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(se abrirá en una nueva ventana).
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(se abrirá en una nueva ventana).
3. High flexoelectric constants in Janus transition-metal dichalcogenides. PHYSICAL REVIEW MATERIALS,
https://link.aps.org/article/10.1103/PhysRevMaterials.3.125402(se abrirá en una nueva ventana).
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(se abrirá en una nueva ventana).
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(se abrirá en una nueva ventana).
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(se abrirá en una nueva ventana).
7. Intrinsic bending flexoelectric constants in two-dimensional materials. PHYSICAL REVIEW B,
https://link.aps.org/article/10.1103/PhysRevB.99.054105(se abrirá en una nueva ventana).
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.
