Electronic thermoelectrics use semiconductors to convert waste heat into electricity. This is an established energy generation technology, for example, used by NASA to power the Mars Rovers. However, it is not very suitable for low-grade waste heat recovery due to poor power generation from small temperature differences. Ionic conductors generate much larger thermal voltages and are better suited to near room temperature operation. However, they cannot be used in the same mode of operation as this would require a continuous flow of ions. The innovative solution proposed is to couple the ionic conductor with an energy storage system that converts the ionic potential to an electronic one. This proposal will investigate novel ionic thermoelectric power generation devices consisting of an ionic conductor sandwiched between two energy stores, including supercapacitors and insertion materials. This is a novel approach targeted at recovery of low-grade waste heat, increasing the sustainability of industrial processes and reducing carbon emissions.

Thermoelectric devices are devices that use electricity to pump heat. They can provide both heating and cooling in the same device. Their lack of moving parts makes them good choices for robust, small, quiet, environmentally friendly systems with minimal maintenance. Existing thermoelectric systems are rigid, and more complex shapes or softer surfaces such as the body are difficult to interact with. Our proposal, entitled FlexiTEC, is to develop a fully flexible thermoelectric system. This will increase the ease of use of thermoelectric systems, and encourage take up in personal thermoelectric temperature control systems, for example in active heating and cooling seating products. Such local environment control can significantly save energy, as only the environment that you immediately feel is controlled, rather than the entire space around you. In addition thermoelectric systems have a higher efficiency in heating then local electrical heaters. These efficiency advantages are especially important in electric vehicle development, where cabin temperature control can have up to a 40% impact on range for example in freezing conditions. In order to achieve this aim, full system level modelling and optimisation of the coupled impact of thermoelectric materials, device architecture and flexible heat sinks will be performed in order to achieve the required balance between electrical, thermal and mechanical properties. This will direct the material, device and system innovation in order to accelerate progress towards a high performance, robust, flexible system. Development work will include novel processing routes to enable next generation miniaturisation, coupled with a module designed to be more resistant to failure than conventional devices. In addition, flexible heat sinks will be optimised and constructed using novel low cost processing. This work will be undertaken at European Thermodynamics Ltd near Leicester, a leading UK centre for industrial thermoelectrics research, and will partner with University of Leicester and Queen Mary University of London to harness their expertise in the mechanics of thermoelectric materials and advanced thermoelectric processing routes respectively.

Electronic thermoelectrics use semiconductors to convert waste heat into electricity. This is an established energy generation technology, for example, used by NASA to power the Mars Rovers. However, it is not very suitable for low-grade waste heat recovery due to poor power generation from small temperature differences. Ionic conductors generate much larger thermal voltages and are better suited to near room temperature operation. However, they cannot be used in the same mode of operation as this would require a continuous flow of ions. The innovative solution proposed is to couple the ionic conductor with an energy storage system that converts the ionic potential to an electronic one. This proposal will investigate novel ionic thermoelectric power generation devices consisting of an ionic conductor sandwiched between two energy stores, including supercapacitors and insertion materials. This is a novel approach targeted at recovery of low-grade waste heat, increasing the sustainability of industrial processes and reducing carbon emissions.

Application of the Spin-Seebeck-Effect (SSE), only demonstrated in 2008/10, potentially allows new types of large area single layer thermoelectric (TE) devices for heat-energy exchange (waste heat energy recovery or micro Peltier cooling) under near ambient temperature applications. Present SSE research demonstrations (based on synthetic garnets coated with Pt) are unsuited and unsustainable for real-World application. We proposed two new ways to attain more sustainable, lower cost SSE devices: (i) Use of a facilitating organic interface between the SSE and metal layers to facilitate spin transfer out of the SSE layer; (ii) replacement of the Pt metal layer by more sustainable metals.

The UK is committed to achieving Net Zero by 2050. Waste heat is a huge cause of energy losses in domestic and industrial settings. Large scale thermoelectric recovery of waste heat into electricity can lead to significant reductions in CO2 emissions. In addition, there is a need to power the internet of things (IoT), which dictates the deployment of billions of interconnected sensor devices. Here thermoelectrics can provide free electricity by scavenging waste heat, eliminating the need for batteries or grid connectivity. However, despite the many advantages of the use of thermoelectricity in energy generation and scavenging, commercially it is still an inefficient and expensive technology which relies on scarce materials, mainly Tellurium compounds. New, abundant materials with ease of processing, which can enable large scale production in order to become competitive sources of electricity are needed. Amongst the many new materials investigated lately to increase performance and replace the prominent Bi2Te3 and PbTe for use in thermoelectric generators, half-Heuslers are leading contenders for mass production and commercialisation. They are stable, mechanically robust and are composed of abundant, inexpensive elements. However, a substantial improvement in their power output (i.e. improving W/£), which would largely exceed the power output of current thermoelectric devices is also needed. To radically improve the power output from thermoelectric materials, new approaches are required, beyond reducing the heat transport through them, which has been the key paradigm in the field. We propose an alternative, challenging and disruptive approach based on insights from advanced modelling of charge transport in half-Heusler materials. This shows that the power output, even of already studied materials, can be increased by 2-10-fold by improved materials growth, control of defect chemistry, doping and bandstructure engineering. This will reduce the £/W cost by up to an order of magnitude as the overall material compositions remain similar. This work is a paradigm shift in thermoelectric materials research away from the mainstream focus on nanostructuring and thermal conductivity reduction, to materials with huge electronic responses to a temperature difference. Success of this research will enable the application of Heusler alloys in large-scale waste-heat recovery (kW range energy harvesting) and/ or powering the internet of things (mW-W range of energy scavenging). The project team brings together leading UK expertise in Heusler materials synthesis and thermoelectric materials modelling and will work closely with Industrial and Academic partners to ensure success and translation into working technologies. The resulting developments in synthetic and computational methodologies will be highly relevant to other electronic and opto-electronic materials fields as well.