Silicon-nanoforest-based solvent-free micro-supercapacitors with ultrahigh spatial resolution via IC-compatible in situ fabrication for on-chip energy storage

Abstract

Micro-supercapacitors (MSCs) provide a promising on-chip solution for powering future microdevices. However, their practical applications have been seriously hindered by IC-incompatible manufacturing processes and dimensional limitations. Here, interdigital MSCs with in situ fabricated 3D polysilicon/nickel nanoforest (SNNF) electrodes were developed through a scalable IC-compatible process. The produced MSCs exhibit an exceptionally small footprint area and an ultra-high spatial resolution that is one order of magnitude higher than those obtained by ex situ methods. With a new solid polymer electrolyte (PVDF-HFP)/LiBOB/TiO₂, the all-solid-state MSCs demonstrated a superior device areal capacitance up to 0.53 mF cm⁻² (electrode areal capacitance: 5.47 mF cm⁻²), high volumetric power density of 4.15 W cm⁻³ with an energy density of 0.15 mW h cm⁻³, excellent cycling stability (>90% capacitance retention after 10 000 cycles) and fast frequency response (relaxation time: 1.09 ms), showing great potential as a high-performance and reliable on-chip power source for miniaturized devices.