Enhanced Potassium Storage Capability of Two-Dimensional Transition-Metal Chalcogenides Enabled by a Collective Strategy

Abstract

Potassium-ion batteries (PIBs) have been considered as a promising alternative to lithium-ion batteries due to their merits of high safety and low cost. Two-dimensional transition-metal chalcogenides (2D TMCs) with high theoretical specific capacities and unique layered structures have been proven to be amenable materials for PIB anodes. However, some intrinsic properties including severe stacking and unsatisfactory conductivity restrict their electrochemical performance, especially rate capability. Herein, we prepared a heterostructure of high-crystallized ultrathin MoSe2 nanosheet-coated multiwall carbon nanotubes and investigated its electrochemical properties with a view to demonstrating the enhancement of a collective strategy for K storage of 2D TMCs. In such a heterostructure, the constructive contribution of CNTs not only suppresses the restacking of MoSe2 nanosheets but also accelerates electron transport. Meanwhile, the MoSe2 nanosheets loaded on CNTs exhibit an ultrathin feature, which can expose abundant active sites for the electrochemical reaction and shorten K+ diffusion length. Therefore, the synergistic effect between ultrathin MoSe2 and CNTs endows the resulting nanocomposite with superior structural and electrochemical properties. Additionally, the high crystallinity of the MoSe2 nanosheets further leads to the improvement of electrochemical performance. The composite electrode delivers high-rate capacities of 209.7 and 186.1 mAh g–1 at high current densities of 5.0 and 10.0 A g–1, respectively.

Carbon-Free Crystal-like Fe1–xS as an Anode for Potassium-Ion Batteries

“…To date, a variety of materials, such as carbon materials, alloying materials, and organic materials, have been explored as PIB anodes. Among them, metal chalcogenides (MCs) owing to their high theoretical capacities and robust structures have received significant interest. − As a member of the MCs’ family, iron sulfides possess numerous prominent merits including relatively high-voltage plateaus, environmental benignity, and low toxicity . Besides, it is worth mentioning that iron sulfides have unparalleled competitiveness in cost.…”

Nanostructured metal selenides as anodes for potassium-ion batteries

“…This means that K c Se d produced by CMSs and K z Se w produced by CAMSs may be composite forms of various potassium selenides. 12 This process is considered as a reason for the large capacity loss of CAMSs during the initial cycle. Meanwhile, electrode materials suffer severe volume expansion during the breaking and forming of chemical bonds.…”

“…1a). 12–16 And traditional LIBs graphite anodes have reached the capacity limit (387 W h kg −1 ), therefore, LIBs are increasingly unable to meet the growing demand for energy storage in electric vehicles and large-scale power grids. 17 To this end, it is urgent to develop novel rechargeable battery technology as complements or alternatives to LIBs.…”

Emerging carbon-based flexible anodes for potassium-ion batteries: Progress and opportunities

“…So far, researchers have tried to solve these inherent problems of metal and chalcogenide nanoparticle anodes ( Wu et al, 2021a ; Zheng et al, 2020 ). By combining the high specific capacity of metal and chalcogenides with the stable structure of various carbonaceous materials, the carbon-based composite anode can simultaneously alleviate the volume expansion and increase the K + storage capacity to a large extent ( Wu et al, 2021b ).…”