Search

Summary: Ferrous sulfides have high theoretical capacity in the electrochemical storage of Na‐ion and K‐ion, but its obvious volume change during the storage process greatly affects its cycling performance at high current density. In this regard, we construct a unique composites structure of Nitrogen‐doped carbon shell coated FeS nanoparticle with inner void spaces. As an anode in Na‐ion and K‐ion batteries, this structure could provide excellent cycling performance at high rate of charge/discharge process (560 mAh/g at 0.5 A/g for 300 cycles in Na‐ion battery and 322 mAh/g at 1 A/g for 300 cycles in K‐ion battery). Further research finds the inner void space could not only provide buffer space for the volume change of FeS nanoparticles, but also maintain a stable outer carbon shell during the electrochemical process. These behaviors greatly promote the reversibility of FeS at high rate charge transfer process. Consequently, the construction of inner void space in graphitized carbon shell in this work could be considered as an important reference for the promotion of electrochemical storage in other transitional metal compound system. [ABSTRACT FROM AUTHOR]

Summary: Ferrous sulfides have high theoretical capacity in the electrochemical storage of Na‐ion and K‐ion, but its obvious volume change during the storage process greatly affects its cycling performance at high current density. In this regard, we construct a unique composites structure of Nitrogen‐doped carbon shell coated FeS nanoparticle with inner void spaces. As an anode in Na‐ion and K‐ion batteries, this structure could provide excellent cycling performance at high rate of charge/discharge process (560 mAh/g at 0.5 A/g for 300 cycles in Na‐ion battery and 322 mAh/g at 1 A/g for 300 cycles in K‐ion battery). Further research finds the inner void space could not only provide buffer space for the volume change of FeS nanoparticles, but also maintain a stable outer carbon shell during the electrochemical process. These behaviors greatly promote the reversibility of FeS at high rate charge transfer process. Consequently, the construction of inner void space in graphitized carbon shell in this work could be considered as an important reference for the promotion of electrochemical storage in other transitional metal compound system. [ABSTRACT FROM AUTHOR]

Constructing polycrystalline structure is an effective strategy to improve the electrochemical performance of electrode materials. To enhance the electroactivity of anisotropic VO 2 (M), polycrystalline VO 2 (M) with well-dispersed crystalline zones is successfully synthesized by a facile one-step hydrothermal method, and then their electrochemical performances as an anode of lithium-ion batteries are systematically explored. Results show that the synergistic effect of crystalline zones and amorphous matrices in polycrystalline structure can dramatically activate the anisotropic VO 2 (M) electrode, which contributes to increasing the electroactive zones and facilitating the charge transfer kinetics. Compared with single-crystal VO 2 (M), polycrystalline VO 2 (M) shows the significantly enhanced electrochemical performance, delivering a high reversible capacity of 476 mAhg−1 at 100 mAg−1 after 150 cycles, which is far superior to the theoretical capacity and the reported mixture of VO 2 (M) and VO 2 (B). This work opens up new insights for the activation of anisotropic electrode materials. • Polycrystalline VO 2 (M) with well-dispersed crystalline zones is synthesized. • Synergistic effect of crystalline zones and amorphous matrices is revealed. • The activity of anisotropic VO 2 (M) electrode is dramatically improved. • Polycrystalline VO 2 (M) shows capacity of 476 mAhg−1 at 100 mAg−1 after 150 cycles. [ABSTRACT FROM AUTHOR]

Owing to the high theoretical capacity, Sb 2 Se 3 has been regarded as one of the best choices for Sodium-ion batteries (SIBs) anode materials. However, Sb 2 Se 3 anode suffers from huge volume change with poor electrode structure stability, resulting in limited cycling and rate performance. Herein, inspired by the formation of inclusion complex an effective strategy for improving unstable molecules in biological fields, we encapsulate Sb 2 Se 3 in capsular carbon shell via a hydrothermal and calcinations process. Furthermore, by adjusting the thickness of the capsule carbon shell, an ultra-stable Sb 2 Se 3 electrode structure is realized. Equipped with this ultra-stable electrode structure, Sb 2 Se 3 anode exhibits high capacity of 475 mA h g−1 at 2 A g−1 even after 600 cycles, showing compelling advantage on Na storage performance compared to other reported Sb-based anode materials. The analysis results indicate that the intact capsular carbon shell can effectively remit huge volume change of Sb 2 Se 3 , and act like a reaction vessel in which the sodiation/desodiation reaction of Sb 2 Se 3 is carried out regularly. Therefore, this ultra-stable electrode provides stable redox reactions, easy charge transfer and fast sodium ion diffusion, resulting in excellent Na storage performance of Sb 2 Se 3 anode. Encapsulating Sb 2 Se 3 in capsular carbon shell to from inclusion complex can achieve ultra-stable electrode structure with excellent Na storage performance. Image 1 • An ultra-stable Sb 2 Se 3 anode is realized by encapsulating Sb 2 Se 3 in a capsular carbon shell. • The as-prepared ultra-stable Sb 2 Se 3 anode exhibits high capacity of 475 mA h g−1 at 2 A g−1 after 600 cycles. • Forming inclusion complex is an effective strategy to achieve ultra-stable structure with good Na storage performance. [ABSTRACT FROM AUTHOR]