N-DOPED VERTICAL SILICON NANOWIRE ARRAYS AS THE ANODE FOR LITHIUM-ION BATTERY

• Main Author: Pandu Nugroho, Andika
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/49666
• Institution: Institut Teknologi Bandung

Lithium-ion battery (LIB) is a type of secondary battery that has been scientifically and commercially proven for its high energy density as compared to the other type of secondary batteries. Currently, commercial LIB uses graphite as the anode, however, graphite anode exhibits moderate specific capacity (372 mAhg-1) . On the other hand, silicon is one of the most promising substitutes because it acquires a much higher energy density (4200 mAhg-1). Nonetheless, silicon has poor intrinsic electrical conductivity and has a high risk of losing its active material due to its large volume expansion (up to 420%) during reaction. One of the ways to overcome this drawback is to transform the morphology of silicon into nanowire and to improve the intrinsic property of silicon through doping. Hence, there are still rooms to improve the manufacturing method of silicon nanowire, especially on its arrangement on the anode of LIB. In this report, n-doped vertical silicon nanowire arrays (V-SiNW) as the anode for lithium ion battery and their effects of the novel arrangement were studied. The n- and p-doped V-SiNW was fabricated using soft ultraviolet based nanoimprint lithography and inductively coupled plasma dry reactive ion etching at cryogenic temperature. The anode was characterized by XRD, SEM, EIS, and four-point probe in order to initially identify its crystal structure, nano morphology and resistivity, respectively. Then, lithium half-cell battery was assembled using the chosen n-doped V-SiNW as its counter electrode of lithium metal. The cell performance was examined using battery analyzer to know the capacity and stability. The result showed that n-doped V-SiNW obtained a <100> directional silicon and cylindrical shaped nanowire morphology with the diameter of 2500 nm. The resistivity of V-SiNW through-thickness was 3 x 105 ? cm, while the surface resistivity was 35 ? cm. The V-SiNW half-cell achieved the capacity of 0.45 mAh/cm2 for 70 cycles at the current density of 0.06 mAcm- 2. As conclusion, the improved performance of uniquely fabricated V-SiNW is due to the enhanced electron mobility route in the SiNW. Furthermore, the arrayed spacing of the silicon anode serves as a buffer space for lithiation expansion, resulting in the better stability of LIB.