Few‐Layered Tin Sulfide Nanosheets Supported on Reduced Graphene Oxide as a High‐Performance Anode for Potassium‐Ion Batteries

Abstract

Anodes involving conversion and alloying reaction mechanisms are attractive for potassium‐ion batteries (PIBs) due to their high theoretical capacities. However, serious volume change and metal aggregation upon potassiation/depotassiation usually cause poor electrochemical performance. Herein, few‐layered SnS2 nanosheets supported on reduced graphene oxide (SnS2@rGO) are fabricated and investigated as anode material for PIBs, showing high specific capacity (448 mAh g−1 at 0.05 A g−1), high rate capability (247 mAh g−1 at 1 A g−1), and improved cycle performance (73% capacity retention after 300 cycles). In this composite electrode, SnS2 nanosheets undergo sequential conversion (SnS2 to Sn) and alloying (Sn to K4Sn23, KSn) reactions during potassiation/depotassiation, giving rise to a high specific capacity. Meanwhile, the hybrid ultrathin nanosheets enable fast K storage kinetics and excellent structure integrity because of fast electron/ionic transportation, surface capacitive‐dominated charge storage mechanism, and effective accommodation for volume variation. This work demonstrates that K storage performance of alloy and conversion‐based anodes can be remarkably promoted by subtle structure engineering.

Interlayer Expanded SnS2 Anchored on Nitrogen‐Doped Graphene Nanosheets with Enhanced Potassium Storage

“…These phases are matched well with the in‐situ XRD results, shown in Figure a. The phase of potassium polysulfide K 2 S 5 is ascribed to the side reactions between SnS 2 and potassium ions . These observations indicate that the conversion reaction has occurred between SnS 2 and the intercalation of K ions.…”

Metal chalcogenides for potassium storage

“…There are four main approaches to enhance the ionic and electrical conductivity, buffer or accommodate the volume changes, increase the structural integrity and stability, and boost the reaction kinetics of metal chalcogenides (Figure ): limitation of discharge depth, nanostructure engineering, confinement by carbon nanophases, or ternary alloying. The majority of these modification methods described above have already been verified to be effective for potassium‐based energy storage according to the results reported previously . Furthermore, the interface between the anode and electrolyte in PIBs has drawn recent attention and is another non‐negligible factor for stabilizing these energy‐storage systems.…”

“…For metal chalcogenides utilized for PIB anodes, they can be mainly classified into two categories according to their different potassium insertion (potassiation) processes: conversion type and conversion/alloying‐coupling type. The former consists of electrochemically inactive metal atoms (such as Co, Fe, Ni, Mo, and V) and chalcogens, whereas the latter is comprised of active metal atoms with the ability to store potassium through alloying reactions with metals (such as Sn, Sb, and Ge) and chalcogens. In common cases, conversion/alloying‐coupling type metal chalcogenides deliver higher specific capacities but suffer from greater volume expansion than their individual conversion‐type counterparts.…”

“…Illustration of the classification and dominant modification strategies that have been reported for metal chalcogenides‐based PIB anodes. Some of the inset pictures are reproduced with permission from Wiley‐VCH, American Chemical Society, The Royal Society of Chemistry and Elsevier …”

Nature of Bimetallic Oxide Sb2MoO6/rGO Anode for High‐Performance Potassium‐Ion Batteries

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markets of electric vehicles and grid-level energy storage systems, in addition to an uneven distribution of lithium resources as well as the relatively high cost of lithiumion batteries (LIBs). [12][13][14][15][16] Therefore, searching for the high performance KIBs anode (a critical component of KIBs) to alleviate the dramatic volume change is highly demanded to build high performance KIBs.Besides the carbonaceous anodes (graphite, soft carbon, hard carbon, etc.) However, in comparison with the smaller lithium ions (a radius of 0.76 Å), the large-sized potassium ions (a radius of 1.38 Å) could arouse a severe volume change of the electrode material during charge/discharge, seriously weakening the electrode stability and resulting in an unsatisfied battery performance.

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