This research is about batteries used in hybrid cars. Most batteries consist of three main parts: a positive electrode, a negative electrode and an electrolyte. The electrodes are connected to the terminals of a battery and allow electricity to flow in and out; charging and discharging the battery. The electrodes are covered in "active material", which reacts with the electrolyte to release or store electrical energy in the form of chemical bonds. In older car batteries, it used to be possible to top up the electrolyte by adding de-ionised water; however, modern batteries are generally not made this way for automotive applications any more.

Lead acid batteries have been used in vehicle ignition systems for more than 70 years. They are safe, reliable at low and high temperatures, easy to recycle and can have a long working life. In the last decade, several car manufacturers have started selling hybrid electric vehicles, such as the Nissan Leaf, Toyota Prius and Honda Insight. These vehicles, and others like them, store some energy in a battery. There are several approaches to how the energy is stored, but a common one is to store energy when the driver slows down and release it when the driver accelerates. This evens out the demand on the internal combustion engine and saves fuel. Lead batteries have not been used in a production electric car yet, but have been used in several test vehicles.

Some lead acid batteries have been used in prototype hybrid vehicles and then dismantled to observe how they aged. This has shown that battery electrodes do not age evenly. A number of researchers have proposed various designs of battery electrode to make the electrode age more evenly and therefore use the battery as efficiently as possible. These designs have mostly been limited to situations in which the electrodes are flat or are coiled into a spiral shape. Even in a spiral shape, the distance between the electrodes is more or less constant (they are parallel). There is little appetite among battery manufacturers to move away from parallel plates because it is believed that the cost of production will increase or that production will be more difficult and expensive.

However, CO2 targets are now at such stringent levels that every effort must be made to maximise the use of renewable energy sources or secondary energy sources (like rechargeable batteries). Transport (excluding international air travel) is responsible for about a quarter of CO2 emissions. Therefore, considerable overall CO2 reduction is possible by focusing on automotive applications. Of course, any improvements in this area are applicable to other areas, such as domestic electricity storage from wind turbines and solar panels. If it can be shown to be advantageous to vary the geometry in a test battery and a single manufacture takes up the design other manufacturers will follow or risk being at a commercial disadvantage.

This research will change the shape of lead acid battery electrodes to make the battery age more evenly under most circumstances. This will ensure that the battery is as light and small as possible. This research will also investigate the feasibility of manufacturing more complex electrodes to ensure that the output of the work has practical value. The idea of geometry adjustment of battery electrodes is not limited to Lead batteries. With suitable consideration it is likely to be amenable to most battery types including Lithium.

Potential Impact:
Transport utilises more than 30% of our primary energy resources. The power electronics supply chain in the UK is estimated to be worth £1 bn (£40 bn worldwide), supporting a direct global power electronics market of £135 bn growing at 10% pa (2011 figures). Transport accounts for approximately 13% of this market. UK automotive production exceeded 1.6 million vehicles in 2013 and 2.5 million engines, with 80% of these exported. Production is expected to grow to 2 million vehicles by 2017. By replacing end of life products with more energy efficient ones, this strong growth will increase the efficiency of energy use and help to meet UK government targets that require a 34% cut in 1990 CO2 emission levels by 2020 and 80% by 2050. In 2013, UK transport produced 116.7 MtCO2 equivalent. This is approximately 25% of the UK total and excludes international aviation and international shipping. It is approximately equal to the 1990 emission level. Methods to deliver the ~34% reduction must be found in the next five years. The automotive manufacturing supply chain has benefited from approximately £6 bn investment in the last three years, yet two thirds of the materials and subsystems used by Tier 1 suppliers in the UK are imported. This represents a £3 bn opportunity for UK industry to supply the presently imported materials and systems. The ONS annual business survey indicates that, in 2012, 1233 companies provided 50,000 jobs to the UK economy, which were supported directly by manufacturing of "automotive parts". A second estimate by BIS suggests a total of 380,000 jobs are supported by the automotive industry.

The proposed research will significantly impact on the UK's hybrid automotive supply chain. The successful development and adoption of improved, safe, secondary energy storage devices is essential to the UK maintaining its competitive position automotive design. The UK automotive strategy makes specific reference to energy storage in its roadmap, including "key areas for progress: electrolytes, catalysts, dopants, additives, surface modification and coatings" and "Innovative storage technologies that offer improved cost, energy density & packaging" (Department for Business, Innovation & Skills, July 2013. Driving success: a strategy for growth and sustainability in the UK automotive sector BIS/13/975).

This research will apply a new measurement technique to battery design which may result in a step change in lead battery performance in a rapidly expanding application area, which will lead to skilled engineering design job creation in the UK.

Direct industrial beneficiaries include over 77 ALABC member companies, including battery manufacturers Johnson Controls, Exide Technologies, Axion Power and Banner Batterien Systems, Northstar, East Penn and Furukawa as well as supply chain companies such as Hollinsgworth and Vose (spacers) and Hammond Expanders. These companies and other ALABC members will have direct access to the research outputs and to the research team at the project open days and steering group meetings. Large automotive companies such as Nissan and JLR will have access to this work through their existing links with Sheffield.

The industrial beneficiaries listed above, and research organisations such as the Transport Research Laboratory, Berkshire and the Energy Technologies Institute, Birmingham will gain new insight into the potential of moving away from parallel plate battery designs. The automotive industry will gain new data that may influence battery chemistry choice or pack sizing looking forward.

The academic community will benefit via dissemination in high impact journals and conference proceedings and through the two laboratory open days. A vibrant research community exists in the UK in the energy storage field. Key workers are with Imperial (London), Southampton, Warwick, Cambridge, Oxford, Bath, Glasgow, Birmingham and Sheffield, among others.