On chip interdigitated micro-supercapacitors based on sputtered bifunctional vanadium nitride thin films with finely tuned inter- and intracolumnar porosities
Résumé
Micro-supercapacitors (MSC) are considered as promising miniaturized electrochemical energy storage devices for Internet of Things applications. Unfortunately, the technological readiness level of these devices is still at the lab scale with the development of individual prototypes due to the difficulty to produce high performance porous electrode material with microelectronic equipment available in pilot production lines. Here, the collective fabrication of on chip MSC based on sputtered porous vanadium nitride (VN) bifunctional material is reported. For the first time in the field of MSC, the porosity of the sputtered VN thin films is fine-tuned at the nanoscale level in order to produce high capacitance and high conductive electrodes. Interdigitated MSC based on optimized VN thin films are fabricated on silicon wafers using microelectronic facilities. 2 μWh cm-2/10 mWh cm-3 energy densities are reached while keeping a high power density (10 mW cm-2/>50 W cm-3) owing to high electrical conductivity of VN layers. Sputtered vanadium nitride thin films are demonstrated to be suitable pseudocapacitive electrodes and highly conductive current collectors for MSC applications. These findings represent a major advance in order to go toward the large-scale deployment of such miniaturized power sources.