Alloxazine and ferrocyanide are suggested as the redox couple for an aqueous organic redox flow battery (AORFB). Alloxazine is further modified by carboxylic acid (COOH) groups (alloxazine-COOH) to ...increase the aqueous solubility and to pursue a desirable shift in the redox potential. For obtaining a better AORFB performance, the overall redox reactivity of AORFB should be improved by the enhancement of the rate-determining reaction of the redox couple. A carboxylic acid-doped carbon nanotube (CA-CNT) catalyst is considered for increasing the reactivity. The utilization of CA-CNT allows for the induction of a better redox reactivity of alloxazine-COOH because of the role of COOH within alloxazine-COOH as a proton donor, the fortified hydrophilic attribute of alloxazine-COOH, and the increased number of active sites. With the assistance of these attributes, the mass transfer of aqueous alloxazine-COOH molecules can be promoted. However, CA-CNT does not have an effect on the increase of the redox reactivity of ferrocyanide because the redox reaction is not affected by the same influence of protons that the redox reactivity of alloxazine-COOH is affected by. Such a behavior is proven by measuring the electron transfer rate constant and diffusivity. With regard to AORFB full cell testing, when CA-CNT is used as a catalyst for the negative electrode, the performance of the AORFB increases. Specifically, the charge–discharge overpotential and infrared drop potential are improved. As a result, the voltage efficiency affected by the potentials increases to 64%. Furthermore, the discharging capacity reaches 26.7 A h·L–1, and the state of charge attains 83% even after 30 cycles.
Abstract Lithium batteries with solid-state electrolytes are an appealing alternative to state-of-the-art non-aqueous lithium-ion batteries with liquid electrolytes because of safety and energy ...aspects. However, engineering development at the cell level for lithium batteries with solid-state electrolytes is limited. Here, to advance this aspect and produce high-energy lithium cells, we introduce a cell design based on advanced parametrization of microstructural and architectural parameters of electrode and electrolyte components. To validate the cell design proposed, we assemble and test (applying a stack pressure of 3.74 MPa at 45 °C) 10-layer and 4-layer solid-state lithium pouch cells with a solid polymer electrolyte, resulting in an initial specific energy of 280 Wh kg −1 (corresponding to an energy density of 600 Wh L −1 ) and 310 Wh kg −1 (corresponding to an energy density of 650 Wh L −1 ) respectively.
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•Mixed NQ derivatives and FeCN are introduced as active materials for AORFB.•The solubility of NQ-SO is enhanced with mixing NQ-S and Lawsone (NQ-OH).•–SO32− groups and polar-polar ...interactions induce the solubility increase of NQ-SO.•Optimal Lawsone to NQ-S ratio is determined by the hygroscopic properties of –SO32−.•Discharge capacity and SOC of AORFB using NQ-SO and FeCN is 40.3 Ah·L−1 and 83%.
Mixture of 1,2-naphthoquinone-4-sulfonic acid sodium salt (NQ-S) and 2-hydroxy-1,4-naphthoquinone (Lawsone) is used as negative active species for aqueous organic redox flow battery (AORFB), while ferrocyanide (FeCN) is considered as positive active species in alkaline electrolyte. NQ-S is initially transformed to NQ-OH that has the same chemical structure with Lawsone by the nucleophilic attack under potassium hydroxide (KOH) electrolyte. The mixture of NQ-S and Lawsone (NQ-SO) has a higher solubility in KOH electrolyte (1.26 M in 1 M KOH) than the individual NQ-SO and NQ-S (0.42 and 0.83 M in 1 M KOH, respectively) because of the hydrophilic sulfite (–SO32−) groups eliminated from NQ-S over the transformation and the polar-polar interaction amid –SO32− group, organic species and KOH electrolyte. Lawsone to NQ-S ratio for optimal NQ-SO is 2:1, and this ratio is determined by the hygroscopic properties of –SO32− group. The cell voltage of AORFB using 0.6 M NQ-SO and 0.4 M FeCN is 1.01 V and its charge efficiency, discharge capacity, state of charge (SOC) and power density under 100 mA∙cm−2 are 99%, 23 Ah·L−1, 70% and 90 mW·cm−2. Furthermore, when the concentration of NQ-SO increases to 1.2 M (AORFB using 1.2 M NQ-SO and 0.4 M FeCN), its discharge capacity considerably increased to 40.3 Ah·L−1 with SOC of 83% and power density of 72 mW·cm−2.
안트라퀴논과 템포 활물질 기반 수계 유기 레독스 흐름 전지에서의 멤브레인 효과 이원미; Wonmi Lee; 권용재 ...
Korean Chemical Engineering Research(HWAHAK KONGHAK), 57(5),
10/2019, Letnik:
57, Številka:
5
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본 연구에서는 유기물인 안트라퀴논(AQDS)와 템포(TEMPO) 를 활물질로 사용하고 N 중성 전해질 기반 수계 유기레독스 흐름전지 성능이 멤브레인에 따라 어떻게 영향을 받는지 분석하였다. 안트라퀴논과 템포 모두 중성 전해질인 염화칼륨(KCl) 전해질에 대해 높은 전자전달성(0.068 V의 산화 반응 및 환원 반응의 피크 전위차) 및 셀전압(1.17 ...V)을 얻을 수 있었다. 성능비교를 위해 사용한 멤브레인으로, 상용 양이온 교환막 중 하나인 Nafion 212를 사용하였을 때, 0.1M 활물질을 1 M 염화칼륨 전해질에 용해해서 작동한 레독스 흐름전지 완전지 테스트를 통해, 전류효율 97%, 전압 효율 59%의 성능을 나타내었지만, 방전 용량(discharge capacity)은 4 사이클에서 0.93 Ah·L -1 로 이론 용량(2.68 Ah·L -1 )의 35%를 도달하였으며, 총 10사이클 동안 방전 용량의 용량 손실율(capacity loss rate)은 0.018 Ah·L-1/cycle이다. 그 외에도 Nafion 117 멤브레인, SELEMION CSO 멤브레인을 사용하여 단전지 성능을 테스트하였을 때, 오히려 저항 증가 및 투과 유도로 인해 더 큰 용량 손실을 이끌었다.
In this study, the evaluation of performance of AORFB using anthraquinone derivative and TEMPO derivative as active materials in neutral supporting electrolyte with various membrane types was performed. Both anthraquinone derivative and TEMPO derivative showed high electron transfer rate (the difference between anodic and cathodic peak potential was 0.068 V) and the cell voltage is 1.17 V. The single cell test of the AORFB using 0.1 M active materials in 1 M KCl solution with using Nafion 212 membrane, which is commercial cation exchange membrane was performed, and the charge efficiency (CE) was 97% and voltage efficiency (VE) was 59%. In addition, the discharge capacity was 0.93 Ah·L -1 which is 35% of theoretical capacity (2.68 Ah·L -1 ) at 4 th cycle and the capacity loss rate was 0.018 Ah·L -1 /cycle during 10 cycles. The single cell tests were performed with using Nafion 117 membrane and SELEMION CSO membrane. However, the results were more not good because of increased resistance because of thicker thickness of membrane and increased cross-over of active materials, respectively.
Anthraquinone-2,7-disulfonic acid (2,7-AQDS) and ferrocyanide including potassium and sodium salts are used as a redox couple for neutral aqueous redox flow batteries (ARFBs). In 1 M potassium ...chloride (KCl) electrolyte of neutral pH, the electron transfer rate and redox reactivity of 2,7-AQDS are better than those in acidic electrolyte. Furthermore, ferrocyanide is attacked by the hydroxyl group within the alkaline electrolyte, however this does not happen in KCl because there are no hydroxyl groups in KCl. The low solubility of 2,7-AQDS is enhanced in 1 M KCl using an ethyleneglycol (EG) additive and the solubility of the ferrocyanide also increases when using the mixed cations of potassium and sodium. This benefit arises because of the fact that the EG additive forms hydrogen bonds with water within the electrolyte and 2,7-AQDS, while ferrocyanide mixed with different cations increases the solubility due to ion pair formation. Based on that, the ARFB using 2,7-AQDS and ferrocyanide shows high coulombic efficiency (98% at 40 mA cm
−2
) and capacity (17.8 A h L
−1
) with a low capacity decay rate (>99% until 100 cycle).
Anthraquinone-2,7-disulfonic acid (2,7-AQDS) and ferrocyanide including potassium and sodium salts are used as a redox couple for neutral aqueous redox flow batteries (ARFBs).
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•Tiron and AQDS are suggested as redox couple for AORFB.•By the adoption of new activation, the required volume of AQDS is decreased.•Amberlyst 15 plays a role in increasing ...solubility of redox couple up to 0.9 M.•Proper increase of H2SO4 concentration promotes solubility increase of redox couple.•AORFB preserves discharge capacity to 99% with discharge capacity of 24.4 Ahr L−1.
4,5- dihydroxybenzene-1,3-disulfonic acid (Tiron) and anthraquinone-2,7-disulfonic acid (AQDS) are proposed as new redox couple with sulfuric acid (H2SO4) for aqueous organic redox flow battery (AORFB). Two-electron redox reactions of the new redox couple induce a fast reaction rate. However, Tiron undergoes transformation by undesirable Michael addition reaction during the first cycle. Additionally, sodium ions contained in redox couple lower their solubility in H2SO4. As a result, AORFB capacity loss and AQDS precipitation occur. To alleviate the loss in capacity by the transformation of Tiron, activation process is newly adopted. With the process, Tiron is transformed into reversable and desirable 2,4,5,6-tetrahydroxybenzene-1,3-disulfonic acid before actual operation, and the performance of AORFB operated under the process is similar to that operated without the process although the considerable amount of AQDS is relieved in AORFB operation including activation. In addition, a cation exchange resin, Amberlyst 15, is utilized to transform sodium ions into protons, and a proper increase of H2SO4 concentration provides the appropriate amount of protons for the promotion of redox reactions. AORFB using optimal process demonstrates the benefit (i) decreasing the volume of AQDS, (ii) increasing the solubility of Tiron and AQDS up to 0.9 M and (iii) preserving the discharge capacity up to 99% after 50 cycles with the maximum possible discharge capacity of 24.4 Ahr L−1.
본 연구에서는 유기물인 메틸 바이올로겐(methyl viologen, MV)과 템폴(4-hydroxy-TEMPO, TEMPOL)을 활물질로 사용하고 NaCl의 중성 전해질 기반 수계 유기 레독스 흐름전지 성능이 멤브레인에 따라 어떻게 영향을 받는지 분석하였다. 메틸 바이올로겐(MV)과 템폴(TEMPOL)은 중성 전해질인 염화나트륨(NaCl) 전해질에 대해 ...높은 셀전압(1.37 V)을 얻을 수 있다. 성능 비교를 위해 사용한 멤브레인은 두 가지이다. 첫째로, 상용 양이온 교환막 중 하나인 Nafion 117를 사용하였을 때 성능은 첫번째 사이클에서 충전만 일어났을 뿐 그 후 높은 저항 때문에 완전지가 작동하지 않았다. 하지만 두번째로 사용한 Fumasep 음이온 교환막(FAA-3-50)은 Nafion 117 멤브레인을 사용했을 때와는 다르게 비교적 안정적인 충방전 사이클링을 보였다. 전류 밀도 40 mA·cm -2 , 컷-오프 전압 0.55~1.7 V에서 전류 효율(charge efficiency)은 97%, 전압 효율(voltage efficiency)은 78%로 높게 나타났다. 방전 용량(discharge capacity)은 10사이클에서 1.44 Ah·L -1 로 이론 용량(2.68 Ah·L -1 )의 54%를 나타내었다. 방전 용량의 용량 손실율(capacity loss rate)은 0.0015 Ah·L-1/cycle 로 나타났다. 순환주사전류 실험을 통해 Nafion 117 멤브레인과 Fumasep 음이온 교환막 사이의 이러한 성능차이는 활물질의 크로스 오버(cross over) 현상으로 인한 방전 용량 손실이 아닌 멤브레인과 활물질의 화학적 반응으로 인한 저항 증가가 원인임을 파악할 수 있었다.
In this study, the evaluation of performance of AORFB using methyl viologen and TEMPOL as organic active materials in neutral supporting electrolyte (NaCl) with various membrane types was performed. Using methyl viologen and TEMPOL as active materials in neutral electrolyte solution, the cell voltage is 1.37V which is relatively high value for AORFB. Two types of membranes were examined for performance comparison. First, when using Nafion 117 membrane which is commercial cation exchange membrane, only the charge process occurred in the first cycle and the single cell couldn’t work because of its high resistance. However, when using Fumasep anion exchange membrane (FAA-3-50) instead of Nafion 117 membrane, the result was obtained as the totally different charge-discharge graphs. When current density was 40mA·cm -2 and cut off voltage range was from 0.55 V to 1.7 V, the charge efficiency (CE) was 97% and voltage efficiency (VE) was 78%. In addition, the discharge capacity was 1.44 Ah·L -1 which was 54% of theoretical capacity (2.68 Ah·L -1 ) at 10th cycle and the capacity loss rate was 0.0015 Ah·L -1 per cycle during 50 cycles. Through cyclic voltammetry test, it seems that this difference in the performance between the full cell using Nafion 117 membrane and Fumasep anion exchange membrane came from increasing resistance due to chemical reaction between membrane and active material, not the capacity loss due to cross-over of active material through membrane.
수계 유기 레독스 흐름 전지 성능에서의 첨가제 효과 추천호; Cheonho Chu; 이원미 ...
Korean Chemical Engineering Research(HWAHAK KONGHAK), 57(6),
12/2019, Letnik:
57, Številka:
6
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본 연구에서는 퀴노잘린(quinoxaline)과 페로시아나이드(ferrocyanide)를 활물질로 활용한 알칼리 전해질 기반 수계유기 레독스 흐름전지에 대해 다양한 첨가제를 적용하여 성능을 비교하는 실험을 진행하였다. 퀴노잘린(quinoxaline)의 경우 염화칼륨(KCl) 전해질보다는 수산화칼륨(KOH) 전해질에서의 레독스 전위(-0.97 V)가 더 ...작은 위치에 있으며, 이에 따라 KOH 전해질에 대해 페로시아나이드와 조합을 이루었을 때, 셀 전압 값은 1.3 V로 높게 나타났다. 상용 양이온 교환막 중 하나인 Nafion 117 멤브레인을 사용하였을 때, 퀴노잘린(quinoxaline)의 부반응 현상을 반전지 상에서 관찰 할 수 있었으며, 이에 따라 충방전 자체가 잘 되지 않는 문제점이 있다. 따라서, 문제점이 되는 퀴노잘린(quinoxaline)의 부반응을 해결하기 위해 친전자체와 친핵체 중 하나인 포타슘설페이트(K 2 SO 4 )와 포타슘아이오다이드(KI)를 사용하였으며, 포타슘아이오다이드(KI)를 사용하였을 때, 용량 손실율 측면에서 포타슘 아이오다이드(KI)를 첨가제로 넣지 않았을 때(0.29 Ah·L -1 per cycle) 보다 더 낮은 용량 손실율(0.21 Ah·L -1 per cycle)로 더 높은 용량 유지율을 보였다.
In this study, the effect of additives on the performance of aqueous organic redox flow battery (AORFB) using quinoxaline and ferrocyanide as active materials in alkaline supporting electrolyte is investigated. Quinoxaline shows the lowest redox potential (-0.97 V) in KOH supporting electrolyte, while when quinoxaline and ferrocyanide are used as the target active materials, the cell voltage of this redox combination is 1.3 V. When the single cell tests of AORFBs using 0.1 M active materials in 1 M KCl supporting electrolyte and Nafion 117 membrane are implemented, it does not work properly because of the side reaction of quinoxaline. To reduce or prevent the side reaction of quinoxaline, the two types of additives are considered. They are the potassium sulfate as electrophile additive and potassium iodide as nucleophilie additive. Of them, when the single cell tests of AORFBs using potassium iodide as additive dissolved in quinoxaline solution are performed, the capacity loss rate is reduced to 0.21 Ah·L -1 per cycle and it is better than that of the single cell test of AORFB operated without additive (0.29 Ah·L -1 per cycle).
메틸렌블루와 바나듐을 활물질로 활용한 수계 유기 레독스 흐름 전지의 성능 평가 이원미; Wonmi Lee; 권용재 ...
Korean Chemical Engineering Research(HWAHAK KONGHAK), 56(6),
12/2018, Letnik:
56, Številka:
6
Journal Article
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본 연구에서는 염료 물질 중 하나인 메틸렌 블루(methylene blue)를 수계 레독스 흐름 전지의 활물질로 처음으로 도입하였다. Methylene blue의 레독스 전위는 pH가 높아짐에 따라 음의 방향으로 이동하는 것을 확인할 수 있었다. 이 methylene blue를 음극 활물질로 활용하고, 양극 활물질로는 바나듐(vanadium) 을 활용하여 ...산 전해질을 기반으로 셀 성능 평가를 진행하였다. Methylene blue/V 4+ 레독스 조합의 산 전해질에 대한 셀 전압은 0.45 V로 낮으며, Methylene blue의 물에 대한 용해도 또한 0.12 M로 굉장히 낮다. 이에 따라 0.0015 M의 낮은 농도로 단전지 셀 성능을 평가하였으며, Nafion 212 멤브레인을 사용하여 0~0.8 V 컷-오프 전압으로 1 mA/㎠ 전류밀도 하에서 4 cycle에서 충방전 효율 96.67%, 전압효율 88.83%, 에너지효율 85.87%, 방전 용량(0.0500 Ah·L -1 )의 성능을 보였으며, 낮은 방전용량은 활물질의 낮은 농도에 의한 것이므로 활물질인 메틸렌 블루의 농도를 0.1 M로, 전류밀도는 10 mA/㎠로 더 높였을 때 4 cycle에서 CE 99%, VE 85%, EE 85%의 효율로 더 높은 방전 용량(3.8122 Ah·L -1 )을 도출함을 확인할 수 있었다.
In this study, methylene blue which is one of dye materials was introduced as active material for aqueous redox flow battery. The redox potential of methylene blue was shifted to negative direction as pH increased. The full-cell performance was evaluated by using methylene blue as the negative active material and vanadium as the positive active material with acid supporting electrolytes. The cell voltage of methylene blue/V 4+ is very low (0.45 V). In addition, the maximum solubility of methylene blue in water is only 0.12 M. Therefore, the cell test was performed with very low concentration (0.0015 M methylene blue, 0.15 M V 4+ ) at first time. Cut-off voltage range was 0 to 0.8 V and 1 mA·cm -2 current density was adopted during cycling. As a result, current efficiency (CE) was 99.67%, voltage efficiency (VE), 88.83% and energy efficiency (EE) was 85.87% and discharge capacity was (0.0500 Ah·L -1 ) at 4 cycle. In addition, the cell test was performed with increased concentration (0.1 M methylene blue, 0.15 M V 4+ ) with 10 mA·cm -2 current density, leading to higher discharge capacity (3.8122 Ah·L -1 ) with similar efficiency (CE=99%, VE=85%, EE=85% at 4 cycle).
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•2,7-AQDS and KI are firstly introduced as active species for AORFB.•EG additive increases the solubility of 2,7-AQDS and the redox activity of KI.•PVP acts as a barrier preventing ...the production of iodine gas.•EE of AORFB using the 2,7-AQDS and KI including EG and PVP is 82%.
An aqueous organic redox flow battery (AORFB) using anthraquinone-2,7-disulfonic acid disodium salt (2,7-AQDS) and potassium iodide (KI) as the negative and positive active species is suggested. The active species are dissolved into an aqueous potassium chloride (KCl) solution, while ethylene glycol (EG) and polyvinylpyrrolidone (PVP) are added to improve the solubility of 2,7-AQDS and prevent the side reactions of KI. The aqueous solubility of redox couple improved by the utilization of additive plays a role in increasing both capacity and the performance of AORFB, while as kinetic parameters to affect the capacity, electron transfer rate constant (ks) and diffusion coefficient (D) are measured. As a result, when EG is used, the solubility of 2,7-AQDS increases from 0.3 to 0.8 M in KCl solution and PVP acts as a barrier preventing the production of iodine gas that is a product generated by the side reaction of KI. The increase in solubility by the use of EG is because it has two hydroxyl groups and they form hydrogen bonding with the oxygen of sulfonyl or carbonyl group within 2,7-AQDS, while the alkyl group of its backbone that is in non-polar nature interacts with the phenyl group within 2,7-AQDS. In addition, EG increases the redox activity of KI because this significantly increases the nucleophilic ability of the iodide anion. Regarding the effect of PVP, when PVP is added to the solution containing iodine gas, povidone-iodine complex is formed and this complex impedes the side reaction of KI and maintains iodate that is a reactant for redox reaction as it is in the system. With that, when the AORFB using the 2,7-AQDS and KI including EG and PVP is run for ten cycle, it shows excellent performances like the discharge capacity of 0.7 AhL−1 and the coulombic and energy efficiencies of 98% and 82%.
