An Integrated Free‐Standing Flexible Electrode with Holey‐Structured 2D Bimetallic Phosphide Nanosheets for Sodium‐Ion Batteries

Abstract

An integrated, free-standing, and binder-free type of flexible anode electrode is fabricated from numerous holey-structured, 2D nickel-based phosphide nanosheets connected with carbon nanotubes. This electrode architecture can not only uniformly disperse the nanosheets throughout the whole electrode to avoid aggregation or detachment, but also provide an ideal sodium ion and electrolyte diffusion and penetration network with high electronic conductivity. Meanwhile, bimetallic phosphide formation by introducing secondary metal species will lead to a synergistic effect to modify the electrochemical properties. Due to the excellent compositional and structural characteristics of this electrode, it delivers superior performance. This designed flexible anode with Ni 1.5 Co 0.5 P x nanosheets demonstrates a reversible capacity of 496.4 mAh g −1 at 0.5 C and a good rate capacity of 276.1 mAh g −1 at 8 C. Meanwhile, this connected integrated network woven from carbon nanotubes can effectively restrain volumetric expansion and shrinkage, and affect the conversion reaction products formation as well, from large-sized microspheres to film structure, which is primarily credited with the improvement in electrochemical performance. This work may open up a new path for the synthesis of morphology-controlled phosphides and promote the further development of flexible devices.

Two Birds with One Stone: Metal–Organic Framework Derived Micro‐/Nanostructured Ni2P/Ni Hybrids Embedded in Porous Carbon for Electrocatalysis and Energy Storage

“…The peaks at 853.3 and 870.6 eV correspond to the Ni 2p 3/2 and Ni 2p 1/2 of Ni‐P, and the peaks at 857.3 and 875.2 eV relate to the Ni 2p 3/2 and Ni 2p 1/2 of NiO. Moreover, another two satellite peaks located at 861.9 and 880.7 eV can be observed due to the shakeup excitation of the high‐spin Ni 2+ . The high‐resolution spectrum of P 2p reveals the existence of P 2p 3/2 at 129.9 eV and P 2p 1/2 at 130.7 eV, which is consistent with the chemical bond between P and Ni.…”

Metallic‐State SnS2 Nanosheets with Expanded Lattice Spacing for High‐Performance Sodium‐Ion Batteries

“…[14,16,[18][19][20] However,t hese methods cannota ddress the electronic conductivity issues of SnS 2 semiconductors from am aterialp erspective.R ecently,t he approach of dopingm etal ions hasp rovenv ery fruitful and effective for improving the electrochemical performance by increasing the electronic conductivity and ion mobility.F or example, Se and Fe (or Co and Ni)c o-doped NbS 2 nanosheets showed significantly improved Li + /Na + storage properties compared with those of pure NbS 2 . [23][24][25][26][27] [22] However,t here are few studies devotedt oi nvestigating the role of the positiono fd oped metal ions in the lattice of ah ost materiala nd the related properties with respectt oc harged ensity redistribution, electron state density,a nd energy band structure.…”

“…The architecture resulted in several inherenta dvantages such as shorter paths for ion insertion and extraction, larger contact area for more sodium diffusion pathways and superior electrolyte penetration. [23][24][25][26][27]…”

Fe‐Doped CoP Flower‐Like Microstructure on Carbon Membrane as Integrated Electrode with Enhanced Sodium Ion Storage

“…The energy densities of reported cathode materials for sodium ion batteries are comparable to those of lithium ion batteries (180 mA hg À1 ). [11][12][13] However, carbon as ac ommercial anode materiali nl ithiumi on batteries is not suitable for sodium ion batteries. Novel anode materials such as metal oxides, [14] sulfides, [15] and phosphides, [16] with their high theoretical capacities, have become the research focus in the development of anodem aterialsf or sodium ion batteries.…”