Microstructural Evolution of Tin Nanoparticles during In Situ Sodium Insertion and Extraction

Abstract

The microstructural changes and phase transformations of tin nanoparticles during electrochemical sodiation were studied with a nanosized sodium ion battery using in situ transmission electron microscopy. It was found that the first sodiation process occurred in two steps; that is, the crystalline Sn nanoparticles were initially sodiated via a two-phase mechanism with a migrating phase boundary to form a Na-poor, amorphous Na(x)Sn alloy (x ~ 0.5), which was further sodiated to several Na-rich amorphous phases and finally to the crystallized Na(15)Sn(4) (x = 3.75) via a single-phase mechanism. The volumetric expansion was about 60% in the first step and 420% after the second step. However, despite the huge expansion, cracking or fracture was not observed, which is attributed to the second step of the single-phase sodiation that accommodates large portion of the sodiation-induced stress over the entire particle. Excellent cyclability was also observed during the reversible sodiation/desodiation cycles, showing great potential of Sn nanoparticles as a robust electrode material for rechargeable batteries.

Tin-phosphate glass anode for sodium ion batteries

“…As shown in Fig. 3, we also obtained some shoulders at 0.14 V, 0.27 V, 0.5 V, and 0.8 V those correspond the presence of Na 9 Sn 4 , NaSn, and NaSn 3 metastable phases proposed by Wang et al 21 Furthermore, the first charge capacity was obtained as 619 mAh/g that corresponds to formation of Na 11 Sn 4 phase as calculated by Eq. (2).…”

Metallic Sn‐Based Anode Materials: Application in High‐Performance Lithium‐Ion and Sodium‐Ion Batteries

“…The SnS NCs exhibited the best rate capability, which had the strongest transformation tendency toward α‐Sn. Wang et al45 used in situ TEM to study the electrochemical sodiation mechanism of Sn nanoparticles in a nanobattery configuration. It was found that pristine Sn could be sodiated in two steps.…”

A Safer Sodium‐Ion Battery Based on Nonflammable Organic Phosphate Electrolyte

“…Similar to their Li counterparts,1 though sodium‐based system has similar electrochemical reaction characteristics compared to lithium‐based one, the larger ionic radius for sodium ion cause sluggish kinetics and volume change during Na storage, leading to lower capacity, poor cycling and rate properties of the Na storage materials. Recently, major efforts have been devoted to promote the electrochemical performance of Na storage materials, for example, Na x MO 2 ,2, 3, 4, 5, 6, 7, 8, 9, 10 polyanionic framework compounds,11, 12, 13, 14, 15, 16, 17, 18, 19 hexacyanoferrate,20, 21, 22, 23, 24, 25, 26, 27 for the cathode materials, and hard carbons,28, 29, 30, 31, 32, 33 alloys,34, 35, 36, 37, 38, 39, 40, 41 oxides,42, 43 sulfides37, 44, 45, 46 for the anode materials.…”