Synergetic design of a coralline-like Si/Ni/C anode material with microstructure and gradient interface for lithium-ion batteries

The practical application of a high-capacity silicon anode is still impeded by its interfacial instability, low electronic conductivity, and compact density. Here, we propose a coralline-like Si/Ni/C anode material by utilizing a metal-organic framework as the metal and carbon source. By coreduction and carbonization of silica-coated Ni-MOF, an interlayer of NiSi2 is in situ formed at the interface of the carbon skeleton and Si nanoparticles, resulting in excellent compatibility and gradient interface between them. The efficiently utilized inner void, containing multiple Si, NiSi2, and carbon skeleton, improves the compact density of the as-prepared Si/Ni/C. The electronic conductivity was also improved by the bridge space between the carbon skeleton and Si nanoparticles through a highly conductive NiSi2. The three-dimensional coral carbon skeleton provides excellent mechanical properties and suitable space for the volume change of Si. As a result, the as-prepared Si/Ni/C composite demonstrates a high reversible capacity of 1044 mA h g−1 with a capacity retention of 82.4 % after 100 cycles. The carbon-coated Si/Ni/C composite exhibits enhanced rate capability (695 mA h g−1at 10 A g−1). Such improved performances are attributed to the synergetic effects of stable structural integrity and good interface stability, which can be used to guide the design of Si anode for industrial applications.