| 1. |
- Jiao, Xingxing, et al.
(författare)
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Electro-chemo-mechanical failure of solid-state electrolyte caused from intergranular or transgranular damage propagation in polycrystalline aggregates
- 2024
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Ingår i: Acta Materialia. - 1359-6454. ; 265
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Tidskriftsartikel (refereegranskat)abstract
- Electro-chemo-mechanical failure of solid-state electrolytes (SEs) caused by the internal growth of lithium dendrites significantly impedes the application of solid-state batteries under high applied current density. The grain boundary is usually the key to the mechanical properties of polycrystalline ceramic SEs. Here, strength and width of grain boundary in SEs that are exampled by garnet-type Li7La3Zr2O12 are evaluated under the deposition of lithium by visualizing the stress field, damage accumulation and crack propagation. The enhancement of grain boundary strength triggers a dramatic increase stress when the ratio of tensile strength between grain boundary and grain (λ) is lower than 0.9. With the variation of λ, three damage processes are revealed as intergranular-damage, inter/transgranular-damage and transgranular-damage, leading to different propagation of cracks and the transformation of intergranular failure to transgranular failure. Furthermore, the width of the grain boundary is found to induce more transgranular-damage with its widening. A critical value of grain boundary width for the formation of displacement is obtained under various strengths, as δ = 21 nm for λ = 0.2, δ = 25 nm for λ = 0.5 and δ = 31 nm for λ = 0.9. The findings in this work indicate the coupling effect of grain boundary width and strength on the failure of SEs, providing an insightful perspective for the future design of solid-state batteries.
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| 2. |
- Jiao, Xingxing, et al.
(författare)
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Grain size and grain boundary strength: Dominative role in electro-chemo-mechanical failure of polycrystalline solid-state electrolytes
- 2024
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Ingår i: Energy Storage Materials. - 2405-8297. ; 65
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Tidskriftsartikel (refereegranskat)abstract
- Solid-state batteries with lithium metal anode have been accepted extensively as the competitive option to fulfill the upping requirement for safe and efficient energy devices. Nevertheless, its wide-ranging application has been impeded by the failure of solid-state electrolyte (SSE) induced by development of lithium (Li) filament. Based on the nature of polycrystalline ceramic SSE with varying grain size and boundary strength, the constitutive equation coupled with electrochemical kinetics was applied to picture the propagation of damage and corresponding disintegration caused by the development of Li filament. Based on the results, we found that the stress generated along with the growth of Li filament spreads away via the opening and sliding of grain boundary. Thus, damage occurs along grain boundaries, of which propagation behavior and damage level are controlled by grain size. Especially, over-refinement and under-refinement of grains of SSE can cause flocculent damage with inordinate damage degree and accelerate the failure time of SSE, respectively. On the other hand, the failure time is powerfully prolongated through strengthening the grain boundary of SSE. Eventually, grain size of 0.2 μm and tensile strength of grain boundary of 0.8-time-of-grain are posted as the threshold to realize the postponed failure of NASICON-based SSE. Inspiringly, electro-chemo-mechanical model in this contribution is generally applicable to other type of ceramic SSE to reveal the failure process and provide the design guideline, fostering the improvement of solid-state batteries.
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| 3. |
- Jiao, Xingxing, et al.
(författare)
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Viability of all-solid-state lithium metal battery coupled with oxide solid-state electrolyte and high-capacity cathode
- 2024
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Ingår i: Journal of Energy Chemistry. - 2095-4956. ; 91, s. 122-131
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Tidskriftsartikel (refereegranskat)abstract
- Owing to the utilization of lithium metal as anode with the ultrahigh theoretical capacity density of 3860 mA h g−1 and oxide-based ceramic solid-state electrolytes (SE), e.g., garnet-type Li7La3Zr2O12 (LLZO), all-state-state lithium metal batteries (ASLMBs) have been widely accepted as the promising alternatives for providing the satisfactory energy density and safety. However, its applications are still challenged by plenty of technical and scientific issues. In this contribution, the co-sintering temperature at 500 °C is proved as a compromise method to fabricate the composite cathode with structural integrity and declined capacity fading of LiNi0.5Co0.2Mn0.3O2 (NCM). On the other hand, it tends to form weaker grain boundary (GB) inside polycrystalline LLZO at inadequate sintering temperature for LLZO, which can induce the intergranular failure of SE during the growth of Li filament inside the unavoidable defect on the interface of SE. Therefore, increasing the strength of GB, refining the grain to 0.4 μm, and precluding the interfacial defect are suggested to postpone the electro-chemo-mechanical failure of SE with weak GB. Moreover, the advanced sintering techniques to lower the co-sintering temperature for both NCM-LLZO composite cathode and LLZO SE can be posted out to realize the viability of state-of-the-art ASLMBs with higher energy density as well as the guaranteed safety.
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| 4. |
- Kang, Hyokyeong, et al.
(författare)
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Relaxation of Stress Propagation in Alloying-Type Sn Anodes for K-Ion Batteries
- 2024
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Ingår i: Small Methods. - 2366-9608. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Alloying-type metallic tin is perceived as a potential anode material for K-ion batteries owing to its high theoretical capacity and reasonable working potential. However, pure Sn still face intractable issues of inferior K+ storage capability owing to the mechanical degradation of electrode against large volume changes and formation of intermediary insulating phases K4Sn9 and KSn during alloying reaction. Herein, the TiC/C–carbon nanotubes (CNTs) is prepared as an effective buffer matrix and composited with Sn particles (Sn–TiC/C–CNTs) through the high-energy ball-milling method. Owing to the conductive and rigid properties, the TiC/C–CNTs matrix enhances the electrical conductivity as well as mechanical integrity of Sn in the composite material and thus ultimately contributes to performance supremacy in terms of electrochemical K+ storage properties. During potassiation process, the TiC/C–CNTs matrix not only dissipates the internal stress toward random radial orientations within the Sn particle but also provides electrical pathways for the intermediate insulating phases; this tends to reduce microcracking and prevent considerable electrode degradation.
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| 5. |
- Oh, Gwangeon, et al.
(författare)
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Stabilizing Layered-Type K 0.4 V 2 O 5 Cathode by K Site Substitution with Strontium for K-Ion Batteries
- 2024
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Ingår i: Advanced Functional Materials. - 1616-3028 .- 1616-301X. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- Developing suitable cathodes with high capacity and high power is challenging for K-ion batteries. Herein, electrochemical K-ion storage properties of the layered-type K0.4V2O5 (KVO) cathode by incorporating divalent strontium ions (Sr2+) into its crystal structure are enhanced. Divalent strontium ions (1.18 Å) are preferentially incorporated into the octahedrally coordinated K (1.38 Å) layers due to the similar ionic size compared to V4+ (0.58 Å). The introduction of 3 mmol of Sr ions in the KVO crystal improves electrical conductivity and reduces K-ion diffusion energy barriers. In addition, the strong Sr2+ and O2− interaction acts as a structural pillar, suppressing irreversible phase transition during charge–discharge process. Multi-physics simulations clearly confirm that the K0.34Sr0.03V2O5 (KS3VO) cathode exhibits a more uniform K-ion distribution and enhanced reactions of K-ions compared to the KVO cathode at various depths of discharge. As a result, the KS3VO cathode demonstrates improved reversible capacity, cycling stability, and power capability over the KVO cathode in a K-ion cell. Synchrotron X-ray analysis reveals how Sr substitution enhances the electrochemical K-ion storage properties of the KS3VO cathode. In addition, the KS3VO cathode exhibits superior thermal stability and cycling stability in a full cell coupled with a hard carbon anode compared to the KVO cathode.
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| 6. |
- Park, Jimin, et al.
(författare)
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Introduction of a nitrate anion with solubility mediator in a carbonate-based electrolyte for a stable potassium metal anode
- 2024
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Ingår i: Energy Storage Materials. - 2405-8297. ; 69
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Tidskriftsartikel (refereegranskat)abstract
- In this study, sodium nitrate (NaNO3) dissolves in a carbonate electrolyte for K-metal batteries (KMBs) using a dimethylacetamide (DMA) solvent with a higher Gutmann donor number than that of NO3−. The K-metal anode in 0.02 M NaNO3 electrolyte exhibits enhanced stability due to the modified solid-electrolyte interphase (SEI) layer resulting from the preferential reduction of NaNO3. Reduced NaNO3 forms ionically conductive and mechanically robust compounds in the SEI layer. This compound plays a critical role in altering the morphology of electrodeposited K-metal from dendritic to spherical, reducing the barrier energy of nucleation potential for K-ions. These unique features make K-metal highly resistant to dendrite formation and aggressive electrolyte chemistry. Therefore, the K-metal anode in the proposed electrolyte containing 0.02 M NaNO3 additive ensures excellent cycle life with stable Coulombic efficiency in both symmetrical K/K half cells and full-cells coupled with a Prussian green FeFe(CN)6 cathode.
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