| 1. |
- Chien, Yu-Chuan, 1990-, et al.
(författare)
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Impact of Compression on the Electrochemical Performance of the Sulfur/Carbon Composite Electrode in Lithium-Sulfur Batteries
- 2022
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Ingår i: Batteries & Supercaps. - : Wiley-VCH Verlagsgesellschaft. - 2566-6223. ; 5:7
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Tidskriftsartikel (refereegranskat)abstract
- While lithium-sulfur batteries theoretically have both high gravimetric specific energy and volumetric energy density, only its specific energy has been experimentally demonstrated to surpass that of the state-of-the-art lithium-ion systems at cell level. One major reason for the unrealized energy density is the low capacity density of the highly porous sulfur/carbon composite as the positive electrode. In this work, mechanical compression at elevated temperature is demonstrated to be an effective method to increase the capacity density of the electrode by at least 90 % and moreover extends its cycle life. Distinct impacts of compression on the resistance profiles of electrodes with different thickness are investigated by tortuosity factors derived from both electrochemical impedance spectroscopy, X-ray computed tomography and kinetic analysis based on operando X-ray diffraction. The results highlights the importance of a homogeneous electrode structure highlight lithium-sulfur system.
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| 2. |
- Li, He, et al.
(författare)
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Operando Characterization of Active Surface Area and Passivation Effects on Sulfur-Carbon Composites for Lithium-Sulfur Batteries
- 2022
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 403
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur electrodes for lithium-sulfur batteries necessarily contain a conductive additive,typically carbon, to enable the electrochemical reactions, since sulfur and the dischargeproduct, Li2S, are insulators. Consequently, the full passivation of carbon, by depositionof sulfur and/or Li2S, would necessarily produce the death of the battery. However, herewe demonstrate that for high-performance lithium-sulfur batteries operated under leanelectrolyte conditions (electrolyte to sulfur ratio of 6 µL mgS-1 in Li-S coin cells), theextent of passivation of carbon is not severe enough to limit performance. This is shownby performing impedance measurements of fully charged lithium-sulfur batteries, fromwhich we demonstrate that we can evaluate the specific surface area of carbon, and wefind that the capacity fade with cycling is not due to a decrease in the electrochemicallyactive specific surface area of carbon. These results show that introducing a higher sur-face area carbon in the sulfur electrode formulation is not needed to prevent passivation,and that the focus of lithium-sulfur development should be directed towards other is-sues, such as mitigating undesirable reactions at the lithium electrode and achievingrobust sulfur electrode structures enabling fast transport of electrolyte species and, thus,more homogeneous reactions.
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| 3. |
- Pretty, Jules, et al.
(författare)
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Global assessment of agricultural system redesign for sustainable intensification
- 2018
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Ingår i: Nature Sustainability. - : Springer Science and Business Media LLC. - 2398-9629. ; 1:8, s. 441-446
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Tidskriftsartikel (refereegranskat)abstract
- The sustainable intensification of agricultural systems offers synergistic opportunities for the co-production of agricultural and natural capital outcomes. Efficiency and substitution are steps towards sustainable intensification, but system redesign is essential to deliver optimum outcomes as ecological and economic conditions change. We show global progress towards sustainable intensification by farms and hectares, using seven sustainable intensification sub-types: integrated pest management, conservation agriculture, integrated crop and biodiversity, pasture and forage, trees, irrigation management and small or patch systems. From 47 sustainable intensification initiatives at scale (each > 10(4) farms or hectares), we estimate 163 million farms (29% of all worldwide) have crossed a redesign threshold, practising forms of sustainable intensification on 453 Mha of agricultural land (9% of worldwide total). Key challenges include investment to integrate more forms of sustainable intensification in farming systems, creating agricultural knowledge economies and establishing policy measures to scale sustainable intensification further. We conclude that sustainable intensification may be approaching a tipping point where it could be transformative.
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