Porous silicon electrodes for high performance integrated supercapacitors

We demonstrate high performance porous Si based supercapacitor electrodes that can be utilized in integrated micro supercapacitors. The key enabler here is ultra-thin TiN coating of the porous Si matrix leading to high power and stability. The TiN layer is deposited by atomic layer deposition (ALD), which provides sufficient conformality to reach the bottom of the high aspect ratio pores. Our porous Si supercapacitor devices exhibit almost ideal double layer capacitor characteristic with electrode volumetric capacitance of 7.3 F/cm. Several orders of magnitude increase in power and energy density is obtained comparing to uncoated porous silicon electrodes. Good stability of devices is confirmed performing over 5 000 charge/discharge cycles.