Oxide Perovskites – Pioneering Materials for the battery technology of the future?

Ulm University paves the way for sustainable electric mobility with innovative post-lithium battery solutions

The electrification of the transport sector is a key step towards achieving the climate targets. Lithium-ion batteries are currently the dominant technology in electric vehicles due to their high energy density and performance. However, they face challenges such as growing demand, which is leading to increasing scarcity, and the environmental impact of mining and processing these materials. As a result, there is intense research into alternative battery technologies based on less critical materials. One promising approach is to use oxide perovskites as the cathode material. Oxide perovskites are materials with a characteristic crystal structure that are flexible and easy to process. They can be doped with different metal ions to achieve the desired properties.

Oxide perovskites as an alternative

Oxide perovskites as a cathode material for post-lithium batteries are a promising alternative to lithium-ion batteries because they are easy to synthesise. They also have high specific energies and energy densities and are generally considered to be more environmentally friendly. As part of a computer-aided study at the University of Ulm, led by M.Sc. Johannes Döhn and Prof Dr Axel Groß, 280 different oxide perovskites were investigated for their suitability as cathode materials for post-lithium batteries. The specific energy, energy density and other relevant properties of these compounds were calculated using density functional theory (DFT)

Of the 280 compounds, 30 passed the initial screening process. A further 17 were discarded because the perovskite structure collapsed during the DFT geometry optimisation, leaving only 13 compounds. Figure 1 shows a cathode material for batteries based on a perovskite structure, as analysed in this study. The material ABO3 represents the state at low charge and consists of a complete intercalation of components (shown here in blue) in the lattice. In contrast, BO3 shows the material in a charged state, characterised by the removal of these components. 

The investigation of the remaining 13 compounds was based on the diffusion barriers for the migration of the shuttle ions, a critical factor for battery performance. For example, poorer ion migration at low temperatures is the main reason for the reduced range of battery-powered vehicles in winter. The selected materials and their specific diffusion pathways are shown in Figure 2, which also shows the diffusion barriers of the 13 successfully screened compounds. It is particularly noteworthy that MgNbO3, ZnVO3 and AlMoO3 show low values at the upper vacancy limit, indicating high ionic mobility.

MgNbO3: The most promising candidate

MgNbO3 was identified as a particularly promising candidate for applications. Figure 3 shows a detailed analysis of the diffusion path of MgNbO3, with the diffusion path running downwards in the intercalated material. This indicates an energetically favourable intermediate configuration rather than a final configuration. Examination of individual structural images shows that the characteristic corner-linked oxygen octahedrons of the perovskite structure are preserved throughout, ensuring structural integrity and suggesting no collapse of the structure. This suggests that the effective energy barrier for solid-state diffusion may be lower than originally thought, allowing particles to move more easily than expected. 

Everyday relevance

The results of the study, which was co-financed by the MEZ Starck Foundation, have the potential to have a significant impact on everyday mobility. By improving the range and performance of electric vehicles, these technologies could help to reduce operating costs. This would make electric vehicles affordable to a wider range of buyers, which could have a positive impact on reducing CO2 emissions. On an individual level, progress means that consumers could have access to electric vehicles with better performance and greater range, making electric vehicles a more viable alternative for personal transport. At a societal level, the introduction of this new battery technology could reduce dependence on lithium and other critical raw materials, thereby reducing the environmental impact of their extraction and processing. In short, the use of oxide perovskites in batteries could have far-reaching positive consequences for individuals and society as a whole, from financial savings to environmental protection.

Looking to the future

Ulm University’s research represents a significant step forward in the development of more sustainable and efficient post-lithium batteries. The study lays the groundwork for optimising the synthesis of MgNbO3, a promising material for future battery technologies. Further research is needed to confirm the theoretical properties in practice. Future studies, in collaboration with the MEZ Starck Foundation, could focus not only on improving the production of MgNbO3, but also on increasing the lifetime of oxide perovskite-based batteries. The aim is also to develop new oxide perovskite compounds with even higher specific energies and energy densities.

In the coming years, the rapidly developing field of oxide perovskite research could make a decisive contribution to the realisation of batteries that are not only more powerful and durable, but also have a lower environmental impact. The advantages of oxide perovskites, such as high specific energy and energy density, make them a key material for the sustainable battery technology of the future. The current research results provide a solid basis for the commercial use of oxide perovskite batteries, but further research will be crucial to realise the full potential of this material and confirm it in real applications.

Johannes Döhn and Axel Groß, Computational Screening of Oxide Perovskites as Insertion-Type Cathode Material, Adv. Energy Sustainability Res. 2300204 (2023), Open Access, DOI: 10.1002/aesr.202300204, posted on ChemRxiv, DOI: 10.26434/chemrxiv-2023-vj973 [Paper-Link]

Lasse S. Martinsen