<i>In situ</i> combined analysis of gases and electrochemical signals of an activated carbon-based supercapacitor at 2.7–4 V

Li, Jie; Zhou, Xu; Zhang, ZhiAn

doi:10.1039/c8ra06568c

Cited by 7 publications

(3 citation statements)

References 21 publications

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“…Ni 3 (HITP) 2 has a significantly smaller stable voltage window of ˜1-1.5 V, compared to ˜2.5-2.7 V for YP-50F porous carbon (Figure 3c and Table 1). [67,[85][86][87][88][89][90][91] As a result, despite the comparable specific capacitance of Ni 3 (HITP) 2 , it has both a lower energy and power density compared to YP-50F porous carbon, as both quantities are dependent on the square of the operating voltage window. This drawback is also seen in many other 2D MOFs, with all MOFs that have been studied with organic electrolytes in the literature having lower stable voltage windows than porous carbons (Table 1).…”

Section: Electrolytementioning

confidence: 99%

Metal-Organic Framework Supercapacitors: Challenges and Opportunities

Shin

Gittins

Balhatchet

et al. 2023

Preprint

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Supercapacitors offer superior energy storage capabilities than traditional capacitors, making them useful for applications such as electric vehicles and rapid large-scale energy storage. The energy storage performance of these devices relies on electrical double-layer capacitance and/or pseudo-capacitance from rapid reversible redox reactions. Metal-organic frameworks (MOFs) have recently emerged as a new class of electrode materials with promising supercapacitor performances and capacitances that exceed those of traditional materials. However, our comparison of the supercapacitor performance of a porous carbon and a state-of-the-art MOF highlights a number of challenges for MOF supercapacitors, including low potential windows, limited cycle lifetimes, and poor rate performances. We propose that the well-defined and tuneable chemical structures of MOFs present a number of avenues for improving supercapacitor performance. We also discuss recent experimental and theoretical work on charging mechanisms in MOF-based supercapacitors, and find a need for more studies that elucidate the charge storage and degradation mechanisms. Ultimately, a deeper understanding will lead to design principles for realising improved supercapacitor energy storage devices.

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Section: Electrolytementioning

confidence: 99%

Metal-Organic Framework Supercapacitors: Challenges and Opportunities

Shin

Gittins

Balhatchet

et al. 2023

Preprint

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“…Regarding the solvent, gaseous decomposition products from non-aqueous electrolytes (e.g., ACN, PC) include hydrogen, ethene, propene, carbon monoxide, carbon dioxide, metaboric acid, and alkylboranes. [16] While the last two are related to the salt (e.g., Et 4 NBF 4 , Et 3 MeNBF 4 ), most of the gas evolution stems from solvent decomposition (e.g., hydrolysis of solvents in the negative compartment or electrochemical oxidation of solvent and carbon surface functional groups), [21][22][23] with ACN being more prone to gas evolution than propylene carbonate (PC). [24] With the above in mind, after determining the physicochemical and electrochemical properties of the SPBF 4 /ACN electrolyte against other conductive ACN-based analogues ( Size (nm) [13] 0 monitor the pressure evolution under ambient conditions.…”

Section: Introductionmentioning

confidence: 99%

Comparative Internal Pressure Evolution at Interfaces of Activated Carbon for Supercapacitors Containing Electrolytes Based on Linear and Cyclic Ammonium Tetrafluoroborate Salts in Acetonitrile

Nikiforidis

Phadke

Anouti

2022

Adv Materials Inter

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EDLC), where the prevalent mechanism entails non-Faradaic charge storage at the interface between a high surface area material and a liquid electrolyte. These energy storage devices are intriguing due to their high power density (10 kW kg −1 ), rapid response time (1 s), cycle-life (10 5 cycles) and safety. [1] Nanoporous carbon materials are commonly used in EDLCs. Their porous structures act as a bulk buffering reservoir for any medium, curtailing the ion transport resistance to the interior surface of the pores. [2] Increased pore accessibility caters to a larger number of cations to populate the electrode's double layer, leading to specific capacitances of the order of 200 F g −1 , as is for the case of activated carbon. [3] The latter is widely used in these energy storage devices as it is inexpensive, i.e., the carbonization process originates from wood, coal, and nutshell and is easily prepared compared with other porous materials such as templated carbons and carbide-derived carbons. With a specific surface area of ≈2000 m 2 g −1 , it can provide ≈30 mAh g −1 V −1 counter to 150 mAh g −1 V −1 for standard battery electrodes. [4,5] Typically, the electrochemical window of EDLCs is lower than that of batteries (e.g., 4.3 V for nickel manganese oxidegraphite battery). Thus, as the energy stored is proportional to the square root of the voltage (E EDLC = ½ C × V 2 ; C denotes capacitance and V voltage), their energy density is hindered, i.e., E LIB = 3-30 × E EDLC . It should be noted that E EDLC hinges on the nature of the double layer, that is, the specific Helmholtz compact layer geometry, the size of electrolyte cations and anions, their degree of solvation, and the orientation of the electrolyte solvent dipoles in the imposed electric field. [6] Accordingly, organic electrolytes are an attractive choice as they can reach operating voltages as high as 3.5 V. Acetonitrile (ACN) is a representative dipolar aprotic solvent that boasts operating temperatures at sub-zero range (T melting ACN = −45 °C), fluidity (η = 0.345 mPa s −1 at 25 °C), a large operating voltage window (>3.0 V), [7] low internal resistance, facile ionic adsorption within the pores of carbon-based electrodes and electrochemical stability due to its low viscosity and high dielectric constant (e = 38) In this study, the real-time increase in pressure of the accumulated gases at the electrode/electrolyte interface serves as a safety criterion for four conductive electrolytes comprising acetonitrile (ACN) and organic salts. They include tetrafluoroborate as an anion and cyclic 1,1-dimethylpyrrolidinium (Pyr11 + ), spiro-(1,1′)-bipyrrolidinium (SBP + ), acyclic methyl triethyl ammonium (Et 3 MeN + ) or standard tetraethylammonium (Et 4 N + ) as cations. The main focus lies on the SPBF 4 /ACN system. While the concentrated Pyr11BF 4 /ACN exhibits a minimal pressure evolution (≈25 Pa) under ambient conditions at 3.0 V, its electrochemical stability is inferior to SPBF 4 at high operating voltage. The electrolytes with acyclic tetrafluoroborate s...

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“…[5,16] These degradation reactions occur at the interface of carbon electrode and electrolyte. As for the electrolyte side, many groups have reported the decomposition of electrolyte solvents [2,6,17,18] and electrolyte salts, [5,17,19,20] based on the results obtained by X-ray photoelectron spectroscopy, [5,17,21] nuclear magnetic resonance spectroscopy, [5] infrared spectroscopy, [17] gas chromatography, [12,19] mass spectrometry, [6] energy dispersion Xray fluorescence spectroscopy, [14] and scanning electron microscopy. [14] On the other hand, there have been not many papers reporting the origin of degradation reactions at the carbon electrode side in organic electrolytes which are used for commercial supercapacitors.…”

Section: Introductionmentioning

confidence: 99%

Effect of carbon surface on degradation of supercapacitors in a negative potential range

Tang

Yamamoto

Nomura

et al. 2020

Journal of Power Sources

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The stability of supercapacitors is the key factor for their use under high temperature and high voltage conditions, and also for long-term durability. To improve the supercapacitor stability, understanding of the degradation mechanism is essential. In this work, the degradation sites in a carbon electrode at negative potential range are investigated in two types of common organic electrolytes, 1 M Et4NBF4 dissolved in propylene carbonate and in acetonitrile. To elucidate the common factor over a wide range of carbon materials, eight kinds of very different carbon materials are examined, including four activated carbons, two carbon blacks, zeolite-template carbon (high surface area and a large amount of carbon edge sites) and graphene mesosponge (high surface area and a little amount of carbon edge sites). Their surface structures are distinguished into two regions: carbon basal planes and edge sites, by the characterization techniques of nitrogen physisorption and high-sensitivity temperature-programmed desorption up to 1800 °C. Unlike the degradation at positive potential range, degradation reactions at negative potential range occur mainly on the carbon basal planes rather than the edge sites, and this is corroborated by the theoretical calculation.

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In situ combined analysis of gases and electrochemical signals of an activated carbon-based supercapacitor at 2.7–4 V

Abstract: Charging supercapacitors with high purity activated carbon provided different gas information and suggested the decomposition of salt prior to the solvent (PC).

Cited by 7 publications

References 21 publications

Metal-Organic Framework Supercapacitors: Challenges and Opportunities

Metal-Organic Framework Supercapacitors: Challenges and Opportunities

Comparative Internal Pressure Evolution at Interfaces of Activated Carbon for Supercapacitors Containing Electrolytes Based on Linear and Cyclic Ammonium Tetrafluoroborate Salts in Acetonitrile

Effect of carbon surface on degradation of supercapacitors in a negative potential range

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