Sb-Doped metallic 1T-MoS2 nanosheets embedded in N-doped carbon as high-performance anode materials for half/full sodium/potassium-ion batteries.

Metal 1T phase molybdenum disulfide (1T-MoS2) is being actively considered as a promising anode due to its high conductivity, which can improve electron transfer. Herein, we elaborately designed stable Sb-doped metallic 1T phase molybdenum sulfide (1T-MoS2-Sb) with a few-layered nanosheet structure via a simple calcination technique. The N-doping of the carbon and Sb-doping induce the formation of T-phase MoS2, which not only effectively enhances the entire stability of the structure, but also improves its cycling performance and stability. When employed as an anode of sodium-ion batteries (SIBs), 1T-MoS2-Sb exhibits a reversible capacity of 493 mA h g-1 at 0.1 A g-1 after 100 cycles and delivers prominent long-term performance (253 mA h g-1 at 1 A g-1 after 2200 cycles) along with decent rate capability. Paired with a Na3V2(PO4)3 cathode, it displays a superior capacity of 242 mA h g-1 at 0.5 A g-1 over 100 cycles, which is one of the best performances of a MoS2-based full cell for SIBs. Employed as the anode for potassium-ion batteries (PIBs), it exhibits a satisfactory specific capacity of 343 mA h g-1 at 0.1 A g-1 after 100 cycles. This facile strategy will provide new insights for designing T-phase advanced anode materials for SIBs/PIBs.

Dual carbon decorated germanium-carbon composite as a stable anode for sodium/potassium-ion batteries.

In the present work, we introduce a dual carbon accommodated structure in which germanium nanoparticles are encapsulated into an ordered mesoporous carbon matrix (Ge-CMK) and further coated with an amorphous carbon layer (Ge@C-CMK) through a nano-casting route followed by chemical vapor deposition (CVD) treatment. In the resultant Ge@C-CMK composite, the unique lane-like pore structure that cooperates with the amorphous carbon surface can not only mitigate the volume expansion of germanium particles, but also improve the electrical conductivity of germanium as well as facilitate Na+/K+ diffusion. When employed as the anode of sodium-ion batteries, the Ge@C-CMK electrode exhibits stable capacity as well as long-term cycling stability (a stable capacity of 176 mAh g-1 at 1 A g-1 after 5000 cycles). Furthermore, it also delivers a reversible capacity when used as the anode of potassium-ion batteries. This demonstrates that the Ge@C-CMK electrode possesses promising application potential as an alternative anode in sodium and potassium ion storage applications.

Facile fabrication of a vanadium nitride/carbon fiber composite for half/full sodium-ion and potassium-ion batteries with long-term cycling performance.

Vanadium-based composite anodes have been designed for applications in alkali metal ion batteries, including lithium-ion batteries (LIBs), sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). However, the problems of inferior long-term cycling stability caused by the large volume change and dissolution of vanadium-based active materials during cycles and slow diffusion for large radii of Na+ and K+ still limit their underlying capability and need to be addressed. In the present work, we initially designed and fabricated a vanadium nitride/carbon fiber (VN/CNF) composite via a facile electrospinning method followed by the ammonization process. The obtained VN/CNF composite anode exhibited excellent half/full sodium and potassium storage performance. When used as an anode material for SIBs, it delivered a high capacity of 403 mA h g-1 at 0.1 A g-1 after 100 cycles and as large as 237 mA h g-1 at 2 A g-1 even after 4000 cycles with negligible capacity fading. More importantly, the VN/CNFs//Na3V2(PO4)3 full cell by coupling the VN/CNF composite anode with the Na3V2(PO4)3 (NVP) cathode also exhibited a desirable capacity of 257 mA h g-1 at 500 mA g-1 after 50 cycles. Besides, when further evaluated as an anode for PIBs, the VN/CNF composite anode achieved a large capacity of 266 mA h g-1 after 200 cycles at 0.1 A g-1 and maintained a stable capacity of 152 mA h g-1 at 1 A g-1 even after 1000 cycles, showing significant long-term cycling stability. This is one of the best performances of vanadium-based anode materials for SIBs and PIBs reported so far.

Facile Synthesis of Ultra-Small Few-Layer Nanostructured MoSe2 Embedded on N, P Co-Doped Bio-Carbon for High-Performance Half/Full Sodium-Ion and Potassium-Ion Batteries.

Sodium/potassium-ion batteries (SIBs/PIBs) arouse intensive interest on account of the natural abundance of sodium/potassium resources, the competitive cost and appropriate redox potential. Nevertheless, the huge challenge for SIBs/PIBs lies in the scarcity of an anode material with high capacity and stable structure, which are capable of accommodating large-size ions during cycling. Furthermore, using sustainable natural biomass to fabricate electrodes for energy storage applications is a hot topic. Herein, an ultra-small few-layer nanostructured MoSe2 embedded on N, P co-doped bio-carbon is reported, which is synthesized by using chlorella as the adsorbent and precursor. As a consequence, the MoSe2 /NP-C-2 composite represents exceedingly impressive electrochemical performance for both sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). It displays a promising reversible capacity (523 mAh g-1 at 100 mA g-1 after 100 cycles) and impressive long-term cycling performance (192 mAh g-1 at 5 A g-1 even after 1000 cycles) in SIBs, which are some of the best properties of MoSe2 -based anode materials for SIBs to date. To further probe the great potential applications, full SIBs pairing the MoSe2 /NP-C-2 composite anode with a Na3 V2 (PO4 )3 cathode also exhibits a satisfactory capacity of 215 mAh g-1 at 500 mA g-1 after 100 cycles. Moreover, it also delivers a decent reversible capacity of 131 mAh g-1 at 1 A g-1 even after 250 cycles for PIBs.

Electrospun VSe1.5/CNF composite with excellent performance for alkali metal ion batteries.

Exploring advanced anode materials with excellent electrochemical performance for rechargeable batteries, including lithium-ion batteries (LIBs), sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs), has attracted great attention. However, low electronic conductivity, severe particle agglomeration and lack of effective synthesis methods have still greatly hampered their rapid development. Herein, we initially fabricate a novel VSe1.5/CNF composite through a facile electrospinning method followed by selenization. The electrochemical measurements show that VSe1.5/CNFs can enable the rapid and durable storage of Li+, Na+, and K+ ions. When used as an anode material for LIBs, the VSe1.5/CNF composite delivers a high capacity of 932 mA h g-1 after 400 cycles at a high current density of 1 A g-1. In addition, for SIBs, the VSe1.5/CNF composite manifests a high reversible capacity of 668 mA h g-1 after 50 cycles and an excellent capacity of 265 mA h g-1 at 2 A g-1 even after an ultra-long 6000 cycles. This is one of the best performances of vanadium-based anode materials for SIBs reported so far. Most remarkably, the VSe1.5/CNF composite also demonstrates a satisfactory reversible K+ storage performance. The simple synthetic route and excellent ion storage properties make the VSe1.5/CNF composite a great prospect for application as an anode material for alkali metal ion batteries.

Facile synthesis of hierarchical lychee-like Zn3V3O8@C/rGO nanospheres as high-performance anodes for lithium ion batteries.

In the present work, the hierarchical Zn3V3O8@C/rGO composite with a unique lychee-like architecture was fabricated by a simple one-pot ethanol thermal reduction strategy. When used as an anode material, it exhibited outstanding electrochemical performance for lithium-ion batteries (LIBs). For instance, the Zn3V3O8@C/rGO composite delivers high reversible capacities (1012 mAh g-1 at 0.1 A g-1 after 200 cycles) and high rate stability (448 mAh g-1 at 4 A g-1 after 1000 cycles). This outstanding performance can be attributed to the synergistic effect of the diverse structural virtues, effective interface and dual-spatially hybrid carbon network. Significantly, this one-pot simple strategy can be extended to fabricating highly stable and high rate performance of vanadates or other anode materials for LIBs.

Preparation of a Si/SiO2 -Ordered-Mesoporous-Carbon Nanocomposite as an Anode for High-Performance Lithium-Ion and Sodium-Ion Batteries.

In this work, an Si/SiO2 -ordered-mesoporous carbon (Si/SiO2 -OMC) nanocomposite was initially fabricated through a magnesiothermic reduction strategy by using a two-dimensional bicontinuous mesochannel of SiO2 -OMC as a precursor, combined with an NaOH etching process, in which crystal Si/amorphous SiO2 nanoparticles were encapsulated into the OMC matrix. Not only can such unique porous crystal Si/amorphous SiO2 nanoparticles uniformly dispersed in the OMC matrix mitigate the volume change of active materials during the cycling process, but they can also improve electrical conductivity of Si/SiO2 and facilitate the Li+ /Na+ diffusion. When applied as an anode for lithium-ion batteries (LIBs), the Si/SiO2 -OMC composite displayed superior reversible capacity (958 mA h g-1 at 0.2 A g-1 after 100 cycles) and good cycling life (retaining a capacity of 459 mA h g-1 at 2 A g-1 after 1000 cycles). For sodium-ion batteries (SIBs), the composite maintained a high capacity of 423 mA h g-1 after 100 cycles at 0.05 A g-1 and an extremely stable reversible capacity of 190 mA h g-1 was retained even after 500 cycles at 1 A g-1 . This performance is one of the best long-term cycling properties of Si-based SIB anode materials. The Si/SiO2 -OMC composites exhibited great potential as an alternative material for both lithium- and sodium-ion battery anodes.