Si7Ti4Ni4 as a buffer material for Si and its electrochemical study for lithium ion batteries

Abstract

Nano-Si embedded Si7Ti4Ni4 is synthesized with the melt spinning method, which is facile, and applicable to mass-production. Si7Ti4Ni4, the buffer material, is electrochemically inactive toward lithium. Nevertheless, Si 7Ti4Ni4 has good electrical conductivity, in the order of 105 S m-1, which is more conductive than amorphous carbon that is usually used as a coating material for active material. Furthermore, the surrounding grain boundaries of Si7Ti 4Ni4 effectively relax volume expansion of Si. Therefore, it plays a critical role in maintaining the structure of electrode and the integrity of active materials. As a result, nano-Si embedded in Si 7Ti4Ni4 shows outstanding cycle performance over 50 cycles at 400 mA g-1, and it maintains 86% of its specific capacity at 3200 mA g-1, compared with that of 400 mA g-1. This indicates that nano-Si embedded in Si7Ti4Ni 4 can be a promising anode material for lithium ion batteries. © 2013 Elsevier B.V. All rights reserved.