Cross-section nano-Auger analysis to reveal bulk chemical/morphological information in composites for energy storage

In the field of energy storage, bulk chemical/morphological information of composite materials and electrodes and their evolution during cycling are of high interest. However, conventional analytical methods are often limited to access to the bulk properties of composites as they are buried. To tackle this challenge, samples preparation by cross-section coupled to nano-Auger analysis is developed as a suitable alternative.In the case of conversion-based electrodes for Li-ion batteries and beyond, direct evidence of the conversion reaction after long term cycling remains to be elucidated so far. Here, cross-section Auger imaging allows revealing the chemical/morphological evolution of TiSnSb conversion material at the electrode scale with a nano resolution. Importantly, results show that the conversion mechanism still occurs even after 400 cycles, which was unexpected. In the case of pseudocapacitive composite materials for hybrid supercapacitors, their bulk organization and structure remain a challenge to investigate. Here, cross-section Auger imaging allows revealing the nanoscale assembly and porosity of Mn-Co composites prepared by exfoliation/restacking, which could not be proven so far. Overall, a good correlation between the restacking method, the nanoscale organization/structure of composites and resulting electrochemical performance was obtained. Finally, the innovative cross-section Auger approach presented here is suitable to get reliable and relevant bulk chemical/morphological information in composites for energy storage and will also benefit to other research fields.