Periodic Reporting for period 3 - HARVESTORE (Energy HarveStorers for Powering the Internet of Things)
Reporting period: 2021-06-01 to 2023-05-31
IoT is an universe in fast expansion. A countless number of applications can be imagined: smart cities, remote health care, automated production lines…. We expect 27 billion devices to be installed by 2025, but how will they be powered? Batteries are bulky and environmentally unfriendly, thus strongly limiting the possibility of device miniaturization, at the same time posing serious problems of sustainability. Embracing the IoT in our lives will require the advent of a new generation of portable power sources. For this, the project HarveStore aims to introduce a family of micro-energy sources (micro-Harvestorers) which will be autonomous, rechargeable and will offer high specific power for full integration with the nodes of the future IoT. The micro-Harvestorers will work on two steps: energy harvesting from ubiquitous heat and light and energy storage in the form of a fuel or of electric charge. Such two steps will be carried out at the same time and the total footprint of the device will not exceed 1 cm3. Harvestore will provide power on your fingertip.
The scientific and technological foundations of the project are related to the highly advanced concepts of Nanoioncs and Iontronics, for which new materials can be designed ad-hoc by taking advantage of local effects at the nanoscale. This way, surprising properties of fast conduction and high storage capacity can be obtained. The concepts behind Nanoionics and Iontronics have already been proven by advanced research experiments and, with HarveStore, we want to feed them into mainstream technology by taking advantage of silicon microfabrication techniques. Silicon ensures superior manufacturability, cost-effectiveness and the possibility to host dense structures in a seamless architecture; all in an environmentally friendly material. Silicon is the champion to bring micro and nano technologies to the economy of scale and is therefore the material of choice for the support of the micro-Harvestorers.
New experimental tools have been made available for the analysis of the ions distribution across interfaces with high resolution and for following the ionic migration during operation (in-situ/in-operando measurements). Such tools comprise a spectroscopic ellipsometer coupled to closed chambers for the analysis of the state of charge in electrode materials and an in-situ Raman to perform kinetic studies and extract the transport coefficients of functional oxide thin films for electrochemical devices. Decisive advances for reaching high resolution in surface and local chemical analysis via low-energy ion scattering (LEIS) and unique Plasma Focused Ion Beam-Secondary Ion Mass Spectrometry (Hi-5) have been obtained. As a support to the investigation, partners have developed theoretical models for solid/gas reaction and simulations of relevant materials for the project, which allow predicting the mechanism of conduction and the thermochemical stability at the interface level. At the experimental level, the consortium has focused on the definition of the thin film layer materials for the devices. This activity is the first step towards property engineering via nanoionics and iontronics. New nanoionics effects have been identified for the enhancement of the oxygen exchange kinetics in doped lanthanides, paving the way towards the universal understanding of fast oxygen diffusion and incorporation at the grain boundary level. Effects related to iontronics have been revealed especially in relation to light harvesting, where the intimate relation between light absorption and charge accumulation in the form of ion migration has been brought to the fore. The design of scalable manufacturing processes compatible with silicon technology has been addressed via the optimization of large area deposition techniques of lithium and oxygen-ion conductors via radio frequency sputtering, large area pulsed laser deposition and spatial atomic layer deposition.