Battery & Supercapacitor Interface Studies

Only by optimising the structure of the storage element electrode interface, ultimately on the atomic scale, can we fully exploit the intrinsic advantages that new energy storage electrode architectures offer and retain these performance advantages over realistic cycle life and performance conditions. There is presently enormous  interest in supercapacitors for automotive and portable device applications: the high power delivered by these devices makes them useful complements to batteries, in the energy storage domain.  The key research challenge however,  is their wider integration to bring significant increases in their specific energies without sacrificing their performance over cycling.

One material being examined is graphene which has the potential to provide/produce significant improvements in both the power and energy density of rechargeable batteries and supercapacitors. Our research also investigates other forms of carbon  such as nanotube-based systems   and carbon aerogels in addition to pseudo-capacitive storage.

Project highlight: Electrochemical Graphene

Fuel Cells

Low temperature fuel cells are being studied to facilitate their route to market in a range of portable applications from mobile phones to vehicles.

A range of challenges have prevented the widespread adoption of fuel cell technologies across energy generation sectors. A significant portion of these challenges are related to the materials incorporated in a fuel cell being either very expensive (eg platinum) or non-ideal (eg Nafion in Direct Methanol Fuel Cells). The aim of the research is to utilise novel materials and synthetic approaches to try and tackle these issues. Organophobic materials have been incorporated into membranes to selectively repel methanol and novel structures such as graphene, graphene oxide and graphene supported nobel metals are being trialled to demonstrate if the reported enhancements are effective in a fuel cell environment. The work is closely linked to the Graphene Institute along with Prof Peter Budd in Chemistry, Dr Flor Siperstein and Dr Paola Carbone in CEAS and Dr Sarah Haig in Materials Science.

Characterisation and Lifetime Management of High Power Storage Devices

The high cost and weight of energy storage devices and their finite capacity and lifetime demands highly optimised system design / integration, intelligent control and precise through-life management to ensure the most effective asset utilisation. The management of supercapacitor and battery energy storage devices is a major research theme at Manchester with a particular focus being on transport applications (vehicles, aircraft and ships) where the severely  limited capacity of power sources and the highly dynamic nature of the loads (such as traction drives) places extreme demands on energy storage systems. Current / on-going research collaborations in this area include Rolls-Royce (aerospace / marine sector) and Prodrive (automotive sector).

The drive to develop more efficient and longer lasting storage devices such as those that exploit new materials, for example graphene, and the need to maximise the utilisation of storage assets, is creating research challenges to understand the behaviour and characteristics of existing and emerging storage technologies under representative operating profiles (including through-life and end-of-life degradation) and to devise the most effective ways of packaging, interconnecting and managing the storage devices to fulfil the requirements of existing and new applications.

High power electrical energy storage testing over a wide range of representative operating duties and environmental conditions, enables the complex inter-relationships between cell design, operating duty, environmental conditions, round-trip efficiency and lifetime to be examined.   This provides  feedback into the cell development process to help focus research effort at the cell level, and establishes a sound basis for devising the most effective storage bank architectures and control, health monitoring and management methods. This includes the thermal management of the entire bank, requirements and techniques for inter-cell balancing, and protection and fault management within the bank.

Energy Storage System Control

A fully-instrumented, programmable high-power AC grid connected energy storage system linked into the campus low voltage system enables control algorithms for grid services, including power flow compensation and power system stabilisation, to be examined. This includes the impact that these will have on the energy storage assets and the associated control and management systems. Control algorithms and functions can be implemented on the energy storage system to demonstrate the performance and assess the impact on the power network. This also includes the integration of the energy storage assets with renewable systems, smart grids and frequency compensation devices.

Our research also investigates the optimum combinations of storage devices, i.e. supercapacitors and various battery types (low cost lead-acid, lithium-ion and emerging technologies), and optimised operating regimes for load sharing / profiling between cells to ensure maximum efficiency and lifetime, whilst fulfilling the load requirements. The large scale storage bank, designed for grid ancillary services which requires the rapid injection/absorption of energy over shorter durations ( power-to-energy ratio of 2:1), will provide a test bed for the validation of the storage device combinations and associated control techniques.

Network Integration

Our work seeks to develop a detailed understanding of the issues involved in the integration of energy storage onto a network that must also support other low carbon technologies (from renewables to electric heat pumps). One of the main challenges to make storage technologies as cost-effective as possible is ensuring their optimal integration with the electricity distribution and transmission networks, ensuring the systems are deployed effectively and utilised in a way that maximises their benefits to the system while protecting their life. Energy storage technologies have the ability to    alter the steady state and dynamic behaviour and operation of existing systems. Therefore, if such energy storage schemes are to be successfully integrated, their impact on the networks and their operation within the networks must be carefully studied. Ongoing work in Manchester in the areas of network integration of low carbon technologies, particularly in terms of control aspects and state estimation, provides a solid basis for these studies. Manchester’s ambition goes beyond the traditional preventive control approaches, moving to the corrective control and wide area protection and control era, in which energy storage is expected to be the enabler of new Smart Grid solutions.

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