Energy storage microsystems composed of thin-film devices (supercapacitors and batteries) have attracted attention to ensure autonomy of complex devices for wearable microelectronics. Recently, flexible systems have been investigated as deformation and integration of rigid micropower sources cannot be achieved.^1-5 The technological challenge is to design energy storage devices showing high electrochemical performance with advanced mechanical properties to prevent crack issues during electrochemical and mechanical tests. But in simple flexible micropower sources, the strains experienced by the active materials during bending usually remain well below the typical levels required leading to multiple fractures and subsequent loss of electrical contact.

In this work, the fabrication of LNMO micropillars supported on Al serpentine interconnects has been achieved by laser patterning technique. Morphological and chemical characterizations confirm the formation of independent micropillars while preserving the underlying Al film. We show that unlike compact and continuous electrode thin-films, vertical micropillar structures supported on serpentines can be stretched up to 70% without structural damaging owing to the presence of empty spaces that can prevent the formation of cracks and the electrode delamination. The present approach based on the fabrication of microstructured electrodes supported on serpentine interconnects can be extended to a wide range of materials, which opens promising perspectives for the conception of truly stretchable devices such as stretchable micro-batteries.⁶

References

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6. M. Nasreldin, R. Delattre, B. Marchiori, M. Ramuz, S. Maria, J. L. de Bougrenet de la Tocnaye, Microstructured electrodes supported on serpentine interconnects for stretchable electronics, APL Mat., 7, 031507 (2019).

Figure 1. Morphological and chemical characterizations of stretchable electrodes fabricated onto PDMS. (a) Tilted and (b) cross-sectional SEM images of LNMO micropillars supported on Al serpentines. (c) EDS chemical mapping of a region carrying 14 micropillars.