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- Menon, Ashok S., et al.
(författare)
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Influence of Synthesis Routes on the Crystallography, Morphology, and Electrochemistry of Li2MnO3
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 12:5, s. 5939-5950
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Tidskriftsartikel (refereegranskat)abstract
- With the potential of delivering reversible capacities of up to 300 mAh/g, Li-rich transition-metal oxides hold great promise as cathode materials for future Li-ion batteries. However, a cohesive synthesis-structure-electrochemistry relationship is still lacking for these materials, which impedes progress in the field. This work investigates how and why different synthesis routes, specifically solid-state and modified Pechini sol-gel methods, affect the properties of Li2MnO3, a compositionally simple member of this material system. Through a comprehensive investigation of the synthesis mechanism along with crystallographic, morphological, and electrochemical characterization, the effects of different synthesis routes were found to predominantly influence the degree of stacking faults and particle morphology. That is, the modified Pechini method produced isotropic spherical particles with approximately 57% faulting and the solid-state samples possessed heterogeneous morphology with approximately 43% faulting probability. Inevitably, these differences lead to variations in electrochemical performance. This study accentuates the importance of understanding how synthesis affects the electrochemistry of these materials, which is critical considering the crystallographic and electrochemical complexities of the class of materials more generally. The methodology employed here is extendable to studying synthesis-property relationships of other compositionally complex Li-rich layered oxide systems.
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| 2. |
- Ojwang, Dickson O., et al.
(författare)
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Influence of sodium content on the thermal behavior of low vacancy Prussian white cathode material
- 2020
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Ingår i: Dalton Transactions. - : ROYAL SOC CHEMISTRY. - 1477-9226 .- 1477-9234. ; 49:11, s. 3570-3579
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Tidskriftsartikel (refereegranskat)abstract
- Rechargeable sodium-ion batteries are the most attractive substitutes for lithium-ion batteries in large-scale energy storage devices due to wide spread reserves and low-cost of sodium resources and the similarities between sodium and lithium chemistry. However, finding a suitable cathode material is still a hurdle to be overcome. To date, Prussian white (PW), NaxFe[Fe(CN)(6)](y)center dot nH(2)O has stood out as one of the most promising Na-host materials due to its low cost, facile synthesis and competitive electrochemical capacity. Despite this, there are concerns that this material will thermally decompose at relatively low temperatures to form cyanogen gas, which is a safety hazard. Thus, low vacancy NaxFe[Fe(CN)(6)](y)center dot nH(2)O (x = 1.5, 1, 0.5 and 0) has been synthesized, and the influence of x on its thermal behavior systematically investigated. It is demonstrated that the thermal decomposition temperature, water content and moisture sensitivity of the samples strongly depend on the sodium content. The sample with x = 1.5 is found to be the most thermally stable and has the highest water content under the same experimental conditions. In addition, the sodium-rich samples (x = 1.5, 1 and 0.5) have higher surface water than the sodium-deficient one (x = 0). The local structure for this sample is also very different to the sodium-rich ones. Our findings offer new insights into the profound implications of proper material handling and safer operating conditions for practical Na-ion batteries and may be extended to analogous systems.
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