Surface‐Confined SnS₂@C@rGO as High‐Performance Anode Materials for Sodium‐ and Potassium‐Ion Batteries

Abstract

Potassium‐ (PIBs) and sodium‐ion batteries (SIBs) are emerging as promising alternatives to lithium‐ion batteries owing to the low cost and abundance of K and Na resources. However, the large radius of K+ and Na+ lead to sluggish kinetics and relatively large volume variations. Herein, a surface‐confined strategy is developed to restrain SnS2 in self‐generated hierarchically porous carbon networks with an in situ reduced graphene oxide (rGO) shell (SnS2@C@rGO). The as‐prepared SnS2@C@rGO electrode delivers high reversible capacity (721.9 mAh g−1 at 0.05 A g−1) and superior rate capability (397.4 mAh g−1 at 2.0 A g−1) as the anode material of SIB. Furthermore, a reversible capacity of 499.4 mAh g−1 (0.05 A g−1) and a cycling stability with 298.1 mAh g−1 after 500 cycles at a current density of 0.5 A g−1 were achieved in PIBs, surpassing most of the reported non‐carbonaceous anode materials. Additionally, the electrochemical reactions between SnS2 and K+ were investigated and elucidated.

Structural Engineering of SnS2Encapsulated in Carbon Nanoboxes for High‐Performance Sodium/Potassium‐Ion Batteries Anodes

“…[26,59] Consistent with the XRD results, during the in situ Raman characterization (Figure 7b), the A 1g vibration mode of SnS 2 (≈313 cm −1 ) gradually decreases (Stage I) due to the phase transition, and the newly emerged peak at ≈214 and ≈451 cm −1 should be attributed to Na 2 S 5 . [27,68] Afterwards, the intensity of Na 2 S 5 peak decreases and a strong peak of Na 2 S at ≈188 cm −1 increases along with the developing sodiation depth (Stage II), which matches well with the above ex situ XRD results. [69] During the charge process, the peaks of Sn become sharp and strong again, indicating the reform of metallic Sn due to the dealloying process of Na-Sn alloy.…”

“…During the initial sweep, the cathodic peak at ≈0.95 V, which disappears in the subsequent sweeps, should be ascribed to the SEI formation, as well as the initial intercalation of K + into SnS 2 . [27] The peak at ≈0.51 V is ascribed to the combination of phase transition (from SnS 2 to K-Sn compounds and Sn) and the alloying of K and Sn. [33] As for the initial anodic sweep, the peaks at 0.98 and 1.44 V are assigned to the dealloying of K-Sn alloy and the depotassiation of K-S compounds.…”

Metal chalcogenides for potassium storage

“…Inspired by the existing pioneering work involving graphite, tremendous efforts have been devoted to this area of research. To date, several categories of materials are verified to be effective for potassium storage in terms of anodes, including carbon nanophases (eg, hard carbon, graphite, and heteroatom‐doped carbon), alloy‐type (semi‐)metals (eg, Sn, Bi, Sb, and P), metal oxides (eg, Nb 2 O 5 , SnO 2 , Fe x O, and Sb 2 MoO 6 )/sulfides (eg, MoS 2 , VS 2 , SnS 2 , and Sb 2 S 3 ) and phosphides (eg, FeP, CoP, Sn 4 P 3 , and GeP 5 ), sylvite compounds (eg, KVPO 4 F, K 2 V 3 O 8 , KTi 2 (PO 4 ) 3 , and K x Mn y O z ), metal‐organic composites (eg, Co 3 [Co(CN) 6 ] 2 and K 1.81 Ni[Fe(CN) 6 ] 0.97 ·0.086H 2 O), and pure organic polymers (eg, boronic ester, fluorinated covalent triazine, perylene‐tetracarboxylate, perylenetetracarboxylic diimide, azobenzene‐4,4′‐dicarboxylic acid potassium, 2,2′‐azobis[2‐methylpropionitrile], and poly[pyrene‐ co ‐benzothiadiazole]). However, most carbon materials barely deliver reversible capacities exceeding 300 mAh g −1 despite their excellent electrochemical cyclability.…”

Silicon Anodes for High‐Performance Storage Devices: Structural Design, Material Compounding, Advances in Electrolytes and Binders

“…However, crystalline silicon exhibits electrochemical inertness in Na/K ion batteries and cannot be alloyed with Na/K ions. This is the opposite of what is expected from an early calculation . Recently, researchers have studied the sodium storage properties of Si using a 3D porous copper frame as a current collector, and reported the sodium ion insertion behavior of amorphous silicon .…”