| 1. |
- Chen, Yuqing, et al.
(författare)
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A review of lithium-ion battery safety concerns : the issues, strategies, and testing standards
- 2021
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Ingår i: Journal of Energy Chemistry. - : Elsevier. - 2095-4956 .- 2096-885X. ; 59, s. 83-99
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Tidskriftsartikel (refereegranskat)abstract
- Efficient and reliable energy storage systems are crucial for our modern society. Lithium-ion batteries (LIBs) with excellent performance are widely used in portable electronics and electric vehicles (EVs), but frequent fires and explosions limit their further and more widespread applications. This review summarizes aspects of LIB safety and discusses the related issues, strategies, and testing standards. Specifically, it begins with a brief introduction to LIB working principles and cell structures, and then provides an overview of the notorious thermal runaway, with an emphasis on the effects of mechanical, electrical, and thermal abuse. The following sections examine strategies for improving cell safety, including approaches through cell chemistry, cooling, and balancing, afterwards describing current safety standards and corresponding tests. The review concludes with insights into potential future developments and the prospects for safer LIBs.
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| 2. |
- Chen, Yuqing, et al.
(författare)
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Breaking solvation dominance of ethylene carbonate via molecular charge engineering enables lower temperature battery
- 2023
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Low temperatures severely impair the performance of lithium-ion batteries, which demand powerful electrolytes with wide liquidity ranges, facilitated ion diffusion, and lower desolvation energy. The keys lie in establishing mild interactions between Li+ and solvent molecules internally, which are hard to achieve in commercial ethylene-carbonate based electrolytes. Herein, we tailor the solvation structure with low-ε solvent-dominated coordination, and unlock ethylene-carbonate via electronegativity regulation of carbonyl oxygen. The modified electrolyte exhibits high ion conductivity (1.46 mS·cm−1) at −90 °C, and remains liquid at −110 °C. Consequently, 4.5 V graphite-based pouch cells achieve ~98% capacity over 200 cycles at −10 °C without lithium dendrite. These cells also retain ~60% of their room-temperature discharge capacity at −70 °C, and miraculously retain discharge functionality even at ~−100 °C after being fully charged at 25 °C. This strategy of disrupting solvation dominance of ethylene-carbonate through molecular charge engineering, opens new avenues for advanced electrolyte design.
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| 3. |
- Fan, Lei, et al.
(författare)
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Satellite-observed pantropical carbon dynamics
- 2019
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Ingår i: Nature Plants. - : Springer Science and Business Media LLC. - 2055-0278. ; 5:9, s. 944-951
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Tidskriftsartikel (refereegranskat)abstract
- Changes in terrestrial tropical carbon stocks have an important role in the global carbon budget. However, current observational tools do not allow accurate and large-scale monitoring of the spatial distribution and dynamics of carbon stocks1. Here, we used low-frequency L-band passive microwave observations to compute a direct and spatially explicit quantification of annual aboveground carbon (AGC) fluxes and show that the tropical net AGC budget was approximately in balance during 2010 to 2017, the net budget being composed of gross losses of −2.86 PgC yr−1 offset by gross gains of −2.97 PgC yr−1 between continents. Large interannual and spatial fluctuations of tropical AGC were quantified during the wet 2011 La Niña year and throughout the extreme dry and warm 2015–2016 El Niño episode. These interannual fluctuations, controlled predominantly by semiarid biomes, were shown to be closely related to independent global atmospheric CO2 growth-rate anomalies (Pearson’s r = 0.86), highlighting the pivotal role of tropical AGC in the global carbon budget.
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| 4. |
- Li, Zhao, et al.
(författare)
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Non-uniform seasonal warming regulates vegetation greening and atmospheric CO2 amplification over northern lands
- 2018
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 13:12
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Tidskriftsartikel (refereegranskat)abstract
- The enhanced vegetation growth by climate warming plays a pivotal role in amplifying the seasonal cycle of atmospheric CO2 at northern lands (>50° N) since 1960s. However, the correlation between vegetation growth, temperature and seasonal amplitude of atmospheric CO2 concentration have become elusive with the slowed increasing trend of vegetation growth and weakened temperature control on CO2 uptake since late 1990s. Here, based on in situ atmospheric CO2 concentration records from the Barrow observatory site, we found a slowdown in the increasing trend of the atmospheric CO2 amplitude from 1990s to mid-2000s. This phenomenon was associated with the paused decrease in the minimum CO2 concentration ([CO2]min), which was significantly correlated with the slowdown of vegetation greening and growing-season length extension. We then showed that both the vegetation greenness and growing-season length were positively correlated with spring but not autumn temperature over the northern lands. Furthermore, such asymmetric dependences of vegetation growth upon spring and autumn temperature cannot be captured by the state-of-art terrestrial biosphere models. These findings indicate that the responses of vegetation growth to spring and autumn warming are asymmetric, and highlight the need of improving autumn phenology in the models for predicting seasonal cycle of atmospheric CO2 concentration.
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| 5. |
- Xiong, Xiangming, et al.
(författare)
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Turbulent bands in plane-Poiseuille flow at moderate Reynolds numbers
- 2015
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Ingår i: Physics of fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 27:4
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we show via numerical simulations that the typical flow structures appearing in transitional channel flows at moderate Reynolds numbers are not spots but isolated turbulent bands, which have much longer lifetimes than the spots. Localized perturbations can evolve into isolated turbulent bands by continuously growing obliquely when the Reynolds number is larger than 660. However, interactions with other bands and local perturbations cause band breaking and decay. The competition between the band extension and breaking does not lead to a sustained turbulence until Re becomes larger than about 1000. Above this critical value, the bands split, providing an effective mechanism for turbulence spreading.
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