Search

As post‐lithium ion batteries, both sodium‐ion batteries (SIBs) and potassium ion batteries (PIBs) possess great potential for large scale energy storage. However, the application of both SIBs and PIBs are hindered by the lack of suitable electrode materials. Here, we synthesized the sulfur decorated Ti3C2Tx (S−T3C2Tx) MXene as electrode material for SIBs and PIBs. Thanks to the sulfur functional group and the formation of Ti−S bond, which facilitates the sodium in‐/desertion and strengthens the potassium ion adsorption ability, as well as enhances ion reaction kinetics and improved structure stability, the S−T3C2Tx exhibit excellent sodium/potassium storage performance, high reversible capacities of 151 and 101 mAh g−1 at 0.1 mA g−1 were achieved for SIBs and PIBs, respectively. Moreover, the S−T3C2Tx exhibits remarkable long‐term capacity stability at a high density of 500 mA g−1, providing an impressive storage of 88 mAh g−1 for SIBs and 41 mAh g−1 for PIBs even after 2000 cycles. This work could give a deep comprehension of the heteroatom modification influence on the MXene‐based framework and promote the application of MXene electrodes. [ABSTRACT FROM AUTHOR]

To achieve high‐quality hard carbon nanofibers (HCNFs), and particularly flexible HCNFs films is the eternal pursuit from low‐cost coal pitch (CP). However, it is still trapped seriously by the inborn bottleneck of low‐softening‐point (LSP) characteristics of CP itself. Herein, an efficient Bi(NO3)3·5H2O‐assisted electrospinning‐carbonization methodology is creatively devised to obtain flexible HCNFs films directly from LSP CP. The essential roles of Bi(NO3)3·5H2O and pre‐oxidation in constructing flexible films are rationally proposed. With further regulation in Bi(NO3)3·5H2O dosage and calcination temperatures, specific micro‐structures/morphologies of flexible HCNFs films are finely optimized. The optimum HCNFs‐1.2 film is endowed with robust structural flexibility/stability, high‐content active oxygen/nitrogen groups, abundant graphic microcrystalline zones of large interlayer spacing, and convenient ion‐diffusion channels. Thanks to such remarkable merits, HCNFs‐1.2 retains a large reversible capacity of 125.3 mAh g‒1 over 1000 cycles at 1.0 A g‒1, when evaluated as a self‐supporting film anode for sodium dual‐ion batteries (SDIBs). Furthermore, the HCNFs‐1.2‐based SDIBs deliver a specific capacity of 90.9 mAh g‒1 at 0.1 A g‒1, along with a capacity retention of 78.4% after 1500 cycles at 1.0 A g‒1. The insightful understanding here will provide meaningful guidance for rational design of advanced flexible film electrodes toward next‐generation SDIBs and beyond. [ABSTRACT FROM AUTHOR]

As post-lithium ion batteries, both sodium-ion batteries (SIBs) and potassium ion batteries (PIBs) possess great potential for large scale energy storage. However, the application of both SIBs and PIBs are hindered by the lack of suitable electrode materials. Here, we synthesized the sulfur decorated Ti 3 C 2 T x (S-T 3 C 2 T x ) MXene as electrode material for SIBs and PIBs. Thanks to the sulfur functional group and the formation of Ti-S bond, which facilitates the sodium in-/desertion and strengthens the potassium ion adsorption ability, as well as enhances ion reaction kinetics and improved structure stability, the S-T 3 C 2 T x exhibit excellent sodium/potassium storage performance, high reversible capacities of 151 and 101 mAh g -1 at 0.1 mA g -1 were achieved for SIBs and PIBs, respectively. Moreover, the S-T 3 C 2 T x exhibits remarkable long-term capacity stability at a high density of 500 mA g -1 , providing an impressive storage of 88 mAh g -1 for SIBs and 41 mAh g -1 for PIBs even after 2000 cycles. This work could give a deep comprehension of the heteroatom modification influence on the MXene-based framework and promote the application of MXene electrodes., (© 2023 Wiley-VCH GmbH.)