Tin-nanoparticle as anode material in lithium-ion batteries - Influence of morphological and surface properties on the electrochemical performance

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In this project, anode systems based on nanoscale tin particles as active material will be studied. These anode systems have a high potential for application in lithium-ion batteries, because tin as active material offers a high lithium storage capacity, which results in a high specific energy. However, tin-based anodes display only a limited cycling stability, so far. In order to improve their electrochemical characteristics, the behavior of the tin-based materials needs to be understood fundamentally. So far, little is known about the dependence of the lithium storage mechanism on the properties of the particles, such as their morphology and surface. Also the formation and structure of the SEI layer on the surface of the tin electrodes, and the reasons for the loss of the contact between the active material particles and conductive carbon particles and/or the current collector need to be studied in more detail to gain a deeper understanding.The main focus of the project lies on the specific nanoparticle design in terms of their size and shape, as well as on the optimization of their surface functionalization with polymers (ligand shells). Furthermore, we will study the correlation between the morphological properties and the surface properties of the particles and their electrochemical behavior. In this project, we will optimize the size of the particles and their size distribution in order to obtain a high specific capacity as well as a high cycling stability. Furthermore, the electrode preparation, in terms of the dispersion procedure, binder material and composition, needs to be optimized and adjusted to the properties of the particles. What is more, fundamental questions that have not been sufficiently answered so far need to be addressed. In particular, the interaction of the polymer binder with the surface of the particles has to be studied, as well as its impact on the electrochemical properties, such as, the reversible and irreversible capacity, SEI formation and capacity retention.