Silicon nanowires have already demonstrated their excellent ability as anode materials in lithium-ion batteries [1]. First, silicon has the best gravimetric and volumetric capacity as an alloy anode material, allowing to increase the overall battery capacity up to 35% [2,3]. On the other hand, its nanowire morphology is perfect to accommodate the big volume changes and avoiding electrode delamination. Nevertheless, their synthesis remained a gap for industrial development, being too costly compared to simple silicon nanoparticles, and offering only one layer of nanowires attached to the current collector [4]. We present here a new synthesis for silicon nanowires, patented in 2015[5], where silicon nanowires are synthesized on a powder substrate which can be sacrificial. This synthesis allows an easy production of many types of silicon nanowires by varying the catalyst (Au or Sn), the diameter (from 10 to 100 nm) or the growth substrate (sacrificial or carbon). This provides a unique occasion to study different parameters of silicon nanowire structure and chemical composition in a similar environment, with the aim to overcome silicon drawbacks: high initial irreversible capacity, unstable solid electrolyte interphase and swelling. Electrochemical analysis show that silicon nanowires associated with tin and graphite is the best material suited for lithium-ion batteries, with a high stability over 300 cycles and 82% initial coulombic efficiency, as shown in Figure 1. Combining material characterization techniques and operando study in synchrotron facility helps us to understand why, and participates in improving their performances. It seems that the formation of the Li15Si4 phase is one of the keys in electrochemical stability. Its appearance is dependent of the type of material used [6]. Finally, this material also offers the best synthesis conditions, because the use of tin as a catalyst allows lowering the synthesis temperature and replacing gold with tin decreases its average cost. [1]C.K. Chan, H. Peng, G. Liu, K. McIlwrath, X.F. Zhang, R.A. Huggins, Y. Cui, Nat. Nanotechnol. 3 (2008) 31–35. [2]M.N. Obrovac, V.L. Chevrier, Chem. Rev. 114 (2014) 11444–11502. [3]U. Kasavajjula, C. Wang, A.J. Appleby, J. Power Sources 163 (2007) 1003–1039. [4]K.-Q. Peng, X. Wang, L. Li, Y. Hu, S.-T. Lee, Nano Today 8 (2013) 75–97. [5]P. Chenevier, P. Reiss, O. Burchak, Method for Producing Silicon Nanowires, FR3022234 (A1) Abstract of corresponding document: WO2015189827 (A1), 2015. [6]C. Keller, A. Desrues, S. Karuppiah, E. Martin, J.P. Alper, F. Boismain, C. Villevieille, N. Herlin-Boime, C. Haon, P. Chenevier, Nanomaterials 11 (2021) 307.