Pub Date : 2021-12-07DOI: 10.33961/jecst.2021.00864
Jongkwang Lee, K. Heo, Young-Woong Song, Dahee Hwang, Minyoung Kim, Hyejeong Jeong, D. Shin, Jinsub Lim
Lithium-sulfur batteries (LSBs) have emerged as a promising alternative to lithium-ion batteries (LIBs) owing to their high energy density and economic viability. In addition, all-solid-state LSBs, which use solid-state electrolytes, have been pro-posed to overcome the polysulfide shuttle effect while improving safety. However, the high interfacial resistance and poor ionic conductivity exhibited by the electrode and solid-state electrolytes, respectively, are significant challenges in the development of these LSBs. Herein, we apply a poly (ethylene oxide) (PEO)-based composite solid-state electrolyte with oxide Li 7 La 3 Zr 2 O 12 (LLZO) solid-state electrolyte in an all-solid-state LSB to overcome these challenges. We use an electrochemical method to evaluate the degradation of the all-solid-state LSB in accordance with the carbon content and loading weight within the cathode. The all-solid-state LSB, with sulfur-carbon content in a ratio of 3:3, exhibited a high initial discharge capacity (1386 mAh g -1 ), poor C-rate performance, and capacity retention of less than 50%. The all-solid-state LSB with a high loading weight exhibited a poor overall electrochemical performance. The factors influencing the electrochemical performance degradation were revealed through systematic analysis. 7 La 3 Zr 2 O 12 (LLZO), Poly(Ethylene Oxide) (PEO)
{"title":"Degradation of All-Solid-State Lithium-Sulfur Batteries with PEO-Based Composite Electrolyte","authors":"Jongkwang Lee, K. Heo, Young-Woong Song, Dahee Hwang, Minyoung Kim, Hyejeong Jeong, D. Shin, Jinsub Lim","doi":"10.33961/jecst.2021.00864","DOIUrl":"https://doi.org/10.33961/jecst.2021.00864","url":null,"abstract":"Lithium-sulfur batteries (LSBs) have emerged as a promising alternative to lithium-ion batteries (LIBs) owing to their high energy density and economic viability. In addition, all-solid-state LSBs, which use solid-state electrolytes, have been pro-posed to overcome the polysulfide shuttle effect while improving safety. However, the high interfacial resistance and poor ionic conductivity exhibited by the electrode and solid-state electrolytes, respectively, are significant challenges in the development of these LSBs. Herein, we apply a poly (ethylene oxide) (PEO)-based composite solid-state electrolyte with oxide Li 7 La 3 Zr 2 O 12 (LLZO) solid-state electrolyte in an all-solid-state LSB to overcome these challenges. We use an electrochemical method to evaluate the degradation of the all-solid-state LSB in accordance with the carbon content and loading weight within the cathode. The all-solid-state LSB, with sulfur-carbon content in a ratio of 3:3, exhibited a high initial discharge capacity (1386 mAh g -1 ), poor C-rate performance, and capacity retention of less than 50%. The all-solid-state LSB with a high loading weight exhibited a poor overall electrochemical performance. The factors influencing the electrochemical performance degradation were revealed through systematic analysis. 7 La 3 Zr 2 O 12 (LLZO), Poly(Ethylene Oxide) (PEO)","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47557826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-02DOI: 10.33961/jecst.2021.00857
H. Im, Seongkyun Park, Hyo-Jeong Ha, Sumin Lee, S. Heo, Sang Won Im, Ki Tae Nam, Sung Yul Lim
The preparation of low-cost, simple, and scalable electrodes is crucial for the commercialization of water electrolyzers for H 2 production. Herein, we demonstrate the fabrication of cathodes through Mo-modified Zn phosphating of Ni foam (NiF) for water electrolysis, which has been largely utilized in surface coating industry. In situ growth of electrocatalytically active layers in the hydrogen evolution reaction (HER) was occurred after 1 min of phosphating to form ZnNiMoP i , and sub-sequent thermal treatment and electrochemical activation resulted in the formation of ZnNiMoPO x H y . ZnNiMoPO x H y exhibited superior HER performance than NiF, primarily because of the increased electrochemically active surface area of ZnNiMoPO x H y compared to that of bare NiF. Although further investigations to improve the intrinsic electrochemical activity toward the HER and detailed mechanistic studies are required, these results suggest that phosphating is a promising coating method and will possibly advance the fabrication procedure of electrodes for water electrolyzers with better practical applications.
低成本、简单且可扩展的电极的制备对于H2生产用水电解槽的商业化至关重要。在此，我们展示了通过Mo改性的水电解用泡沫镍（NiF）锌磷化制备阴极的方法，该方法已在表面涂层工业中得到广泛应用。在析氢反应（HER）中，电催化活性层在磷化1分钟后原位生长，形成ZnNiMoP i，随后的热处理和电化学活化导致ZnNiMoPO x H y的形成。ZnNiMoPO x H y表现出比NiF更好的HER性能，主要是因为与裸NiF相比，ZnNiMoPOx H y的电化学活性表面积增加。尽管还需要进一步的研究来提高HER的固有电化学活性和详细的机理研究，但这些结果表明，磷化是一种很有前途的涂层方法，可能会推进水电解槽电极的制造过程，具有更好的实际应用。
{"title":"Fabrication of Ni−Mo-based Electrocatalysts by Modified Zn Phosphating for Hydrogen Evolution Reaction","authors":"H. Im, Seongkyun Park, Hyo-Jeong Ha, Sumin Lee, S. Heo, Sang Won Im, Ki Tae Nam, Sung Yul Lim","doi":"10.33961/jecst.2021.00857","DOIUrl":"https://doi.org/10.33961/jecst.2021.00857","url":null,"abstract":"The preparation of low-cost, simple, and scalable electrodes is crucial for the commercialization of water electrolyzers for H 2 production. Herein, we demonstrate the fabrication of cathodes through Mo-modified Zn phosphating of Ni foam (NiF) for water electrolysis, which has been largely utilized in surface coating industry. In situ growth of electrocatalytically active layers in the hydrogen evolution reaction (HER) was occurred after 1 min of phosphating to form ZnNiMoP i , and sub-sequent thermal treatment and electrochemical activation resulted in the formation of ZnNiMoPO x H y . ZnNiMoPO x H y exhibited superior HER performance than NiF, primarily because of the increased electrochemically active surface area of ZnNiMoPO x H y compared to that of bare NiF. Although further investigations to improve the intrinsic electrochemical activity toward the HER and detailed mechanistic studies are required, these results suggest that phosphating is a promising coating method and will possibly advance the fabrication procedure of electrodes for water electrolyzers with better practical applications.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2021-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49038228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-08DOI: 10.33961/jecst.2021.00451
J.F. Zhao, Q. Liang, Y.F. Liang, M. Li, J.Y. Hu
Compared with hydrogen, ammonia has the advantages of high gravimetric hydrogen densities (17.8 wt.%), ease of storage and transportation as a chemical hydrogen storage medium, while its application in small-scale on-site hydrogen production scenarios is limited by the need for complex separation equipment during high purity hydrogen production. Therefore, the study of PEMFC, which can directly utilize ammonia decomposition gas, can greatly expand the application of fuel cells. In this paper, the output characteristics, fuel efficiency and the variation trend of hydrogen concentration and local current density in the anode channel of fuel cell with the output voltage of PEMFC fueled by ammonia decomposition gas were studied by experiment and simulation. The results indicate that the maximum output power of the hybrid fuel decreases by 9.6% compared with that of the pure hydrogen fuel at the same inlet hydrogen equivalent. When the molar concentration of hydrogen in the anode channel is less than 0.12, the output characteristics of PEMFC will be seriously affected. Employ-ing ammonia decomposition gas as fuel, the efficiency corresponding to the maximum output power of PEMFC is approx-imately 47%, which is 10% lower than the maximum efficiency of pure hydrogen.
{"title":"Experimental and simulation study of PEMFC based on ammonia decomposition gas as fuel","authors":"J.F. Zhao, Q. Liang, Y.F. Liang, M. Li, J.Y. Hu","doi":"10.33961/jecst.2021.00451","DOIUrl":"https://doi.org/10.33961/jecst.2021.00451","url":null,"abstract":"Compared with hydrogen, ammonia has the advantages of high gravimetric hydrogen densities (17.8 wt.%), ease of storage and transportation as a chemical hydrogen storage medium, while its application in small-scale on-site hydrogen production scenarios is limited by the need for complex separation equipment during high purity hydrogen production. Therefore, the study of PEMFC, which can directly utilize ammonia decomposition gas, can greatly expand the application of fuel cells. In this paper, the output characteristics, fuel efficiency and the variation trend of hydrogen concentration and local current density in the anode channel of fuel cell with the output voltage of PEMFC fueled by ammonia decomposition gas were studied by experiment and simulation. The results indicate that the maximum output power of the hybrid fuel decreases by 9.6% compared with that of the pure hydrogen fuel at the same inlet hydrogen equivalent. When the molar concentration of hydrogen in the anode channel is less than 0.12, the output characteristics of PEMFC will be seriously affected. Employ-ing ammonia decomposition gas as fuel, the efficiency corresponding to the maximum output power of PEMFC is approx-imately 47%, which is 10% lower than the maximum efficiency of pure hydrogen.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2021-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47232031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-02DOI: 10.33961/jecst.2020.01746
J. A. Navarro-Franco, M. Garzón-Zúñiga, P. Drogui, G. Buelna, P. Gortáres-Moroyoqui, B. E. Barragán-Huerta, J. M. Vigueras-Cortés
Persistent organic pollutants (POPs) and emerging pollutants (EP) are characterized by their difficulty to be removed through biological oxidation processes (BOPs); they persist in the environment and could have adverse effects on the aquatic ecosystem and human health. The electro-oxidation (EO) process has been successfully used as an alternative technique to oxidize many kinds of the aforementioned pollutants in wastewater. However, the EO process has been criticized for its high energy consumption cost and its potential generation of by-products. In order to decrease these drawbacks, its combination with biological oxidation processes has been reported as a solution to reduce costs and to reach high rates of recalcitrant pollutants removal from wastewaters. Thus, the location of EO in the treatment line is an important decision to make, since this decision affects the formation of by-products and biodegradability enhancement. This paper reviews the advantages and disadvantages of EO as a pre and post-treatment in combination with BOPs. A perspective of the EO scaleup is also presented, where hydrodynamics and the relationship of A/V (area of the electrode/working volume of the electrochemical cell) experiments are examined and discussed.
{"title":"Electro-Oxidation in Combination with Biological Processes for Removal of Persistent Pollutants in Wastewater: A Review","authors":"J. A. Navarro-Franco, M. Garzón-Zúñiga, P. Drogui, G. Buelna, P. Gortáres-Moroyoqui, B. E. Barragán-Huerta, J. M. Vigueras-Cortés","doi":"10.33961/jecst.2020.01746","DOIUrl":"https://doi.org/10.33961/jecst.2020.01746","url":null,"abstract":"Persistent organic pollutants (POPs) and emerging pollutants (EP) are characterized by their difficulty to be removed through biological oxidation processes (BOPs); they persist in the environment and could have adverse effects on the aquatic ecosystem and human health. The electro-oxidation (EO) process has been successfully used as an alternative technique to oxidize many kinds of the aforementioned pollutants in wastewater. However, the EO process has been criticized for its high energy consumption cost and its potential generation of by-products. In order to decrease these drawbacks, its combination with biological oxidation processes has been reported as a solution to reduce costs and to reach high rates of recalcitrant pollutants removal from wastewaters. Thus, the location of EO in the treatment line is an important decision to make, since this decision affects the formation of by-products and biodegradability enhancement. This paper reviews the advantages and disadvantages of EO as a pre and post-treatment in combination with BOPs. A perspective of the EO scaleup is also presented, where hydrodynamics and the relationship of A/V (area of the electrode/working volume of the electrochemical cell) experiments are examined and discussed.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2021-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41645010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-27DOI: 10.33961/jecst.2021.00710
G. Ghanashyam, H. Jeong
Molybdenum disulfide (MoS 2 ) has been widely used as a catalyst for the bifunctional activities of hydrogen and oxygen evolution reactions (HER and OER). Here, we investigated size dependent HER and OER performance of MoS 2 . The smallest size (90 nm) of MoS 2 exhibits the lowest overpotential of -0.28 V at -10 mAcm -2 and 1.52 V at 300 mAcm -2 with the smallest Tafel slopes of 151 and 176 mVdec -1 for HER and OER, respectively, compared to bigger sizes (2 µm and 6 µm) of MoS 2 . The better HER and OER performance is attributed to high electrochemical active surface area (6 × 10 -4 cm 2 ) with edge sites and low charge transfer resistance (18.1 Ω), confirming that the smaller MoS 2 nanosheets have the better catalytic behavior.
{"title":"Size Effects of MoS2 on Hydrogen and Oxygen Evolution Reaction","authors":"G. Ghanashyam, H. Jeong","doi":"10.33961/jecst.2021.00710","DOIUrl":"https://doi.org/10.33961/jecst.2021.00710","url":null,"abstract":"Molybdenum disulfide (MoS 2 ) has been widely used as a catalyst for the bifunctional activities of hydrogen and oxygen evolution reactions (HER and OER). Here, we investigated size dependent HER and OER performance of MoS 2 . The smallest size (90 nm) of MoS 2 exhibits the lowest overpotential of -0.28 V at -10 mAcm -2 and 1.52 V at 300 mAcm -2 with the smallest Tafel slopes of 151 and 176 mVdec -1 for HER and OER, respectively, compared to bigger sizes (2 µm and 6 µm) of MoS 2 . The better HER and OER performance is attributed to high electrochemical active surface area (6 × 10 -4 cm 2 ) with edge sites and low charge transfer resistance (18.1 Ω), confirming that the smaller MoS 2 nanosheets have the better catalytic behavior.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2021-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47926469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-27DOI: 10.33961/jecst.2021.00640
Nur-E.-Habiba, Rokon Uddin, K. Salminen, V. Sariola, S. Kulmala
This paper presents a simple and inexpensive method to fabricate chemically and mechanically resistant hot electron-emit-ting composite electrodes on reusable substrates. In this study, the hot electron emitting composite electrodes were man-ufactured by doping a polymer, nylon 6,6, with few different brands of carbon particles (graphite, carbon black) and by coating metal substrates with the aforementioned composite ink layers with different carbon-polymer mass fractions. The optimal mass fractions in these composite layers allowed to fabricate composite electrodes that can inject hot electrons into aqueous electrolyte solutions and clearly generate hot electron- induced electrochemiluminescence (HECL). An aromatic terbium (III) chelate was used as a probe that is known not to be excited on the basis of traditional electrochemistry but to be efficiently electrically excited in the presence of hydrated electrons and during injection of hot electrons into aqueous solution. Thus, the presence of hot, pre-hydrated or hydrated electrons at the close vicinity of the composite electrode surface were monitored by HECL. The study shows that the extreme pH conditions could not damage the present composite electrodes. These low-cost, simplified and robust composite electrodes thus demonstrate that they can be used in HECL bioaffinity assays and other applications of hot electron electrochemistry.
{"title":"Carbon Particle-Doped Polymer Layers on Metals as Chemically and Mechanically Resistant Composite Electrodes for Hot Electron Electrochemistry","authors":"Nur-E.-Habiba, Rokon Uddin, K. Salminen, V. Sariola, S. Kulmala","doi":"10.33961/jecst.2021.00640","DOIUrl":"https://doi.org/10.33961/jecst.2021.00640","url":null,"abstract":"This paper presents a simple and inexpensive method to fabricate chemically and mechanically resistant hot electron-emit-ting composite electrodes on reusable substrates. In this study, the hot electron emitting composite electrodes were man-ufactured by doping a polymer, nylon 6,6, with few different brands of carbon particles (graphite, carbon black) and by coating metal substrates with the aforementioned composite ink layers with different carbon-polymer mass fractions. The optimal mass fractions in these composite layers allowed to fabricate composite electrodes that can inject hot electrons into aqueous electrolyte solutions and clearly generate hot electron- induced electrochemiluminescence (HECL). An aromatic terbium (III) chelate was used as a probe that is known not to be excited on the basis of traditional electrochemistry but to be efficiently electrically excited in the presence of hydrated electrons and during injection of hot electrons into aqueous solution. Thus, the presence of hot, pre-hydrated or hydrated electrons at the close vicinity of the composite electrode surface were monitored by HECL. The study shows that the extreme pH conditions could not damage the present composite electrodes. These low-cost, simplified and robust composite electrodes thus demonstrate that they can be used in HECL bioaffinity assays and other applications of hot electron electrochemistry.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2021-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41577730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-18DOI: 10.33961/jecst.2021.00584
A. Mustafa, Bachirou Guene Lougou, Y. Shuai, Samia Razzaq, Zhijiang Wang, Enkhbayar Shagdar, Jiupeng Zhao
The electrochemical CO 2 reduction (ECR) to produce value-added fuels and chemicals using clean energy sources (like solar and wind) is a promising technology to neutralize the carbon cycle and reproduce the fuels. Presently, the ECR has been the most attractive route to produce carbon-building blocks that have growing global production and high market demand. The electrochemical CO 2 reduction could be extensively implemented if it produces valuable products at those costs which are financially competitive with the present market prices. Herein, the electrochemical conversion of CO 2 obtained from flue gases of a power plant to produce diesel and formic acid using a consistent techno-economic approach is presented. The first scenario analyzed the production of diesel fuel which was formed through Fischer-Tropsch processing of CO (obtained through electroreduction of CO 2 ) and hydrogen, while in the second scenario, direct electrochemical CO 2 reduction to formic acid was considered. As per the base case assumptions extracted from the previous outstanding research studies, both processes weren’t competitive with the existing fuel prices, indicating that high electrochemical (EC) cell capital cost was the main limiting component. The diesel fuel production was predicted as the best route for the cost-effective production of fuels under conceivable optimistic case assumptions, and the formic acid was found to be costly in terms of stored energy contents and has a facile production mechanism at those costs which are financially competitive with its bulk market price. In both processes, the liquid product cost was greatly affected by the parameters affecting the EC cell capital expenses, such as cost concerning the electrode area, faradaic efficiency, and current density.
{"title":"A Techno-Economic Study of Commercial Electrochemical CO2 Reduction into Diesel Fuel and Formic Acid","authors":"A. Mustafa, Bachirou Guene Lougou, Y. Shuai, Samia Razzaq, Zhijiang Wang, Enkhbayar Shagdar, Jiupeng Zhao","doi":"10.33961/jecst.2021.00584","DOIUrl":"https://doi.org/10.33961/jecst.2021.00584","url":null,"abstract":"The electrochemical CO 2 reduction (ECR) to produce value-added fuels and chemicals using clean energy sources (like solar and wind) is a promising technology to neutralize the carbon cycle and reproduce the fuels. Presently, the ECR has been the most attractive route to produce carbon-building blocks that have growing global production and high market demand. The electrochemical CO 2 reduction could be extensively implemented if it produces valuable products at those costs which are financially competitive with the present market prices. Herein, the electrochemical conversion of CO 2 obtained from flue gases of a power plant to produce diesel and formic acid using a consistent techno-economic approach is presented. The first scenario analyzed the production of diesel fuel which was formed through Fischer-Tropsch processing of CO (obtained through electroreduction of CO 2 ) and hydrogen, while in the second scenario, direct electrochemical CO 2 reduction to formic acid was considered. As per the base case assumptions extracted from the previous outstanding research studies, both processes weren’t competitive with the existing fuel prices, indicating that high electrochemical (EC) cell capital cost was the main limiting component. The diesel fuel production was predicted as the best route for the cost-effective production of fuels under conceivable optimistic case assumptions, and the formic acid was found to be costly in terms of stored energy contents and has a facile production mechanism at those costs which are financially competitive with its bulk market price. In both processes, the liquid product cost was greatly affected by the parameters affecting the EC cell capital expenses, such as cost concerning the electrode area, faradaic efficiency, and current density.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45106625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-18DOI: 10.33961/jecst.2021.00780
A. S. Rahim, M. Z. Kufian, A. Arof, Z. Osman
For this study, the sol gel method was used to synthesize the spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) electrode material. Structural, morphological, electrochemical, and kinetic aspects of the LNMO have been characterized. The synthesized LNMO was indexed with the Fd3m cubic space group. The excellent capacity retention indicates that the spinel framework of LNMO has the ability to withstand high rate charge-discharge throughout long cycle tests. The Li diffusion coefficient (D Li ) changes non-monotonically across three orders of magnitude, from 10 -9 to 10 -12 cm 2 s -1 determined from GITT method. The variation of D Li seemed to be related to three oxidation reactions that happened throughout the charging process. A small dip in D Li at the beginning stage of Li deintercalation is correlated with the oxidation of Mn 3+ to Mn 4+ . While two pronounced D Li minima at 4.7 V and 4.75 V are due to the oxidation of Ni 2+ /Ni 3+ and Ni 3+ /Ni 4+ respectively. The depletion of D Li at the high voltage region is attributed to the occurrence of two successive phase transformation phenomena.
{"title":"Variation of Li Diffusion Coefficient during Delithiation of Spinel LiNi0.5Mn1.5O4","authors":"A. S. Rahim, M. Z. Kufian, A. Arof, Z. Osman","doi":"10.33961/jecst.2021.00780","DOIUrl":"https://doi.org/10.33961/jecst.2021.00780","url":null,"abstract":"For this study, the sol gel method was used to synthesize the spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) electrode material. Structural, morphological, electrochemical, and kinetic aspects of the LNMO have been characterized. The synthesized LNMO was indexed with the Fd3m cubic space group. The excellent capacity retention indicates that the spinel framework of LNMO has the ability to withstand high rate charge-discharge throughout long cycle tests. The Li diffusion coefficient (D Li ) changes non-monotonically across three orders of magnitude, from 10 -9 to 10 -12 cm 2 s -1 determined from GITT method. The variation of D Li seemed to be related to three oxidation reactions that happened throughout the charging process. A small dip in D Li at the beginning stage of Li deintercalation is correlated with the oxidation of Mn 3+ to Mn 4+ . While two pronounced D Li minima at 4.7 V and 4.75 V are due to the oxidation of Ni 2+ /Ni 3+ and Ni 3+ /Ni 4+ respectively. The depletion of D Li at the high voltage region is attributed to the occurrence of two successive phase transformation phenomena.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46487290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-18DOI: 10.33961/jecst.2021.00836
Jaeyoung Kim, Sangbin Park, Sunhyun Hwang, W. Yoon
Lithium-ion battery development is one of the most active contemporary research areas, gaining more attention in recent times, following the increasing importance of energy storage technology. The galvanostatic intermittent titration technique (GITT) has become a crucial method among various electrochemical analyses for battery research. During one titration step in GITT, which consists of a constant current pulse followed by a relaxation period, transient and steady-state voltage changes were measured. It draws both thermodynamic and kinetic parameters. The diffusion coefficients of the lithium ion, open-circuit voltages, and overpotentials at various states of charge can be deduced by a series of titration steps. This mini-review details the theoretical and practical aspects of GITT analysis, from the measurement method to the derivation of the diffusivity equation for research cases according to the specific experimental purpose. This will shed light on a better understanding of electrochemical reactions and provide insight into the methods for improving lithium-ion battery performance.
{"title":"Principles and Applications of Galvanostatic Intermittent Titration Technique for Lithium-ion Batteries","authors":"Jaeyoung Kim, Sangbin Park, Sunhyun Hwang, W. Yoon","doi":"10.33961/jecst.2021.00836","DOIUrl":"https://doi.org/10.33961/jecst.2021.00836","url":null,"abstract":"Lithium-ion battery development is one of the most active contemporary research areas, gaining more attention in recent times, following the increasing importance of energy storage technology. The galvanostatic intermittent titration technique (GITT) has become a crucial method among various electrochemical analyses for battery research. During one titration step in GITT, which consists of a constant current pulse followed by a relaxation period, transient and steady-state voltage changes were measured. It draws both thermodynamic and kinetic parameters. The diffusion coefficients of the lithium ion, open-circuit voltages, and overpotentials at various states of charge can be deduced by a series of titration steps. This mini-review details the theoretical and practical aspects of GITT analysis, from the measurement method to the derivation of the diffusivity equation for research cases according to the specific experimental purpose. This will shed light on a better understanding of electrochemical reactions and provide insight into the methods for improving lithium-ion battery performance.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48924870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-18DOI: 10.33961/jecst.2021.00668
Dohyeong Kim, H. Kim, S. Song, Kiyoung Kim, S. Lim, Ju Young Woo, Haksoo Han
, ABSTRACT Molten carbonate fuel cells (MCFCs) are environmentally friendly, large-capacity power generation devices operated at approximately 650 o C. If MCFCs are to be commercialized by improving their competitiveness, their cell life should be increased by operating them at lower temperatures. However, a decrease in the operating temperature causes a reduction in the cell performance because of the reduction in the electrochemical reaction rate. The cell performance can be improved by introducing a coating on the cathode of the cell. A coating with a high surface area expands the triple phase boundaries (TPBs) where the gas and electrolyte meet on the electrode surface. And the expansion of TPBs enhances the oxygen reduction reaction of the cathode. Therefore, the cell performance can be improved by increasing the reaction area, which can be achieved by coating nanosized LiCoO 2 particles on the cathode. However, although a coating improves the cell performance, a thick coating makes gas difficult to diffuse into the pore of the coating and thus reduces the cell performance. In addition, LiCoO 2 -coated cathode cell exhibits stable cell performance because the coating layer maintains a uniform thickness under MCFC operating conditions. Therefore, the performance and stability of MCFCs can be improved by applying a LiCoO 2 coating with an appropriate thickness on the cathode. Stable Long-Term Operation
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