Herein, we suggest to design newly 3-D network structures which could load massive Ge anode materials for high energy and power density per unit area. We fabricated highly ordered 3-D Ge nanoarrays loaded on Cu nanowire-network current collectors (Ge/Cu Nanowire-Networks). As the Cu nanowire-network current collector, the Cu nanonets were synthesized by MOCVD (metal-organic chemical vapor deposition) using a Cu(C₂H₃O₂)₂∙H₂O powder. And then, the Ge nanowires as anode materials were deposited onto the as-prepared Cu nanonets using the thermal evaporation of Ge powder. Loading mass of the Ge nanowires is dependent on deposition time. To provide porous structures, the prepared samples removed spontaneous oxide layers by 0.2 vol% H₂SO₄ solution.

We performed electrochemical performance tests of the Ge/Cu Nanowire-Networks with various mass loadings (from 0.7 to 7.0 mg cm^-2). The Ge/Cu Nanowire-Networks showed stable high areal capacity (> 2 mA h cm^-2) at a current density of 1 mA cm^-2 over 140 cycles and the excellent rate capability of 1.3 mA h cm^-2 at a current density of 5 mA cm^-2. The Ge/Cu Nanowire-Networks with a mass loading density 7.0 g cm^-2 has been fabricated, achieving a high areal capacity of 6.4 mA h cm^-2 after 40 cycles. Also, we performed EIS analysis to determine the relationship between the electrochemical performance and electrode kinetics. To investigate morphologies and phases of the Ge/Cu Nanowire-Networks, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were employed.