Dresden 2017 – scientific programme

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SYLI: Symposium Interfacial Challenges in Solid-State Li Ion Batteries

SYLI 5: Structure - property relationships I

SYLI 5.1: Talk

Tuesday, March 21, 2017, 11:45–12:00, IFW A

Hierarchically Structured Electrode Materials for Lithium-Ion Batteries — •Michael Fischer, Xiao Hua, Preston Sutton, and Ullrich Steiner — Adolphe Merkle Institute, Chemin des Verdiers 4, 1700 Fribourg, Switzerland

We present a facile synthetic approach for the fabrication of hierarchically structured electrode materials for lithium-ion batteries. Amphiphilic block copolymers are known to form well-defined morphologies on a mesoscale. By confining sol-gel chemistry to one of the blocks of the polymer these structures can be transferred to various inorganic materials, including functional materials that find use in batteries. Blending the sol-gel precursor/block copolymer mixture with a homopolymer induces phase separation and leads to structure formation on a secondary (micrometre) scale. Following this method, we synthesized mesoporous microspheres of TiO2 and Li4Ti5O12/C as anode materials and hollow LiFePO4/C nanospheres as a cathode. These compounds suffer from intrinsically low ionic and electronic conductivities but are of great interest due to their inherent stability and safety. The aforementioned morphologies circumvent this drawback by providing shortened solid-state diffusion distances, facilitating ionic transport. In addition, we can tune the mesopore size by employing block copolymers of different chemical composition and molecular weight. Studying the relationship between pore size and electrochemical performance enables us to identify design principles for the optimization of electrode architectures.