On chip MnO2-based 3D micro-supercapacitors with ultra-high areal energy density

In the near future, Internet of Things will be widely deployed all over the connected world. Powering will be crucial for miniaturized electronic devices requiring fast charging, high energy density and long term-durability. 3D micro-supercapacitors are an attractive energy storage solution at the millimeter scale to power miniaturized IoT devices exhibiting small form factor packaging issues. However, there are nowadays not any microdevices on the shelves that could fulfill both energy and mass production requirements. Here, we demonstrate the collective fabrication of 3D micro-supercapacitors (MSCs) integrated on silicon wafer and using MnO2 as the active electrode material and 5 M aqueous LiNO3 as the electrolyte. 0.05 - 0.1 mWh cm(-2) energy densities reached by the fabricated 3D MSCs are remarkable, exceeding those of state-of-the-art micro-supercapacitors, competing those of hybrid microdevices and approaching the performance of lithium micro-batteries. Without sacrificing the power performance (> 1 mW cm(-2)), the 3D MSCs demonstrate a very good cycling behavior over 10 000 cycles (similar to 15% loss).