Amorphous hierarchical porous GeO _x as high-capacity anodes for Li ion batteries with very long cycling life

Many researchers have focused in recent years on resolving the crucial problem of capacity fading in Li ion batteries when carbon anodes are replaced by other group-IV elements (Si, Ge, Sn) with much higher capacities. Some progress was achieved by using different nanostructures (mainly carbon coatings), with which the cycle numbers reached 100-200. However, obtaining longer stability via a simple process remains challenging. Here we demonstrate that a nanostructure of amorphous hierarchical porous GeO _x whose primary particles are ∼3.7 nm diameter has a very stable capacity of ∼1250 mA h g ^-1 for 600 cycles. Furthermore, we show that a full cell coupled with a Li(NiCoMn) _1/3O ₂ cathode exhibits high performance.