Efficient sulfur atom-doped three-dimensional porous MXene-assisted sodium ion batteries.

Recently, it has been reported that MXene is a promising pseudocapacitive material for energy storage, primarily due to its intercalation mechanism. However, Ti3C2Tx MXenes face challenges, such as inadequate layer spacing and low specific capacity, which greatly hinder their potential as anode materials for sodium storage. In this study, MXene was doped with sulfur to create a three-dimensional porous structure that resulted in an increased layer spacing. The sulfur-doped porous MXene (SPM) demonstrated exceptional performance as sodium ion battery anodes, with a capacity of 335.2 mA h g-1 after 490 cycles at 2 A g-1 and a long-term cycling performance of 256.1 mA h g-1 even after 2480 cycles at 5 A g-1. It is worth noting that the porous structure formed after sulfur-doping exhibits superior sodium storage performance compared to previously reported MXene-based electrodes. This highlights the feasibility of the structural construction strategy, offering an effective solution for energy storage and conversion applications.

N-Doped Porous Carbon-Nanofiber-Supported Fe3C/Fe2O3 Nanoparticles as Anode for High-Performance Supercapacitors.

Exploring anode materials with an excellent electrochemical performance is of great significance for supercapacitor applications. In this work, a N-doped-carbon-nanofiber (NCNF)-supported Fe3C/Fe2O3 nanoparticle (NCFCO) composite was synthesized via the facile carbonizing and subsequent annealing of electrospinning nanofibers containing an Fe source. In the hybrid structure, the porous carbon nanofibers used as a substrate could provide fast electron and ion transport for the Faradic reactions of Fe3C/Fe2O3 during charge-discharge cycling. The as-obtained NCFCO yields a high specific capacitance of 590.1 F g-1 at 2 A g-1, superior to that of NCNF-supported Fe3C nanoparticles (NCFC, 261.7 F g-1), and NCNFs/Fe2O3 (NCFO, 398.3 F g-1). The asymmetric supercapacitor, which was assembled using the NCFCO anode and activated carbon cathode, delivered a large energy density of 14.2 Wh kg-1 at 800 W kg-1. Additionally, it demonstrated an impressive capacitance retention of 96.7%, even after 10,000 cycles. The superior electrochemical performance can be ascribed to the synergistic contributions of NCNF and Fe3C/Fe2O3.