Computational Modelling, Topological Optimization and Design of Flexoelectric Nano Energy Harvesters

Project Information

COTOFLEXI

Grant agreement ID: 802205

DOI

10.3030/802205

Project closed

EC signature date 5 October 2018

Start date 1 August 2019

End date 31 July 2025

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 499 938,00

EU contribution

€ 1 499 938,00

Coordinated by

GOTTFRIED WILHELM LEIBNIZ UNIVERSITAET HANNOVER
Germany

Periodic Reporting for period 3 - COTOFLEXI (Computational Modelling, Topological Optimization and Design of Flexoelectric Nano Energy Harvesters)

Reporting period: 2022-08-01 to 2024-01-31

Summary of the context and overall objectives of the project

What is the problem/issue being address?

Flexoelectricity is the polarization of dielectric materials under the gradient of the strain. At nanoscale, flexoelectricity can be up to 1000 times higher than the conventional way. Flexoelectricity is faced with many challenging issues. First, we do not know the flexoelectric parameters. Currently, the theoretical predictions and experimental values are contradictory to each other, not only by orders of magnitude but even signs opposite. Second, we do not know the interplay between surface piezo, flexo and free charge carriers. Third, there is no simulation and modelling tool.


Why is it important for society?

Flexoelectricity shows many advantages over the conventional piezoelectricity. 1. Non toxic materials. Flexoelectricity can be generated from all type of crystals including silicon and polymer ideal for medical implant and device 2. High power density. Among many rising and exciting perspective of flexoelectricity, in this project, our team focuses on nano energy harvester. The market for energy harvester will grow to 3 billion dollars by 2020. By converting mechanical energy, energy harvester generates sustainable and inexhaustible electricity. It is a key enabling technology to power micro/nano devices, deep brain simulator for Pakinson patient and retinal implant for eyes. Due to these advantages, the development and application of energy harvesters are rapidly growing. It is estimated that the market of energy harvesting systems will grow up to 3.3 billion dollars by 2020


What are the overall objectives?

The final objective of this project is to develop, implement and validate a novel computational framework for the characterization, design, virtual testing and optimization of the next generation flexoelectric
energy harvesters. Computationally designed and optimized innovative flexoelectric energy harvesters expectantly outperforming current piezoelectric energy harvesters of the same size will be manufactured
and tested.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Energy is among most important and relevant topics for our society. Almost nothing works without energy. Energy supply for electronic devices such as medical implant device or online sensors are quite different from other type of appliances such as TV or microwave at home that consumes energy from utility electric network. The key factors for these type of electronic device supply is not the quantities but the sustainability and reusability. In COTOFLEXI, a team of scientists lead by Prof. Xiaoying Zhuang has successfully developed nano scale model and structure of the flexoelectric energy harvester, a new generation highly efficient energy harvester. Many micro- and nano-electromechanics systems are limited by their size, which is especially a challenge for medical implant device. The implant device size is limited by many factors and one of them is the size of the energy supply, such as batteries. Scientists have made efforts to develop nano energy harvester to overcome this issue. In our project, we support the design and exploration of novel materials and structures. It can enable us to have compact and highly efficient energy harvester. There are some promising materials especially 2D materials that are suitable these solutions. Our team has explored and tested a group of 2D materials. We related the huge potential from 2D materials for energy harvesting. One example is to generate high voltage from the large deformation of a graphene sheet. Moreover there are further exciting chances in other 2D materials and even 1D materials and they come as a group, meaning they will belong to a family with similar structures of atoms. These interesting findings are shown in Publication 4, 7, 8, 9, 10 on graphene spring and transitional metal groups and other 2D materials family from Publication 2 and 3. Our team has overcome several challenges in the structural model of flexoelectricity. Traditional method is lack of smoothness in approximation of the model. We proposed a novel method to analyze large deformation of energy harvesting structures. It also enabled us to optimize the topology of the energy harvester e.g. substrate and vibration metamaterials for better efficiency and high energy density, see Publication 1, 5 and 6.

1. Three-dimensional topology optimization of auxetic metamaterial using isogeometric analysis and model order reduction. Computer Methods in Applied Mechanics and Engineering, doi:10.1016/j.cma.2020.113306 https://hal.archives-ouvertes.fr/hal-02954721.

2. Exceptional piezoelectricity, high thermal conductivity and stiffness and promising photocatalysis in two-dimensional MoSi2N4 family confirmed by first-principles. Nano Energy, doi:10.1016/j.nanoen.2020.105716 http://arxiv.org/abs/2012.14706.

3. High flexoelectric constants in Janus transition-metal dichalcogenides. PHYSICAL REVIEW MATERIALS, https://link.aps.org/article/10.1103/PhysRevMaterials.3.125402.

4. Exploration of mechanical, thermal conductivity and electromechanical properties of graphene nanoribbon springs. Nanoscale Advances, doi: 10.1039/d0na00217h http://pubs.rsc.org/en/content/articlepdf/2020/NA/D0NA00217H.

5. Topologically switchable behavior induced by an elastic instability in a phononic waveguide. Journal of Applied Physics, doi: http://aip.scitation.org/doi/am-pdf/10.1063/5.0005331.

6. A meshfree formulation for large deformation analysis of flexoelectric structures accounting for the surface effects. Engineering Analysis with Boundary Elements 120 doi: 10.1016/j.enganabound.2020.07.021 https://api.elsevier.com/content/article/PII:S0955799720301971?httpAccept=text/xml.

7. Intrinsic bending flexoelectric constants in two-dimensional materials. PHYSICAL REVIEW B, https://link.aps.org/article/10.1103/PhysRevB.99.054105.

8. Multilevel Monte Carlo method for topology optimization of flexoelectric composites with uncertain material properties.Engineering Analysis with Boundary Elements, 10.1016/j.enganabound.2021.10.008.

9. Outstandingly high thermal conductivity, elastic modulus, carrier mobility and piezoelectricity in two-dimensional semiconducting CrC2N4: a first-principles study. Materials Today Energy, 10.1016/j.mtener.2021.100839.

10. Exploring tensile piezoelectricity and bending flexoelectricity of diamane monolayers by machine learning. Carbon, 10.1016/j.carbon.2021.09.007.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Our team discovered the high power density of several types of 2D materials during the course of the project. The extensive experimental realization of numerous two-dimensional materials attracts further investigation of their applications. The exploration of the multilayer 2D materials for flexoelectricity was beyond the expectation of the project and their properties become very interesting as compared to single layer 2D materials. By the end of the project, we will realize a machine learning based search and characterization of 2D materials that is suitable for energy harvesting. We exploited the machine learning to compute the interatomic potentials and used our model for fast and efficient search of potential candidate materials. The simulation framework will enable scientists to model, characterize, virtually test and optimize flexoelectric energy harvesters. Computationally designed and optimized energy harvesters expectantly outperforming current piezoelectric energy harvesters of the same size will be manufactured and tested by the end of the project.

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