Ultrafast Nonvolatile Ionic Liquids-Based Supercapacitors with Al Foam-Enhanced Carbon Electrode

Abstract

The ultrafast frequency response supercapacitor is a promising candidate for alternating current line filtering. We report the fabrication of a special structured ionic liquid-based supercapacitor with an ultrafast response of only 1.5 ms. The three-dimensional aluminum (Al) foam in situ coated with carbon layer (∼500 nm) serves as the novel, highly efficient electrode-current collector. The high porosity (95%) of Al foam allows the rapid ion diffusion and the as-obtained Al/C interface with atomic-level mixing allows the fast electron transfer, two crucial factors for ultrafast response. Hence, it possesses an excellent specific mass capacitance of 68 mF g–1 at 120 Hz, as well as an ultrahigh rate of up to 3000 V s –1. The supercapacitors exhibit frequency modulation performance in the range of 20 kHz to 16 MHz. They exhibit the similar even better alternating current filtering performance, as compared to the commercial aluminum electrolytic capacitors, detected at 10 Hz, 60 Hz, 100 Hz and 1 M Hz. These results suggest that, although ILs have high viscosity and low ion mobility, the IL-based supercapacitor has a great potential to be used as a device for alternating current line filtering, as well as providing nonvolatile and nonflammability safety.

The Progress and Comprehensive Analysis of Supercapacitors for Alternating Current Line Filtering: A Review

“…According to the spherical‐aberration corrected transmission electron microscope (ACTEM) characterization (Figure 7b–d), the atomic interaction of C−Al in the interface was obtained. This contributed to excellent ohmic coupling and ultrafast frequency response of SCs in the ionic liquid electrolyte [26] …”

“…Based on the 60 Hz AC frequency in the USA and 50 Hz AC frequency in China, the $${{\tau }_{{\rm R}{\rm C}}}$$ and the impedance phase angle at 100 Hz/120 Hz are crucial to evaluate the filtering performance [10,26] . For AC filtering capacitors, a $${{\tau }_{{\rm R}{\rm C}}{\rm \ }}$$ of 8.3 ms at 120 Hz is generally needed.…”

“…A small interface resistance prompts excellent ohmic contact to enhance the charge transfer. As a result, the in‐situ growth of electrode materials on the current collector surface was explored to acquire a small interface resistance [26,34b,56] . As shown in Figure 7(a), both the low interfacial impedance and the ultrafast response of SCs were achieved by the in‐situ coating active carbon layer on the sketch of 3D Al foam [26] or by the growing VOG in situ on Al substrate [34b] .…”

“…As a result, the in‐situ growth of electrode materials on the current collector surface was explored to acquire a small interface resistance [26,34b,56] . As shown in Figure 7(a), both the low interfacial impedance and the ultrafast response of SCs were achieved by the in‐situ coating active carbon layer on the sketch of 3D Al foam [26] or by the growing VOG in situ on Al substrate [34b] . According to the spherical‐aberration corrected transmission electron microscope (ACTEM) characterization (Figure 7b–d), the atomic interaction of C−Al in the interface was obtained.…”

Fabrication of γ-Al2O3 Nanoarrays on Aluminum Foam Assisted by Hydroxide for Monolith Catalysts

“…Metal substrates can be covered by a “washcoat” with in situ growth, resulting in greater adhesion between substrates and overlayer due to chemical linkages. Open-cell metal substrates, for example, have been proposed for the removal of gaseous pollutants, − water treatment, , reforming of methane, supercapacitors, fuel cells, thermal storage, and so on. Furthermore, the coefficient of thermal conductivity of metals such as Al (∼237 W m –1 K –1 ) is hundreds of times greater than that of cordierite, resulting in more uniform temperature distribution and improved heat efficiency when employed on a broad scale.…”