Three-Dimensional Ni/TiO2 Nanowire Network for High Areal Capacity Lithium Ion Microbattery Applications

The areal capacity of nanowire-based micro-batteries can be potentially increased by increasing the length of nanowires. However, agglomeration of high aspect ratio nanowire arrays could greatly degrade the performance of nanowires for lithium ion (Li-ion) battery applications. In this work, a three-dimensional (3-D) Ni/TiO2 nanowire network was successfully fabricated using a 3-D porous anodic alumina (PAA) template-assisted electrodeposition of Ni followed by TiO2 coating using atomic layer deposition. Compared to the straight Ni/TiO2 nanowire arrays fabricated using conventional PAA templates, the 3-D Ni/TiO2 nanowire network shows higher areal discharging capacity. The areal capacity increases proportionally with the length of nanowires. With a stable Ni/TiO2 nanowire network structure, 100% capacity is retained after 600 cycles. This work paves the way to build reliable 3-D nanostructured electrodes for high areal capacity microbatteries.