Intrinsic Pinning Property of NaFe2Se2 Superconductor

Sugai, K.; Tatsumi, Rei; Uehara, M.; Kuramoto, T.; Kimishima, Y.

doi:10.1016/j.phpro.2014.09.044

Cited by 2 publications

(1 citation statement)

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“…After careful indexing, these new reflections can be attributed to ThCr 2 Si 2 ‐structured Na y Fe 2 Se 2 with space group of I 4/ mmm . [ 43 ] Also, the reflection of h ‐FeSe at 32.3° disappears completely upon Na + insertion, consistent with the small plateau at 1.14 V. Further Na + insertion induces the flat voltage plateau at 0.75 V, where Na y Fe 2 Se 2 decomposes and converts to Na 2 Se and Fe, as evidenced by the vanish of these reflections and the simultaneous appearance of broad diffraction peaks at 22.5° (Na 2 Se), 37.6° (Na 2 Se), and 44.6° (Fe). During the charging process, the reflections of Na 2 Se and Fe gradually disappear and fully convert into t ‐FeSe, which means the Na + ions stored by discharging process could be fully released to the external and achieve high Coulombic efficiency in the cycle and response for the excellent cycle performance.…”

Section: Resultsmentioning

confidence: 99%

Polymorph Engineering for Boosted Volumetric Na‐Ion and Li‐Ion Storage

et al. 2021

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So far, most research pursue extremely high gravimetric capacity which, however, is not the only important metric for LIBs applications. [4] In areas of consumer electronics, microelectronics, military, aerospace, and even in electric vehicles, LIBs are needed not only to own light weight but compact size. [5,6] Thus, volumetric capacity should have been prioritized over gravimetric one, yet this crucial metric is often neglected. [7] Pitifully, the same situation also applies to the newly built sodium-ion batteries (SIBs), which is at the early stage of their development. [8] As for their potential application in the smart grid, the battery size is also decisive when being stored in the outdoors. [9] In comparison with the cathode, anode volumetric capacity is of particular importance because cathode materials usually offer much higher volumetric capacity than the state-of-the-art anode materials. [10] Till now, the strategies used to enhance volumetric capacity mainly focus on the material-level design, like the synthesis of Si@graphitic carbon nanowire array [7] or thick CNT-Si film, [11] which increased the tap density of electrode and thus improved the volumetric capacity up to 1500 mAh cm -3 . Another method is to composite the low-volumetric-capacity material with the ones owning high volume density. Taking advantage of high-volume density of SnO 2 (6.5 g cm -3 ), several nanocomposites were reported to deliver an enhanced volumetric capacity, like hollow structured SnO 2 @ Si nanospheres [12] and Si@SnO 2 core-shell particles. [13] Besides the materials level, the electrode-level performance is also crucial for volumetric capacity. [14] As we all know, a working electrode generally consists of active material and a certain amount of electrochemical inactive components, such as binder and conducting additive (hereafter denoted as CA), which usually account for ca. 20-30% of the total electrode mass (Table S1, Supporting Information). Although much effort has been attempted to increase the energy density via electrode components optimization, like the binder-free electrode, [15] the CA (Super P in most cases) seem to be indispensable since the electronic conductivity of most electrode candidates is inherently low. [16] Even worse, in most anodes, additional carbonaceous framework is highly needed for better rate capability and long-term stability. [17] It has been demonstrated that, interestingly, Li 4 Ti 5 O 12 electrode works well after removing To meet the ever-growing demand for advanced rechargeable batteries with light weight and compact size, much effort has been devoted to improving the volumetric capacity of electrodes. Herein, an effective strategy of polymorph engineering is proposed to boost the volumetric capacity of FeSe. Owing to the inherent metallic electronic conductivity of tetragonal-FeSe, a conductive additive-free electrode (hereafter denoted as CA-free) can be assembled with an enhanced sodium storage volumetric capacity of 1011 mAh cm −3 , significantly higher than semiconducting hex...

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Section: Resultsmentioning

confidence: 99%