Guilong Liu,Mingyuan Xu,Ruping Cao,Zihan Zhao,Wenzhuo Yuan,Yong Liu,Ang Cao,Lijuan Wang,Xianming Liu
SnS with high theoretical capacity, large lamellar spacing, and favorable voltage plateau is considered as a highly prospective anode material for sodium-ion batteries (SIBs). Nevertheless, the unsatisfied intrinsic conductivity and damaging volume variation during cycles restricted its specific capacity and potential application. In this work, a synergistic sodium storage of interfacial engineering and Na 2 S adsorption was proposed to boost the electrochemical kinetics of SnS by vertically growing SnS@C nanosheets on MBenes. The experimental and theoretical calculation results verified that the nanosheets, heterogeneous interface, and charge transfer between Mo 4/3 B 2 T x and SnS offered rapid ion diffusion pathways and ameliorated the intrinsic conductivity, promoting the electrochemical kinetics. The sufficient sulfur vacancies and strong adsorption ability of Na 2 S on MBenes provided supplementary active sites for ion adsorption and suppressed the shuttle effect of Na 2 S, improving the electrochemical capacity and reversibility. Consequently, the MBenes-SnS@C anode delivered high capacities of 411 mAh g −1 at 1 A g −1 and 420 mAh g −1 after 100 cycles at 0.5 A g −1 . The synergistic sodium storage mechanism arising from interfacial effects and Na 2 S adsorption offered novel insights for the rational design of high-performance transition metal sulfide anodes for SIBs.
Wenxi Zhao,Xiaodeng Wang,Xiaoqing Ma,Luchao Yue,Qian Liu,Yonglan Luo,Yang Liu,Abdullah M. Asiri,Xuping Sun
Pseudocapacitive electrochemical Na+-storage has been highlighted as one of the exploitable strategies for overcoming the sluggish diffusion-limited redox kinetics due to the effective structural preservation and fast ion-adsorption/desorption at the surface or quasi-surface of electrode materials. However, exploiting pseudocapacitive hosts with a micro–nano hierarchitecture and further achieving competitive pseudocapacitive contributions are still in their infancy so far. Herein, a yolk–shell NiS2/CuS hollow microspherical architecture with superb kinetically pseudocapacitive features was successfully constructed through an in situ hydrothermal sulfidation and subsequent ion-exchange route using Ni-based bimetallic (NiZn) organic frameworks (NiZn-MOFs) as a template precursor. As expected, the strongly synergistic coupling effect and hollow structural characteristic of the NiS2/CuS heterostructure enabled fast charge transfer and Na+ immigration, as well as the release of the mechanical stress/strain induced by the conversion reaction, and not unexpectedly, the NiS2/CuS electrode afforded extraordinary Na+-storage capability, including a remarkable specific capacity of 410.9 mA h g−1 after 750 cycles at 2.0 A g−1, excellent rate capability, and prolonged cyclability in terms of a remarkable 283.4 mA h g−1 even after 4200 cycles at 20.0 A g−1. More significantly, the kinetic analysis demonstrated that the electrochemical charge storage of the NiS2/CuS electrode manifested considerable pseudocapacitive contributions at all rates (90.0% to 96.9%), distinctly outperforming the previously reported NiS2-/CuS-based anodes. Furthermore, the density functional theoretical calculations suggested a fast Na+-transport kinetics and enhanced antibonding state energy level and Na2S adsorption energy due to the electronic redistribution and lattice distortion in the NiS2/CuS heterointerfaces.
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