Caichao Wang,Yan Zhu,Kang Xu,Shuhong Sun,Mingrong Dong,Jinkun Liu,Yongmao Hu
Semiconductors Ag 8 SnS 6 (ATS) nanoparticles were synthesized by a simple one-pot method. Meanwhile, Se was added to the ATS process to form semiconductors Ag 8 SnS 6-x Se x (ATSSe) (x = 0.0, 0.2, 0.4, 0.6, 0.8) nanoparticles. The prepared ATS nanoparticles were mainly triangle in shape with grain sizes ranging from 15 ∼ 60 nm, and ATSSe nanoparticles were formed after the addition of Se during the synthesis process. Phase transformation of the synthesized nanoparticles rhombohedral crystalline ATS to cubic ATSe was observed for Se substitution ratios x in the range of 0.2 ∼ 0.8. The band gap of ATSSe nanoparticles was in the range of 1.16 ∼ 0.85 eV. This finding suggests that Se substitution is an effective method to regulate the band gap and structure of ATS.
Leveraging abundant natural reserves and lower cost profiles, sodium-ion batteries (SIBs) are poised to supersede lithium-ion batteries (LIBs) within the domain of large-scale energy storage systems. Many achievements have been made in improving the properties of anodes in SIBs from the aspects of nanostructure and surface modification. Recently, the incorporation of anionic species into metal sulfides via defect engineering has emerged as an innovative strategy to boost sodium storage capabilities. Herein, a nitrogen-doped carbon-coated two-dimensional metal sulfide with partial selenium substitution (SnS 0.6 Se 1.4 @NC) is constructed and utilized as an anode material for SIBs. The substitution of Se 2- effectively expanded the interlayer distance of SnS 2 , making it more favorable for Na + intercalation/deintercalation. The lattice defects introduced thereby have catalyzed the swift nucleation of conversion-alloying reaction products, acting as effective stabilizers and dispersants. The establishment of heterogeneous interfaces has expedited ion/electron transport, thereby enhancing electrochemical kinetics. Furthermore, the external carbon layer has mitigated the volumetric expansion of the electrode material. This innovative strategy has endowed the anodes with superior cyclic performance (506.6 mA h g −1 at 0.1 A g −1 after 200 cycles) and rate capability (312.4 mA h g −1 at 1 A g −1 after 500 cycles) in SIBs, offering a novel pathway for the design of high-performance metal sulfide anode materials.
Wenmiao Zhao,Lishi Mo,Xiaoyuan Shi,Bo Liu,Guangmin Yang,Ting Deng
CoTe 2 as a potential electrode material for sodium-ion batteries (SIBs) suffers severe volume expansion and rapid capacity degradation. Herein, we propose an anionic chemistry regulation strategy to enhance the redox performance of CoTe 2 by Se substitution which creates more porosity inside the structure to accommodate the volume expansion. Physical characterizations and theoretical calculations have studied the structural and dynamical influence of Se/Te ratio on the overall performance. As a result, CoSe 1.33 Te 0.67 @C with a 〈1 1 1〉 preferential growth direction exhibited the most balanced performance, which delivered a high initial specific capacity of 795 mAh/g at 0.05 A/g, a high rate performance of 5 A/g and a capacity retention of 370 mAh/g after 400 cycles at 0.5 A/g. Accordingly, a full SIB was constructed with a Na 3 V 2 (PO 4 ) 3 cathode and a CoSe 0.67 Te 0.33 @C anode, delivering a maximum energy density of 197.2 Wh kg −1 . These results have proved that anionic chemistry regulation is quite efficient to synthesize metal tellurides with high redox activity and long life-span for SIB .
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