The development of rechargeable lithium-ion batteries (LIBs) with higher capacity and longer cycle life is still in progress. LIBs are the ideal choice as power sources for portable electronic devices and electric vehicles (EVs). However, recent LIBs are not satisfactory for the consumer’s demands due to the inherent capacity restriction of conventional electrode materials such as a graphite. Si, which can be alloyed with Li at lower potential, is a potential alternative to the conventional graphite, due to its high theoretical specific capacity (4200 mAh g^-1), natural abundance, and environmental friendliness. However, for Si, the poor Li diffusivity, intrinsic low electrical conductivity, and large volume variation (>300%) during lithiation reduce the practical application of Si as an anode material. Thus far, to overcome these issues, researchers have used strategies such as using Si nanostructures (nanowires, nanorods, nanotubes, and nanoparticles) and employing conductive carbon coatings. Nevertheless, to prevent the capacity fading and exhibit longer cycle life comparable to that of graphite, a breakthrough is needed.

In the present work, the Si nanoparticles (SiNPs) was coated with the two-dimensional conductive Cu-ion containing metal-organic framework (Cu-MOF) for the LIBs with high capacity and longer cycle life LIBs. The Cu-MOF grew directly on the highly porous SiNPs. The highly porous Cu-MOF alleviated the stress resulting from volume expansion and acted as a connected channel for the transport of Li-ion and electron. As a result, the SiNPs coated with Cu-MOF (Si@Cu-MOF) could exhibit high capacity, rate capability, and cyclability. In particular, the Si@5Cu-MOF electrode delivered an initial discharge and charge capacities of 3201 and 2511 mAh g^-1, respectively, which corresponded to a Coulombic efficiency of 78.5%, at a rate of 0.1C. The reversible capacity retention after 100 cycles was 2529 mAh g^-1, which was even higher than that of the first reversible capacity due to the activation effect. In addition, the Si@5Cu-MOF electrode exhibited an excellent rate capability: 2621, 2486, 2096, and 468 mAh g^-1 at the rates of 0.2C, 0.5C, 2C, and 20C, respectively. These encouraging properties will assure use of the Si@Cu-MOF as a potential anode material for LIBs.