Stretchable apparatus have drawn increasing attention nowadays, especially in the applications of sensors, monitors, and optoelectronic devices.^1-3 Thus far, the development of stretchable Li-ion battery is impeded by the lack of flexible electrodes associated with proper interconnecting structures for high utilization of active materials.⁴ As inspired by nature, a common biomaterial, shrimp shells (SSs)⁵, attracted our attention for fabricating an efficient, stretchable Li-ion batteries as considering its advantages, including i) the C-O, C-N and N-H stretches contained in the protein and chitin (poly-b(1/4)-N-acetyl-D-glucosamine) are beneficial for excellent electrochemical performance; ii) the constituent inorganic calcium carbonate acts as an in-situ template for the porous configuration (Fig. a); iii) The as-designed substrate could not only possess continuous electric conductivity when stretching but also accommodate a high active material loading.

In this work, we successfully demonstrated a flexible, stretchable supercapacitor by using a hybrid electrode, wherein the as-prepared SSs carbon is interpenetrated into a polydimethylsiloxane (PDMS)-supported substrate. In this regard, the open network of pores was filled by the SSs carbon to provide high conductivity and stretchability. Besides, SWCNT was further sprayed onto this porous substrate to form a 3D interconnected porous structure as shown in Fig. b. Finally, by using a bifunctional polymeric electrolyte (BMITFSI-P(EO)₂₀-LiTFSI, serving as separator and solid electrolyte with a high ionic conductivity of 1.6×10^-4 S cm^-1 to assemble the battery, the as-fabricated stretchable porous electrode can deliver a high energy density of 44.1 Wh kg^-1 under 20% applied tensile strain. In addition, the capacitance retention shows 90% after bending from 0^o to 180^o. This study would pay the way for the future development of wearable supercapacitors, Li-ion batteries and beyond.

1. W. Liu, M. S. Song, B. Kong and Y. Cui, Advanced Materials, 2016.
2. D. J. Lipomi, M. Vosgueritchian, B. C. K. Tee, S. L. Hellstrom, J. A. Lee, C. H. Fox and Z. Bao, Nat Nano, 2011, 6, 788-792.
3. Y. Huang, M. Zhong, F. Shi, X. Liu, Z. Tang, Y. Wang, Y. Huang, H. Hou, X. Xie and C. Zhi, Angewandte Chemie (International ed. in English), 2017, 56, 9141.
4. W. Liu, Z. Chen, G. Zhou, Y. Sun, H. R. Lee, C. Liu, H. Yao, Z. Bao and Y. Cui, Advanced Materials, 2016, 28, 3578-3583.
5. N. Yan and X. Chen, Nature, 2015, 524, 155-158.