Simple synthesis of SiGe@C porous microparticles as high-rate anode materials for lithium-ion batteries

We report the synthesis of SiGe@C porous microparticles (PoSiGe@C) via the decomposition of Mg2Si/Mg2Ge composites, acid pickling and subsequent carbon coating processes, respectively. The content of Ge can be tuned by the initial ratio of Mg2Si and Mg2Ge in the composite. The as-synthesized PoSiGe@C has been used as the anode material of lithium-ion batteries, which shows an enhanced cyclic and rate performance compared to bare Si, PoSiGe as well as PoSi@C porous microparticles. Briefly, the PoSiGe@C delivers a good cycling stability with 70% capacity retention after 400 cycles and only 0.075% capacity loss per cycle at the current density of 0.8 A g(-1). Furthermore, super rate capability is also expressed by the PoSiGe@C. The unique porous structure, and synergistic effect of Si and Ge, may lead to the inherent high lithium-ion diffusivity and electrical conductivity of Ge, and good volume alleviation, which results in the good electrochemical performance.