Influences of annealing on lithium-ion storage performance of thick germanium film anodes

A high performance germanium (Ge) based anode is achieved through an appropriate air annealing post-treatment. Annealed Ge is fabricated by sputtering of Ge onto a stainless steel (SS) current collector and then annealed in air. It shows high specific and volumetric capacities of 1186 mA h g(-1) and 5887.4 mA h cm(-3), respectively, at the rate of 812 mA g(-1) up to 50 cycles. These specific and volumetric capacities are approximately a factor of 20 higher than those from as-deposited Ge on the SS substrate. In addition, the annealed Ge has a higher initial Coulombic efficiency of 90.8% than the as-deposited Ge of 81%. The improved performance of the annealed Ge can be attributed to the enhanced adhesion of annealed Ge film to SS substrate through interdiffusion at the SS/Ge interface due to the annealing post-treatment. (C) 2015 Elsevier Ltd. All rights reserved.