Lithium-ion batteries (LIBs) have attracted considerable interest because of their wide range of environmentally friendly applications, such as portable electronics, electric vehicles (EVs), and hybrid electric vehicles (HEVs). [1][2][3][4][5] For the next generation of LIBs with high energy and high power density, improvements on currently used electrode materials are urgently needed. [6][7][8][9][10] Among various anode materials, Si has been extensively studied owing to its highest theoretical capacity (4200 mA h g À1 ), abundance in nature, low cost, and nontoxicity. However, Si-based anodes are notoriously plagued by poor capacity retention resulting from large volume changes during alloy/de-alloy processes (400 %). The intrinsic strain generated during such expansion and contraction easily leads to electrode pulverization and capacity fading. Thus, it is a big challenge to achieve both excellent cyclability and enhanced capacity of Si-based anode materials.Significant efforts have been devoted to circumvent this issue caused by the volume change of silicon. [11][12][13][14][15] Recently, a number of Si nanostructures, including nanoparticles, [15,16] nanowires/nanorods, [17][18][19] nanotubes, [20] and porous nanostructures [21,22] as well as their composites, [23] have been fabricated to achieve improved cycling performance.Among them, tubular structures, with extra interior space for electron and ion transport, as well as for accommodating volume changes, are one of the most attractive and promising configurations for LIBs. However, such anode materials are still far from commercialization, and new strategies for the synthesis of novel structures with superior cycling performance and stability are still much sought-after.Herein, we report a new tubular configuration made from naturally rolled-up C/Si/C trilayer nanomembranes, which exhibits a highly reversible capacity of approximately 2000 mA h g À1 at 50 mA g À1 , and approximately 100 % capacity retention at 500 mA g À1 after 300 cycles. The sandwich-structured C/Si/C composites, with moderate kinetic properties toward Li + ion and electron transport, are of the highest quality. The excellent cycling performance is related to the thin-film effect combined with carbon coating, which play a structural buffering role in minimizing the mechanical stress induced by the volume change of Si. The energy reduction in C/Si/C trilayer nanomembranes after rolling up into multi-winding microtubes results in a significantly reduced intrinsic strain, which can improve capacity and cycling performance. This synthetic process could be compatible with existing industrial sputtering deposition processes as well as roll-to-roll thin-film fabrication technology.The strategy for the self-release of C/Si/C trilayer nanomembranes using rolled-up nanotechnology [24] to form multilayer C/Si/C microtubes is shown in Scheme 1. First, a sacrificial layer (red color, photoresist ARP 3510) was deposited on top of the Si substrates by spin-coating, then trilayer C/Si/C (10/40/10 nm, ...