Synthesis and characterization of paper-like, nanostructured electrodes for advanced secondary batteries

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The major task of the present project is the development of paper-like electrodes with improved performance for use in Li-ion batteries. The layered architecture of these nanocomposites is envisioned to simultaneously exploit the extraordinary mechanical/chemical stability and electrical conductivity of graphene and the efficient lithium ion storage capability of inorganic nanostructures, in order to enhance the charge-discharge kinetics and lifetime of the electrodes. In the first project period, the self-assembly of V2O5 nanofibers was improved to yield tough and flexible paper-like films, and the other required inorganic components SnO2 nanosheets/-fibers and LiMnPO4 nanoplatelets were successfully synthesized and characterized. Importantly, it could be proven in particular for composites comprising V2O5 nanofibers and graphene oxide (GO) that the implementation of graphene sheets indeed leads to improved mechanical stability, electrical conductivity and actuation properties. Moreover, a correlation was observed between the structural quality of these composites and their mechanical performance. On this basis, the second project stage aims at completing the synthesis and characterization of the three different types of composites, including the investigation of films with alternating layer structure. A major focus will be on determining the films' mechanical and electrochemical properties in dependence of the content, distribution and reduction extent of the incorporated GO. Another central task is the detailed evaluation of the impact of electrochemical cycling on the micro- and nanostructure as well as mechanical performance for the electrodes. In this manner, valuable insights shall be gained into the major mechanisms responsible for electrochemical performance degradation of such type of Li-ion electrodes. Of particular relevance in this respect will be the influence of parameters such as the volume fraction of graphene and the inorganic nanostructures, as well as the interfacial coupling between the two components.