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Satellite meeting organised by Professor Saiful Islam, Professor Peter Bruce FRS, Professor Richard Catlow FRS, Professor Jenny Nelson FRS

This meeting focused on the challenges posed by battery, fuel cell, solar and thermoelectric technologies and aimed to identify the specific needs in terms of materials development for these technologies to have wider spread deployment. It explored our current individual technologies, and set the priorities for research in materials for energy technologies in the coming decades.

Download a one page summary of the satellite meeting talk schedule (PDF).

The schedule of talks and speaker biographies are below. Recorded audio of the presentations will be available on this page after the meeting has taken place. 

Enquiries: Contact the Scientific Programmes team.

Organisers

Schedule


Chair

09:05-09:25
Post-Li-ion batteries: promises and challenges

Abstract

Current societal challenges in terms of energy storage have prompted an intensification in the research aiming at unravelling new high energy density battery technologies, with the potential of having disruptive effects in the world transition towards a less carbon dependent energy economy through transport by electrification and renewable energy integration. Aside from controversial debates on lithium supply, the development of new sustainable battery chemistries based on abundant elements is appealing, especially for large scale stationary applications. Interesting alternatives are to use sodium, magnesium or calcium instead of lithium. While for the Na-ion case fast progresses are expected as a result of chemical similarities with lithium and the cumulated Li-ion battery know how over the years, for Ca and Mg the situation is radically different.  On one hand, the possibility to use Ca or Mg metal anodes would bring a breakthrough in terms of energy density, on the other, development of suitable electrolytes and cathodes with efficient multivalent ion diffusion are bottlenecks to overcome.The presentation will serve to discuss such promises and challenges and describe the current state-of-the-art of research in the field.

Speakers


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09:25-09:45
Discussion
09:45-10:05
Recent findings on vanadium based phosphates for Na batteries

Speakers


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10:05-10:30
Discussion
10:30-11:00
Coffee
11:00-11:20
Beyond lithium? Battery materials and manufacturing

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11:20-11:40
Discussion
11:40-12:00
The role of materials characterisation in materials design and optimisation for energy applications

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12:00-12:30
Discussion

Chair

13:30-13:50
Air electrodes for solid oxide cells; complex materials in a complex environment

Abstract

Solid Oxide Cells (SOCs) such as Solid Oxide Fuel Cells (SOFCs), Solid Oxide Electrolysis Cells (SOECs) and Solid Protonic Fuel Cells (SPFCs) are important devices in future energy conversion, storage and fuel processing systems. One particularly attractive feature is the possibility of reversible operation (eg SOFC/SOEC) for operation with renewable energy systems.  All components of these cells are the subject of intense research activity to optimise performance, lower operating temperatures and, above all, improve durability and lower costs. One key component in these SOCs is the porous ceramic air electrode, which usually comprises of a composite of the electrolyte material with a Mixed Ionic Electronic Conducting (MIEC) oxide. An example would be a composite of Ce0.9Gd0.1O2-x as the electrolyte phase combined with La0.6Sr0.4Co0.2Fe0.8O3- as the MIEC.  The microstructure of the porous electrode is also a very important factor in determining the activity of the air electrode. All this results in a multicomponent complex system which is very difficult to optimise, particularly when factors such as interdiffusion, segregation and reaction are included. Added to this complexity of materials parameters is the range of gaseous environments in which the SOC air electrode has to operate, particularly if reversible operation is to be achieved.  In the case of the SOFC cathode the electrode has to operate in air, which includes the active minor components such as H2O and CO2, plus possible contaminants, eg NOx and SOx. In the case of the SOEC anode this changes to high purity O2 and in the case of the SPFC cathode, highly humidified air. Understanding the relative impact of all these solid state and gas phase phenomena is clearly daunting task but progress can be made by designing selective experiments to limit the range of phenomena under investigation. In this presentation details will be described of recent studies of segregation phenomena in MIEC and electrolyte materials and oxygen exchange experiments in single phase and composite air electrode materials in a variety of oxygen containing atmospheres.

Speakers

13:50-14:10
Discussion
14:10-14:30
Chemical and electrochemical stability of perovskite oxide surfaces in energy conversion: mechanisms and improvements

Abstract

A broad range of highly active doped ternary oxides, including perovskites, are desirable materials in electrochemical energy conversion, catalysis and information processing applications. At elevated temperatures related to synthesis or operation, however, the structure and chemistry of their surfaces can deviate from the bulk. This can give rise to large variations in the kinetics of reactions taking place at their surfaces, including oxygen reduction, oxygen evolution, and splitting of H2O and CO2. In particular, aliovalent dopants introduced for improving the electronic and ionic conductivity enrich and phase separate at the surface perovskide oxides. This gives rise to detrimental effects on surface reaction kinetics in energy conversion devices such as fuel cells, electrolysers and thermochemical H2O and CO2 splitting. This talk will have three parts. First, the mechanisms behind such near-surface chemical evolution will be discussed. Second, the dependence of surface chemistry on environmental conditions, including temperature, gas composition, electrochemical potential and crystal orientation will be described. Third, modifications of the surface chemistry that improve electrochemical stability and activity, designed based on the governing mechanisms, will be presented. Guidelines for enabling high performance perovskite oxides in energy conversion technologies will be presented.

Speakers

14:30-15:00
Discussion
15:00-15:30
Tea
15:30-15:50
The surface space-charge layer in ionic solids: prediction, detection, and consequences

Abstract


Speakers

15:50-16:15
Discussion
16:15-16:35
Participation of bonding and non-bonding oxygen redox states for energy storage and conversion

Speakers

16:35-17:00
Discussion
17:00-18:30
Poster session

Chair

09:00-09:20
Exploiting interfaces at different length scales to enhance thermoelectric performance

Abstract

Traditional thermoelectrics based on Bi2Te3 are well established commercially but restricted to low temperature applications; concerns about stability, cost and environmental issues have limited their wider exploitation. The last 20 years have witnessed significant improvements in the performance of a wide variety of thermoelectric materials, with maximum values of the thermoelectric figure of merit (ZT) exceeding 2.5 in some cases. Whilst peak ZT is important there is growing recognition of stability issues and the need for a wide ‘thermal window’ over which the thermoelectric module can be employed. In order to improve the material performance (by maximising ZT) efforts have focused on reducing thermal conductivity and electrical resistivity. One strategy is to employ microstructural engineering at the nanoscale to increase phonon scattering in order to reduce thermal conductivity. By taking examples from systems including oxides, selenides and tellurides and materials exhibiting self-assembly nanostructures, the nature and benefits of interface structures will be examined. Details of atom level structures revealed by use of high resolution TEM and information from DFT modelling can reveal important mechanisms. Finally, the potential benefits of oxide/metal-carbon interactions will be outlined.

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09:20-09:40
Discussion
09:40-10:00
Carbon based thermoelectrics as heat harvesters

Abstract

Heat is a ubiquitous source of energy. About half of the energy that the sun delivers to the Earth is in the form of infrared radiation. Moreover, two/thirds of the energy produced for human consumption is lost in the form of heat. In this scenario, solid state heat-to-electricity converters, ie thermoelectrics, have strong potential to harvest part of this untapped diluted energy source. Widespread use of thermoelectric generators has been thus far elusive due to the relatively high cost of the technology, and the fact that most thermoelectric materials operating at low temperatures are based on non-abundant or toxic materials. Solution processed carbon based materials are currently being investigated as a very promising alternative for low-cost, low temperature thermoelectrics. In this talk the researcher will describe the progress and challenges for three carbon based systems: highly doped conjugated polymers, carbon nanotubes, and composites thereof. The researcher will focus on our current understanding of what governs the main material thermoelectric properties, namely electrical conductivity, Seebeck coefficient and thermal conductivity.

Speakers


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10:00-10:30
Discussion
10:30-11:00
Coffee
11:00-11:20
Investigation of the magnetism influence on the thermoelectric properties in chalcogenides

Speakers

11:20-11:45
Discussion
11:45-12:05
Atomistic simulation of interfaces in the development of improved thermoelectric materials

Abstract

An important component of the development in thermoelectric materials, for waste heat recovery systems, has been the investigation of doping, nano-engineering and dimensionality reduction. Part of the reason is that these approaches improve the efficiency via the lowering of the thermal conductivity. The challenge is however, to lower the thermal conductivity while maintaining a high electrical conductivity and Seebeck coefficient. Atomistic simulation has the advantage of being able to examine the effect of interfaces and doping on each of the key properties separately, and thereby help devise a strategy for finding the structure and composition for optimum thermoelectric performance. The scope of atomistic simulation will be illustrated, by first reviewing the approach we use for generating interfaces and calculating properties then giving several recent examples. These will include the group’s work on SrTiO3 where the group has explored the effect of nanostructuring on suppressing thermal conductivity by means of the introduction of grain boundaries. The researchers demonstrate that structural features impact strongly on the mean free path of the phonons and are responsible for the enhanced phonon scattering. The electronic and thermal properties can also be adjusted through doping, from cation substitution to graphene incorporation. In each case the major influence is normally at the interfaces.

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12:05-12:30
Discussion

Chair

13:30-13:50
Challenges and opportunities in printed photovoltaics

Abstract

Professor Durrant will address some of the key challenges and opportunities for organic and perovskite based solar cells. He will start by discussing the motivations for such printed photovoltaic technologies, and the market opportunities for these technologies. He will discuss some of the recent advances in the efficiencies and stabilities of these devices, including in particular the development of non-fullerene acceptors for organic solar cells, and stability limitations for both organic and perovskite solar cells.

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13:50-14:10
Discussion
14:10-14:30
Designing dopants for higher performance transparent conducting oxides

Abstract

The combination of electrical conductivity and optical transparency in a single material gives transparent conducting oxides (TCOs) an important role in modern optoelectronic applications such as in solar cells, flat panel displays, and smart coatings. The most commercially successful TCO so far is tin doped indium oxide (Indium Tin Oxide – ITO), which has become the industrial standard TCO for many optoelectronics applications: the ITO market share was 93% in 2013. Its widespread use stems from the fact that lower resistivities have been achieved in ITO than in any other TCO; resistivities in ITO have reached as low as 7.2 × 10-5Ω cm, while retaining >90% visible transparency. In recent years, the demand for ITO has increased considerably, mainly due to the continuing replacement of cathode ray tube technology with flat screen displays. However, indium is quite a rare metal, having an abundance in the Earth’s crust of only 160 ppb by weight, compared with abundances for Zn and Sn of 79000 ppb and 2200 ppb respectively, and is often found in unstable geopolitical areas. The overwhelming demand for ITO has led to large fluctuations in the cost of indium over the past decade. There has thus been a drive in recent years to develop reduced-indium and indium-free materials which can replace ITO as the dominant industrial TCO. In this talk Dr Scanlon will outline a new doping mechanism, and a new TCO which should usurp ITO as the industry standard.

Speakers


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14:30-15:00
Discussion
15:00-15:30
Tea
15:30-15:50
Tandem dye-sensitised solar cells for energy conversion and storage

Abstract

One way of improving the efficiency of dye-sensitised solar cells is to use two photoelectrodes in a tandem device, one harvesting the high energy photons, and the other harvesting the low energy photons [1]. This enables the photovoltage to be increased, whilst maximizing light harvesting across the solar spectrum. Despite their promise, a tandem cell with a higher efficiency than the state-of-the-art ‘Grätzel’ cell has not yet been achieved. This is because the performances of photocathodes are significantly lower than TiO2-based anodes, and the p-type concept has been largely unexplored since the first device was prepared in 1999 [2]. The small potential difference between the valence band of the NiO, p-type semiconductor, and the redox potential of the electrolyte and the faster charge-recombination reactions compared to the TiO2 system limits the efficiency. In recent years the researchers have made progress by developing new photosensitisers [3]. In parallel the researchers have investigated the charge-transfer processes to determine the mechanism and limitations to efficiency [4]. This has increased our understanding of the redox processes at the dye/electrolyte and NiO/electrolyte interfaces [5]. The fundamental limitation of these devices arises from the NiO material itself and the researchers have re-focussed our efforts on finding a replacement transparent p-type semiconductor. The group’s strategy and recent results will be presented. Recent work to expand the applications to photoelectrochemical water splitting for energy storage will be described, briefly [6].

References

  1. EA Gibson, AL Smeigh, L Le Pleux, L Hammarström, F Odobel, G Boschloo, A Hagfeldt., Angew. Chem Int Ed 2009, 48, 4402 –4405.

  2. J He, H Lindström, A Hagfeldt, S Lindquist, J Phys Chem B, 1999, 103, 8940–8943.

  3. CJ Wood, GH Summers, EA Gibson. Chem Commun 2015, 51, 3915 – 3918.

  4. J-F Lefebvre, X-Z Sun, JA Calladine, MW George, EA Gibson. 2014, 50, 5258 – 5260. G Boschloo,  EA Gibson, A Hagfeldt J Phys Chem Lett, 2011, 2, 3016–302. EA Gibson, L Le Pleux, J Fortage, Y Pellegrin, E Blart, F Odobel, A Hagfeldt, G Boschloo, Langmuir 2012, 28, 6485–6493.

  5. FA Black, CJ Wood, S Ngwerume, GH Summers, IP Clark, M Towrie, Jason E Camp, EA Gibson, Faraday Discussions, 2017, 198, 449 – 461. L D'Amario, R Jiang, U Cappel, EA Gibson, G Boschloo, H Rensmo, L Sun, L Hammarström, H Tian, ACS Appl Mater  Interfaces. 2017, 9, 33470–33477.

  6. EA Gibson, Chem Soc Rev, 2017, 46, 6194 – 6209. N Põldme, L O’Reilly, I Fletcher, I Sazanovich, M Towrie, C Long, JG Vos, MT Pryce, EA Gibson Chem Sci In press.

Speakers


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15:50-16:10
Non-conventional solar cells: need for new techniques for new devices

Abstract

During his lecture Professor Palomares will present his group latest results on the characterisation of different type of solar cells from DSSC and OPV to MAPI using advanced photo-induced time resolved techniques [1-4]. Using PICE (Photo-induced charge extraction), PIT-PV (Photo-induced Transient PhotoVoltage) and other techniques, the researchers have been able to distinguish between capacitive electronic charge, and a larger amount of charge due to the intrinsic properties of the perovskite material. Moreover, the results allow us to compare different materials, used as hole transport materials (HTM), and the relationship between their HOMO and LUMO energy levels, the solar cell efficiency and the charge losses due to interfacial charge recombination processes occurring at the device under illumination. These techniques and the measurements carried out are key to understand the device function and improve further the efficiency and stability on perovskite MAPI based solar cells.

References

1.  1) JM Marin-Beloqui; L Lanzetta; E Palomares; Decreasing Charge Losses in Perovskite Solar Cells Through mp-TiO2/MAPI Interface Engineering. Chem Mater 2016, 28, 207-213.

2) BC O'Regan; PRF Barnes; X Li; C Law; E Palomares; JM Marin-Beloqui; Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO2: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J-V Hysteresis. J Am Chem Soc 2015, 137, 5087-5099.

3.  3) A Matas Adams; JM Marin-Beloqui; G Stoica; E Palomares; The influence of the mesoporous TiO2 scaffold on the performance of methyl ammonium lead iodide (MAPI) perovskite solar cells: charge injection, charge recombination and solar cell efficiency relationship. J Mater Chem A 2015, 3, 22154-22161.

4.  4)  L Cabau; I Garcia-Benito; A Molina-Ontoria; NF Montcada; N Martin; A Vidal-Ferran; E Palomares; Diarylamino-substituted tetraarylethene (TAE) as an efficient and robust hole transport material for 11% methyl ammonium lead iodide perovskite solar cells. Chem Commun 2015, 51, 13980-13982.

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16:10-17:00
Panel discussion

Speakers

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Energy materials for a low carbon future

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Scientific discussion meeting organised by Professor Saiful Islam, Professor Peter Bruce FRS, Professor Richard Catlow FRS, Professor Jenny Nelson FRS