Electrochemical Properties of Trimethylammonium Tetrafluoroborate in Electrochemical Double-Layer Capacitors

Lee, Sooyeon,Lee, Kyung Min,Kim, Ketack The Korean Electrochemical Society 2022 Journal of electrochemical science and technology Vol.13 No.2

Trimethylammonium tetrafluoroborate (TriMA BF₄), consisting of the smallest trialkylammonium ion, was investigated for use in electrochemical double-layer capacitors. Despite the presence of a proton in TriMA⁺, cycle life tests in acetonitrile (AN) and -butyrolactone (GBL) showed a good capacity retention with a 1.8 V cut-off voltage. The rate of electrolysis of TriMA BF₄ in GBL was lower than that in AN because of the lower conductivity in GBL. As a consequence, the cells based on GBL achieved a higher capacitance and longer life than those with AN. TriMA BF₄ had a higher conductivity and lower viscosity than the quaternary salt tetraethylammonium tetrafluoroborate in GBL, as well as higher ionic mobility, these factors resulted in a higher rate capability.

Electrochemical and structural characteristics of activated carbon-based electrodes modified via phosphoric acid

Yu, H.R.,Cho, S.,Jung, M.J.,Lee, Y.S. Elsevier 2013 Microporous and mesoporous materials Vol.172 No.-

To improve the electrochemical performance of an activated carbon (AC)-based electric double-layer capacitor (EDLC), the AC surface, which is used as an electrode, was modified using different concentrations of phosphoric acid. The effects of the treatment on the surface and electrochemical properties of the AC electrodes were investigated. The specific capacitance increased from 256F/g for an untreated sample to 452F/g for a sample treated with a 2M solution at a scan rate of 5mV/s. This increase can be attributed to an increase in the mesopore volume caused by the etching effect of the reaction between the carbon surfaces and phosphoric acid. In addition, oxygen functional groups, which were introduced by the treatment, improved the electrochemical properties of the resulting AC-based electrode. Therefore, simultaneous etching and oxygen introduction with phosphoric acid can easily bind oxygen functional groups (particularly C?O) onto the surface of an AC electrode. This method is effective at preparing AC for use in an EDLC with improved electrochemical properties.

Analysis of electrochemical double-layer capacitors using a Natural Rubber-Zn based polymer electrolyte

Nanditha Rajapaksha,Kumudu S. Perera,Kamal P. Vidanapathirana Techno-Press 2022 Advances in energy research Vol.8 No.1

Electrochemical double-layer capacitors (EDLCs) based on solid polymer electrolytes (SPEs) have gained an immense recognition in the present world due to their unique properties. This study is about preparing and characterizing EDLCs using a natural rubber (NR) based SPE with natural graphite (NG) electrodes. NR electrolyte was consisted with 49% methyl grafted natural rubber (MG49) and zinc trifluoromethanesulfonate ((Zn(CF₃SO₃)₂-ZnTF). It was characterized using electrochemical impedance spectroscopy (EIS) test, dc polarization test and linear sweep voltammetry (LSV) test. NG electrodes were made using a slurry of NG and acetone. EIS test, cyclic voltammetry (CV) test and galvanostatic charge discharge (GCD) test have been done to characterize the EDLC. Optimized electrolyte composition with NR: 0.6 ZnTF (weight basis) exhibited a conductivity of 0.6 x 10^-4 Scm^-1 at room temperature. Conductivity was predominantly due to ions. The electrochemical stability window was found to be from 0.25 V to 2.500 V. Electrolyte was sandwiched between two identical NG electrodes to fabricate an EDLC. Single electrode specific capacitance was about 2.26 Fg^-1 whereas the single electrode discharge capacitance was about 1.17 Fg^-1. The EDLC with this novel NR-ZnTF based SPE evidences its suitability to be used for different applications with further improvement.

Effect of emulsified polymer binders on the performance of activated carbon electrochemical double-layer capacitors

Eun-Suok Oh,Seul Lee,Bolormaa Gendensuren,Boyeon Kim,Sangik Jeon,Young-Hyun Cho,Taewon Kim 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.11

The electrochemical properties of two water-emulsified polymers, styrene-butadiene rubber, and polytetrafluoroethylene, on activated carbon electrochemical capacitors were systematically compared. All electrodes were fabricated with different ratios of styrene-butadiene rubber and polytetrafluoroethylene: 4 : 0, 3 : 1, 2 : 2, and 1 : 3. A good dispersion of styrene-butadiene rubber nanoparticles maintains mesopores in activated carbon, whereas an increase in polytetrafluoroethylene binder content in the electrodes reduces mesoporous surface area significantly due to the lump polytetrafluoroethylene structure coagulated by smashed particles in water. The relatively strong adhesion of the styrene- butadiene rubber binder also leads to better cyclability for extremely long cycles and the rate capability with various current densities at room temperature. At a high temperature of 60 oC, however, the electrodes containing polytetrafluoroethylene binder showed comparable high specific capacitance due to the high thermal stability of polytetrafluoroethylene.

The effect of textural changes of ACFs on electrochemical properties

김경훈,박미선,이시은,이영석 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

In this study, the electrochemical properties of activated carbon fibers (ACFs) have been investigated by different heating treatment temperature of the pitch-based ACFs in order to improve the specific capacitance of electric double-layer capacitor (EDLC). The samples were prepared at 1050 and 1450oC heating treatment, after activation with 4 M KOH at 800oC using As-spun pitch fiber. The specific surface area of ACFs increased from 828 m2/g to 987 m2/g, and the micro-, meso-pore volume of ACFs were also increased. The pore size of ACFs was increased during heating treatment process. These results were due to desorbing oxygen and hydrogen elements within the ACFs. The specific capacitance of EDLC prepared from the ACFs with heating treatment in 1450oC was increased 163% compared to ACFs with heating treatment in 800oC.

Nano Carbon Black Powder Synthesized via Liquid Phase Plasma Process as a Supercapacitor Active Material

Thai, Nguyen M.,Kim, Sun-Jae The Electrochemical Society 2015 Journal of the Electrochemical Society Vol.162 No.8

<P>In this study, synthesized carbon black powder (SC) was obtained from benzene via a liquid phase plasma (LPP) process. This powder was then activated by KOH to obtain activated SC (A-SC). Both of SC and A-SC powders were compared with commercial carbon black powder (CCB) and activated commercial carbon black (A-CCB) via Brunauer–Emmett–Teller surface area analysis, Raman spectroscopy, scanning electron microscopy, and X-ray diffraction for physical and chemical investigations. SC, A-SC, CCB and A-CCB powders were used as active materials of electrochemical double-layer capacitors (EDLC), which were studied via cyclic voltammetry, galvanostatic measurements, and impedance spectroscopy. Their electrochemical performance shows that SC electrode has higher specific capacitance, capacity, and energy than CCB electrode. Non-aqueous electrolyte EDLC using A-SC electrode, especially exhibited suitable cyclic stability over 8000 cycles at various charge–discharge current densities from 250 mA g<SUP>−1</SUP> to 2000 mA g<SUP>−1</SUP>. This study indicates that the LPP process successfully created specific nano-scaled CB particles supported by KOH activation process, which are noteworthy electrode materials for supercapacitor applications.</P>

다공성 탄소전극의 전위에 따른 복소캐패시턴스 분석

장종현,윤성훈,가복현,오승모,Jang, Jong H.,Yoon, Song-Hun,Ka, Bok H.,Oh, Seung M. 한국전기화학회 2003 한국전기화학회지 Vol.6 No.4

다공성 탄소전극의 전위에 짜른 EDLC(e)ectric double-layer capacitor)특성을 조사하기 위해 복소캐패시턴스분석(complex capacitance analysis)을 수행하였다. 하나의 원통형 기공에 대해 복소캐패시턴스를 이론적으로 유도하였고, 기공의 분포를 고려하여 다공성 전극에 대하여서도 계산하였다. 복소캐패시턴스의 허수부를 주파수에 대해 도시하면 피크 형태의 곡선이 얻어지는데, 이때 피크의 면적은 캐패시턴스 값의 크기와, 피크의 위치는 다공성전극의 전기화학 파라매터와 기공구조에 의해 결정되는 $\alpha_0$와 상관관계가 있음을 알 수 있었다. 이를 이용하면, 동일한 기공구조를 갖는 전극에 대해, 전위에 따른 캐패시턴스와 기공 내 이온전도도의 변화를 측정할 수 있다. 메조포러스 탄소전극에 대하여 전위를 변화시키며 electrochemical impedance spectroscopy를 측정하고 이를 복소캐패시턴스법에 의해 분석하였다. 피크 면적으로부터 구한 전위에 따른 캐패시턴스는 0.3V부근에서 최대값을 가졌는데, 이는 cyclic voltammetry 실험결과와도 일치하였다. 한편, 피크 위치로부터 구한 기공 내 이온전도도는 0.2V에서 최대 값을 가지고 전위가 증가할 수록 서서히 감소하였다. 이를 탄소 표면전하의 증가로 인해 이온/표면의 전기적 작용력이 커졌기 때문으로 해석하였다. The complex capacitance analysis was performed in order to examine the potential-dependent EDLC characteristics of porous carbon electrodes. The imaginary capacitance profiles $(C_{im}\;vs.\;log\lf)$ were theoretically derived for a cylindrical pore and further extended to multiple pore systems. Two important electrochemical parameters in EDLC can be estimated from the peak-shaped imaginary capacitance plots: total capacitance from the peak area and $\alpha_0$ from the peak position. Using this method, the variation of capacitance and ion conductivity in pores can be traced as a function of electric potential. The electrochemical impedance spectroscopy was recorded on the mesoporous carbon electrode as a function of electric potential and analyzed by complex capacitance method. The capacitance values obtained from the peak area showed a maximum at 0.3V (vs. SCE), which was in accordance with cyclic voltammetry result. The ionic conductivity in pores calculated from the peak position showed a maximum at 0.2 V (vs. SCE), then decreased with an increase in potential. This behavior seems due to the enhanced electrostatic interaction between ion and surface charge that becomes enriched at more positive potentials.

Activated carbons prepared from mixtures of coal tar pitch and petroleum pitch and their electrochemical performance as electrode materials for electric double-layer capacitor

Eunji Lee,Soon Hyung Kwon,Poo Reum Choi,Ji Chul Jung,Myung-Soo Kim 한국탄소학회 2015 Carbon Letters Vol.16 No.2

Activated carbons (ACs) were prepared by activation of coal tar pitch (CTP) in the range of 700°C-1000°C for 1-4 h using potassium hydroxide (KOH) powder as the activation agent. The optimal activation conditions were determined to be a CTP/KOH ratio of 1:4, activation temperature of 900°C, and activation time of 3 h. The obtained ACs showed increased pore size distribution in the range of 1 to 2 nm and the highest specific capacitance of 122 F/g in a two-electrode system with an organic electrolyte, as measured by a charge-discharge method in the voltage range of 0-2.7 V. In order to improve the performance of the electric double-layer capacitor electrode, various mixtures of CTP and petroleum pitch (PP) were activated at the optimal activation conditions previously determined for CTP. Although the specific capacitance of AC electrodes prepared from CTP only and the mixtures of CTP and PP was not significantly different at a current density of 1 A/g, the AC electrodes from CTP and PP mixtures showed outstanding specific capacitance at higher current rates. In particular, CTP-PP61 (6:1 mixture) had the highest specific capacitance of 132 F/g, and the specific capacitance remained above 90% at a high current density of 3 A/g. It was found that the high specific capacitance could be attributed to the increased micro-pore volume of ACs with pore sizes from 1 to 2 nm, and the high power density could be attributed to the increased meso-pore volume.

High-capacitance activated bio-carbons with controlled pore size distribution for sustainable energy storage

Kim, Yong Il,Lee, Yun Jung,Yoo, Jungjoon,Kim, Jong-Huy Elsevier 2019 Journal of Power Sources Vol.438 No.-

<P><B>Abstract</B></P> <P>Depletion of fossil-fuel energy resources creates a demand for sustainable energy technologies and therefore necessitates the development of sustainable energy storage devices with sustainable materials, eco-efficient synthetic methods, and robust cycle life. Electric double layer capacitors are potential candidates for sustainable energy storage because they usually employ carbon-based electrode materials with semi-permanent lifetimes and high powers. Although various carbon materials are commercially available, new methods are needed to produce eco-efficient synthesized carbon materials with high performances. Herein, we introduce an effective strategy that uses biomaterials as carbon sources and adopts a reusable KOH solution soaking method for the activation process to reduce KOH consumption, which includes a pore-size control process to enhance electrochemical performances. The obtained bio-carbons exhibit specific capacitances (160.6 and 151.2 F g<SUP>−1</SUP> in aqueous and organic electrolytes, respectively) superior to that of commercially available activated carbon (~80 F g<SUP>−1</SUP>), which is attributed to the synergetic effect between the pore-size-controlled activated carbon for efficient ion transport and the well-matched electrolyte. Our strategy provides a versatile method for the scalable fabrication of sustainable energy storage materials and is promising for the development of high-performance supercapacitors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> •Activated bio-carbons for sustainable energy storage were prepared </LI> <LI> •Physical properties of the pore-size controlled materials were evaluated </LI> <LI> •Activated carbon electrodes were applied in electric double-layer capacitors </LI> <LI> •The electrodes showed excellent capacitance in aqueous and organic electrolytes </LI> <LI> •The large specific surface area and ion-matched pore size were key to performance </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

수소이온전도성 고분자 겔전해질을 적용한 활성탄소계 전기이중층 캐패시터의 전기화학적 특성

모하메드라티파두 ( Mohammed Latifatu ),김광만 ( Kwang Man Kim ),김용주 ( Yong Joo Kim ),고장면 ( Jang Myoun Ko ) 한국고무학회 2012 엘라스토머 및 콤포지트 Vol.47 No.4

폴리비닐알콜, 규소텅스텐산, 인산 및 수용액으로 구성된 80 μm의 두께의 고분자겔 전해질 필름을 제조하여 활성탄소계 전기이중층 케페시터를 제조하였다. 제조한 고분자겔 전해질 필름은 상온에서 10-2 Scm-1의 높은 이온전 도도를 나타내었으며, 본 전해질 필름을 적용한 활성탄소계 전기이중층 케패시터는 100 mV/s에서 58 Fg-1의 높은 캐패시턴스 특성과 우수한 수명특성을 나타내었다. An electric double-layer capacitor (ELDC) of activated carbon electrode is prepared using a proton-conducting hydrogel polymer electrolyte, which is composed of poly(vinyl alcohol), silicotungstic acid, H3PO4, and deionized water. A solid film by evaporating the hydrogel polymer electrolyte is also prepared for comparison. The hydrogel polymer electrolyte also acts as a separator with the thickness of about 80 μm and the room-temperature ionic conductivity of 10-2 S cm-1. The EDLC containing the symmetric electrodes of activated carbon shows the specific capacitance of 58 F g-1 at 100 mV s-1 with a good cycle life, implying that the hydrogel polymer electrolyte is very promising for use in EDLCs.