Supercapacitors with alternating current line-filtering performance

Abstract

Alternating current (AC) line filters have been widely used to smooth the leftover AC ripples on direct current voltage. Currently available commercial aluminum electrolytic capacitors (AECs) are primarily used for this application. However, the bulky volume and low capacitance of AECs have become incompatible with the rapidly developed intelligent electronic devices and industry dynamics. Supercapacitors with high specific capacitance and AC line-filtering performance could become the next-generation candidates to replace AECs for smoothing leftover AC ripples. Thus, most conventional supercapacitors behave like a resistor and not a capacitor at 120 Hz mainly because complex pore structures of electrode materials prevent the diffusion of electrolyte ions. Various electrode materials have been reported to reveal supercapacitors with AC line-filtering performance; however, the balance of high specific capacitance and an excellent filtering efficiency is a prodigious challenge. This review summarizes recently reported supercapacitors based on different types of electrode materials with AC filtering performance and attempts to develop the relationship between different influencing factors and features of functional materials.

In Situ Dynamic Manipulation of Graphene Strain Sensor with Drastically Sensing Performance Enhancement

“…Previous work on graphene stacking structures has shown that this system relies on nanosheet slip to detect small mechanical signals. [ 20–23 ] However, direct experimental verification evidence is still lacking. [ 24 ] In particular, it is extremely challenging to directly observe how the relative position of the nanosheet changes the charge transport in the channel.…”

History and Perspectives on Ultrafast Supercapacitors for AC Line Filtering

“…Especially, for the past decade, the ultrafast SCs have been investigated to replace the commercial aluminum electrolytic capacitors (AECs) in alternating current (AC) line filtering applications. [16][17][18] AECs are currently used as a reservoir capacitor, smoothing pulsating direct current (DC) signal of 120 Hz (rectified by diodes from a wall AC power outlet of 60 Hz) to a constant DC output voltage required in most line-powered electronics. While the AECs exhibit significantly high-frequency responses greater than ≈10 kHz, their small capacitances with bulky sizes remain one of the main obstacles to scale down circuit boards.…”

“…[21] The essential requirements of SCs for adequate 60-Hz AC-line filtering applications are fast frequency response characteristics at 120 Hz (e.g., a phase angle close to the ideal capacitor value of −90° and a small resistancecapacitance (RC) time constant less than 8.3 ms at 120 Hz), high areal/volumetric capacitance (responsible for low ripple in the output voltage), and compact size. [17,18,22] Therefore, considerable effort has been devoted to developing high-performance SCs for AC-line filtering applications by investigating key elements such as electrodes, electrolytes, and cell configurations.The electrode is a key component of SCs for closing the power performance gap between the SCs and electrolytic capacitors as well as achieving high capacitance. The traditional SCs based on activated carbon have an extremely slow frequency response, acting as a resistor in the required frequency range for AC line filtering (e.g., phase angle of 0° at 120 Hz).…”

“…[21] The essential requirements of SCs for adequate 60-Hz AC-line filtering applications are fast frequency response characteristics at 120 Hz (e.g., a phase angle close to the ideal capacitor value of −90° and a small resistancecapacitance (RC) time constant less than 8.3 ms at 120 Hz), high areal/volumetric capacitance (responsible for low ripple in the output voltage), and compact size. [17,18,22] Therefore, considerable effort has been devoted to developing high-performance SCs for AC-line filtering applications by investigating key elements such as electrodes, electrolytes, and cell configurations.…”

Electrosynthesis of a hyperbranched dendrimeric porphyrin polymer: optical and electronic characterization as a material for bifunctional electrochromic supercapacitors

“…54 Also, the use of 2D soft nanomaterials is an emerging technology for the development of micro-supercapacitors with ultra-high volumetric power density. [55][56][57][58] In our case, specific capacitances as high as 277 F g -1 at a current density of 4.5 A g -1 were measured. This last property is based on the pseudocapacitance generated by the oxidation-reduction reactions that can be induced in the 7 conducting dendrimeric film.…”