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

The areal capacity of nanowire-based microbatteries 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.