Micromechanical assessment of structural batteries

Structural batteries combine the load bearing and electrochemical storage capabilities of carbon fibres (CFs), offering significant opportunities for weight saving in aerospace and automotive applications. Recent research has showcased the potential of polyacrylonitrile (PAN) based CFs for structural battery anodes, and LiFePO4 coated carbon fibres as cathodes. Both anode and cathode fibres are embedded in a biphasic Structural Battery Electrolyte (SBE), composed of a liquid electrolyte phase for high ionic conductivity, and a porous stiff polymer matrix for mechanical performance. The resulting carbon fibre-polymer composite structure has the high specific strength/stiffness required for lightweight structural applications, and the high ionic conductivity required for battery functionality.

Optimisation and design of the multifunctionality of such systems requires an understanding of the coupling of physical phenomena, including thermal, electro-chemical and mechanical processes. In particular, quantifying the mechanical response at different charge states is crucial in the reliable use of these systems in structural applications. In order to achieve this, the project aims are twofold and iterative:

The first aim is the construction of a comprehensive multiphysics model on MSC Marc of a structural battery composite in order to predict the multifunctional performance of structural batteries in various load cases. This will commence with the development of a multiphysics Representative Volume Element (RVE), to couple electrochemical, thermal and mechanical phenomena. Following this, the RVE overall properties may be used to define larger scale modelling. These simulations will supply an enhanced understanding and facilitate the improved design of structural batteries with the ultimate goal of unlocking their significant potential for reducing carbon emissions.

In order to define both the physical parameters and constants present in the multiphysics model, characterisation of material properties is required on a multiscale basis; quantification of individual structural battery components in isolation, and at the full composite level. In order to achieve this, the project will utilise a broad spectrum of experimental methods at different length scales; from the length scale of the fibre (10's of microns) using synchrotron techniques, to the microscale using nanoindentation and other methods.

Additionally, it is key to include assessment of individual component interactions at the multiphysics level. The scope of the project will focus on quantification of the property descriptor coefficients relating charge/electro-chemical load to mechanical response as required to embed this response into multiphysics simulations. In parallel, quantification of the property descriptor coefficients relating mechanical load to electro-chemical response will thereby fully encapsulate the structural battery system.

Impact Summary

This proposal has been developed from the ground up to guarantee the highest level of impact. The two principal routes towards impact are via the graduates that we train and by the embedding of the research that is undertaken into commercial activity. The impact will have a significant commercial value through addressing skills requirements and providing technical solutions for the automotive industry - a key sector for the UK economy.

The graduates that emerge from our CDT (at least 84 people) will be transformative in two distinct ways. The first is a technical route and the second is cultural.

In a technical role, their deep subject matter expertise across all of the key topics needed as the industry transitions to a more sustainable future. This expertise is made much more accessible and applicable by their broad understanding of the engineering and commercial context in which they work. They will have all of the right competencies to ensure that they can achieve a very significant contribution to technologies and processes within the sector from the start of their careers, an impact that will grow over time. Importantly, this CDT is producing graduates in a highly skilled sector of the economy, leading to jobs that are £50,000 more productive per employee than average (i.e. more GVA). These graduates are in demand, as there are a lack of highly skilled engineers to undertake specialist automotive propulsion research and fill the estimated 5,000 job vacancies in the UK due to these skills shortages. Ultimately, the CDT will create a highly specialised and productive talent pipeline for the UK economy.

The route to impact through cultural change is perhaps of even more significance in the long term. Our cohort will be highly diverse, an outcome driven by our wide catchment in terms of academic background, giving them a 'diversity edge'. The cultural change that is enabled by this powerful cohort will have a profound impact, facilitating a move away from 'business as usual'.

The research outputs of the CDT will have impact in two important fields - the products produced and processes used within the indsutry. The academic team leading and operating this CDT have a long track record of generating impact through the application of their research outputs to industrially relevant problems. This understanding is embodied in the design of our CDT and has already begun in the definition of the training programmes and research themes that will meet the future needs of our industry and international partners. Exchange of people is the surest way to achieve lasting and deep exchange of expertise and ideas. The students will undertake placements at the collaborating companies and will lead to employment of the graduates in partner companies.

The CDT is an integral part of the IAAPS initiative. The IAAPS Business Case highlights the need to develop and train suitably skilled and qualified engineers in order to achieve, over the first five years of IAAPS' operations, an additional £70 million research and innovation expenditure, creating an additional turnover of £800 million for the automotive sector, £221 million in GVA and 1,900 new highly productive jobs.

The CDT is designed to deliver transformational impact for our industrial partners and the automotive sector in general. The impact is wider than this, since the products and services that our partners produce have a fundamental part to play in the way we organise our lives in a modern society. The impact on the developing world is even more profound. The rush to mobility across the developing world, the increasing spending power of a growing global middle class, the move to more urban living and the increasingly urgent threat of climate change combine to make the impact of the work we do directly relevant to more people than ever before. This CDT can help change the world by effecting the change that needs to happen in our industry.