| 1. |
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| 2. |
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| 3. |
- Zhang, Leiting, et al.
(författare)
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Reversible Hydration Enabling High-Rate Aqueous Li-Ion Batteries
- 2024
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 9, s. 959-966
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Tidskriftsartikel (refereegranskat)abstract
- Layered TiS2 has been proposed as a versatile host material for various battery chemistries. Nevertheless, its compatibility with aqueous electrolytes has not been thoroughly understood. Herein, we report on a reversible hydration process to account for the electrochemical activity and structural evolution of TiS2 in a relatively dilute electrolyte for sustainable aqueous Li-ion batteries. Solvated water molecules intercalate in TiS2 layers together with Li+ cations, forming a hydrated phase with a nominal formula unit of Li0.38(H2O)2−δTiS2 as the end-product. We unambiguously confirm the presence of two layers of intercalated water by complementary electrochemical cycling, operando structural characterization, and computational simulation. Such a process is fast and reversible, delivering 60 mAh g–1 discharge capacity at a current density of 1250 mA g–1. Our work provides further design principles for high-rate aqueous Li-ion batteries based on reversible water cointercalation.
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| 4. |
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| 5. |
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| 6. |
- Fu, Xiangxiang, et al.
(författare)
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A 3D Framework with an In Situ Generated Li3N Solid Electrolyte Interphase for Superior Lithium Metal Batteries
- 2023
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Ingår i: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 33:51
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Tidskriftsartikel (refereegranskat)abstract
- The practical application of lithium (Li) metal for next-generation rechargeable batteries is still hampered by uncontrolled growth of Li dendrite and severe volume change under repeated plating/stripping. Introducing a 3D structure to reserve space for Li storage and inducing uniform plating/stripping by a lithophilic interface layer are effective strategies to solve these problems. Herein, a novel 3D composite Li anode (Fe-N@SSM-Li) is constructed via an in situ reaction between Li and lithiophilic Fe2N/Fe3N (Fe-N) uniformly anchored on a stainless-steel mesh (SSM). The unique lithiophilic-conductive structure of the Fe-N@SSM-Li can stabilize the Li anode by effectively inducing uniform and dense deposition and confining Li deposition inside the Fe-N@SSM-Li to alleviate volume changes. The Fe-N@SSM-Li displays a distinguished electrochemical performance, with superior lifespan of 5000, 2250, and 1350 h under 1 mA cm−2/1 mAh cm−2, 5 mA cm−2/3 mAh cm−2, and 20 mA cm−2/3 mAh cm−2 in symmetric cells, respectively. Combined with this highly stable Fe-N@SSM-Li, the full cells using LiFePO4 (LFP) and S/C cathodes both show significantly improved electrochemical performances. This work provides a low-cost and scalable strategy for the construction of high-efficiency Li anode with a novel 3D structure, offers new insights to the research of Li metal batteries and beyond.
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| 7. |
- Hou, Xu, et al.
(författare)
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Interfacial Chemistry in Aqueous Lithium‐Ion Batteries : A Case Study of V2O5 in Dilute Aqueous Electrolytes
- 2023
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Ingår i: Small. - : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829.
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous lithium-ion batteries (ALIBs) are promising for large-scale energy storage systems because of the cost-effective, intrinsically safe, and environmentally friendly properties of aqueous electrolytes. Practical application is however impeded by interfacial side-reactions and the narrow electrochemical stability window (ESW) of aqueous electrolytes. Even though higher electrolyte salt concentrations (e.g., water-in-salt electrolyte) enhance performance by widening the ESW, the nature and extent of side-reaction processes are debated and more fundamental understanding thereof is needed. Herein, the interfacial chemistry of one of the most popular electrode materials, V2O5, for aqueous batteries is systematically explored by a unique set of operando analytical techniques. By monitoring electrode/electrolyte interphase deposition, electrolyte pH, and gas evolution, the highly dynamic formation/dissolution of V2O5/V2O4, Li2CO3 and LiF during dis-/charge is demonstrated and shown to be coupled with electrolyte decomposition and conductive carbon oxidation, regardless of electrolyte salt concentration. The study provides deeper understanding of interfacial chemistry of active materials under variable proton activity in aqueous electrolytes, hence guiding the design of more effective electrode/electrolyte interfaces for ALIBs and beyond.
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| 8. |
- Jeschull, Fabian, et al.
(författare)
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Interphase formation with carboxylic acids as slurry additives for Si electrodes in Li-ion batteries. Part 1 : performance and gas evolution
- 2023
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 2515-7655. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- Rendering the solid electrolyte interphase and the inter-particle connections more resilient to volume changes of the active material is a key challenge for silicon electrodes. The slurry preparation in a buffered aqueous solution offers a strategy to increase the cycle life and capacity retention of silicon electrodes considerably. So far, studies have mostly been focused on a citrate buffer at pH = 3, and therefore, in this study a series of carboxylic acids is examined as potential buffers for slurry preparation in order to assess which chemical and physical properties of carboxylic acids are decisive for maximizing the capacity retention for Si as active material. In addition, the cycling stability of buffer-containing electrodes was tested in dependence of the buffer content. The results were complemented by analysis of the gas evolution using online electrochemical mass spectrometry in order to understand the SEI layer formation in presence of carboxylic acids and effect of high proton concentration.
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| 10. |
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| 11. |
- Li, Biao, et al.
(författare)
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Capturing dynamic ligand-to-metal charge transfer with a long-lived cationic intermediate for anionic redox
- 2022
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Ingår i: Nature Materials. - : Springer Nature. - 1476-1122 .- 1476-4660. ; 21:10, s. 1165-1174
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Tidskriftsartikel (refereegranskat)abstract
- Reversible anionic redox reactions represent a transformational change for creating advanced high-energy-density positive-electrode materials for lithium-ion batteries. The activation mechanism of these reactions is frequently linked to ligand-to-metal charge transfer (LMCT) processes, which have not been fully validated experimentally due to the lack of suitable model materials. Here we show that the activation of anionic redox in cation-disordered rock-salt Li1.17Ti0.58Ni0.25O2 involves a long-lived intermediate Ni3+/4+ species, which can fully evolve to Ni2+ during relaxation. Combining electrochemical analysis and spectroscopic techniques, we quantitatively identified that the reduction of this Ni3+/4+ species goes through a dynamic LMCT process (Ni3+/4+–O2− → Ni2+–On−). Our findings provide experimental validation of previous theoretical hypotheses and help to rationalize several peculiarities associated with anionic redox, such as cationic–anionic redox inversion and voltage hysteresis. This work also provides additional guidance for designing high-capacity electrodes by screening appropriate cationic species for mediating LMCT.
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| 12. |
- Li, Biao, et al.
(författare)
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Constructing “Li-rich Ni-rich” oxide cathodes for high-energy-density Li-ion batteries
- 2023
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry. - 1754-5692 .- 1754-5706. ; 16:3, s. 1210-1222
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Tidskriftsartikel (refereegranskat)abstract
- The current exploration of high-energy-density cathode materials for Li-ion batteries is mainly concentrated on either so-called “Li-rich” or “Ni-rich” oxides. However, both are suffering from formidable practical challenges. Here, we combine these two concepts to obtain “Li-rich Ni-rich” oxides in pursuit of more practical high-energy-density cathodes. As a proof of concept, we synthesized an array of Li1+yNi(3−5y)/3Mo2y/3O2 oxides, whose structures were identified to be the coexistence of LiNiO2-rich and Li4MoO5-rich domains with the aid of XRD, TEM, and NMR techniques. Such an intergrowth structure of 5–20 nm size enables excellent mechanical and structural reversibility for the layered rock-salt LiNiO2-rich domain upon cycling thanks to the robust cubic rock-salt Li4MoO5-rich domain enabling an “epitaxial stabilization” effect. As a result, we achieved high capacities (>220 mA h g−1) with Ni contents as low as 80%; the Li1.09Ni0.85Mo0.06O2 member (y = 0.09) shows much improved cycling performances (91% capacity retention for 100 cycles at C/10) compared with pure LiNiO2. This work validates the feasibility of constructing Li-rich Ni-rich compounds in the form of intergrowing domains and hence unlocks vast possibilities for future cathode design.
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| 13. |
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| 14. |
- Li, Biao, et al.
(författare)
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Decoupling the roles of Ni and Co in anionic redox activity of Li-rich NMC cathodes
- 2023
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Ingår i: Nature Materials. - : Springer Nature. - 1476-1122 .- 1476-4660. ; 22:11, s. 1370-1379
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Tidskriftsartikel (refereegranskat)abstract
- Li[LixNiyMnzCo1−x−y−z]O2 (lithium-rich NMCs) are benchmark cathode materials receiving considerable attention due to the abnormally high capacities resulting from their anionic redox chemistry. Although their anionic redox mechanisms have been much investigated, the roles of cationic redox processes remain underexplored, hindering further performance improvement. Here we decoupled the effects of nickel and cobalt in lithium-rich NMCs via a comprehensive study of two typical compounds, Li1.2Ni0.2Mn0.6O2 and Li1.2Co0.4Mn0.4O2. We discovered that both Ni3+/4+ and Co4+, generated during cationic redox processes, are actually intermediate species for triggering oxygen redox through a ligand-to-metal charge-transfer process. However, cobalt is better than nickel in mediating the kinetics of ligand-to-metal charge transfer by favouring more transition metal migration, leading to less cationic redox but more oxygen redox, more O2 release, poorer cycling performance and more severe voltage decay. Our work highlights a compositional optimization pathway for lithium-rich NMCs by deviating from using cobalt to using nickel, providing valuable guidelines for future high-capacity cathode design.
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| 15. |
- Li, Liansheng, et al.
(författare)
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Optimized functional additive enabled stable cathode and anode interfaces for high-voltage all-solid-state lithium batteries with significantly improved cycling performance
- 2022
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 10:38, s. 20331-20342
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Tidskriftsartikel (refereegranskat)abstract
- Functional additives play important roles in stabilizing the interfaces within all-solid-state lithium batteries (ASSLBs), equally vital as in liquid lithium ion batteries (LLIBs). However, they have not received as much attention as in LLIBs; especially the effects of a unique additive on both of cathode and anode interfaces are not clearly understood. Inspired by this idea, the effects of lithium difluoro(oxalate)borate (LiDFOB) and lithium bisoxalatodifluorophosphate (LiBODFP) on the stabilities of the cathode and anode interfaces within the assembled ASSLBs are systematically compared through a series of characterization techniques in this work. Owing to the different degrees of redox kinetics of the LiDFOB and LiBODFP additives, the as-formed cathode solid electrolyte interface (CEI) and anode solid electrolyte interface (SEI) films exhibit drastically different characteristics. Specifically, the LiDFOB-induced CEI film is unevenly distributed and unstable, while a uniform, thin and dense SEI film, delivering an outside-to-inside structure of organic lithium species-layer/LiF-rich layer/Li2O-rich layer, can be generated in the presence of LiDFOB. By contrast, the formed CEI film induced by the LiBODFP additive exhibits stable, uniformly distributed and thin characteristics. However, the LiBODFP-induced SEI film is flawed due to its slow reduction rate. To take full advantage of the electrochemical activities of LiBODFP and LiDFOB additives, a double-layer PEO-based composite solid electrolyte (CSE) with both additives is designed and fabricated. As a result, the assembled ASSLB with a single crystal LiNi0.6Co0.2Mn0.2 cathode and double-layer CSE shows a high specific capacity and ultra-high capacity retention (87.5% after 1340 cycles at 1C). This novel strategy of stabilizing different electrode/electrolyte interfaces using various functional additives is a promising method to enable ASSLBs with excellent performances.
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| 16. |
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| 17. |
- Morozov, Anatolii V., et al.
(författare)
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Retardation of Structure Densification by Increasing Covalency in Li-Rich Layered Oxide Positive Electrodes for Li-Ion Batteries
- 2022
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 34:15, s. 6779-6791
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Tidskriftsartikel (refereegranskat)abstract
- Because of the outstanding discharge capacity provided by oxygen redox activity, Li-rich layered oxide positive electrode materials for Li-ion batteries attract tremendous attention. However, there is still no full consensus on the role that the ionocovalency of transition metal (TM)–oxygen (O) chemical bonding plays in the reversibility of the oxygen redox as well as on both local crystal and electronic structure transformations. Here, we managed to tune the cationic/anionic redox contributions to the overall electrochemical activity using the xLi2RuO3-(1 – x)Li1.2Ni0.2Mn0.6O2 solid solutions as a model system possessing the same crystal structure and morphology as Li-rich layered oxides. We conclusively traced the whole cascade of events from increasing the covalency of the TM–O bond, suppressing irreversible oxygen oxidation to the generation of the reduced Mn species toward retarding the structure “densification” in the Li-rich layered oxides. The results demonstrate that enhancing the degree of covalency of the TM–O bonding is vitally important for anchoring the reversibility of the charge compensation mechanism occurring through partial oxygen oxidation.
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| 18. |
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| 19. |
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| 20. |
- Tot, Aleksandar, et al.
(författare)
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Tuning of Molecular Water Organization in Water-in-Salt Electrolytes by Addition of Chaotropic Ionic Liquids
- 2023
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society. - 1932-7447 .- 1932-7455. ; 127:50, s. 24065-24076
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Tidskriftsartikel (refereegranskat)abstract
- Water-in-salt electrolytes (WISEs) have expanded the useful electrochemical stability of water, making the development of functional aqueous lithium-ion batteries more accessible. The implementation of additives in the formulation of WISEs can further improve the electrochemical stability of water and avoid potential lithium-ion salt solubility issues. Here, we have used Gemini-type ionic liquids to suppress water activity by designing the structure of ionic-liquid cations. The different water-organizing effects of ionic-liquid cations have been investigated and correlated to battery performance in LTO/LMO full cells. The champion device, containing the most chaotropic ionic liquid, retained at least 99% of its Coulombic efficiency after 500 charging cycles, associated with a final specific discharge capacity of 85 mA h·g-1. These results indicated that water-rich Li+ solvation shells significantly contribute to the excellent device performance and long-term stability of the LTO/LMO-based full battery cells. This work shows that the fine-tuning of the Li+ solvation shell and water structure by the addition of chaotropic cations represents a promising strategy for generating more stable and effective lithium-ion-containing rechargeable aqueous batteries.
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| 21. |
- Tot, Aleksandar, et al.
(författare)
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Water-in-salt electrolytes made saltier by Gemini ionic liquids for highly efficient Li-ion batteries
- 2023
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- The water-in-salt electrolytes have promoted aqueous Li-ion batteries to become one of the most promising candidates to overcome safety concerns/issues of traditional Li-ion batteries. A simple increase of Li-salt concentration in electrolytes can successfully expand the electrochemical stability window of aqueous electrolytes beyond 2 V. However, necessary stability improvements require an increase in complexity of the ternary electrolytes. Here, we have explored the effects of novel, Gemini-type ionic liquids (GILs) as a co-solvent systems in aqueous Li[TFSI] mixtures and investigated the transport properties of the resulting electrolytes, as well as their electrochemical performance. The devices containing pyrrolidinium-based GILs show superior cycling stability and promising specific capacity in the cells based on the commonly used electrode materials LTO (Li4Ti5O12) and LMO (LiMn2O4).
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| 26. |
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| 27. |
- Yik, Jackie T., et al.
(författare)
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Automated electrolyte formulation and coin cell assembly for high-throughput lithium-ion battery research
- 2023
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Ingår i: Digital Discovery. - : Royal Society of Chemistry. - 2635-098X. ; 2:3, s. 799-808
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Tidskriftsartikel (refereegranskat)abstract
- Battery cell assembly and testing in conventional battery research is acknowledged to be heavily time-consuming and often suffers from large cell-to-cell variations. Manual battery cell assembly and electrolyte formulations are prone to introducing errors which confound optimization strategies and upscaling. Herein we present ODACell, an automated electrolyte formulation and battery assembly setup, capable of preparing large batches of coin cells. We demonstrate the feasibility of Li-ion cell assembly in an ambient atmosphere by preparing LiFePO4‖Li4Ti5O12-based full cells with dimethyl sulfoxide-based model electrolyte. Furthermore, the influence of water is investigated to account for the hygroscopic nature of the non-aqueous electrolyte when exposed to ambient atmosphere. The reproducibility tests demonstrate a conservative fail rate of 5%, while the relative standard deviation of the discharge capacity after 10 cycles was 2% for the studied system. The groups with 2 vol% and 4 vol% of added water in the electrolyte showed overlapping performance trends, highlighting the nontrivial relationship between water contaminants in the electrolytes and the cycling performance. Thus, reproducible data are essential to ascertain whether or not there are minor differences in the performance for high-throughput electrolyte screenings. ODACell is broadly applicable to coin cell assembly with liquid electrolytes and therefore presents an essential step towards accelerating research and development of such systems.
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| 28. |
- Yin, Wei, et al.
(författare)
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Structural evolution at the oxidative and reductive limits in the first electrochemical cycle of Li1.2Ni0.13Mn0.54Co0.13O2
- 2020
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- High-energy-density lithium-rich materials are of significant interest for advanced lithium-ion batteries, provided that several roadblocks, such as voltage fade and poor energy efficiency are removed. However, this remains challenging as their functioning mechanisms during first cycle are not fully understood. Here we enlarge the cycling potential window for Li1.2Ni0.13Mn0.54Co0.13O2 electrode, identifying novel structural evolution mechanism involving a structurally-densified single-phase A’ formed under harsh oxidizing conditions throughout the crystallites and not only at the surface, in contrast to previous beliefs. We also recover a majority of first-cycle capacity loss by applying a constant-voltage step on discharge. Using highly reducing conditions we obtain additional capacity via a new low-potential P” phase, which is involved into triggering oxygen redox on charge. Altogether, these results provide deeper insights into the structural-composition evolution of Li1.2Ni0.13Mn0.54Co0.13O2 and will help to find measures to cure voltage fade and improve energy efficiency in this class of material.
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| 29. |
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| 30. |
- Zhang, Leiting, et al.
(författare)
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Elucidating the Humidity-Induced Degradation of Ni-Rich Layered Cathodes for Li-Ion Batteries
- 2022
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:11, s. 13240-13249
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Tidskriftsartikel (refereegranskat)abstract
- Ni-rich layered oxides, in a general term of Li(NixCoyMn1–x–y)O2 (x > 0.5), are widely recognized as promising candidates for improving the specific energy and lowering the cost for next-generation Li-ion batteries. However, the high surface reactivity of these materials results in side reactions during improper storage and notable gas release when the cell is charged beyond 4.3 V vs Li+/Li0. Therefore, in this study, we embark on a comprehensive investigation on the moisture sensitivity of LiNi0.85Co0.1Mn0.05O2 by aging it in a controlled environment at a constant room-temperature relative humidity of 63% up to 1 year. We quantitatively analyze the gassing of the aged samples by online electrochemical mass spectrometry and further depict plausible reaction pathways, accounting for the origin of the gas release. Transmission electron microscopy reveals formation of an amorphous surface impurity layer of ca. 10 nm in thickness, as a result of continuous reactions with moisture and CO2 from the air. Underneath it, there is another reconstructed layer of ca. 20 nm in thickness, showing rock salt/spinel-like features. Our results provide insight into the complex interfacial degradation phenomena and future directions for the development of high-performance Ni-rich layered oxides.
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| 31. |
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| 33. |
- Zhang, Leiting, et al.
(författare)
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Reactivity of TiS2 Anode towards Electrolytes in Aqueous Li‐ion Batteries
- 2022
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Ingår i: Batteries & Supercaps. - : John Wiley & Sons. - 2566-6223. ; 5:12
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous rechargeable batteries are appealing alternatives for large-scale energy storage. Reversible cycling of high-energy aqueous batteries has been showcased using highly concentrated aqueous electrolytes, which lead to a significantly suppressed water activity and formation of a stable solid-electrolyte interphase (SEI). However, the high salt concentration inevitably raises the cost and compromises the environmental sustainability. Herein, we use layered TiS2 as a model anode to explore the feasibility of cycling aqueous cells in dilute electrolytes. By coupling three-electrode cycling data with online electrochemical mass spectrometry measurements, we depict the potential-dependent gas evolution from the cell in the absence of a stable SEI. We offer a comprehensive mechanistic understanding of the complex interfacial chemistry in dilute electrolytes, taking into account material reactivity and interfacial compatibility. Design strategies and research directions of layered-type electrodes for sustainable aqueous batteries with dilute electrolytes are recommended, based on the scientific discovery presented in this work.
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| 34. |
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| 35. |
- Zhang, Leiting, et al.
(författare)
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Unraveling gas evolution in sodium batteries by online electrochemical mass spectrometry
- 2021
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Ingår i: Energy Storage Materials. - : Elsevier. - 2405-8289 .- 2405-8297. ; 42, s. 12-21
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Tidskriftsartikel (refereegranskat)abstract
- Identification of gaseous decomposition products from irreversible side-reactions enables understanding of inner working of rechargeable batteries. Unlike for Li-ion batteries, the knowledge of the gas-evolution processes in Na-ion batteries is limited. Therefore, in this study, we have performed online electrochemical mass spectrometry to understand gassing behavior of model electrodes and electrolytes in Na-ion cells. Our results show that a less stable solid-electrolyte interphase (SEI) layer is developed in Na-ion cells as compared with that in Li-ion cells, which is mainly caused by higher solubility of SEI constituents in Na-electrolytes. Electrolyte reduction on the anode has much larger contribution to the gassing in the Na-ion cells, as gas evolution comes not only from direct electrolyte reduction but also from the soluble species, which migrate to the cathode and are decomposed there. During cell cycling, linear carbonates do not form an SEI layer on the anode, resulting in continuous electrolyte reduction, similar to Li-ion system but with much higher severity, while cyclic carbonates form a more stable SEI, preventing further decomposition of the electrolyte. Besides the standard electrolyte solvents, we have also assessed effects of several common electrolyte additives in their ability to stabilize the interphases. The results of this study provide understanding and guidelines for developing more durable electrode-electrolyte interphase, enabling higher specific energy and improved cycling stability for Na-ion batteries.
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