Graphene Coated Ni Foam As a Current Collector for N-Type Doped Si Thin Film Anode for Li-Ion Batteries

Abstract

Thin film silicon (Si) has gained a significant attention as an anode material for Li-ion batteries (LIBs), since its nanostructure retains structural integrity through minimizing the volume variation. However, 2D Si thin film experiences delamination from the current collector, and loss of electrical contact leads to further capacity fading. To overcome this issue, recent scientific investigations have shown that the 3D structure of electrodes (porous, rough-surface, etc.) is capable of suppressing volume changes upon lithiation/delithiation and providing large contact area between active material and current collector. Here, we propose a novel electrode material for LIBs that comprises of Si on graphene coated Ni foam (G-Ni). Porous Ni foam serves as 3D structured highly electroconductive network, and graphene layer was employed with the purpose of improving adhesion and electrochemical stability of Si thin film electrode. Magnetron sputtering was used to deposit n-type doped amorphous Si thin film on G-Ni. Chemical vapor deposition (CVD) was applied to obtain a few layer graphene (FLG) on catalytic Ni foam. The as-grown anode material was tested in a half-cell configuration with metallic lithium as a counter and reference electrode. The results were compared with n-type doped amorphous Si thin film on pristine Ni foam. Galvanostatic cycling performance was evaluated in the voltage range from 0.1 to 1.5 V at a current density of ~ 32 µA cm-2. Si-G-Ni anode exhibited the initial areal capacity of around 141 µA cm-2 and the stable reversible areal capacity of around 80 µA cm-2 over 100 cycles. Si-Ni anode shows an initial capacity of 91 µA/cm-2 with a rapid capacity fading to approximately 30 µA cm-2 at 100th cycle. The results of characterization and electrochemical tests will be presented at the conference. Figure 1