Stable high-areal-capacity nanoarchitectured germanium anodes on three-dimensional current collectors for Li ion microbatteries

It is of great significance to improve the areal capacity of Li ion microbatteries in pursuit of high-end medical and RFID products and technologies. Here, we investigated germanium (Ge) nanoarray electrodes with high mass loading, directly anchored on three-dimensional (3D) copper (Cu) nanonet current collectors (Ge-na/Cu NNs). These nanoarchitectured electrodes showed superior areal capacity (>2 mA h cm^-2) and usable lifetime at a current density of 1 mA cm^-2 over 140 cycles. In addition, an excellent rate capability of 1.25 mA h cm^-2 (calculated gravimetric capacity of 685 mA h g^-1) at a current density of 5 mA cm^-2 could be achieved using these synergistically fabricated Ge-na/Cu NN electrodes, making them potential electrodes for Li ion microbatteries with large energy and power densities.