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SEM images of (a) Co-Pre, (b) Co-Pre@SiO2, (c) Co-Pre@SiO2@PDA, (f) YS–CoO@NC. TEM images (d and e) and element maps (g–j) of Co-Pre@SiO2@PDA
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Owing to the natural abundance and low-cost of sodium, sodium-ion batteries offer advantages for next-generation portable electronic devices and smart grids. However, the development of anode materials with long cycle life and high reversible capacity is still a great challenge. Herein, we report a yolk-shell structure composed of N,P co-doped carb...
Citations
... A core−shell structure composed of N, P codoped carbon as the shell and CoP nanowires as the yolk (YS-CoP@NPC) was constructed. 155 It possesses enough space to buffer the volume change during the cycle. Ex situ XPS results showed that YS-CoP@NPC possessed a stable solid electrolyte interface film (relatively higher ClO 4− , lower Na 2 CO 3 and Na 2 O than original CoP), high electronic conductivity, and excellent Na + diffusion kinetics, thus delivering a high specific capacity of 211.5 mAh g −1 after 1000 cycles at 2 A g −1 . ...
Rechargeable sodium-ion batteries (SIBs) have been considered as promising energy storage devices owing to the similar "rocking chair" working mechanism as lithium-ion batteries and abundant and low-cost sodium resource. However, the large ionic radius of the Na-ion (1.07 Å) brings a key scientific challenge, restricting the development of electrode materials for SIBs, and the infeasibility of graphite and silicon in reversible Na-ion storage further promotes the investigation of advanced anode materials. Currently, the key issues facing anode materials include sluggish electrochemical kinetics and a large volume expansion. Despite these challenges, substantial conceptual and experimental progress has been made in the past. Herein, we present a brief review of the recent development of intercalation, conversion, alloying, conversion-alloying, and organic anode materials for SIBs. Starting from the historical research progress of anode electrodes, the detailed Na-ion storage mechanism is analyzed. Various optimization strategies to improve the electrochemical properties of anodes are summarized, including phase state adjustment, defect introduction, molecular engineering, nanostructure design, composite construction, heterostructure synthesis, and heteroatom doping. Furthermore, the associated merits and drawbacks of each class of material are outlined, and the challenges and possible future directions for high-performance anode materials are discussed.
Transition metal phosphides hold great potential as sodium-ion batteries anode materials owing to their high theoretical capacity and modest plateau. However, volume changes and low intrinsic conductivity seriously largely hinder the further development of metal phosphide anodes. The design of phosphide anode materials with reasonable structure is conducive to solving the problems of volume expansion and slow reaction kinetics during the reaction. In this work, a composite material integrating zeolite imidazolate backbone (ZIF) and carbon materials was synthesized by the original growth method. Furthermore, by the oxidation-phosphating process, CoP nanoarray composites riveted to carbon fiber (CoP@CF) were obtained. In the CoP@CF, CoP nanoparticles are uniformly distributed on ZIF-derived carbon, reducing agglomeration and volume change during cycling. CF also provides a highly conductive network for the active material, improving the electrode kinetics. Therefore, when evaluated as an anode for sodium-ion batteries, CoP@CF electrode displays enhanced reversible capacity (262 mAh·g−1 at 0.1 A·g−1 after 100 cycles), which is much better than that of pure CF electrode (57 mAh·g−1 at 0.1 A·g−1 after 100 cycles) prepared without the addition of CoP. The rate performance of CoP@CF electrode is also superior to that of pure CF electrode at various current densities from 0.05 to 1 A·g−1. The sodium storage behavior of CoP@CF was revealed by ex-situ X-ray photoelectron spectroscopy, X-ray diffraction, and synchrotron radiation absorption spectroscopy. This method provides a reference for the design and synthesis of anode materials in sodium-ion batteries.
