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  • 1
    Online Resource
    Online Resource
    MDPI AG ; 2019
    In:  International Journal of Environmental Research and Public Health Vol. 16, No. 7 ( 2019-04-03), p. 1195-
    In: International Journal of Environmental Research and Public Health, MDPI AG, Vol. 16, No. 7 ( 2019-04-03), p. 1195-
    Abstract: In China, due to decades of the ‘one-child policy’ and continuous rural-urban labour migration, real population aging in rural areas is increasing more quickly than in urban areas, and the labour inputs in agricultural production are becoming ever more dependent on the elderly. Using CHARLS data, we examine the effect of health on the labour supply of rural elderly people. We construct a latent health stock index (LHSI) to eliminate measurement bias and then use this one-period lagged LHSI and the Heckman two-stage and the Bourguignon-Fournier-Gurand two-stage method to deal with the simultaneous causality of health and labour decisions and sample selectivity in model estimation. The results show that, in the overall level, the labour force participation and work time of rural elderly people increase significantly with the improvement of health. These effects on the males are sharply greater than on the females and are enhanced with age. In the subdivided agricultural and non-agricultural labour supply, health improvement is positively related with labour force participation of rural elderly and brings an employment allocation from agricultural section to non-agricultural section, especially on the males. However, as the work time, these relations are insignificant and invariant with gender and age.
    Type of Medium: Online Resource
    ISSN: 1660-4601
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2175195-X
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  • 2
    In: Journal of Electrochemical Energy Conversion and Storage, ASME International, Vol. 18, No. 4 ( 2021-11-01)
    Type of Medium: Online Resource
    ISSN: 2381-6872 , 2381-6910
    Language: English
    Publisher: ASME International
    Publication Date: 2021
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  • 3
    Online Resource
    Online Resource
    The Electrochemical Society ; 2019
    In:  ECS Meeting Abstracts Vol. MA2019-01, No. 6 ( 2019-05-01), p. 573-573
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2019-01, No. 6 ( 2019-05-01), p. 573-573
    Abstract: Nail penetration is widely used to characterize lithium-ion (Li-ion) battery safety during internal short circuit (ISC) that has caused many high-impact field failures (e.g. Samsung Note 7 battery fires in 2016 [1]). Compared with other ISC triggering methods that require embedding some devices into Li-ion battery cells [2] , nail penetration is much easier to implement without cumbersome modification of testing cells. A challenge for nail penetration, however, is poor control of ISC electrode layers while those methods with embedded devices can accurately achieve single layer ISC [2]. This challenge makes nail penetration triggered ISC less representative of field failures than using those device-embedded methods. It also leads to poor reproducibility of testing results. Here we report a single-layer nail penetration method based on in situ temperature sensing. The method not only keeps nail penetration’s advantage of easy implementation, but also makes nail penetration more representative of field failure ISC with testing results more reproducible. The method works with three key elements. First, a micro temperature sensor is embedded into the tip of a nail, similar to those "smart nails" in earlier reports [3-6], for in situ sensing of ISC temperature. Second, a temperature controller is used to stop the nail penetration when the ISC temperature reaches set value. Third, the nail penetration speed (0.1 mm/s or lower) is much lower than conventional nail penetration speed (up to 80 mm/s [7]). The figure below shows ISC temperature and surface temperature of a 2.4 Ah pouch Li-ion cell during single-layer nail penetration. It can be seen that the ISC temperature is much more sensitive than surface temperature. There is only one ISC temperature peak, suggesting single layer penetration, as compared with our earlier work of full nail penetration which has multiple ISC temperature peaks [8]. With this method, the effects of key parameters, such as ISC resistance, cell dimension and jelly roll structure, on Li-ion battery safety behaviors can be characterized. References: [1] Samsung, Galaxy Note7: What We Discovered. https://news.samsung.com/global/infographic-galaxy-note7-what-we-discovered, (2017). [2] V. Ruiz, A. Pfrang, JRC Exploratory Research: Safer Li-Ion Batteries by Preventing Thermal Propagation, Joint Research Centre (JRC) Workshop Report: Summary & Outcomes (JRC Petten, Netherlands, 8-9 March 2018), http://publications.jrc.ec.europa.eu/repository/bitstream/JRC113320/kjna29384enn.pdf, (2018). [3] T.D. Hatchard, S. Trussler, J.R. Dahn, Building a “Smart Nail” for Penetration Tests on Li-ion Cells, Journal of Power Sources, 247 (2014) 821-823. [4] P. Poramapojana, Experimental Investigation of Internal Short Circuits in Lithium-Ion Batteries, PhD Dissertation, The Pennsylvania State University, https://etda.libraries.psu.edu/catalog/26683, (2015). [5] T.R. Tanim, M. Garg, C.D. Rahn, An Intelligent Nail Design for Lithium Ion Battery Penetration Test, Proceedings of the ASME 2016 Power and Energy Conference, June 26-30, 2016, Charlotte, North Carolina, USA, (2016). [6] D.P. Finegan, B. Tjaden, T. M. M. Heenan, R. Jervis, M.D. Michiel, A. Rack, G. Hinds, D.J.L. Brett, P.R. Shearing, Tracking Internal Temperature and Structural Dynamics during Nail Penetration of Lithium-Ion Cells, Journal of The Electrochemical Society, 164(13) (2017) A3285-A3291. [7] V. Ruiz, A. Pfrang, A. Kriston, N. Omar, P. Van den Bossche, L. Boon-Brett, A Review of International Abuse Testing Standards and Regulations for Lithium Ion Batteries in Electric and Hybrid Electric Vehicles, Renewable and Sustainable Energy Reviews, 81 (2018) 1427-1452. [8] S. Huang, X. Du, G.M. Cavalheiro, M. Richter, T. Iriyama, G. Zhang, Characterizing Lithium-ion Battery Internal Short Circuit with Slow-Penetrating Micro Sensing Nails, NASA Aerospace Battery Workshop, Nov. 27 - 29, 2018, Huntsville, AL, USA, (2018). Figure 1
    Type of Medium: Online Resource
    ISSN: 2151-2043
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2019
    detail.hit.zdb_id: 2438749-6
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  • 4
    Online Resource
    Online Resource
    The Electrochemical Society ; 2020
    In:  Journal of The Electrochemical Society Vol. 167, No. 9 ( 2020-01-07), p. 090526-
    In: Journal of The Electrochemical Society, The Electrochemical Society, Vol. 167, No. 9 ( 2020-01-07), p. 090526-
    Abstract: Here we report a small, slow and in situ sensing (3S) nail penetration test method to understand Li-ion cell internal short circuit (ISC) and thermal runaway. The method not only keeps conventional nail penetration’s advantage of simple implementation, but also enhances its relevance to field failures and enables detailed in situ diagnosis. It was applied to 3-Ah pouch cells and revealed insights that could not be captured by conventional methods. Most interestingly, multiple in situ temperature peaks were observed during a period of over 100 s before thermal runaway. These initial peaks exceeded safety limit but the temperature rapidly decreased after each peak instead of causing immediate thermal runaway. Further investigation suggested that the initial temperature peaks occurred when nail tip reached aluminum foil current collector to form a low resistance ISC between anode and aluminum foil. The rapid temperature decrease after each peak can be attributed to sudden drop of ISC current, which can be further attributed to rupture of aluminum foil and increase of contact resistance. The findings show that 3S nail penetration test can separate processes of ISC from thermal runaway and provide details of ISC at the level of individual electrode and current collector.
    Type of Medium: Online Resource
    ISSN: 0013-4651 , 1945-7111
    RVK:
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2020
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  • 5
    Online Resource
    Online Resource
    The Electrochemical Society ; 2021
    In:  Journal of The Electrochemical Society Vol. 168, No. 9 ( 2021-09-01), p. 090510-
    In: Journal of The Electrochemical Society, The Electrochemical Society, Vol. 168, No. 9 ( 2021-09-01), p. 090510-
    Abstract: Here we report in situ measurement of temperature distributions in a 2.5-Ah pouch format Li-ion cell during internal short circuit (ISC) and thermal runaway. The ISC and thermal runaway were triggered by nail penetration. The local temperatures were measured by embedded K type micro thermocouples in the middle layer of the experimental Li-ion cell. Highly non-uniform temperature distributions were observed during ISC and thermal runaway as compared with those during constant current discharging and external short circuit. The in situ measurement also captured details of how thermal runaway started from the ISC location and spread to the entire cell in a few seconds. Moreover, the comparison between ISC without thermal runaway and ISC with thermal runaway suggests that internal short circuit resistance plays a critical role in the risk of thermal runaway.
    Type of Medium: Online Resource
    ISSN: 0013-4651 , 1945-7111
    RVK:
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2021
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  • 6
    In: Journal of The Electrochemical Society, The Electrochemical Society, Vol. 170, No. 6 ( 2023-06-01), p. 060515-
    Abstract: Here we report a method for in situ measurement of internal short circuit (ISC) resistance during nail penetration testing of lithium-ion cells. The method is demonstrated with dry cells, wet dummy cells, and working cells using a small nail and slow penetration speed. ISC current and ISC temperature are also measured during the tests. It is confirmed that the ISC resistance changes dramatically, by several orders of magnitude, during nail penetration. More importantly, it is found that the stable resistance after full penetration is much higher than the lowest dynamic resistance at earlier stages of nail penetration. Analysis based on such a stable ISC resistance would underestimate the risk of thermal runaway during nail penetration tests. It is also found that ISC in some cases may be mitigated due to melting or rupture of aluminum foil surrounding the nail, implying a mechanism that may be able to be used towards the design of more robust/abuse tolerant Li-ion cells. Lastly, it is found that nail penetration using a larger nail reduces ISC resistance during penetration of cells but the general behaviors of ISC resistance are similar to those during smaller nail penetration.
    Type of Medium: Online Resource
    ISSN: 0013-4651 , 1945-7111
    RVK:
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2023
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  • 7
    Online Resource
    Online Resource
    ASME International ; 2020
    In:  Journal of Electrochemical Energy Conversion and Storage Vol. 17, No. 2 ( 2020-05-01)
    In: Journal of Electrochemical Energy Conversion and Storage, ASME International, Vol. 17, No. 2 ( 2020-05-01)
    Abstract: The effects of nonuniform temperature distribution on the degradation of lithium-ion (Li-ion) batteries are investigated in this study. A Li-ion battery stack consisting of five 3 Ah pouch cells connected in parallel was tested for 2215 cycles and compared with a single baseline cell. The behaviors of temperature distribution, degradation, and current distribution of the stack were characterized and discussed. Results supported the hypothesis that nonuniform temperature distribution causes nonuniform and accelerated degradation. All cells in the stack experienced higher temperature rise and degraded faster than the baseline cell. In particular, capacity retention of the middle cell in the stack decreased to 50.7% after 2215 cycles, while the baseline cell capacity retention was still 87.8%. The resistance of cells in the stack experienced nonuniform but similar pattern of variation with cycling. The resistances remained stable in early cycles, then experienced a rapid increase, and then became stable again. The middle cell resistance increased abruptly in the last 20 cycles before failure. Current distribution behaviors of the stack also changed significantly during cycling, which was consistent with cell resistance behaviors. The middle cell experienced much higher C rate than average, suggesting that its accelerated degradation can be attributed to the synergized effects of higher local temperature and higher local current.
    Type of Medium: Online Resource
    ISSN: 2381-6872 , 2381-6910
    Language: English
    Publisher: ASME International
    Publication Date: 2020
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  • 8
    In: Science of The Total Environment, Elsevier BV, Vol. 752 ( 2021-01), p. 142256-
    Type of Medium: Online Resource
    ISSN: 0048-9697
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 1498726-0
    detail.hit.zdb_id: 121506-1
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    SAGE Publications ; 2021
    In:  SAGE Open Vol. 11, No. 2 ( 2021-04), p. 215824402110156-
    In: SAGE Open, SAGE Publications, Vol. 11, No. 2 ( 2021-04), p. 215824402110156-
    Abstract: The sales-related difficulties faced by cooperatives can be solved by expanding their sales channels through e-commerce. However, extant studies have only examined cooperatives’ e-commerce sales behavior from either a technology perception or government support perspective. To fill this gap, based on survey data of 215 farmer cooperatives in Liaoning province, China, this study employs a probit model to analyze the impact of both technology perception and government support on these cooperatives’ e-commerce sales behavior, as well as their marginal and accelerating effects. Both factors were shown to have a significant positive impact. Technology perception has a greater impact on e-commerce sales behavior than government support, while perceived effectiveness has the most significant impact. This study also found that government support has an accelerating effect on the relationship between technology perception and farmer cooperatives’ e-commerce sales behavior. Therefore, governments should improve cooperative members’ technology perception to aid them in expanding sales.
    Type of Medium: Online Resource
    ISSN: 2158-2440 , 2158-2440
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
    detail.hit.zdb_id: 2628279-3
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  • 10
    Online Resource
    Online Resource
    The Electrochemical Society ; 2021
    In:  ECS Meeting Abstracts Vol. MA2021-01, No. 5 ( 2021-05-30), p. 278-278
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2021-01, No. 5 ( 2021-05-30), p. 278-278
    Abstract: Thermal runaway is a critical safety challenge for Li-ion cells, characterized by rapid temperature rise and potentially rapid energy release. Numerical modeling studies revealed that temperature distribution in Li-ion cells is highly non-uniform during thermal runaway 1 , 2 . However, there is a lack of experimentally measured temperature distribution results for model validation or insightful understanding of thermal runaway. Here we report development of a Li-ion cell with multiple embedded thermocouples and in situ measurement of its temperature distributions during thermal runaway. As schematically shown in Figure 1, seven micro thermocouples are embedded inside a 2.5 Ah Li-ion pouch cell, enabling in situ measurement of temperatures at different locations. Various testing is performed, including nail penetration testing using a 3 mm-diameter stainless steel nail to trigger thermal runaway. Following our earlier practice 3 , the nail speed utilized is lower than 0.1 mm/s and the voltages between the nail and cell tabs are monitored. Figure 2 shows the spatial temperature distribution along the centerline during 5C (12.5 A constant current) discharging in comparison with that during thermal runaway as triggered by slow nail penetration. It can be seen that the maximum temperature rise during 5C discharging is about 25 °C and that local temperatures closer to tabs are always slightly higher than those away from tabs. In comparison, maximum temperature rise during thermal runaway is up to 700 °C. More interestingly, the pattern of spatial temperature distribution changes dramatically and is highly non-uniform during thermal runaway. Before 238s, there is little temperature rise and temperature distribution is quite uniform, indicating very slow heat generation near the nail. At 240s, the rise of local temperature closest to the nail is more than 400 °C while the rise of local temperature near the tab is only 20 °C, indicating highly non-uniform temperature distribution and rapid heat generation near the nail. Note that temperature gradient is directionally opposite to that during 5C discharging. Local temperature farther away from tabs but closer to penetration location rises more and faster than that closer to tabs. All of the local temperatures then continue to rise while the temperature gradient becomes smaller, suggesting propagation of thermal runaway from nail penetration location to entire cell. Such detailed spatial-temporal experimental results will help in better understanding of thermal runaway behavior and the development of safer Li-ion cells. References: W. Zhao, G. Luo and C.Y. Wang, Journal of The Electrochemical Society , 162 , A207 (2015). W. Zhao, G. Luo and C.Y. Wang, Journal of The Electrochemical Society , 162 , A1352 (2015). S. Huang, X. Du, M. Richter, J. Ford, G. M. Cavalheiro, Z. Du, R. T. White and G. Zhang, Journal of The Electrochemical Society , 167 , 090526 (2020). v Figure 1
    Type of Medium: Online Resource
    ISSN: 2151-2043
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2438749-6
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