Investigating the Interface between Ceramic Particles and Polymer Matrix in Hybrid Electrolytes by Electrochemical Strain Microscopy

The interface between ceramic particles and a polymer matrix in a hybrid electrolyte is studied with high spatial resolution by means of Electrochemical Strain Microscopy (ESM), an Atomic Force Microscope (AFM)-based technique. The electrolyte consists of polyethylene oxide with lithium bis(trifluoromethanesulfonyl)imide (PEO(6)–LiTFSI) and Li(6.5)La(3)Zr(1.5)Ta(0.5)O(12) (LLZO:Ta). The individual components are differentiated by their respective contact resonance, ESM amplitude and friction signals. The ESM signal shows increased amplitudes and higher contact resonance frequencies on the ceramic particles, while lower amplitudes and lower contact resonance frequencies are present on the bulk polymer phase. The amplitude distribution of the hybrid electrolyte shows a broader distribution in comparison to pure PEO(6)–LiTFSI. In the direct vicinity of the particles, an interfacial area with enhanced amplitude signals is found. These results are an important contribution to elucidate the influence of the ceramic–polymer interaction on the conductivity of hybrid electrolytes.