discharge processes will involve reduction of the polyanion, in addition to the transition metal centre. A wide range of synthesis and analysis methods shall be used in collaboration with other groups.
This research aims to produce new generations of safe, cheap, high energy density cathode materials, using recently discovered methods to produce and improve new materials. Applications are vast and have potential to revolutionise large-scale industries, including electric vehicles and renewable energy.
This project falls within the EPSRC Energy Storage research area, under the theme of Energy. Research is aligned with the Faraday Institution project- "Lithium Ion Cathode Materials - FutureCat". Collaboration with the group of D. O. Scanlon (UCL) will assess potential synthetic targets through computational methods. Battery testing will be carried out in collaboration with the University of Sheffield.

Potential Impact:
The primary impact of the OxICFM CDT will be the highly-trained world-class scientists that it delivers. This impact will encompass both the short term (during their doctoral studies), the medium term (subsequent employment) and ultimately the longer timescale defined by their future careers and consequent impact on science, engineering and policy in the UK.

The impact of OxICFM students during their doctoral studies will be measured by the culture change in graduate training that the Centre brings about - in working at the interface between inorganic synthesis and manufacturing, and fostering cross-sector industry/academia working practices. By embedding not only from larger companies, but also SMEs, we have developed a training regime that has broader relevance across the sector, and the potential for building bridges by fostering new collaborations spanning enormous diversity in scientific focus and scale. Moreover, at a broader level, OxICFM offers to play a unique role as a major focus (and advocate) for manufacturing engagement with academic inorganic synthetic science in the UK.

From a scientific perspective, OxICFM will be uniquely able to offer a broad training programme incorporating innovative and challenging collaborative projects spanning all aspects of fundamental and applied inorganic synthesis, both molecular and materials based (40+ faculty). These will address key challenges in areas such as energy provision/storage, catalysis, and resource provision/renewal necessary to enhance the capability and durability of UK plc in the medium term. To give some idea of perspective, the output from previous CDTs in Oxford's MPLS Division include two start-up companies and in excess of 30 patents.

It is not only in the industrial and scientific realms that students will have impact during their timeframe of their doctorate. Part of the training programme will be in public engagement: team-based challenges in resource development/training and outreach exercises/implementation will form part of the annual summer school. These in turn will constitute a key part of the impact derived from the CDT by its engagement with the public - both face-to-face and through electronic/web-based media. As the centre matures, our aspiration is that our students - from diverse backgrounds - will act as ambassadors for the programme and promote even higher levels of inclusion from all parts of society.

For our partners, and businesses both large and small in the manufacturing sector, it will be our students who are considered the ultimate output of the OxICFM CDT. Our programme has been shaped by the need of such companies (frequently expressed in preliminary discussions) to recruit doctoral graduates who can apply themselves to a broad spectrum of multi-disciplinary challenges in manufacturing-related synthesis. OxICFM's cohort-based training programme integrates significant industry-led training components and has been designed to deliver a much broader skill set than standard PhD schemes. The current lack of CDT training at the interface of inorganic chemistry and manufacturing (and the relevance of inorganic molecules/materials to numerous industrial sectors) heightens the need for - and the potential impact of - the OxICFM CDT. Our students will represent a tangible and valuable asset to meet the long-term skills demand for scientists to develop new materials and nanotechnology identified in the UK Government's 2013 Foresight report.

In the longer term, the broad and relevant training delivered by OxICFM, and the uniquely wide perspective of the manufacturing sector it will deliver, will allow our graduates to obtain (and thrive in) positions of significant responsibility in industry and in research facilities/institutes. Ultimately we believe that many will go on to be future research leaders, driving innovation and changing research culture, and thereby making a lasting contribution to the UK economy.