Reversible Storage of Lithium in Three-Dimensional Macroporous Germanium

In this work, the preparation of novel macroporous germanium (p-Ge) and its electrochemical characterization as anode material for lithium-ion batteries is presented. Three-dimensional (3D) macroporous germanium particles with a hexagonal-like morphology were successfully prepared using a magnesiothennic reduction method, in which GeO2 serves not only as the template, but also as the germanium source. The obtained material demonstrates uniform pores within the particles, which serve as buffer zone to effectively accommodate the big volume changes of germanium during electrochemical lithiation and gives rise to an improved electrochemical performance. The p-Ge anode delivers not only a high reversible capacity of 1131 rnAh g(-1) at a rate of 1 C after 200 cycles, but also a high rate capability with a capacity of 717 mAh g(-1) at 5 C. The capacity retention for charge/discharge cycling of more than 96% after 200 cycles is also remarkably improved, compared to nonporous Ge materials.