Layered phosphorus-like GeP5: a promising anode candidate with high initial coulombic efficiency and large capacity for lithium ion batteries

Abstract

In this work, we for the first time investigate GeP₅ as an anode material for lithium ion batteries (LIBs). Using a facile high energy mechanical ball milling (HEMM) method, we successfully synthesize pure GeP₅ and GeP₅/C nanocomposite at ambient temperature and pressure. According to XRD Rietveld refinement and first principle calculations, GeP₅ possesses a two-dimensional layered structure similar to that of black P and graphite, and a high conductivity that is 10 000 and 10 times that of black P and graphite, respectively. Serving as novel anode materials, both GeP₅ and its carbon composite deliver an unprecedented high reversible capacity of ca. 2300 mA h g⁻¹, combined with a high initial coulombic efficiency of ca. 95%. Ex situ XRD and CV tests demonstrate that GeP₅ undergoes conversion and alloying type lithium storage mechanism and that its capacity is co-contributed to by both the Ge and P components. In addition, GeP₅/C exhibits superior cycle stability and excellent high-rate performance with a capacity of 2127 mA h g⁻¹ at 5 A g⁻¹. These properties suggest the promising application of these anode materials in next-generation high-energy and high-power LIBs.