| 1. |
- Cai, Bin, et al.
(författare)
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High isotropic dispiro structure hole transporting materials for planar perovskite solar cells
- 2019
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Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier. - 2056-9386. ; 32, s. 152-158
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Tidskriftsartikel (refereegranskat)abstract
- Two novel fluorene-based hole transporting materials (HTMs) were synthesized to be used in perovskite solar cells (PSCs). C102 was designed based on C101 by simply linking the two carbon-carbon single bonds to compose a "dispiro" structure. Their typically similar structures cause them sharing almost the same energy levels. However, their photovoltaic performances are quite different due to the small variations. The PSC that contained the "dispiro" structure, C102, reached a power conversion efficiency (PCE) of 17.4%, while the device contained C101, obtained a lower PCE of 15.5%. Electrochemical properties and Photovoltaic characterization of the two materials have been investigated to explain the result. It is shown that C102 has a stronger ability to transport holes and resist the charge recombination. Thus, the dispiro structure should be more appropriate being used as HTM in PSCs. Physics, Chinese Academy of Sciences.
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| 2. |
- Chang, Qingyan, et al.
(författare)
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Precursor engineering enables high-performance all-inorganic CsPbIBr2 perovskite solar cells with a record efficiency approaching 13%
- 2024
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Ingår i: Journal of Energy Chemistry. - : Elsevier BV. - 2095-4956 .- 2096-885X. ; 90, s. 16-22
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Tidskriftsartikel (refereegranskat)abstract
- All-inorganic CsPbIBr2 perovskite has attracted widespread attention in photovoltaic and other optoelectronic devices because of its superior thermal stability. However, the deposition of high-quality solution-processed CsPbIBr2 perovskite films with large thicknesses remains challenging. Here, we develop a triple-component precursor (TCP) by employing lead bromide, lead iodide, and cesium bromide, to replace the most commonly used double-component precursor (DCP) consisting of lead bromide and cesium iodide. Remarkably, the TCP system significantly increases the solution concentration to 1.3 M, leading to a larger film thickness (∼390 nm) and enhanced light absorption. The resultant CsPbIBr2 films were evaluated in planar n-i-p structured solar cells, which exhibit a considerably higher optimal photocurrent density of 11.50 mA cm−2 in comparison to that of DCP-based devices (10.69 mA cm−2). By adopting an organic surface passivator, the maximum device efficiency using TCP is further boosted to a record efficiency of 12.8% for CsPbIBr2 perovskite solar cells.
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| 3. |
- 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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| 4. |
- Cheng, Ming, et al.
(författare)
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A novel phenoxazine-based hole transport material for efficient perovskite solar cell
- 2015
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Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier. - 2056-9386. ; 24:6, s. 698-706
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Tidskriftsartikel (refereegranskat)abstract
- Based on the previous research work in our laboratory, we have designed and synthesized a small-molecule, hole transport material (HTM) POZ6-2 using phenoxazine (POZ) as central unit and dicyanovinyl units as electron-withdrawing terminal groups. Through the introduction of a 2-ethyl-hexyl bulky chain into the POZ core unit, POZ6-2 exhibits good solubility in organic solvents. In addition, POZ6-2 possesses appropriate energy levels in combination with a high hole mobility and conductivity in its pristine form. Therefore, it can readily be used as a dopant-free HTM in perovskite solar cells (PSCs) and a conversion efficiency of 10.3% was obtained. The conductivity of the POZ6-2 layer can be markedly enhanced via doping in combination with typical additives, such as 4-tert-butylpyridine (TBP) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). Correspondingly, the efficiency of the PSCs was further improved to 12.3% using doping strategies. Under the same conditions, reference devices based on the well-known HTM Spiro-OMeTAD show an efficiency of 12.8%.
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| 5. |
- Choi, Seung Young, et al.
(författare)
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Ex situ aging effect on sulfonated poly(ether ether ketone) membrane : Hydration-dehydration cycling and hydrothermal treatment
- 2022
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Ingår i: Journal of Energy Chemistry. - : Elsevier BV. - 2095-4956. ; 70, s. 583-592
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Tidskriftsartikel (refereegranskat)abstract
- Prolonged hydrothermal treatment for sulfonated poly(ether ether ketone) membranes induces mechanical degradation and developing hydrophilic-hydrophobic phase separation, simultaneously. The enhanced phase separation provides incremental proton conductivity to the membranes, whereas mechanical degradation drastically reduces device stability. On this basis, we describe here the effects of two different ex situ aging processes on sulfonated poly(ether ether ketone) membranes: hydration-dehydration cycling and prolonged hydrothermal treatment. Both aged membranes exhibited enhanced phase separation under the hydrated conditions, as characterized by small angle X-ray scattering. However, when the aged membranes were dried again, the nanostructure of the membranes aged via the hydration-dehydration cycling was recoverable, whereas that of the membranes aged via prolonged hydrothermal treatment was irreversible. Furthermore, the two differently aged membranes showed clear differences in thermal, mechanical, and electrochemical properties. Finally, we implemented both aged membranes in fuel cell application. The sample aged via hydration-dehydration cycling maintained its improved cell performance, whereas the sample aged via hydrothermal treatment showed drastically reduced cell performance after durability test for 50 h.
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| 6. |
- Enterria, Marina, et al.
(författare)
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Driving the sodium-oxygen battery chemistry towards the efficient formation of discharge products : The importance of sodium superoxide quantification
- 2022
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Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier. - 2056-9386. ; 68, s. 709-720
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Tidskriftsartikel (refereegranskat)abstract
- Sodium-oxygen batteries (SOBs) have the potential to provide energy densities higher than the state-of the-art Li-ion batteries. However, controlling the formation of sodium superoxide (NaO2) as the sole discharge product on the cathode side is crucial to achieve durable and efficient SOBs. In this work, the discharge efficiency of two graphene-based cathodes was evaluated and compared with that of a commercial gas diffusion layer. The discharge products formed at the surface of these cathodes in a glyme-based electrolyte were carefully studied using a range of characterization techniques. NaO(2 )was detected as the main discharge product regardless of the specific cathode material while small amounts of Na2O2 center dot & nbsp;2H(2)O and carbonate-like side-products were detected by X-ray diffraction as well as by Raman and infrared spectroscopies. This work leverages the use of X-ray diffraction to determine the actual yield of NaO2 which is usually overlooked in this type of batteries. Thus, the proper quantification of the superoxide formed on the cathode surface is widely underestimated; even though is crucial for determining the efficiency of the battery while eliminating the parasitic chemistry in SOBs. Here, we develop an ex-situ analysis method to determine the amount of NaO2 generated upon discharge in SOBs by transmission X-ray diffraction and quantitative Rietveld analysis. This work unveils that the yield of NaO(2 )depends on the depth of discharge where high capacities lead to very low discharge efficiency, regardless of the used cathode. We anticipate that the methodology developed herein will provide a convenient diagnosis tool in future efforts to optimize the performance of the different cell components in SOBs. (C)& nbsp;2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press.& nbsp;
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| 7. |
- Etman, Ahmed S., et al.
(författare)
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V2O5·nH2O nanosheets and multi-walled carbon nanotube composite as a negative electrode for sodium-ion batteries
- 2019
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Ingår i: Journal of Energy Chemistry. - : Elsevier BV. - 2095-4956 .- 2096-885X. ; 30, s. 145-151
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Tidskriftsartikel (refereegranskat)abstract
- Two dimensional (2D) transition metal oxides and chalcogenides demonstrate a promising performance in sodium-ion batteries (SIBs) application. In this study, we investigated the use of a composite of freeze dried V2O5·nH2O nanosheets and multi-walled carbon nanotube (MWCNT) as a negative electrode material for SIBs. Cyclic voltammetry (CV) results indicated that a reversible sodium-ion insertion/deinsertion into the composite electrode can be obtained in the potential window of 0.1–2.5 V vs. Na+/Na. The composite electrodes delivered sodium storage capacities of 140 and 45 mAh g−1 under applied current densities of 20 and 100 mA g−1, respectively. The pause test during constant current measurement showed a raise in the open circuit potential (OCP) of about 0.46 V, and a charge capacity loss of ∼10%. These values are comparable with those reported for hard carbon electrodes. For comparison, electrodes of freeze dried V2O5·nH2O nanosheets were prepared and tested for SIBs application. The results showed that the MWCNT plays a significant role in the electrochemical performance of the composite material.
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| 8. |
- Ghorbani Shiraz, Hamid, et al.
(författare)
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Towards electrochemical hydrogen storage in liquid organic hydrogen carriers via proton-coupled electron transfers
- 2022
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Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier. - 2056-9386. ; 73, s. 292-300
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Tidskriftsartikel (refereegranskat)abstract
- Green hydrogen is identified as one of the prime clean energy carriers due to its high energy density and a zero emission of CO2. A possible solution for the transport of H2 in a safe and low-cost way is in the form of liquid organic hydrogen carriers (LOHCs). As an alternative to loading LOHC with H2 via a two-step procedure involving preliminary electrolytic production of H2 and subsequent chemical hydrogenation of the LOHC, we explore here the possibility of electrochemical hydrogen storage (EHS) via conversion of proton of a proton donor into a hydrogen atom involved in covalent bonds with the LOHC (R) via a protoncoupled electron transfer (PCET) reaction: . We chose 9-fluorenone/ fluorenol (Fnone/Fnol) conversion as such a model PCET reaction. The electrochemical activation of Fnone via two sequential electron transfers was monitored with in-situ and operando spectroscopies in absence and in presence of different alcohols as proton donors of different reactivity, which enabled us to both quantify and get the mechanistic insight on PCET. The possibility of hydrogen extraction from the loaded carrier molecule was illustrated by chemical activation.
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| 9. |
- Guo, Yu, et al.
(författare)
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Necessity of structural rearrangements for O[sbnd]O bond formation between O5 and W2 in photosystem II
- 2021
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Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier B.V.. - 2056-9386. ; 57, s. 436-442
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Tidskriftsartikel (refereegranskat)abstract
- Numerous aspects of the water oxidation mechanism in photosystem II have not been fully elucidated, especially the O[sbnd]O bond formation pathway. However, a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate candidates. In this work, we studied O[sbnd]O bond formation between O5 and W2 based on the native Mn4Ca cluster by density functional calculations. Structural rearrangements before the formation of the S4 state were found as a prerequisite for O[sbnd]O bond formation between O5 and W2, regardless if the suggested pathways involving the typical Mn1(IV)-O[rad] species or the recently proposed Mn4(VII)(O)2 species. Possible alternatives for the S2 → S3 and S3 → S4 transitions accounting for such required rearrangements are discussed. These findings reflect that the structural flexibility of the Mn4Ca cluster is essential to allow structural rearrangements during the catalytic cycle.
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| 10. |
- Hu, Haiman, et al.
(författare)
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Revealing the role and working mechanism of confined ionic liquids in solid polymer composite electrolytes
- 2024
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Ingår i: Journal of Energy Chemistry. - : Elsevier. - 2095-4956 .- 2096-885X. ; 99, s. 110-119
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Tidskriftsartikel (refereegranskat)abstract
- The confined ionic liquid (IL) in solid polymer composite electrolytes (SCPEs) can improve the performance of lithium metal batteries. However, the impact/role and working mechanism of confined IL in SCPEs remain ambiguous. Herein, IL was immobilized on SiO2 (SiO2@IL-C) and then used to prepare the confined SCPEs together with LiTFSI and PEO to study the impacts of confined-IL on the properties and performance of electrolytes and reveal the Li+ transport mechanism. The results show that, compared to the IL-unconfined SCPE, the IL-confined ones exhibit better performance of electrolytes and cells, such as higher ionic conductivity, higher tLi+, and wider electrochemical windows, as well as more stable cycle performance, due to the increased dissociation degree of lithium salt and enlarged polymer amorphousness. The finite-element/molecular-dynamics simulations suggest that the IL confined on the SiO2 provided an additional Li+ transport pathway (Li+ → SiO2@IL-C) that can accelerate ion transfer and alleviate lithium dendrites, leading to ultrastable stripping/plating cycling over 1900 h for the Li/SCPEs/Li symmetric cells. This study demonstrates that IL-confinement is an effective strategy for the intelligent approach of high-performance lithium metal batteries.
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