The prime motivation in the development of anion-exchange membrane-(AEM)-based fuel cells (AEMFC) and alkaline water electrolysers (AEM-AWE), that use (generate electricity) and produce sustainable hydrogen respectively, is the potential to minimise the use of precious metal electrocatalysts (cf. proton-exchange membrane equivalents); this will reduce costs and lead to systems involving only earth abundant elements (ensures sustainability). Additionally, AEM-AWEs use low-concentration aqueous-alkali or pure-water feeds (cf. traditional non-AEM alkaline water electrolysers), eliminating the need to handle large quantities of highly caustic solution (that comes with significant environmental implications related to leakage and disposal). The AEMFCs will initially be targeted in the backup power stationary sector (including for telecoms) to replace diesel generators with the added consumer convenience of reduced noise and local emissions of pollutants: the current diesel generation market supplies 200 GW of global power demand (valued at £9B in 2015). The global hydrogen electrolyser market is estimated to register a compound annual growth rate of 7.2% between 2018-28 (market expected to reach US$426.3M by 2028), with application in the transport segment expected to grow at a significant pace in Western Europe ["Hydrogen Electrolyzer Market: Alkaline Electrolyzer Expected to Remain Dominant Product Type Through 2028: Global Industry Analysis 2013-17 and Opportunity Assessment 2018-28", Future market insights report, 2019]. The applicants are world-leaders in the development of alkaline polymer electrolyte materials (membranes and powdered forms, the latter for use in electrode manufacture), especially radiation-grafted types. Mechanically robust, alkali stable, and high performance (high conductivity, high water transport) materials have been demonstrated for use in both AEMFCs and AEM-AWEs (temperatures up to 80 degC). The recent improvements in alkali stability means that oxidative-radical degradation mechanisms become relatively significant and now need to be a research focus. The focus of this project is to develop two classes of AEM with further enhanced chemical stabilities (both alkali and radical-oxidative), but where mechanical, ion-transport and water transport properties are not sacrificed: (1) next generation radiation-grafted AEMs (RG-AEM) and (2) new dimensionally-stable, mechanically-strong pore-filled AEMs (PF-AEM). Firstly, the focus will be on the co-incorporation of vinyl-phenolic components into RG-AEMs, where such covalently-bound phenolic components can act as radical traps to enhance radical-oxidative stabilities. Secondly, our prior RG-AEM research has also identified several new advanced monomers (such as the 3-vinylbenzyl chloride) that can form RG-AEMs with enhanced alkali stabilities but, unfortunately, poor ion conductivities and water transport properties (as such monomers cannot be made to radiation-graft at adequate levels, due to the crude radical-based nature of such grafting). Hence, these advanced monomers will be used to make PF-AEMs, which can be fabricated using alternative polymerisation methods (e.g. cationic or advanced controlled-radical polymerisation). Thirdly, co-incorporation of vinyl-phenolic monomers will also be possible with these new PF-AEMs to produce materials with maximised chemical and mechanical stabilities. The RG-AEMs and PF-AEMs will be evaluated in both AEMFCs and AEM-AWEs, to maximise the commercialisation opportunities. This will heavily involve our industrial project partners: AFC Energy (Dunsfold, Surrey) will assist with translating the materials developments into pilot scale AEMFC demonstrator systems, using their fuel cell component integration knowhow and IP (for the backup power sector). PV3 Technologies (Cornwall) will assist with AEM-AWE developments by materials exchange and evaluation and scale-up of AEM-AWE technology in their facilities.

A fuel cell consists of three primary components: the air electrode, fuel electrode and ion transport electrolyte. The function of these components is primarily to carry current, reduce oxygen and oxidise a fuel. As these devices are typically constructed using traditional manufacturing techniques there is little control of the atomic scale processes that occur at the interfaces between each of these components. As the electrochemistry that controls the fuel cell operation is correlated with the structure and strain at the interfaces between the components and with the electrode/environment interfaces, a clear understadning of these processes at the atomic scale is essential if optimised, high performacne, low cost fuel cells are to be produced. In this work we will use a complementary suite of advanced techniques, including X-ray photoelectron spectroscopy, Low energy ion scattering and crystal truncation rods to probe the structure of the interfaces, including buried interfaces, and link this with surface chemistry and fuel cell performance. Once these key factors are understood we will apply this knowledge to the design and manufacture of 2D and 3D electrode structures. We will engage with our international partners to complement the work undertaken at imperial and test devices with our industrial partner, AFC Energy.

We propose to develop a radically new system for low-temperature hydrogen fuel cells that promises a performance that can match proton-exchange membrane fuel cells but costs less and is more robust. Our system involves two new technologies, which we ourselves have developed: alkaline polymer electrolyte fuel cells (that contain alkaline anion-exchange polymer electrolytes materials that conduct hydroxide anions, and use low to zero levels of precious metal catalysts) coupled with a new effective method of hydrogen delivery based on ammonia. Our ammonia will be sourced from a low-carbon grid-balancing project that is led by Siemens AG, funded by the TSB and based at the Rutherford Appleton Laboratory. The ability of ammonia to fulfil both the role of energy buffer and energy vector (that closely mimics fossil fuel hydrocarbons such as propane and butane) indicates its potential to play a central part in a future low-carbon economy. The proposed hydrogen store is liquid ammonia, stored at modest pressures (10 - 20 atmospheres), which is cracked at moderate temperatures (350 - 500 degC) using a novel chemical reaction mechanism that does not involve rare-metal catalysts. Our recently discovered, inexpensive approach to ammonia decomposition involves the concurrent stoichiometric decomposition and regeneration of sodium amide via sodium: it is anticipated to lead to less than a 10% loss of efficiency. In the past decade, there has been an increased level of research into using hydroxide conducting alkaline anion-exchange polymer electrolytes in all-solid-state alkaline polymer electrolyte fuel cells. A major rationale for this is such fuel cells hold the most promise for the elimination of precious metal catalysts. Additionally, low temperature (acidic) proton-exchange membrane fuel cells are irreversibly damaged by < ppm amounts of ammonia. Alkaline fuel cells, on the other hand, can tolerate several % of ammonia in the hydrogen fuel without serious performances or durability losses. Alkaline polymer electrolyte fuel cells have even been operated with pure ammonia as the fuel. The actively managed project (that will fully integrate into the UK's SuperGen Hydrogen and Fuel Cell Hub) will involve the development of novel amide and imide based systems for ammonia decomposition as well as the next generation of conductive and durable anion-exchange polymer electrolytes and low cost catalysts (in close partnership with Amalyst Ltd.) to produce alkaline polymer electrolyte fuel cells with improved performances over the current state-of-art. The polymer electrolyte development will include novel dual role alkaline ionomers that allows conduction of the hydroxide anions in the catalyst layers and also catalyses the decomposition of trace ammonia (to help ensure zero ammonia emissions from the fuel cell). Anode catalysts that can not only oxidise hydrogen in the presence of ammonia, but oxidise the ammonia itself (again to help eliminate ammonia emissions) will be specifically targeted. Non-precious-metal cathode catalysts will be used and ported from current and prior research programmes. The culmination of the project will be the development of a combined system incorporating the ammonia cracker, an alkaline polymer electrolyte fuel cell incorporating developed technologies, balance-of-plant, and a control and monitoring system. Taking the systems approach beyond the test bed, a study will be performed that delivers flowsheet and device designs for a 5 kWe system to be taken forward via future projects in direct collaboration with industry.

The electrode, and the electrolyte-electrode interface, plays a critical role in the performance of all cells. In Solid Oxide Fuel Cells (SOFCs) the microstructures of the porous composite anode and cathode are particularly critical as they determine the electrochemical, electrical, mechanical and transport properties of the electrode, and of current distribution to/from the electrode/electrolyte interface. Current state of the art SOFC electrodes rely on a largely empirical understanding to establish the electrode microstructure, and its influence on key performance characteristics, including long term durability. But recent work by the proposers has established a new suite of tools and techniques that offer the prospect of moving towards a design led approach to manufacture of improved electrodes, based on our ability to image, model, simulate and fabricate new electrode structures with controlled properties. This proposal seeks to develop and demonstrate this, further improving and validating our analysis and modelling tools, using these design optimum structures, fabricating these using three novel processing techniques established by the proposers, and then measuring device performance to feedback into the design process.

Our project aims to develop and optimise a new class of metal-free electroactive graphitic carbon nitride materials (gCNMs) as lithium ion battery (LIB) electrodes, supercapacitors (SC) and fuel cell catalyst supports. These are important energy-related applications. gCNMs are based on layers of sp2-bonded carbon and nitrogen atoms similar to C-graphite or graphene, but they contain voids or channels within and between the layers giving a 3-dimensional character that we will develop here for reversible Li+ intercalation and LIB applications. During proof-of-concept studies supported by a 12-month award from UCL Enterprise we found that the Li+ storage capacity of gCNMs could be competitive with C-graphite (patent application 1311742.9, filed 1/7/13). In this project we will apply a systematic approach combining synthetic chemistry, ab initio theoretical prediction, advanced characterisation and electrochemical testing to control and optimise the potential of gCNMs as LIB electrode materials. The gCNM layers are built from triazine (C3N3) or heptazine (C6N7) units linked by -N= or -NH- groups. Fully condensed structures have composition C3N4: the number of -NH- linkages increases for incomplete polymerisation and this controls the electronic properties as well as voids and channels within and between layers. Non-bonded electron pairs and exchangeable H atoms attached to nitrogen provide charge storage capabilities for metal-free supercapacitors. A second area of our project will optimise gCNMs for SC applications. We will systematically tune the synthesis and processing to control the layer condensation and void arrangements optimised for each application. We will use templates to produce hierarchical structures with controlled porosity and incorporate the materials in electrochemical test devices. We will also build on our observation that gCNMs show promise as catalyst support materials for fuel cell applications. We will optimise the microstructure, surface chemistry and electronic properties to produce a new family of robust and efficient support materials that remain stable over many hundreds of cycles. Our project combines chemistry and chemical engineering approaches leading to design and construction of demonstrator devices. We will work with industrial partners to test and optimise the materials and devices under realistic operating conditions to provide a rapid route to commercialisation. Our gCNMs are physically and chemically compatible with C-based materials in current use and so are compatible with present-day technology. However because of their superior performance they will represent a major step forward in terms of application potential. Our project is designed so that there is constant feedback between prediction-synthesis-testing components of the research to permit efficient and informed identification and optimisation of key materials and properties targets for each application. Our team of researchers is at the forefront of synthesis, characterisation and electrochemical testing of gCNMs and they have patented the first result showing superior performance over C-graphite as LIB electrode materials. They have also observed excellent stability of gCNMs as Pt catalyst support materials for methanol oxidation fuel cells and predicted their action as metal-free supercapacitors. We wish to take advantage of this unique opportunity to build the UK lead in this new area of developing gCNMs for electrochemical applications. The PIs work closely together on several projects that integrate fundamental to applied science and are involved in commercialising products and devices for energy-related applications.