Understanding the challenges and opportunities as demand for bespoke batteries increases

As vehicle electrification gathers pace, there will be an increasing demand for bespoke battery solutions for niche vehicles. Who better to develop them than Ricardo Performance Products, as its managing director, Martin Starkey, explains to RQ’s Ian Adcock.

In 2021 Ricardo received UK Government funding to assess the commercial viability of a facility to assemble battery packs for UK manufacturers which produce fewer than 10,000 electrified vehicles per year. These manufacturers include some of the world’s best known prestige brands, which create their luxury cars, special vehicles or off-highway machines for a customer base in the low thousands. This compares to the hundreds of thousands or, in some cases, millions of vehicles produced for the passenger vehicle market. The economic study was funded by the Advanced Propulsion Centre’s Automotive Transformation Fund supported by the Department for Business, Energy and Industrial Strategy. The study considered how to meet the particular battery hardware needs of these diverse, low volume manufacturers across a wide range of business sectors, by ensuring a UK supply chain in electric vehicle (EV) components.

What is the timescale for the project and its principal gateways?

We started with a white paper1 and developed into a full virtual reality (VR) facility model, ultimately assessing the UK’s potential niche battery supply capabilities: not only the ability to supply the battery packs themselves but also the cells, enclosures, wiring looms, cooling systems and so on. In other words, the bill of materials for a high-performance battery pack and its complete supply chain would be located within the UK. We developed a conceptual facility and rendered it in full VR, then assessed the viability of it to assemble and test a full battery pack. There isn’t currently a fixed timescale to develop a facility as such, more a clear set of gateways we need to pass through to reach that goal: step one was a paper study of the UK’s readiness to supply itself with niche platform, high performance battery packs and there are two reasons why we limited ourselves to this sector: first, quite frankly, it’s Ricardo’s speciality. Second, the UK is predominantly a niche volume, high-performance vehicle manufacturing sector from Lotus and McLaren to the likes of Aston Martin and Bentley, through to aerospace and defence activities and specialist vehicles such as Dennis and JCB. So we’re talking about a battery pack requirement in the thousands to tens of thousands annually. The next gateway that’s currently under discussion is developing a scaled demonstrator within an existing Ricardo site, requiring a prototype battery manufacturing facility capable of showcasing series production pack quality in a safe and appropriate environment.

How much commonality will there be in the different battery packs?

This is both our biggest challenge and opportunity. The cell’s format is hugely variable whether it’s prismatic, cylindrical or pouch; there isn’t even a harmonised view on cell chemistry, format, module size or pack configuration. These variables will require a highly flexible assembly methodology. Done well it provides fantastic opportunity; done poorly it may quickly become a limiting factor. It’s for this reason the next step is a scaled prototype facility. A high-performance car application may require a very power-dense pack for maximum acceleration while range and energy capacity might be secondary, but the weight and shape of the pack could influence vehicle dynamics. At the other end of the spectrum you might have off-highway applications requiring enormous, high-energy packs where the weight and dimensions have more freedom. A cell-to-pack approach is increasingly popular for improving energy and power density in a pack. The elimination of the module and use of larger format cells reduces the number of interconnections between cells and allows a significant increase in the energy available to fit into the same space. This does, however, pose new challenges in assembly as the pack has more electrical connections to do in final assembly and fewer sub-assemblies to optimise process flow. It’s therefore hard to see any level of commonality between our customers at pack level, but with more opportunities at a module level in particular where end applications are similar. I can especially see commonality (driven by strong commercial advantages) where a business has multiple vehicle lines that all have the ability to share a common cell or module. It’s clear that the majority of the cost of a pack sits in the cell and the more that can be done to leverage the positive effects of scale in respect to this, the more commercially viable the final product is.

The white paper mentions power outputs ranging from 130 kilowatt-hours (kWh) to 500 kWh – in what increments?

The brief to the team was to design a facility with any of the current commonly known cell formats that can be used in any sensible module design. Once you have the module, its flexibility is almost infinite because it’s predominantly a manual manufacturing operation. The power ranges mentioned related to potential applications in this UK niche.

Will one of the major challenges be tailoring battery packs for individual marques and models?

Yes, but the earlier we get involved in the product design the better. We can then influence the robustness of the assembly, its reliability and, most importantly, the cost of bringing it to market. With this approach we can achieve things like preventing excessive or unnecessary tooling costs, minimise supply chain investment or development costs and ensure things like pack rework and serviceability are considered. The use of manufacturing-based judgments in the design and development process is critical to ensuring a successful product.

600 kilograms is given as an example weight of an EV battery pack. That’s a hefty weight for a sports car.

Weight is a fundamental issue, especially to a dynamic vehicle, and 600 kg was given as an example placeholder to demonstrate the scale of a finished production pack. It should be noted that the bulk of that, probably in the region of 400 kg, is the cells themselves. Although there is significant ongoing research in new cell chemistries that are lighter and more energy dense, unless you can significantly move the needle in terms of cell weight you are always going to be constrained in terms of light weighting. The next best thing, for a sports car at least, is to get them low enough down in the vehicle to have the least impact on dynamics. When it comes to other factors outside of the cells, things like the pack cooling system starts to become more critical. For example, liquid cooling a pack adds more weight than air cooling but it has benefits in energy and power density, improving how fast you can discharge and recharge the battery. Higher and broader temperature capability of the cells could allow for more options in cooling performance, including more passive thermal options, but with current cells active cooling is expected. Other cooling approaches, like immersion in dielectric fluid, should provide increased thermal control and power density for really high power batteries and will require additional flexibility in assembly.

Why have you opted for pouch cells in the white paper?

When we set out on the study, pouch cells appeared to be the favoured route – although I get the impression that cylindrical and prismatic cells in some areas are making a resurgence and there’s some interesting data emerging on the various merits of each. From an assembly perspective the cell format is not hugely significant other than one specific challenge: how you connect them. There are fundamentally two approaches, either mechanically or by some form of welding; depending on the cell format and manufacturer your joining technology may be fixed. Either way, we can meet our customers’ needs as the facility is designed for prismatic, cylindrical or pouch cells.

How can you minimise the supply chain’s environmental footprint?

This was a really important element of the study. Part of what we’re looking at is how much of the UK supply chain is capable of supplying the sub-systems and components needed for these new battery systems. It’s one of the reasons why we went for a ‘real’ battery design: it allowed us to get drawings and specifications out to companies and ask if they could produce parts in the hundreds or thousands and how they would go about achieving that, while meeting all the various commercial and technical constraints that would be expected in production. On more than one occasion we had to find entirely new suppliers, sometimes outside automotive and often new to battery applications. By working with their manufacturing capabilities and experience we helped them successfully transition into a supplier capable of meeting the needs of a battery application. It’s something we’re very experienced in doing, bringing suppliers along on the journey with us. Brexit has had an impact as well, as the EU’s Rules of Origin require that by 2027, 55 per cent of components must be EU or UK sourced. That will demand the cells are manufactured here in British gigafactories because they make up the majority of the pack. Every additional component after the cells that can be sourced here in the UK further helps with this challenge. One of the very positive aspects coming out of the white paper has been developing relationships with key suppliers including new UK cell producers. This work has already led to discussions around future technical demonstrators, where Ricardo would take a UK-sourced cell and other domestic components to build a 100 per cent British battery and in doing so demonstrate the UK’s ability to meet the Rules of Origin trading requirements. At a cell level it is a fact that the UK isn’t rich in the metals and electrolytes required to support the manufacture of the products and as such these will always require importing. However, this is certainly more environmentally friendly than shipping heavy, less densely packed, chemically-active battery cells around the world. We should remember the purpose of the EV in the first instance is to reduce the tailpipe emissions of the UK’s future vehicle production, helping to create a safe and sustainable world. This sustainability in the supply chain and our manufacturing processes has never been more at the forefront of our thinking and business than it is today. Whether that’s using solar power captured at our manufacturing sites or recovering energy when testing our products to feed back into our business. Eliminating, constantly reviewing and reducing our carbon emissions is central to our actions within Performance Products.

First published in RQ Summer 2022 edition.