Ni foam as the current collector for high capacity C–Si composite electrode

Abstract

Si electrode is very promising as the anode material for next generation lithium ion batteries requiring high capacity and energy because of its high theoretical capacity (4200mAhg−1 compared to 372mAhg−1 for graphite) and low discharge potential (∼0.5V vs. Li/Li+). However, fast capacity fading of Si electrode is suffered from huge volume expansion and contraction during charging and discharging. Although many methods, including nanostructured electrode, thin film and composite electrode, have been proposed to overcome the capacity fading problem, high synthesis cost and/or poor effects prevent them from being used in the commercial applications. In this study, 3-dimensional (3D) Ni foam is adopted as the current collector for high capacity C–Si composite electrode. The results show that Ni foam can effectively suppress the electrode expansion and greatly improve the cycle life of Si electrode due to the 3D structure. Electrochemical impedance spectroscopy also shows that the electrode with Ni foam show much lower impedance after cycling. Therefore, adopting Ni foam as the current collector provides a new way to incorporate the electrode materials with large volume expansion.