Amorphus germanium oxide materials are provided that are composed of germanium and oxygen having a formula GeO.sub.x, where 0.01.ltoreq.x.ltoreq.1.99. The germanium oxide forms nanoscale hierarchical porous agglomerates that have high capacity, high diffusivity of lithium, and enhanced cycling stability. The enhanced or superior performance (structural stability and reactivity) of these materials is due to the formation of ultrafine primary nanoparticles, amorphization, pore formation, preferably of nanoscale nature, and the incorporation of oxygen. These amorphous germanium oxide materials may serve as high-capacity anode materials and afford an enhanced capacity applicable for electrochemical cells such as Li-ion batteries.
STATEMENT OF GOVERNMENT LICENSE RIGHTS
 The present invention was made with government support under contract number DE-ACO2-98CH10886 awarded by the U.S. Department of Energy. The United States government may have certain rights in this invention.